diff options
59 files changed, 2815 insertions, 331 deletions
diff --git a/Documentation/x86/orc-unwinder.txt b/Documentation/x86/orc-unwinder.txt new file mode 100644 index 000000000000..af0c9a4c65a6 --- /dev/null +++ b/Documentation/x86/orc-unwinder.txt @@ -0,0 +1,179 @@ +ORC unwinder +============ + +Overview +-------- + +The kernel CONFIG_ORC_UNWINDER option enables the ORC unwinder, which is +similar in concept to a DWARF unwinder. The difference is that the +format of the ORC data is much simpler than DWARF, which in turn allows +the ORC unwinder to be much simpler and faster. + +The ORC data consists of unwind tables which are generated by objtool. +They contain out-of-band data which is used by the in-kernel ORC +unwinder. Objtool generates the ORC data by first doing compile-time +stack metadata validation (CONFIG_STACK_VALIDATION). After analyzing +all the code paths of a .o file, it determines information about the +stack state at each instruction address in the file and outputs that +information to the .orc_unwind and .orc_unwind_ip sections. + +The per-object ORC sections are combined at link time and are sorted and +post-processed at boot time. The unwinder uses the resulting data to +correlate instruction addresses with their stack states at run time. + + +ORC vs frame pointers +--------------------- + +With frame pointers enabled, GCC adds instrumentation code to every +function in the kernel. The kernel's .text size increases by about +3.2%, resulting in a broad kernel-wide slowdown. Measurements by Mel +Gorman [1] have shown a slowdown of 5-10% for some workloads. + +In contrast, the ORC unwinder has no effect on text size or runtime +performance, because the debuginfo is out of band. So if you disable +frame pointers and enable the ORC unwinder, you get a nice performance +improvement across the board, and still have reliable stack traces. + +Ingo Molnar says: + + "Note that it's not just a performance improvement, but also an + instruction cache locality improvement: 3.2% .text savings almost + directly transform into a similarly sized reduction in cache + footprint. That can transform to even higher speedups for workloads + whose cache locality is borderline." + +Another benefit of ORC compared to frame pointers is that it can +reliably unwind across interrupts and exceptions. Frame pointer based +unwinds can sometimes skip the caller of the interrupted function, if it +was a leaf function or if the interrupt hit before the frame pointer was +saved. + +The main disadvantage of the ORC unwinder compared to frame pointers is +that it needs more memory to store the ORC unwind tables: roughly 2-4MB +depending on the kernel config. + + +ORC vs DWARF +------------ + +ORC debuginfo's advantage over DWARF itself is that it's much simpler. +It gets rid of the complex DWARF CFI state machine and also gets rid of +the tracking of unnecessary registers. This allows the unwinder to be +much simpler, meaning fewer bugs, which is especially important for +mission critical oops code. + +The simpler debuginfo format also enables the unwinder to be much faster +than DWARF, which is important for perf and lockdep. In a basic +performance test by Jiri Slaby [2], the ORC unwinder was about 20x +faster than an out-of-tree DWARF unwinder. (Note: That measurement was +taken before some performance tweaks were added, which doubled +performance, so the speedup over DWARF may be closer to 40x.) + +The ORC data format does have a few downsides compared to DWARF. ORC +unwind tables take up ~50% more RAM (+1.3MB on an x86 defconfig kernel) +than DWARF-based eh_frame tables. + +Another potential downside is that, as GCC evolves, it's conceivable +that the ORC data may end up being *too* simple to describe the state of +the stack for certain optimizations. But IMO this is unlikely because +GCC saves the frame pointer for any unusual stack adjustments it does, +so I suspect we'll really only ever need to keep track of the stack +pointer and the frame pointer between call frames. But even if we do +end up having to track all the registers DWARF tracks, at least we will +still be able to control the format, e.g. no complex state machines. + + +ORC unwind table generation +--------------------------- + +The ORC data is generated by objtool. With the existing compile-time +stack metadata validation feature, objtool already follows all code +paths, and so it already has all the information it needs to be able to +generate ORC data from scratch. So it's an easy step to go from stack +validation to ORC data generation. + +It should be possible to instead generate the ORC data with a simple +tool which converts DWARF to ORC data. However, such a solution would +be incomplete due to the kernel's extensive use of asm, inline asm, and +special sections like exception tables. + +That could be rectified by manually annotating those special code paths +using GNU assembler .cfi annotations in .S files, and homegrown +annotations for inline asm in .c files. But asm annotations were tried +in the past and were found to be unmaintainable. They were often +incorrect/incomplete and made the code harder to read and keep updated. +And based on looking at glibc code, annotating inline asm in .c files +might be even worse. + +Objtool still needs a few annotations, but only in code which does +unusual things to the stack like entry code. And even then, far fewer +annotations are needed than what DWARF would need, so they're much more +maintainable than DWARF CFI annotations. + +So the advantages of using objtool to generate ORC data are that it +gives more accurate debuginfo, with very few annotations. It also +insulates the kernel from toolchain bugs which can be very painful to +deal with in the kernel since we often have to workaround issues in +older versions of the toolchain for years. + +The downside is that the unwinder now becomes dependent on objtool's +ability to reverse engineer GCC code flow. If GCC optimizations become +too complicated for objtool to follow, the ORC data generation might +stop working or become incomplete. (It's worth noting that livepatch +already has such a dependency on objtool's ability to follow GCC code +flow.) + +If newer versions of GCC come up with some optimizations which break +objtool, we may need to revisit the current implementation. Some +possible solutions would be asking GCC to make the optimizations more +palatable, or having objtool use DWARF as an additional input, or +creating a GCC plugin to assist objtool with its analysis. But for now, +objtool follows GCC code quite well. + + +Unwinder implementation details +------------------------------- + +Objtool generates the ORC data by integrating with the compile-time +stack metadata validation feature, which is described in detail in +tools/objtool/Documentation/stack-validation.txt. After analyzing all +the code paths of a .o file, it creates an array of orc_entry structs, +and a parallel array of instruction addresses associated with those +structs, and writes them to the .orc_unwind and .orc_unwind_ip sections +respectively. + +The ORC data is split into the two arrays for performance reasons, to +make the searchable part of the data (.orc_unwind_ip) more compact. The +arrays are sorted in parallel at boot time. + +Performance is further improved by the use of a fast lookup table which +is created at runtime. The fast lookup table associates a given address +with a range of indices for the .orc_unwind table, so that only a small +subset of the table needs to be searched. + + +Etymology +--------- + +Orcs, fearsome creatures of medieval folklore, are the Dwarves' natural +enemies. Similarly, the ORC unwinder was created in opposition to the +complexity and slowness of DWARF. + +"Although Orcs rarely consider multiple solutions to a problem, they do +excel at getting things done because they are creatures of action, not +thought." [3] Similarly, unlike the esoteric DWARF unwinder, the +veracious ORC unwinder wastes no time or siloconic effort decoding +variable-length zero-extended unsigned-integer byte-coded +state-machine-based debug information entries. + +Similar to how Orcs frequently unravel the well-intentioned plans of +their adversaries, the ORC unwinder frequently unravels stacks with +brutal, unyielding efficiency. + +ORC stands for Oops Rewind Capability. + + +[1] https://lkml.kernel.org/r/20170602104048.jkkzssljsompjdwy@suse.de +[2] https://lkml.kernel.org/r/d2ca5435-6386-29b8-db87-7f227c2b713a@suse.cz +[3] http://dustin.wikidot.com/half-orcs-and-orcs diff --git a/arch/um/include/asm/unwind.h b/arch/um/include/asm/unwind.h new file mode 100644 index 000000000000..7ffa5437b761 --- /dev/null +++ b/arch/um/include/asm/unwind.h @@ -0,0 +1,8 @@ +#ifndef _ASM_UML_UNWIND_H +#define _ASM_UML_UNWIND_H + +static inline void +unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, + void *orc, size_t orc_size) {} + +#endif /* _ASM_UML_UNWIND_H */ diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 781521b7cf9e..9b302121584d 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -73,7 +73,6 @@ config X86 select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH - select ARCH_WANT_FRAME_POINTERS select ARCH_WANTS_DYNAMIC_TASK_STRUCT select ARCH_WANTS_THP_SWAP if X86_64 select BUILDTIME_EXTABLE_SORT @@ -157,6 +156,7 @@ config X86 select HAVE_MEMBLOCK select HAVE_MEMBLOCK_NODE_MAP select HAVE_MIXED_BREAKPOINTS_REGS + select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI select HAVE_OPROFILE select HAVE_OPTPROBES @@ -167,7 +167,7 @@ config X86 select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_REGS_AND_STACK_ACCESS_API - select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER && STACK_VALIDATION + select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER_UNWINDER && STACK_VALIDATION select HAVE_STACK_VALIDATION if X86_64 select HAVE_SYSCALL_TRACEPOINTS select HAVE_UNSTABLE_SCHED_CLOCK diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index cd20ca0b4043..71a48a30fc84 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -305,8 +305,6 @@ config DEBUG_ENTRY Some of these sanity checks may slow down kernel entries and exits or otherwise impact performance. - This is currently used to help test NMI code. - If unsure, say N. config DEBUG_NMI_SELFTEST @@ -358,4 +356,61 @@ config PUNIT_ATOM_DEBUG The current power state can be read from /sys/kernel/debug/punit_atom/dev_power_state +choice + prompt "Choose kernel unwinder" + default FRAME_POINTER_UNWINDER + ---help--- + This determines which method will be used for unwinding kernel stack + traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack, + livepatch, lockdep, and more. + +config FRAME_POINTER_UNWINDER + bool "Frame pointer unwinder" + select FRAME_POINTER + ---help--- + This option enables the frame pointer unwinder for unwinding kernel + stack traces. + + The unwinder itself is fast and it uses less RAM than the ORC + unwinder, but the kernel text size will grow by ~3% and the kernel's + overall performance will degrade by roughly 5-10%. + + This option is recommended if you want to use the livepatch + consistency model, as this is currently the only way to get a + reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE). + +config ORC_UNWINDER + bool "ORC unwinder" + depends on X86_64 + select STACK_VALIDATION + ---help--- + This option enables the ORC (Oops Rewind Capability) unwinder for + unwinding kernel stack traces. It uses a custom data format which is + a simplified version of the DWARF Call Frame Information standard. + + This unwinder is more accurate across interrupt entry frames than the + frame pointer unwinder. It also enables a 5-10% performance + improvement across the entire kernel compared to frame pointers. + + Enabling this option will increase the kernel's runtime memory usage + by roughly 2-4MB, depending on your kernel config. + +config GUESS_UNWINDER + bool "Guess unwinder" + depends on EXPERT + ---help--- + This option enables the "guess" unwinder for unwinding kernel stack + traces. It scans the stack and reports every kernel text address it + finds. Some of the addresses it reports may be incorrect. + + While this option often produces false positives, it can still be + useful in many cases. Unlike the other unwinders, it has no runtime + overhead. + +endchoice + +config FRAME_POINTER + depends on !ORC_UNWINDER && !GUESS_UNWINDER + bool + endmenu diff --git a/arch/x86/configs/tiny.config b/arch/x86/configs/tiny.config index 4b429df40d7a..550cd5012b73 100644 --- a/arch/x86/configs/tiny.config +++ b/arch/x86/configs/tiny.config @@ -1,3 +1,5 @@ CONFIG_NOHIGHMEM=y # CONFIG_HIGHMEM4G is not set # CONFIG_HIGHMEM64G is not set +CONFIG_GUESS_UNWINDER=y +# CONFIG_FRAME_POINTER_UNWINDER is not set diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile index 9976fcecd17e..af28a8a24366 100644 --- a/arch/x86/entry/Makefile +++ b/arch/x86/entry/Makefile @@ -2,7 +2,6 @@ # Makefile for the x86 low level entry code # -OBJECT_FILES_NON_STANDARD_entry_$(BITS).o := y OBJECT_FILES_NON_STANDARD_entry_64_compat.o := y CFLAGS_syscall_64.o += $(call cc-option,-Wno-override-init,) diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 05ed3d393da7..640aafebdc00 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -1,4 +1,5 @@ #include <linux/jump_label.h> +#include <asm/unwind_hints.h> /* @@ -112,6 +113,7 @@ For 32-bit we have the following conventions - kernel is built with movq %rdx, 12*8+\offset(%rsp) movq %rsi, 13*8+\offset(%rsp) movq %rdi, 14*8+\offset(%rsp) + UNWIND_HINT_REGS offset=\offset extra=0 .endm .macro SAVE_C_REGS offset=0 SAVE_C_REGS_HELPER \offset, 1, 1, 1, 1 @@ -136,6 +138,7 @@ For 32-bit we have the following conventions - kernel is built with movq %r12, 3*8+\offset(%rsp) movq %rbp, 4*8+\offset(%rsp) movq %rbx, 5*8+\offset(%rsp) + UNWIND_HINT_REGS offset=\offset .endm .macro RESTORE_EXTRA_REGS offset=0 @@ -145,6 +148,7 @@ For 32-bit we have the following conventions - kernel is built with movq 3*8+\offset(%rsp), %r12 movq 4*8+\offset(%rsp), %rbp movq 5*8+\offset(%rsp), %rbx + UNWIND_HINT_REGS offset=\offset extra=0 .endm .macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1 @@ -167,6 +171,7 @@ For 32-bit we have the following conventions - kernel is built with .endif movq 13*8(%rsp), %rsi movq 14*8(%rsp), %rdi + UNWIND_HINT_IRET_REGS offset=16*8 .endm .macro RESTORE_C_REGS RESTORE_C_REGS_HELPER 1,1,1,1,1 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 6d078b89a5e8..64b233ab7cad 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -36,6 +36,7 @@ #include <asm/smap.h> #include <asm/pgtable_types.h> #include <asm/export.h> +#include <asm/frame.h> #include <linux/err.h> .code64 @@ -43,9 +44,10 @@ #ifdef CONFIG_PARAVIRT ENTRY(native_usergs_sysret64) + UNWIND_HINT_EMPTY swapgs sysretq -ENDPROC(native_usergs_sysret64) +END(native_usergs_sysret64) #endif /* CONFIG_PARAVIRT */ .macro TRACE_IRQS_IRETQ @@ -134,6 +136,7 @@ ENDPROC(native_usergs_sysret64) */ ENTRY(entry_SYSCALL_64) + UNWIND_HINT_EMPTY /* * Interrupts are off on entry. * We do not frame this tiny irq-off block with TRACE_IRQS_OFF/ON, @@ -169,6 +172,7 @@ GLOBAL(entry_SYSCALL_64_after_swapgs) pushq %r10 /* pt_regs->r10 */ pushq %r11 /* pt_regs->r11 */ sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */ + UNWIND_HINT_REGS extra=0 /* * If we need to do entry work or if we guess we'll need to do @@ -223,6 +227,7 @@ entry_SYSCALL_64_fastpath: movq EFLAGS(%rsp), %r11 RESTORE_C_REGS_EXCEPT_RCX_R11 movq RSP(%rsp), %rsp + UNWIND_HINT_EMPTY USERGS_SYSRET64 1: @@ -316,6 +321,7 @@ syscall_return_via_sysret: /* rcx and r11 are already restored (see code above) */ RESTORE_C_REGS_EXCEPT_RCX_R11 movq RSP(%rsp), %rsp + UNWIND_HINT_EMPTY USERGS_SYSRET64 opportunistic_sysret_failed: @@ -343,6 +349,7 @@ ENTRY(stub_ptregs_64) DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF popq %rax + UNWIND_HINT_REGS extra=0 jmp entry_SYSCALL64_slow_path 1: @@ -351,6 +358,7 @@ END(stub_ptregs_64) .macro ptregs_stub func ENTRY(ptregs_\func) + UNWIND_HINT_FUNC leaq \func(%rip), %rax jmp stub_ptregs_64 END(ptregs_\func) @@ -367,6 +375,7 @@ END(ptregs_\func) * %rsi: next task */ ENTRY(__switch_to_asm) + UNWIND_HINT_FUNC /* * Save callee-saved registers * This must match the order in inactive_task_frame @@ -406,6 +415,7 @@ END(__switch_to_asm) * r12: kernel thread arg */ ENTRY(ret_from_fork) + UNWIND_HINT_EMPTY movq %rax, %rdi call schedule_tail /* rdi: 'prev' task parameter */ @@ -413,6 +423,7 @@ ENTRY(ret_from_fork) jnz 1f /* kernel threads are uncommon */ 2: + UNWIND_HINT_REGS movq %rsp, %rdi call syscall_return_slowpath /* returns with IRQs disabled */ TRACE_IRQS_ON /* user mode is traced as IRQS on */ @@ -440,13 +451,102 @@ END(ret_from_fork) ENTRY(irq_entries_start) vector=FIRST_EXTERNAL_VECTOR .rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR) + UNWIND_HINT_IRET_REGS pushq $(~vector+0x80) /* Note: always in signed byte range */ - vector=vector+1 jmp common_interrupt .align 8 + vector=vector+1 .endr END(irq_entries_start) +.macro DEBUG_ENTRY_ASSERT_IRQS_OFF +#ifdef CONFIG_DEBUG_ENTRY + pushfq + testl $X86_EFLAGS_IF, (%rsp) + jz .Lokay_\@ + ud2 +.Lokay_\@: + addq $8, %rsp +#endif +.endm + +/* + * Enters the IRQ stack if we're not already using it. NMI-safe. Clobbers + * flags and puts old RSP into old_rsp, and leaves all other GPRs alone. + * Requires kernel GSBASE. + * + * The invariant is that, if irq_count != -1, then the IRQ stack is in use. + */ +.macro ENTER_IRQ_STACK regs=1 old_rsp + DEBUG_ENTRY_ASSERT_IRQS_OFF + movq %rsp, \old_rsp + + .if \regs + UNWIND_HINT_REGS base=\old_rsp + .endif + + incl PER_CPU_VAR(irq_count) + jnz .Lirq_stack_push_old_rsp_\@ + + /* + * Right now, if we just incremented irq_count to zero, we've + * claimed the IRQ stack but we haven't switched to it yet. + * + * If anything is added that can interrupt us here without using IST, + * it must be *extremely* careful to limit its stack usage. This + * could include kprobes and a hypothetical future IST-less #DB + * handler. + * + * The OOPS unwinder relies on the word at the top of the IRQ + * stack linking back to the previous RSP for the entire time we're + * on the IRQ stack. For this to work reliably, we need to write + * it before we actually move ourselves to the IRQ stack. + */ + + movq \old_rsp, PER_CPU_VAR(irq_stack_union + IRQ_STACK_SIZE - 8) + movq PER_CPU_VAR(irq_stack_ptr), %rsp + +#ifdef CONFIG_DEBUG_ENTRY + /* + * If the first movq above becomes wrong due to IRQ stack layout + * changes, the only way we'll notice is if we try to unwind right + * here. Assert that we set up the stack right to catch this type + * of bug quickly. + */ + cmpq -8(%rsp), \old_rsp + je .Lirq_stack_okay\@ + ud2 + .Lirq_stack_okay\@: +#endif + +.Lirq_stack_push_old_rsp_\@: + pushq \old_rsp + + .if \regs + UNWIND_HINT_REGS indirect=1 + .endif +.endm + +/* + * Undoes ENTER_IRQ_STACK. + */ +.macro LEAVE_IRQ_STACK regs=1 + DEBUG_ENTRY_ASSERT_IRQS_OFF + /* We need to be off the IRQ stack before decrementing irq_count. */ + popq %rsp + + .if \regs + UNWIND_HINT_REGS + .endif + + /* + * As in ENTER_IRQ_STACK, irq_count == 0, we are still claiming + * the irq stack but we're not on it. + */ + + decl PER_CPU_VAR(irq_count) +.endm + /* * Interrupt entry/exit. * @@ -485,17 +585,7 @@ END(irq_entries_start) CALL_enter_from_user_mode 1: - /* - * Save previous stack pointer, optionally switch to interrupt stack. - * irq_count is used to check if a CPU is already on an interrupt stack - * or not. While this is essentially redundant with preempt_count it is - * a little cheaper to use a separate counter in the PDA (short of - * moving irq_enter into assembly, which would be too much work) - */ - movq %rsp, %rdi - incl PER_CPU_VAR(irq_count) - cmovzq PER_CPU_VAR(irq_stack_ptr), %rsp - pushq %rdi + ENTER_IRQ_STACK old_rsp=%rdi /* We entered an interrupt context - irqs are off: */ TRACE_IRQS_OFF @@ -515,10 +605,8 @@ common_interrupt: ret_from_intr: DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF - decl PER_CPU_VAR(irq_count) - /* Restore saved previous stack */ - popq %rsp + LEAVE_IRQ_STACK testb $3, CS(%rsp) jz retint_kernel @@ -561,6 +649,7 @@ restore_c_regs_and_iret: INTERRUPT_RETURN ENTRY(native_iret) + UNWIND_HINT_IRET_REGS /* * Are we returning to a stack segment from the LDT? Note: in * 64-bit mode SS:RSP on the exception stack is always valid. @@ -633,6 +722,7 @@ native_irq_return_ldt: orq PER_CPU_VAR(espfix_stack), %rax SWAPGS movq %rax, %rsp + UNWIND_HINT_IRET_REGS offset=8 /* * At this point, we cannot write to the stack any more, but we can @@ -654,6 +744,7 @@ END(common_interrupt) */ .macro apicinterrupt3 num sym do_sym ENTRY(\sym) + UNWIND_HINT_IRET_REGS ASM_CLAC pushq $~(\num) .Lcommon_\sym: @@ -740,6 +831,8 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ENTRY(\sym) + UNWIND_HINT_IRET_REGS offset=8 + /* Sanity check */ .if \shift_ist != -1 && \paranoid == 0 .error "using shift_ist requires paranoid=1" @@ -763,6 +856,7 @@ ENTRY(\sym) .else call error_entry .endif + UNWIND_HINT_REGS /* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */ .if \paranoid @@ -860,6 +954,7 @@ idtentry simd_coprocessor_error do_simd_coprocessor_error has_error_code=0 * edi: new selector */ ENTRY(native_load_gs_index) + FRAME_BEGIN pushfq DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI) SWAPGS @@ -868,8 +963,9 @@ ENTRY(native_load_gs_index) 2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE SWAPGS popfq + FRAME_END ret -END(native_load_gs_index) +ENDPROC(native_load_gs_index) EXPORT_SYMBOL(native_load_gs_index) _ASM_EXTABLE(.Lgs_change, bad_gs) @@ -892,14 +988,12 @@ bad_gs: ENTRY(do_softirq_own_stack) pushq %rbp mov %rsp, %rbp - incl PER_CPU_VAR(irq_count) - cmove PER_CPU_VAR(irq_stack_ptr), %rsp - push %rbp /* frame pointer backlink */ + ENTER_IRQ_STACK regs=0 old_rsp=%r11 call __do_softirq + LEAVE_IRQ_STACK regs=0 leaveq - decl PER_CPU_VAR(irq_count) ret -END(do_softirq_own_stack) +ENDPROC(do_softirq_own_stack) #ifdef CONFIG_XEN idtentry xen_hypervisor_callback xen_do_hypervisor_callback has_error_code=0 @@ -923,14 +1017,14 @@ ENTRY(xen_do_hypervisor_callback) /* do_hypervisor_callback(struct *pt_regs) */ * Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will * see the correct pointer to the pt_regs */ + UNWIND_HINT_FUNC movq %rdi, %rsp /* we don't return, adjust the stack frame */ -11: incl PER_CPU_VAR(irq_count) - movq %rsp, %rbp - cmovzq PER_CPU_VAR(irq_stack_ptr), %rsp - pushq %rbp /* frame pointer backlink */ + UNWIND_HINT_REGS + + ENTER_IRQ_STACK old_rsp=%r10 call xen_evtchn_do_upcall - popq %rsp - decl PER_CPU_VAR(irq_count) + LEAVE_IRQ_STACK + #ifndef CONFIG_PREEMPT call xen_maybe_preempt_hcall #endif @@ -951,6 +1045,7 @@ END(xen_do_hypervisor_callback) * with its current contents: any discrepancy means we in category 1. */ ENTRY(xen_failsafe_callback) + UNWIND_HINT_EMPTY movl %ds, %ecx cmpw %cx, 0x10(%rsp) jne 1f @@ -970,11 +1065,13 @@ ENTRY(xen_failsafe_callback) pushq $0 /* RIP */ pushq %r11 pushq %rcx + UNWIND_HINT_IRET_REGS offset=8 jmp general_protection 1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */ movq (%rsp), %rcx movq 8(%rsp), %r11 addq $0x30, %rsp + UNWIND_HINT_IRET_REGS pushq $-1 /* orig_ax = -1 => not a system call */ ALLOC_PT_GPREGS_ON_STACK SAVE_C_REGS @@ -1020,6 +1117,7 @@ idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vec * Return: ebx=0: need swapgs on exit, ebx=1: otherwise */ ENTRY(paranoid_entry) + UNWIND_HINT_FUNC cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 @@ -1047,6 +1145,7 @@ END(paranoid_entry) * On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it) */ ENTRY(paranoid_exit) + UNWIND_HINT_REGS DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF_DEBUG testl %ebx, %ebx /* swapgs needed? */ @@ -1068,6 +1167,7 @@ END(paranoid_exit) * Return: EBX=0: came from user mode; EBX=1: otherwise */ ENTRY(error_entry) + UNWIND_HINT_FUNC cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 @@ -1152,6 +1252,7 @@ END(error_entry) * 0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode */ ENTRY(error_exit) + UNWIND_HINT_REGS DISABLE_INTERRUPTS(CLBR_ANY) TRACE_IRQS_OFF testl %ebx, %ebx @@ -1161,6 +1262,7 @@ END(error_exit) /* Runs on exception stack */ ENTRY(nmi) + UNWIND_HINT_IRET_REGS /* * Fix up the exception frame if we're on Xen. * PARAVIRT_ADJUST_EXCEPTION_FRAME is guaranteed to push at most @@ -1234,11 +1336,13 @@ ENTRY(nmi) cld movq %rsp, %rdx movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp + UNWIND_HINT_IRET_REGS base=%rdx offset=8 pushq 5*8(%rdx) /* pt_regs->ss */ pushq 4*8(%rdx) /* pt_regs->rsp */ pushq 3*8(%rdx) /* pt_regs->flags */ pushq 2*8(%rdx) /* pt_regs->cs */ pushq 1*8(%rdx) /* pt_regs->rip */ + UNWIND_HINT_IRET_REGS pushq $-1 /* pt_regs->orig_ax */ pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ @@ -1255,6 +1359,7 @@ ENTRY(nmi) pushq %r13 /* pt_regs->r13 */ pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ + UNWIND_HINT_REGS ENCODE_FRAME_POINTER /* @@ -1409,6 +1514,7 @@ first_nmi: .rept 5 pushq 11*8(%rsp) .endr + UNWIND_HINT_IRET_REGS /* Everything up to here is safe from nested NMIs */ @@ -1424,6 +1530,7 @@ first_nmi: pushq $__KERNEL_CS /* CS */ pushq $1f /* RIP */ INTERRUPT_RETURN /* continues at repeat_nmi below */ + UNWIND_HINT_IRET_REGS 1: #endif @@ -1473,6 +1580,7 @@ end_repeat_nmi: * exceptions might do. */ call paranoid_entry + UNWIND_HINT_REGS /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ movq %rsp, %rdi @@ -1510,17 +1618,19 @@ nmi_restore: END(nmi) ENTRY(ignore_sysret) + UNWIND_HINT_EMPTY mov $-ENOSYS, %eax sysret END(ignore_sysret) ENTRY(rewind_stack_do_exit) + UNWIND_HINT_FUNC /* Prevent any naive code from trying to unwind to our caller. */ xorl %ebp, %ebp movq PER_CPU_VAR(cpu_current_top_of_stack), %rax - leaq -TOP_OF_KERNEL_STACK_PADDING-PTREGS_SIZE(%rax), %rsp + leaq -PTREGS_SIZE(%rax), %rsp + UNWIND_HINT_FUNC sp_offset=PTREGS_SIZE call do_exit -1: jmp 1b END(rewind_stack_do_exit) diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c index 724153797209..e0bb46c02857 100644 --- a/arch/x86/ia32/ia32_signal.c +++ b/arch/x86/ia32/ia32_signal.c @@ -226,7 +226,7 @@ static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, if (ksig->ka.sa.sa_flags & SA_ONSTACK) sp = sigsp(sp, ksig); /* This is the legacy signal stack switching. */ - else if ((regs->ss & 0xffff) != __USER32_DS && + else if (regs->ss != __USER32_DS && !(ksig->ka.sa.sa_flags & SA_RESTORER) && ksig->ka.sa.sa_restorer) sp = (unsigned long) ksig->ka.sa.sa_restorer; diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 1c18d83d3f09..a62a12c47233 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -126,15 +126,15 @@ do { \ pr_reg[4] = regs->di; \ pr_reg[5] = regs->bp; \ pr_reg[6] = regs->ax; \ - pr_reg[7] = regs->ds & 0xffff; \ - pr_reg[8] = regs->es & 0xffff; \ - pr_reg[9] = regs->fs & 0xffff; \ + pr_reg[7] = regs->ds; \ + pr_reg[8] = regs->es; \ + pr_reg[9] = regs->fs; \ pr_reg[11] = regs->orig_ax; \ pr_reg[12] = regs->ip; \ - pr_reg[13] = regs->cs & 0xffff; \ + pr_reg[13] = regs->cs; \ pr_reg[14] = regs->flags; \ pr_reg[15] = regs->sp; \ - pr_reg[16] = regs->ss & 0xffff; \ + pr_reg[16] = regs->ss; \ } while (0); #define ELF_CORE_COPY_REGS(pr_reg, regs) \ diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h index 48febf07e828..1310e1f1cd65 100644 --- a/arch/x86/include/asm/io.h +++ b/arch/x86/include/asm/io.h @@ -69,6 +69,9 @@ build_mmio_write(__writeb, "b", unsigned char, "q", ) build_mmio_write(__writew, "w", unsigned short, "r", ) build_mmio_write(__writel, "l", unsigned int, "r", ) +#define readb readb +#define readw readw +#define readl readl #define readb_relaxed(a) __readb(a) #define readw_relaxed(a) __readw(a) #define readl_relaxed(a) __readl(a) @@ -76,6 +79,9 @@ build_mmio_write(__writel, "l", unsigned int, "r", ) #define __raw_readw __readw #define __raw_readl __readl +#define writeb writeb +#define writew writew +#define writel writel #define writeb_relaxed(v, a) __writeb(v, a) #define writew_relaxed(v, a) __writew(v, a) #define writel_relaxed(v, a) __writel(v, a) @@ -88,13 +94,15 @@ build_mmio_write(__writel, "l", unsigned int, "r", ) #ifdef CONFIG_X86_64 build_mmio_read(readq, "q", unsigned long, "=r", :"memory") +build_mmio_read(__readq, "q", unsigned long, "=r", ) build_mmio_write(writeq, "q", unsigned long, "r", :"memory") +build_mmio_write(__writeq, "q", unsigned long, "r", ) -#define readq_relaxed(a) readq(a) -#define writeq_relaxed(v, a) writeq(v, a) +#define readq_relaxed(a) __readq(a) +#define writeq_relaxed(v, a) __writeq(v, a) -#define __raw_readq(a) readq(a) -#define __raw_writeq(val, addr) writeq(val, addr) +#define __raw_readq __readq +#define __raw_writeq __writeq /* Let people know that we have them */ #define readq readq @@ -119,6 +127,7 @@ static inline phys_addr_t virt_to_phys(volatile void *address) { return __pa(address); } +#define virt_to_phys virt_to_phys /** * phys_to_virt - map physical address to virtual @@ -137,6 +146,7 @@ static inline void *phys_to_virt(phys_addr_t address) { return __va(address); } +#define phys_to_virt phys_to_virt /* * Change "struct page" to physical address. @@ -169,11 +179,14 @@ static inline unsigned int isa_virt_to_bus(volatile void *address) * else, you probably want one of the following. */ extern void __iomem *ioremap_nocache(resource_size_t offset, unsigned long size); +#define ioremap_nocache ioremap_nocache extern void __iomem *ioremap_uc(resource_size_t offset, unsigned long size); #define ioremap_uc ioremap_uc extern void __iomem *ioremap_cache(resource_size_t offset, unsigned long size); +#define ioremap_cache ioremap_cache extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size, unsigned long prot_val); +#define ioremap_prot ioremap_prot /** * ioremap - map bus memory into CPU space @@ -193,8 +206,10 @@ static inline void __iomem *ioremap(resource_size_t offset, unsigned long size) { return ioremap_nocache(offset, size); } +#define ioremap ioremap extern void iounmap(volatile void __iomem *addr); +#define iounmap iounmap extern void set_iounmap_nonlazy(void); @@ -203,53 +218,6 @@ extern void set_iounmap_nonlazy(void); #include <asm-generic/iomap.h> /* - * Convert a virtual cached pointer to an uncached pointer - */ -#define xlate_dev_kmem_ptr(p) p - -/** - * memset_io Set a range of I/O memory to a constant value - * @addr: The beginning of the I/O-memory range to set - * @val: The value to set the memory to - * @count: The number of bytes to set - * - * Set a range of I/O memory to a given value. - */ -static inline void -memset_io(volatile void __iomem *addr, unsigned char val, size_t count) -{ - memset((void __force *)addr, val, count); -} - -/** - * memcpy_fromio Copy a block of data from I/O memory - * @dst: The (RAM) destination for the copy - * @src: The (I/O memory) source for the data - * @count: The number of bytes to copy - * - * Copy a block of data from I/O memory. - */ -static inline void -memcpy_fromio(void *dst, const volatile void __iomem *src, size_t count) -{ - memcpy(dst, (const void __force *)src, count); -} - -/** - * memcpy_toio Copy a block of data into I/O memory - * @dst: The (I/O memory) destination for the copy - * @src: The (RAM) source for the data - * @count: The number of bytes to copy - * - * Copy a block of data to I/O memory. - */ -static inline void -memcpy_toio(volatile void __iomem *dst, const void *src, size_t count) -{ - memcpy((void __force *)dst, src, count); -} - -/* * ISA space is 'always mapped' on a typical x86 system, no need to * explicitly ioremap() it. The fact that the ISA IO space is mapped * to PAGE_OFFSET is pure coincidence - it does not mean ISA values @@ -341,13 +309,38 @@ BUILDIO(b, b, char) BUILDIO(w, w, short) BUILDIO(l, , int) +#define inb inb +#define inw inw +#define inl inl +#define inb_p inb_p +#define inw_p inw_p +#define inl_p inl_p +#define insb insb +#define insw insw +#define insl insl + +#define outb outb +#define outw outw +#define outl outl +#define outb_p outb_p +#define outw_p outw_p +#define outl_p outl_p +#define outsb outsb +#define outsw outsw +#define outsl outsl + extern void *xlate_dev_mem_ptr(phys_addr_t phys); extern void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr); +#define xlate_dev_mem_ptr xlate_dev_mem_ptr +#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr + extern int ioremap_change_attr(unsigned long vaddr, unsigned long size, enum page_cache_mode pcm); extern void __iomem *ioremap_wc(resource_size_t offset, unsigned long size); +#define ioremap_wc ioremap_wc extern void __iomem *ioremap_wt(resource_size_t offset, unsigned long size); +#define ioremap_wt ioremap_wt extern bool is_early_ioremap_ptep(pte_t *ptep); @@ -365,6 +358,9 @@ extern bool xen_biovec_phys_mergeable(const struct bio_vec *vec1, #define IO_SPACE_LIMIT 0xffff +#include <asm-generic/io.h> +#undef PCI_IOBASE + #ifdef CONFIG_MTRR extern int __must_check arch_phys_wc_index(int handle); #define arch_phys_wc_index arch_phys_wc_index diff --git a/arch/x86/include/asm/module.h b/arch/x86/include/asm/module.h index e3b7819caeef..9eb7c718aaf8 100644 --- a/arch/x86/include/asm/module.h +++ b/arch/x86/include/asm/module.h @@ -2,6 +2,15 @@ #define _ASM_X86_MODULE_H #include <asm-generic/module.h> +#include <asm/orc_types.h> + +struct mod_arch_specific { +#ifdef CONFIG_ORC_UNWINDER + unsigned int num_orcs; + int *orc_unwind_ip; + struct orc_entry *orc_unwind; +#endif +}; #ifdef CONFIG_X86_64 /* X86_64 does not define MODULE_PROC_FAMILY */ diff --git a/arch/x86/include/asm/orc_lookup.h b/arch/x86/include/asm/orc_lookup.h new file mode 100644 index 000000000000..91c8d868424d --- /dev/null +++ b/arch/x86/include/asm/orc_lookup.h @@ -0,0 +1,46 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ +#ifndef _ORC_LOOKUP_H +#define _ORC_LOOKUP_H + +/* + * This is a lookup table for speeding up access to the .orc_unwind table. + * Given an input address offset, the corresponding lookup table entry + * specifies a subset of the .orc_unwind table to search. + * + * Each block represents the end of the previous range and the start of the + * next range. An extra block is added to give the last range an end. + * + * The block size should be a power of 2 to avoid a costly 'div' instruction. + * + * A block size of 256 was chosen because it roughly doubles unwinder + * performance while only adding ~5% to the ORC data footprint. + */ +#define LOOKUP_BLOCK_ORDER 8 +#define LOOKUP_BLOCK_SIZE (1 << LOOKUP_BLOCK_ORDER) + +#ifndef LINKER_SCRIPT + +extern unsigned int orc_lookup[]; +extern unsigned int orc_lookup_end[]; + +#define LOOKUP_START_IP (unsigned long)_stext +#define LOOKUP_STOP_IP (unsigned long)_etext + +#endif /* LINKER_SCRIPT */ + +#endif /* _ORC_LOOKUP_H */ diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h new file mode 100644 index 000000000000..9c9dc579bd7d --- /dev/null +++ b/arch/x86/include/asm/orc_types.h @@ -0,0 +1,107 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef _ORC_TYPES_H +#define _ORC_TYPES_H + +#include <linux/types.h> +#include <linux/compiler.h> + +/* + * The ORC_REG_* registers are base registers which are used to find other + * registers on the stack. + * + * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the + * address of the previous frame: the caller's SP before it called the current + * function. + * + * ORC_REG_UNDEFINED means the corresponding register's value didn't change in + * the current frame. + * + * The most commonly used base registers are SP and BP -- which the previous SP + * is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is + * usually based on. + * + * The rest of the base registers are needed for special cases like entry code + * and GCC realigned stacks. + */ +#define ORC_REG_UNDEFINED 0 +#define ORC_REG_PREV_SP 1 +#define ORC_REG_DX 2 +#define ORC_REG_DI 3 +#define ORC_REG_BP 4 +#define ORC_REG_SP 5 +#define ORC_REG_R10 6 +#define ORC_REG_R13 7 +#define ORC_REG_BP_INDIRECT 8 +#define ORC_REG_SP_INDIRECT 9 +#define ORC_REG_MAX 15 + +/* + * ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the + * caller's SP right before it made the call). Used for all callable + * functions, i.e. all C code and all callable asm functions. + * + * ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points + * to a fully populated pt_regs from a syscall, interrupt, or exception. + * + * ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset + * points to the iret return frame. + * + * The UNWIND_HINT macros are used only for the unwind_hint struct. They + * aren't used in struct orc_entry due to size and complexity constraints. + * Objtool converts them to real types when it converts the hints to orc + * entries. + */ +#define ORC_TYPE_CALL 0 +#define ORC_TYPE_REGS 1 +#define ORC_TYPE_REGS_IRET 2 +#define UNWIND_HINT_TYPE_SAVE 3 +#define UNWIND_HINT_TYPE_RESTORE 4 + +#ifndef __ASSEMBLY__ +/* + * This struct is more or less a vastly simplified version of the DWARF Call + * Frame Information standard. It contains only the necessary parts of DWARF + * CFI, simplified for ease of access by the in-kernel unwinder. It tells the + * unwinder how to find the previous SP and BP (and sometimes entry regs) on + * the stack for a given code address. Each instance of the struct corresponds + * to one or more code locations. + */ +struct orc_entry { + s16 sp_offset; + s16 bp_offset; + unsigned sp_reg:4; + unsigned bp_reg:4; + unsigned type:2; +} __packed; + +/* + * This struct is used by asm and inline asm code to manually annotate the + * location of registers on the stack for the ORC unwinder. + * + * Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*. + */ +struct unwind_hint { + u32 ip; + s16 sp_offset; + u8 sp_reg; + u8 type; +}; +#endif /* __ASSEMBLY__ */ + +#endif /* _ORC_TYPES_H */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 028245e1c42b..0b03d655db7c 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -22,6 +22,7 @@ struct vm86; #include <asm/nops.h> #include <asm/special_insns.h> #include <asm/fpu/types.h> +#include <asm/unwind_hints.h> #include <linux/personality.h> #include <linux/cache.h> @@ -684,6 +685,7 @@ static inline void sync_core(void) unsigned int tmp; asm volatile ( + UNWIND_HINT_SAVE "mov %%ss, %0\n\t" "pushq %q0\n\t" "pushq %%rsp\n\t" @@ -693,6 +695,7 @@ static inline void sync_core(void) "pushq %q0\n\t" "pushq $1f\n\t" "iretq\n\t" + UNWIND_HINT_RESTORE "1:" : "=&r" (tmp), "+r" (__sp) : : "cc", "memory"); #endif diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index 2b5d686ea9f3..a29f82871699 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -9,6 +9,20 @@ #ifdef __i386__ struct pt_regs { + /* + * NB: 32-bit x86 CPUs are inconsistent as what happens in the + * following cases (where %seg represents a segment register): + * + * - pushl %seg: some do a 16-bit write and leave the high + * bits alone + * - movl %seg, [mem]: some do a 16-bit write despite the movl + * - IDT entry: some (e.g. 486) will leave the high bits of CS + * and (if applicable) SS undefined. + * + * Fortunately, x86-32 doesn't read the high bits on POP or IRET, + * so we can just treat all of the segment registers as 16-bit + * values. + */ unsigned long bx; unsigned long cx; unsigned long dx; @@ -16,16 +30,22 @@ struct pt_regs { unsigned long di; unsigned long bp; unsigned long ax; - unsigned long ds; - unsigned long es; - unsigned long fs; - unsigned long gs; + unsigned short ds; + unsigned short __dsh; + unsigned short es; + unsigned short __esh; + unsigned short fs; + unsigned short __fsh; + unsigned short gs; + unsigned short __gsh; unsigned long orig_ax; unsigned long ip; - unsigned long cs; + unsigned short cs; + unsigned short __csh; unsigned long flags; unsigned long sp; - unsigned long ss; + unsigned short ss; + unsigned short __ssh; }; #else /* __i386__ */ diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h index 661dd305694a..045f99211a99 100644 --- a/arch/x86/include/asm/rmwcc.h +++ b/arch/x86/include/asm/rmwcc.h @@ -1,45 +1,56 @@ #ifndef _ASM_X86_RMWcc #define _ASM_X86_RMWcc +#define __CLOBBERS_MEM "memory" +#define __CLOBBERS_MEM_CC_CX "memory", "cc", "cx" + #if !defined(__GCC_ASM_FLAG_OUTPUTS__) && defined(CC_HAVE_ASM_GOTO) /* Use asm goto */ -#define __GEN_RMWcc(fullop, var, cc, ...) \ +#define __GEN_RMWcc(fullop, var, cc, clobbers, ...) \ do { \ asm_volatile_goto (fullop "; j" #cc " %l[cc_label]" \ - : : "m" (var), ## __VA_ARGS__ \ - : "memory" : cc_label); \ + : : [counter] "m" (var), ## __VA_ARGS__ \ + : clobbers : cc_label); \ return 0; \ cc_label: \ return 1; \ } while (0) -#define GEN_UNARY_RMWcc(op, var, arg0, cc) \ - __GEN_RMWcc(op " " arg0, var, cc) +#define __BINARY_RMWcc_ARG " %1, " -#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc) \ - __GEN_RMWcc(op " %1, " arg0, var, cc, vcon (val)) #else /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */ /* Use flags output or a set instruction */ -#define __GEN_RMWcc(fullop, var, cc, ...) \ +#define __GEN_RMWcc(fullop, var, cc, clobbers, ...) \ do { \ bool c; \ asm volatile (fullop ";" CC_SET(cc) \ - : "+m" (var), CC_OUT(cc) (c) \ - : __VA_ARGS__ : "memory"); \ + : [counter] "+m" (var), CC_OUT(cc) (c) \ + : __VA_ARGS__ : clobbers); \ return c; \ } while (0) +#define __BINARY_RMWcc_ARG " %2, " + +#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */ + #define GEN_UNARY_RMWcc(op, var, arg0, cc) \ - __GEN_RMWcc(op " " arg0, var, cc) + __GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM) + +#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc) \ + __GEN_RMWcc(op " " arg0 "\n\t" suffix, var, cc, \ + __CLOBBERS_MEM_CC_CX) #define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc) \ - __GEN_RMWcc(op " %2, " arg0, var, cc, vcon (val)) + __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0, var, cc, \ + __CLOBBERS_MEM, vcon (val)) -#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */ +#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc) \ + __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0 "\n\t" suffix, var, cc, \ + __CLOBBERS_MEM_CC_CX, vcon (val)) #endif /* _ASM_X86_RMWcc */ diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h index e6676495b125..e9f793e2df7a 100644 --- a/arch/x86/include/asm/unwind.h +++ b/arch/x86/include/asm/unwind.h @@ -12,11 +12,14 @@ struct unwind_state { struct task_struct *task; int graph_idx; bool error; -#ifdef CONFIG_FRAME_POINTER +#if defined(CONFIG_ORC_UNWINDER) + bool signal, full_regs; + unsigned long sp, bp, ip; + struct pt_regs *regs; +#elif defined(CONFIG_FRAME_POINTER_UNWINDER) bool got_irq; - unsigned long *bp, *orig_sp; + unsigned long *bp, *orig_sp, ip; struct pt_regs *regs; - unsigned long ip; #else unsigned long *sp; #endif @@ -24,41 +27,30 @@ struct unwind_state { void __unwind_start(struct unwind_state *state, struct task_struct *task, struct pt_regs *regs, unsigned long *first_frame); - bool unwind_next_frame(struct unwind_state *state); - unsigned long unwind_get_return_address(struct unwind_state *state); +unsigned long *unwind_get_return_address_ptr(struct unwind_state *state); static inline bool unwind_done(struct unwind_state *state) { return state->stack_info.type == STACK_TYPE_UNKNOWN; } -static inline -void unwind_start(struct unwind_state *state, struct task_struct *task, - struct pt_regs *regs, unsigned long *first_frame) -{ - first_frame = first_frame ? : get_stack_pointer(task, regs); - - __unwind_start(state, task, regs, first_frame); -} - static inline bool unwind_error(struct unwind_state *state) { return state->error; } -#ifdef CONFIG_FRAME_POINTER - static inline -unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) +void unwind_start(struct unwind_state *state, struct task_struct *task, + struct pt_regs *regs, unsigned long *first_frame) { - if (unwind_done(state)) - return NULL; + first_frame = first_frame ? : get_stack_pointer(task, regs); - return state->regs ? &state->regs->ip : state->bp + 1; + __unwind_start(state, task, regs, first_frame); } +#if defined(CONFIG_ORC_UNWINDER) || defined(CONFIG_FRAME_POINTER_UNWINDER) static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) { if (unwind_done(state)) @@ -66,20 +58,46 @@ static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) return state->regs; } - -#else /* !CONFIG_FRAME_POINTER */ - -static inline -unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) +#else +static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) { return NULL; } +#endif -static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) +#ifdef CONFIG_ORC_UNWINDER +void unwind_init(void); +void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, + void *orc, size_t orc_size); +#else +static inline void unwind_init(void) {} +static inline +void unwind_module_init(struct module *mod, void *orc_ip, size_t orc_ip_size, + void *orc, size_t orc_size) {} +#endif + +/* + * This disables KASAN checking when reading a value from another task's stack, + * since the other task could be running on another CPU and could have poisoned + * the stack in the meantime. + */ +#define READ_ONCE_TASK_STACK(task, x) \ +({ \ + unsigned long val; \ + if (task == current) \ + val = READ_ONCE(x); \ + else \ + val = READ_ONCE_NOCHECK(x); \ + val; \ +}) + +static inline bool task_on_another_cpu(struct task_struct *task) { - return NULL; +#ifdef CONFIG_SMP + return task != current && task->on_cpu; +#else + return false; +#endif } -#endif /* CONFIG_FRAME_POINTER */ - #endif /* _ASM_X86_UNWIND_H */ diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h new file mode 100644 index 000000000000..5e02b11c9b86 --- /dev/null +++ b/arch/x86/include/asm/unwind_hints.h @@ -0,0 +1,103 @@ +#ifndef _ASM_X86_UNWIND_HINTS_H +#define _ASM_X86_UNWIND_HINTS_H + +#include "orc_types.h" + +#ifdef __ASSEMBLY__ + +/* + * In asm, there are two kinds of code: normal C-type callable functions and + * the rest. The normal callable functions can be called by other code, and + * don't do anything unusual with the stack. Such normal callable functions + * are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this + * category. In this case, no special debugging annotations are needed because + * objtool can automatically generate the ORC data for the ORC unwinder to read + * at runtime. + * + * Anything which doesn't fall into the above category, such as syscall and + * interrupt handlers, tends to not be called directly by other functions, and + * often does unusual non-C-function-type things with the stack pointer. Such + * code needs to be annotated such that objtool can understand it. The + * following CFI hint macros are for this type of code. + * + * These macros provide hints to objtool about the state of the stack at each + * instruction. Objtool starts from the hints and follows the code flow, + * making automatic CFI adjustments when it sees pushes and pops, filling out + * the debuginfo as necessary. It will also warn if it sees any + * inconsistencies. + */ +.macro UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=0 type=ORC_TYPE_CALL +#ifdef CONFIG_STACK_VALIDATION +.Lunwind_hint_ip_\@: + .pushsection .discard.unwind_hints + /* struct unwind_hint */ + .long .Lunwind_hint_ip_\@ - . + .short \sp_offset + .byte \sp_reg + .byte \type + .popsection +#endif +.endm + +.macro UNWIND_HINT_EMPTY + UNWIND_HINT sp_reg=ORC_REG_UNDEFINED +.endm + +.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 iret=0 + .if \base == %rsp && \indirect + .set sp_reg, ORC_REG_SP_INDIRECT + .elseif \base == %rsp + .set sp_reg, ORC_REG_SP + .elseif \base == %rbp + .set sp_reg, ORC_REG_BP + .elseif \base == %rdi + .set sp_reg, ORC_REG_DI + .elseif \base == %rdx + .set sp_reg, ORC_REG_DX + .elseif \base == %r10 + .set sp_reg, ORC_REG_R10 + .else + .error "UNWIND_HINT_REGS: bad base register" + .endif + + .set sp_offset, \offset + + .if \iret + .set type, ORC_TYPE_REGS_IRET + .elseif \extra == 0 + .set type, ORC_TYPE_REGS_IRET + .set sp_offset, \offset + (16*8) + .else + .set type, ORC_TYPE_REGS + .endif + + UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type +.endm + +.macro UNWIND_HINT_IRET_REGS base=%rsp offset=0 + UNWIND_HINT_REGS base=\base offset=\offset iret=1 +.endm + +.macro UNWIND_HINT_FUNC sp_offset=8 + UNWIND_HINT sp_offset=\sp_offset +.endm + +#else /* !__ASSEMBLY__ */ + +#define UNWIND_HINT(sp_reg, sp_offset, type) \ + "987: \n\t" \ + ".pushsection .discard.unwind_hints\n\t" \ + /* struct unwind_hint */ \ + ".long 987b - .\n\t" \ + ".short " __stringify(sp_offset) "\n\t" \ + ".byte " __stringify(sp_reg) "\n\t" \ + ".byte " __stringify(type) "\n\t" \ + ".popsection\n\t" + +#define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE) + +#define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE) + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_X86_UNWIND_HINTS_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index a01892bdd61a..287eac7d207f 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -126,11 +126,9 @@ obj-$(CONFIG_PERF_EVENTS) += perf_regs.o obj-$(CONFIG_TRACING) += tracepoint.o obj-$(CONFIG_SCHED_MC_PRIO) += itmt.o -ifdef CONFIG_FRAME_POINTER -obj-y += unwind_frame.o -else -obj-y += unwind_guess.o -endif +obj-$(CONFIG_ORC_UNWINDER) += unwind_orc.o +obj-$(CONFIG_FRAME_POINTER_UNWINDER) += unwind_frame.o +obj-$(CONFIG_GUESS_UNWINDER) += unwind_guess.o ### # 64 bit specific files diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index dbce3cca94cb..f13b4c00a5de 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -94,6 +94,9 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, if (stack_name) printk("%s <%s>\n", log_lvl, stack_name); + if (regs && on_stack(&stack_info, regs, sizeof(*regs))) + __show_regs(regs, 0); + /* * Scan the stack, printing any text addresses we find. At the * same time, follow proper stack frames with the unwinder. @@ -118,10 +121,8 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, * Don't print regs->ip again if it was already printed * by __show_regs() below. */ - if (regs && stack == ®s->ip) { - unwind_next_frame(&state); - continue; - } + if (regs && stack == ®s->ip) + goto next; if (stack == ret_addr_p) reliable = 1; @@ -144,6 +145,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, if (!reliable) continue; +next: /* * Get the next frame from the unwinder. No need to * check for an error: if anything goes wrong, the rest @@ -153,7 +155,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, /* if the frame has entry regs, print them */ regs = unwind_get_entry_regs(&state); - if (regs) + if (regs && on_stack(&stack_info, regs, sizeof(*regs))) __show_regs(regs, 0); } @@ -265,7 +267,7 @@ int __die(const char *str, struct pt_regs *regs, long err) #ifdef CONFIG_X86_32 if (user_mode(regs)) { sp = regs->sp; - ss = regs->ss & 0xffff; + ss = regs->ss; } else { sp = kernel_stack_pointer(regs); savesegment(ss, ss); diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c index e5f0b40e66d2..4f0481474903 100644 --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -37,7 +37,7 @@ static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info) * This is a software stack, so 'end' can be a valid stack pointer. * It just means the stack is empty. */ - if (stack < begin || stack > end) + if (stack <= begin || stack > end) return false; info->type = STACK_TYPE_IRQ; @@ -62,7 +62,7 @@ static bool in_softirq_stack(unsigned long *stack, struct stack_info *info) * This is a software stack, so 'end' can be a valid stack pointer. * It just means the stack is empty. */ - if (stack < begin || stack > end) + if (stack <= begin || stack > end) return false; info->type = STACK_TYPE_SOFTIRQ; diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c index 3e1471d57487..225af4184f06 100644 --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -55,7 +55,7 @@ static bool in_exception_stack(unsigned long *stack, struct stack_info *info) begin = end - (exception_stack_sizes[k] / sizeof(long)); regs = (struct pt_regs *)end - 1; - if (stack < begin || stack >= end) + if (stack <= begin || stack >= end) continue; info->type = STACK_TYPE_EXCEPTION + k; @@ -78,7 +78,7 @@ static bool in_irq_stack(unsigned long *stack, struct stack_info *info) * This is a software stack, so 'end' can be a valid stack pointer. * It just means the stack is empty. */ - if (stack < begin || stack > end) + if (stack <= begin || stack > end) return false; info->type = STACK_TYPE_IRQ; diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 1f85ee8f9439..0332664eb158 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -457,12 +457,9 @@ early_idt_handler_common: /* The vector number is in pt_regs->gs */ cld - pushl %fs /* pt_regs->fs */ - movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */ - pushl %es /* pt_regs->es */ - movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */ - pushl %ds /* pt_regs->ds */ - movw $0, 2(%esp) /* clear high bits (some CPUs leave garbage) */ + pushl %fs /* pt_regs->fs (__fsh varies by model) */ + pushl %es /* pt_regs->es (__esh varies by model) */ + pushl %ds /* pt_regs->ds (__dsh varies by model) */ pushl %eax /* pt_regs->ax */ pushl %ebp /* pt_regs->bp */ pushl %edi /* pt_regs->di */ @@ -479,9 +476,8 @@ early_idt_handler_common: /* Load the vector number into EDX */ movl PT_GS(%esp), %edx - /* Load GS into pt_regs->gs and clear high bits */ + /* Load GS into pt_regs->gs (and maybe clobber __gsh) */ movw %gs, PT_GS(%esp) - movw $0, PT_GS+2(%esp) movl %esp, %eax /* args are pt_regs (EAX), trapnr (EDX) */ call early_fixup_exception @@ -493,10 +489,10 @@ early_idt_handler_common: popl %edi /* pt_regs->di */ popl %ebp /* pt_regs->bp */ popl %eax /* pt_regs->ax */ - popl %ds /* pt_regs->ds */ - popl %es /* pt_regs->es */ - popl %fs /* pt_regs->fs */ - popl %gs /* pt_regs->gs */ + popl %ds /* pt_regs->ds (always ignores __dsh) */ + popl %es /* pt_regs->es (always ignores __esh) */ + popl %fs /* pt_regs->fs (always ignores __fsh) */ + popl %gs /* pt_regs->gs (always ignores __gsh) */ decl %ss:early_recursion_flag addl $4, %esp /* pop pt_regs->orig_ax */ iret diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index a870910c8565..f0e64db18ac8 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -21,6 +21,25 @@ #include <asm/mmu_context.h> #include <asm/syscalls.h> +static void refresh_ldt_segments(void) +{ +#ifdef CONFIG_X86_64 + unsigned short sel; + + /* + * Make sure that the cached DS and ES descriptors match the updated + * LDT. + */ + savesegment(ds, sel); + if ((sel & SEGMENT_TI_MASK) == SEGMENT_LDT) + loadsegment(ds, sel); + + savesegment(es, sel); + if ((sel & SEGMENT_TI_MASK) == SEGMENT_LDT) + loadsegment(es, sel); +#endif +} + /* context.lock is held for us, so we don't need any locking. */ static void flush_ldt(void *__mm) { @@ -32,6 +51,8 @@ static void flush_ldt(void *__mm) pc = &mm->context; set_ldt(pc->ldt->entries, pc->ldt->nr_entries); + + refresh_ldt_segments(); } /* The caller must call finalize_ldt_struct on the result. LDT starts zeroed. */ diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index f67bd3205df7..62e7d70aadd5 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -35,6 +35,7 @@ #include <asm/page.h> #include <asm/pgtable.h> #include <asm/setup.h> +#include <asm/unwind.h> #if 0 #define DEBUGP(fmt, ...) \ @@ -213,7 +214,7 @@ int module_finalize(const Elf_Ehdr *hdr, struct module *me) { const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL, - *para = NULL; + *para = NULL, *orc = NULL, *orc_ip = NULL; char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { @@ -225,6 +226,10 @@ int module_finalize(const Elf_Ehdr *hdr, locks = s; if (!strcmp(".parainstructions", secstrings + s->sh_name)) para = s; + if (!strcmp(".orc_unwind", secstrings + s->sh_name)) + orc = s; + if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name)) + orc_ip = s; } if (alt) { @@ -248,6 +253,10 @@ int module_finalize(const Elf_Ehdr *hdr, /* make jump label nops */ jump_label_apply_nops(me); + if (orc && orc_ip) + unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size, + (void *)orc->sh_addr, orc->sh_size); + return 0; } diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index c6d6dc5f8bb2..efc5eeb58292 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -68,7 +68,7 @@ void __show_regs(struct pt_regs *regs, int all) if (user_mode(regs)) { sp = regs->sp; - ss = regs->ss & 0xffff; + ss = regs->ss; gs = get_user_gs(regs); } else { sp = kernel_stack_pointer(regs); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index c3169be4c596..e04941fb67fb 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -69,8 +69,7 @@ void __show_regs(struct pt_regs *regs, int all) unsigned int fsindex, gsindex; unsigned int ds, cs, es; - printk(KERN_DEFAULT "RIP: %04lx:%pS\n", regs->cs & 0xffff, - (void *)regs->ip); + printk(KERN_DEFAULT "RIP: %04lx:%pS\n", regs->cs, (void *)regs->ip); printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx", regs->ss, regs->sp, regs->flags); if (regs->orig_ax != -1) @@ -279,6 +278,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) struct tss_struct *tss = &per_cpu(cpu_tss, cpu); unsigned prev_fsindex, prev_gsindex; + WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) && + this_cpu_read(irq_count) != -1); + switch_fpu_prepare(prev_fpu, cpu); /* We must save %fs and %gs before load_TLS() because diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 3486d0498800..ecab32282f0f 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -115,6 +115,7 @@ #include <asm/microcode.h> #include <asm/mmu_context.h> #include <asm/kaslr.h> +#include <asm/unwind.h> /* * max_low_pfn_mapped: highest direct mapped pfn under 4GB @@ -1310,6 +1311,8 @@ void __init setup_arch(char **cmdline_p) if (efi_enabled(EFI_BOOT)) efi_apply_memmap_quirks(); #endif + + unwind_init(); } #ifdef CONFIG_X86_32 diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index cc30a74e4adb..e04442345fc0 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -256,7 +256,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, sp = current->sas_ss_sp + current->sas_ss_size; } else if (IS_ENABLED(CONFIG_X86_32) && !onsigstack && - (regs->ss & 0xffff) != __USER_DS && + regs->ss != __USER_DS && !(ka->sa.sa_flags & SA_RESTORER) && ka->sa.sa_restorer) { /* This is the legacy signal stack switching. */ diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c index 5f25cfbd952e..5ee663836c08 100644 --- a/arch/x86/kernel/step.c +++ b/arch/x86/kernel/step.c @@ -13,7 +13,7 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re unsigned long addr, seg; addr = regs->ip; - seg = regs->cs & 0xffff; + seg = regs->cs; if (v8086_mode(regs)) { addr = (addr & 0xffff) + (seg << 4); return addr; diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index b9389d72b2f7..7574ef5f16ec 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -10,20 +10,22 @@ #define FRAME_HEADER_SIZE (sizeof(long) * 2) -/* - * This disables KASAN checking when reading a value from another task's stack, - * since the other task could be running on another CPU and could have poisoned - * the stack in the meantime. - */ -#define READ_ONCE_TASK_STACK(task, x) \ -({ \ - unsigned long val; \ - if (task == current) \ - val = READ_ONCE(x); \ - else \ - val = READ_ONCE_NOCHECK(x); \ - val; \ -}) +unsigned long unwind_get_return_address(struct unwind_state *state) +{ + if (unwind_done(state)) + return 0; + + return __kernel_text_address(state->ip) ? state->ip : 0; +} +EXPORT_SYMBOL_GPL(unwind_get_return_address); + +unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) +{ + if (unwind_done(state)) + return NULL; + + return state->regs ? &state->regs->ip : state->bp + 1; +} static void unwind_dump(struct unwind_state *state) { @@ -66,15 +68,6 @@ static void unwind_dump(struct unwind_state *state) } } -unsigned long unwind_get_return_address(struct unwind_state *state) -{ - if (unwind_done(state)) - return 0; - - return __kernel_text_address(state->ip) ? state->ip : 0; -} -EXPORT_SYMBOL_GPL(unwind_get_return_address); - static size_t regs_size(struct pt_regs *regs) { /* x86_32 regs from kernel mode are two words shorter: */ diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c index 039f36738e49..4f0e17b90463 100644 --- a/arch/x86/kernel/unwind_guess.c +++ b/arch/x86/kernel/unwind_guess.c @@ -19,6 +19,11 @@ unsigned long unwind_get_return_address(struct unwind_state *state) } EXPORT_SYMBOL_GPL(unwind_get_return_address); +unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) +{ + return NULL; +} + bool unwind_next_frame(struct unwind_state *state) { struct stack_info *info = &state->stack_info; diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c new file mode 100644 index 000000000000..570b70d3f604 --- /dev/null +++ b/arch/x86/kernel/unwind_orc.c @@ -0,0 +1,582 @@ +#include <linux/module.h> +#include <linux/sort.h> +#include <asm/ptrace.h> +#include <asm/stacktrace.h> +#include <asm/unwind.h> +#include <asm/orc_types.h> +#include <asm/orc_lookup.h> +#include <asm/sections.h> + +#define orc_warn(fmt, ...) \ + printk_deferred_once(KERN_WARNING pr_fmt("WARNING: " fmt), ##__VA_ARGS__) + +extern int __start_orc_unwind_ip[]; +extern int __stop_orc_unwind_ip[]; +extern struct orc_entry __start_orc_unwind[]; +extern struct orc_entry __stop_orc_unwind[]; + +static DEFINE_MUTEX(sort_mutex); +int *cur_orc_ip_table = __start_orc_unwind_ip; +struct orc_entry *cur_orc_table = __start_orc_unwind; + +unsigned int lookup_num_blocks; +bool orc_init; + +static inline unsigned long orc_ip(const int *ip) +{ + return (unsigned long)ip + *ip; +} + +static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table, + unsigned int num_entries, unsigned long ip) +{ + int *first = ip_table; + int *last = ip_table + num_entries - 1; + int *mid = first, *found = first; + + if (!num_entries) + return NULL; + + /* + * Do a binary range search to find the rightmost duplicate of a given + * starting address. Some entries are section terminators which are + * "weak" entries for ensuring there are no gaps. They should be + * ignored when they conflict with a real entry. + */ + while (first <= last) { + mid = first + ((last - first) / 2); + + if (orc_ip(mid) <= ip) { + found = mid; + first = mid + 1; + } else + last = mid - 1; + } + + return u_table + (found - ip_table); +} + +#ifdef CONFIG_MODULES +static struct orc_entry *orc_module_find(unsigned long ip) +{ + struct module *mod; + + mod = __module_address(ip); + if (!mod || !mod->arch.orc_unwind || !mod->arch.orc_unwind_ip) + return NULL; + return __orc_find(mod->arch.orc_unwind_ip, mod->arch.orc_unwind, + mod->arch.num_orcs, ip); +} +#else +static struct orc_entry *orc_module_find(unsigned long ip) +{ + return NULL; +} +#endif + +static struct orc_entry *orc_find(unsigned long ip) +{ + if (!orc_init) + return NULL; + + /* For non-init vmlinux addresses, use the fast lookup table: */ + if (ip >= LOOKUP_START_IP && ip < LOOKUP_STOP_IP) { + unsigned int idx, start, stop; + + idx = (ip - LOOKUP_START_IP) / LOOKUP_BLOCK_SIZE; + + if (unlikely((idx >= lookup_num_blocks-1))) { + orc_warn("WARNING: bad lookup idx: idx=%u num=%u ip=%lx\n", + idx, lookup_num_blocks, ip); + return NULL; + } + + start = orc_lookup[idx]; + stop = orc_lookup[idx + 1] + 1; + + if (unlikely((__start_orc_unwind + start >= __stop_orc_unwind) || + (__start_orc_unwind + stop > __stop_orc_unwind))) { + orc_warn("WARNING: bad lookup value: idx=%u num=%u start=%u stop=%u ip=%lx\n", + idx, lookup_num_blocks, start, stop, ip); + return NULL; + } + + return __orc_find(__start_orc_unwind_ip + start, + __start_orc_unwind + start, stop - start, ip); + } + + /* vmlinux .init slow lookup: */ + if (ip >= (unsigned long)_sinittext && ip < (unsigned long)_einittext) + return __orc_find(__start_orc_unwind_ip, __start_orc_unwind, + __stop_orc_unwind_ip - __start_orc_unwind_ip, ip); + + /* Module lookup: */ + return orc_module_find(ip); +} + +static void orc_sort_swap(void *_a, void *_b, int size) +{ + struct orc_entry *orc_a, *orc_b; + struct orc_entry orc_tmp; + int *a = _a, *b = _b, tmp; + int delta = _b - _a; + + /* Swap the .orc_unwind_ip entries: */ + tmp = *a; + *a = *b + delta; + *b = tmp - delta; + + /* Swap the corresponding .orc_unwind entries: */ + orc_a = cur_orc_table + (a - cur_orc_ip_table); + orc_b = cur_orc_table + (b - cur_orc_ip_table); + orc_tmp = *orc_a; + *orc_a = *orc_b; + *orc_b = orc_tmp; +} + +static int orc_sort_cmp(const void *_a, const void *_b) +{ + struct orc_entry *orc_a; + const int *a = _a, *b = _b; + unsigned long a_val = orc_ip(a); + unsigned long b_val = orc_ip(b); + + if (a_val > b_val) + return 1; + if (a_val < b_val) + return -1; + + /* + * The "weak" section terminator entries need to always be on the left + * to ensure the lookup code skips them in favor of real entries. + * These terminator entries exist to handle any gaps created by + * whitelisted .o files which didn't get objtool generation. + */ + orc_a = cur_orc_table + (a - cur_orc_ip_table); + return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1; +} + +#ifdef CONFIG_MODULES +void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size, + void *_orc, size_t orc_size) +{ + int *orc_ip = _orc_ip; + struct orc_entry *orc = _orc; + unsigned int num_entries = orc_ip_size / sizeof(int); + + WARN_ON_ONCE(orc_ip_size % sizeof(int) != 0 || + orc_size % sizeof(*orc) != 0 || + num_entries != orc_size / sizeof(*orc)); + + /* + * The 'cur_orc_*' globals allow the orc_sort_swap() callback to + * associate an .orc_unwind_ip table entry with its corresponding + * .orc_unwind entry so they can both be swapped. + */ + mutex_lock(&sort_mutex); + cur_orc_ip_table = orc_ip; + cur_orc_table = orc; + sort(orc_ip, num_entries, sizeof(int), orc_sort_cmp, orc_sort_swap); + mutex_unlock(&sort_mutex); + + mod->arch.orc_unwind_ip = orc_ip; + mod->arch.orc_unwind = orc; + mod->arch.num_orcs = num_entries; +} +#endif + +void __init unwind_init(void) +{ + size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip; + size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind; + size_t num_entries = orc_ip_size / sizeof(int); + struct orc_entry *orc; + int i; + + if (!num_entries || orc_ip_size % sizeof(int) != 0 || + orc_size % sizeof(struct orc_entry) != 0 || + num_entries != orc_size / sizeof(struct orc_entry)) { + orc_warn("WARNING: Bad or missing .orc_unwind table. Disabling unwinder.\n"); + return; + } + + /* Sort the .orc_unwind and .orc_unwind_ip tables: */ + sort(__start_orc_unwind_ip, num_entries, sizeof(int), orc_sort_cmp, + orc_sort_swap); + + /* Initialize the fast lookup table: */ + lookup_num_blocks = orc_lookup_end - orc_lookup; + for (i = 0; i < lookup_num_blocks-1; i++) { + orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, + num_entries, + LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i)); + if (!orc) { + orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n"); + return; + } + + orc_lookup[i] = orc - __start_orc_unwind; + } + + /* Initialize the ending block: */ + orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries, + LOOKUP_STOP_IP); + if (!orc) { + orc_warn("WARNING: Corrupt .orc_unwind table. Disabling unwinder.\n"); + return; + } + orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind; + + orc_init = true; +} + +unsigned long unwind_get_return_address(struct unwind_state *state) +{ + if (unwind_done(state)) + return 0; + + return __kernel_text_address(state->ip) ? state->ip : 0; +} +EXPORT_SYMBOL_GPL(unwind_get_return_address); + +unsigned long *unwind_get_return_address_ptr(struct unwind_state *state) +{ + if (unwind_done(state)) + return NULL; + + if (state->regs) + return &state->regs->ip; + + if (state->sp) + return (unsigned long *)state->sp - 1; + + return NULL; +} + +static bool stack_access_ok(struct unwind_state *state, unsigned long addr, + size_t len) +{ + struct stack_info *info = &state->stack_info; + + /* + * If the address isn't on the current stack, switch to the next one. + * + * We may have to traverse multiple stacks to deal with the possibility + * that info->next_sp could point to an empty stack and the address + * could be on a subsequent stack. + */ + while (!on_stack(info, (void *)addr, len)) + if (get_stack_info(info->next_sp, state->task, info, + &state->stack_mask)) + return false; + + return true; +} + +static bool deref_stack_reg(struct unwind_state *state, unsigned long addr, + unsigned long *val) +{ + if (!stack_access_ok(state, addr, sizeof(long))) + return false; + + *val = READ_ONCE_TASK_STACK(state->task, *(unsigned long *)addr); + return true; +} + +#define REGS_SIZE (sizeof(struct pt_regs)) +#define SP_OFFSET (offsetof(struct pt_regs, sp)) +#define IRET_REGS_SIZE (REGS_SIZE - offsetof(struct pt_regs, ip)) +#define IRET_SP_OFFSET (SP_OFFSET - offsetof(struct pt_regs, ip)) + +static bool deref_stack_regs(struct unwind_state *state, unsigned long addr, + unsigned long *ip, unsigned long *sp, bool full) +{ + size_t regs_size = full ? REGS_SIZE : IRET_REGS_SIZE; + size_t sp_offset = full ? SP_OFFSET : IRET_SP_OFFSET; + struct pt_regs *regs = (struct pt_regs *)(addr + regs_size - REGS_SIZE); + + if (IS_ENABLED(CONFIG_X86_64)) { + if (!stack_access_ok(state, addr, regs_size)) + return false; + + *ip = regs->ip; + *sp = regs->sp; + + return true; + } + + if (!stack_access_ok(state, addr, sp_offset)) + return false; + + *ip = regs->ip; + + if (user_mode(regs)) { + if (!stack_access_ok(state, addr + sp_offset, + REGS_SIZE - SP_OFFSET)) + return false; + + *sp = regs->sp; + } else + *sp = (unsigned long)®s->sp; + + return true; +} + +bool unwind_next_frame(struct unwind_state *state) +{ + unsigned long ip_p, sp, orig_ip, prev_sp = state->sp; + enum stack_type prev_type = state->stack_info.type; + struct orc_entry *orc; + struct pt_regs *ptregs; + bool indirect = false; + + if (unwind_done(state)) + return false; + + /* Don't let modules unload while we're reading their ORC data. */ + preempt_disable(); + + /* Have we reached the end? */ + if (state->regs && user_mode(state->regs)) + goto done; + + /* + * Find the orc_entry associated with the text address. + * + * Decrement call return addresses by one so they work for sibling + * calls and calls to noreturn functions. + */ + orc = orc_find(state->signal ? state->ip : state->ip - 1); + if (!orc || orc->sp_reg == ORC_REG_UNDEFINED) + goto done; + orig_ip = state->ip; + + /* Find the previous frame's stack: */ + switch (orc->sp_reg) { + case ORC_REG_SP: + sp = state->sp + orc->sp_offset; + break; + + case ORC_REG_BP: + sp = state->bp + orc->sp_offset; + break; + + case ORC_REG_SP_INDIRECT: + sp = state->sp + orc->sp_offset; + indirect = true; + break; + + case ORC_REG_BP_INDIRECT: + sp = state->bp + orc->sp_offset; + indirect = true; + break; + + case ORC_REG_R10: + if (!state->regs || !state->full_regs) { + orc_warn("missing regs for base reg R10 at ip %p\n", + (void *)state->ip); + goto done; + } + sp = state->regs->r10; + break; + + case ORC_REG_R13: + if (!state->regs || !state->full_regs) { + orc_warn("missing regs for base reg R13 at ip %p\n", + (void *)state->ip); + goto done; + } + sp = state->regs->r13; + break; + + case ORC_REG_DI: + if (!state->regs || !state->full_regs) { + orc_warn("missing regs for base reg DI at ip %p\n", + (void *)state->ip); + goto done; + } + sp = state->regs->di; + break; + + case ORC_REG_DX: + if (!state->regs || !state->full_regs) { + orc_warn("missing regs for base reg DX at ip %p\n", + (void *)state->ip); + goto done; + } + sp = state->regs->dx; + break; + + default: + orc_warn("unknown SP base reg %d for ip %p\n", + orc->sp_reg, (void *)state->ip); + goto done; + } + + if (indirect) { + if (!deref_stack_reg(state, sp, &sp)) + goto done; + } + + /* Find IP, SP and possibly regs: */ + switch (orc->type) { + case ORC_TYPE_CALL: + ip_p = sp - sizeof(long); + + if (!deref_stack_reg(state, ip_p, &state->ip)) + goto done; + + state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, + state->ip, (void *)ip_p); + + state->sp = sp; + state->regs = NULL; + state->signal = false; + break; + + case ORC_TYPE_REGS: + if (!deref_stack_regs(state, sp, &state->ip, &state->sp, true)) { + orc_warn("can't dereference registers at %p for ip %p\n", + (void *)sp, (void *)orig_ip); + goto done; + } + + state->regs = (struct pt_regs *)sp; + state->full_regs = true; + state->signal = true; + break; + + case ORC_TYPE_REGS_IRET: + if (!deref_stack_regs(state, sp, &state->ip, &state->sp, false)) { + orc_warn("can't dereference iret registers at %p for ip %p\n", + (void *)sp, (void *)orig_ip); + goto done; + } + + ptregs = container_of((void *)sp, struct pt_regs, ip); + if ((unsigned long)ptregs >= prev_sp && + on_stack(&state->stack_info, ptregs, REGS_SIZE)) { + state->regs = ptregs; + state->full_regs = false; + } else + state->regs = NULL; + + state->signal = true; + break; + + default: + orc_warn("unknown .orc_unwind entry type %d\n", orc->type); + break; + } + + /* Find BP: */ + switch (orc->bp_reg) { + case ORC_REG_UNDEFINED: + if (state->regs && state->full_regs) + state->bp = state->regs->bp; + break; + + case ORC_REG_PREV_SP: + if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp)) + goto done; + break; + + case ORC_REG_BP: + if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp)) + goto done; + break; + + default: + orc_warn("unknown BP base reg %d for ip %p\n", + orc->bp_reg, (void *)orig_ip); + goto done; + } + + /* Prevent a recursive loop due to bad ORC data: */ + if (state->stack_info.type == prev_type && + on_stack(&state->stack_info, (void *)state->sp, sizeof(long)) && + state->sp <= prev_sp) { + orc_warn("stack going in the wrong direction? ip=%p\n", + (void *)orig_ip); + goto done; + } + + preempt_enable(); + return true; + +done: + preempt_enable(); + state->stack_info.type = STACK_TYPE_UNKNOWN; + return false; +} +EXPORT_SYMBOL_GPL(unwind_next_frame); + +void __unwind_start(struct unwind_state *state, struct task_struct *task, + struct pt_regs *regs, unsigned long *first_frame) +{ + memset(state, 0, sizeof(*state)); + state->task = task; + + /* + * Refuse to unwind the stack of a task while it's executing on another + * CPU. This check is racy, but that's ok: the unwinder has other + * checks to prevent it from going off the rails. + */ + if (task_on_another_cpu(task)) + goto done; + + if (regs) { + if (user_mode(regs)) + goto done; + + state->ip = regs->ip; + state->sp = kernel_stack_pointer(regs); + state->bp = regs->bp; + state->regs = regs; + state->full_regs = true; + state->signal = true; + + } else if (task == current) { + asm volatile("lea (%%rip), %0\n\t" + "mov %%rsp, %1\n\t" + "mov %%rbp, %2\n\t" + : "=r" (state->ip), "=r" (state->sp), + "=r" (state->bp)); + + } else { + struct inactive_task_frame *frame = (void *)task->thread.sp; + + state->sp = task->thread.sp; + state->bp = READ_ONCE_NOCHECK(frame->bp); + state->ip = READ_ONCE_NOCHECK(frame->ret_addr); + } + + if (get_stack_info((unsigned long *)state->sp, state->task, + &state->stack_info, &state->stack_mask)) + return; + + /* + * The caller can provide the address of the first frame directly + * (first_frame) or indirectly (regs->sp) to indicate which stack frame + * to start unwinding at. Skip ahead until we reach it. + */ + + /* When starting from regs, skip the regs frame: */ + if (regs) { + unwind_next_frame(state); + return; + } + + /* Otherwise, skip ahead to the user-specified starting frame: */ + while (!unwind_done(state) && + (!on_stack(&state->stack_info, first_frame, sizeof(long)) || + state->sp <= (unsigned long)first_frame)) + unwind_next_frame(state); + + return; + +done: + state->stack_info.type = STACK_TYPE_UNKNOWN; + return; +} +EXPORT_SYMBOL_GPL(__unwind_start); diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index c8a3b61be0aa..f05f00acac89 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -24,6 +24,7 @@ #include <asm/asm-offsets.h> #include <asm/thread_info.h> #include <asm/page_types.h> +#include <asm/orc_lookup.h> #include <asm/cache.h> #include <asm/boot.h> @@ -148,6 +149,8 @@ SECTIONS BUG_TABLE + ORC_UNWIND_TABLE + . = ALIGN(PAGE_SIZE); __vvar_page = .; diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 0ea8afcb929c..fb2ddcdf7c73 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -142,7 +142,7 @@ void __init early_fixup_exception(struct pt_regs *regs, int trapnr) * undefined. I'm not sure which CPUs do this, but at least * the 486 DX works this way. */ - if ((regs->cs & 0xFFFF) != __KERNEL_CS) + if (regs->cs != __KERNEL_CS) goto fail; /* diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h index 7ef015eb3403..b4531e3b2120 100644 --- a/include/asm-generic/io.h +++ b/include/asm-generic/io.h @@ -915,6 +915,9 @@ extern void ioport_unmap(void __iomem *p); #endif /* CONFIG_GENERIC_IOMAP */ #endif /* CONFIG_HAS_IOPORT_MAP */ +/* + * Convert a virtual cached pointer to an uncached pointer + */ #ifndef xlate_dev_kmem_ptr #define xlate_dev_kmem_ptr xlate_dev_kmem_ptr static inline void *xlate_dev_kmem_ptr(void *addr) @@ -954,6 +957,14 @@ static inline void *bus_to_virt(unsigned long address) #ifndef memset_io #define memset_io memset_io +/** + * memset_io Set a range of I/O memory to a constant value + * @addr: The beginning of the I/O-memory range to set + * @val: The value to set the memory to + * @count: The number of bytes to set + * + * Set a range of I/O memory to a given value. + */ static inline void memset_io(volatile void __iomem *addr, int value, size_t size) { @@ -963,6 +974,14 @@ static inline void memset_io(volatile void __iomem *addr, int value, #ifndef memcpy_fromio #define memcpy_fromio memcpy_fromio +/** + * memcpy_fromio Copy a block of data from I/O memory + * @dst: The (RAM) destination for the copy + * @src: The (I/O memory) source for the data + * @count: The number of bytes to copy + * + * Copy a block of data from I/O memory. + */ static inline void memcpy_fromio(void *buffer, const volatile void __iomem *addr, size_t size) @@ -973,6 +992,14 @@ static inline void memcpy_fromio(void *buffer, #ifndef memcpy_toio #define memcpy_toio memcpy_toio +/** + * memcpy_toio Copy a block of data into I/O memory + * @dst: The (I/O memory) destination for the copy + * @src: The (RAM) source for the data + * @count: The number of bytes to copy + * + * Copy a block of data to I/O memory. + */ static inline void memcpy_toio(volatile void __iomem *addr, const void *buffer, size_t size) { diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index da0be9a8d1de..fffc9bdae025 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -680,6 +680,31 @@ #define BUG_TABLE #endif +#ifdef CONFIG_ORC_UNWINDER +#define ORC_UNWIND_TABLE \ + . = ALIGN(4); \ + .orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__start_orc_unwind_ip) = .; \ + KEEP(*(.orc_unwind_ip)) \ + VMLINUX_SYMBOL(__stop_orc_unwind_ip) = .; \ + } \ + . = ALIGN(6); \ + .orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(__start_orc_unwind) = .; \ + KEEP(*(.orc_unwind)) \ + VMLINUX_SYMBOL(__stop_orc_unwind) = .; \ + } \ + . = ALIGN(4); \ + .orc_lookup : AT(ADDR(.orc_lookup) - LOAD_OFFSET) { \ + VMLINUX_SYMBOL(orc_lookup) = .; \ + . += (((SIZEOF(.text) + LOOKUP_BLOCK_SIZE - 1) / \ + LOOKUP_BLOCK_SIZE) + 1) * 4; \ + VMLINUX_SYMBOL(orc_lookup_end) = .; \ + } +#else +#define ORC_UNWIND_TABLE +#endif + #ifdef CONFIG_PM_TRACE #define TRACEDATA \ . = ALIGN(4); \ @@ -866,7 +891,7 @@ DATA_DATA \ CONSTRUCTORS \ } \ - BUG_TABLE + BUG_TABLE \ #define INIT_TEXT_SECTION(inittext_align) \ . = ALIGN(inittext_align); \ diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index bdb80c4aef6e..310f51d42550 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -201,17 +201,6 @@ #endif #endif -#ifdef CONFIG_STACK_VALIDATION -#define annotate_unreachable() ({ \ - asm("%c0:\t\n" \ - ".pushsection .discard.unreachable\t\n" \ - ".long %c0b - .\t\n" \ - ".popsection\t\n" : : "i" (__LINE__)); \ -}) -#else -#define annotate_unreachable() -#endif - /* * Mark a position in code as unreachable. This can be used to * suppress control flow warnings after asm blocks that transfer diff --git a/include/linux/compiler.h b/include/linux/compiler.h index eca8ad75e28b..109b1460ecee 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -185,8 +185,34 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, #endif /* Unreachable code */ +#ifdef CONFIG_STACK_VALIDATION +#define annotate_reachable() ({ \ + asm("%c0:\n\t" \ + ".pushsection .discard.reachable\n\t" \ + ".long %c0b - .\n\t" \ + ".popsection\n\t" : : "i" (__LINE__)); \ +}) +#define annotate_unreachable() ({ \ + asm("%c0:\n\t" \ + ".pushsection .discard.unreachable\n\t" \ + ".long %c0b - .\n\t" \ + ".popsection\n\t" : : "i" (__LINE__)); \ +}) +#define ASM_UNREACHABLE \ + "999:\n\t" \ + ".pushsection .discard.unreachable\n\t" \ + ".long 999b - .\n\t" \ + ".popsection\n\t" +#else +#define annotate_reachable() +#define annotate_unreachable() +#endif + +#ifndef ASM_UNREACHABLE +# define ASM_UNREACHABLE +#endif #ifndef unreachable -# define unreachable() do { } while (1) +# define unreachable() do { annotate_reachable(); do { } while (1); } while (0) #endif /* diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 98fe715522e8..32a48e739e26 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -374,6 +374,9 @@ config STACK_VALIDATION pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure that runtime stack traces are more reliable. + This is also a prerequisite for generation of ORC unwind data, which + is needed for CONFIG_ORC_UNWINDER. + For more information, see tools/objtool/Documentation/stack-validation.txt. @@ -1121,7 +1124,7 @@ config LOCKDEP bool depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT select STACKTRACE - select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE + select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE && !ARC && !SCORE && !X86 select KALLSYMS select KALLSYMS_ALL @@ -1540,7 +1543,7 @@ config FAULT_INJECTION_STACKTRACE_FILTER depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT depends on !X86_64 select STACKTRACE - select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE + select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !SCORE && !X86 help Provide stacktrace filter for fault-injection capabilities @@ -1549,7 +1552,7 @@ config LATENCYTOP depends on DEBUG_KERNEL depends on STACKTRACE_SUPPORT depends on PROC_FS - select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC + select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND && !ARC && !X86 select KALLSYMS select KALLSYMS_ALL select STACKTRACE diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 4a9a2cec0a1b..80ed14809a05 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -258,10 +258,14 @@ ifneq ($(SKIP_STACK_VALIDATION),1) __objtool_obj := $(objtree)/tools/objtool/objtool -objtool_args = check +objtool_args = $(if $(CONFIG_ORC_UNWINDER),orc generate,check) + ifndef CONFIG_FRAME_POINTER objtool_args += --no-fp endif +ifdef CONFIG_GCOV_KERNEL +objtool_args += --no-unreachable +endif # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file @@ -276,6 +280,11 @@ objtool_obj = $(if $(patsubst y%,, \ endif # SKIP_STACK_VALIDATION endif # CONFIG_STACK_VALIDATION +# Rebuild all objects when objtool changes, or is enabled/disabled. +objtool_dep = $(objtool_obj) \ + $(wildcard include/config/orc/unwinder.h \ + include/config/stack/validation.h) + define rule_cc_o_c $(call echo-cmd,checksrc) $(cmd_checksrc) \ $(call cmd_and_fixdep,cc_o_c) \ @@ -298,13 +307,13 @@ cmd_undef_syms = echo endif # Built-in and composite module parts -$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE +$(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE $(call cmd,force_checksrc) $(call if_changed_rule,cc_o_c) # Single-part modules are special since we need to mark them in $(MODVERDIR) -$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_obj) FORCE +$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE $(call cmd,force_checksrc) $(call if_changed_rule,cc_o_c) @{ echo $(@:.o=.ko); echo $@; \ @@ -399,7 +408,7 @@ cmd_modversions_S = \ endif endif -$(obj)/%.o: $(src)/%.S $(objtool_obj) FORCE +$(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE $(call if_changed_rule,as_o_S) targets += $(real-objs-y) $(real-objs-m) $(lib-y) diff --git a/tools/objtool/Build b/tools/objtool/Build index 6f2e1987c4d9..749becdf5b90 100644 --- a/tools/objtool/Build +++ b/tools/objtool/Build @@ -1,6 +1,9 @@ objtool-y += arch/$(SRCARCH)/ objtool-y += builtin-check.o +objtool-y += builtin-orc.o objtool-y += check.o +objtool-y += orc_gen.o +objtool-y += orc_dump.o objtool-y += elf.o objtool-y += special.o objtool-y += objtool.o diff --git a/tools/objtool/Documentation/stack-validation.txt b/tools/objtool/Documentation/stack-validation.txt index 17c1195f11f4..6a1af43862df 100644 --- a/tools/objtool/Documentation/stack-validation.txt +++ b/tools/objtool/Documentation/stack-validation.txt @@ -11,9 +11,6 @@ analyzes every .o file and ensures the validity of its stack metadata. It enforces a set of rules on asm code and C inline assembly code so that stack traces can be reliable. -Currently it only checks frame pointer usage, but there are plans to add -CFI validation for C files and CFI generation for asm files. - For each function, it recursively follows all possible code paths and validates the correct frame pointer state at each instruction. @@ -23,6 +20,10 @@ alternative execution paths to a given instruction (or set of instructions). Similarly, it knows how to follow switch statements, for which gcc sometimes uses jump tables. +(Objtool also has an 'orc generate' subcommand which generates debuginfo +for the ORC unwinder. See Documentation/x86/orc-unwinder.txt in the +kernel tree for more details.) + Why do we need stack metadata validation? ----------------------------------------- @@ -93,37 +94,14 @@ a) More reliable stack traces for frame pointer enabled kernels or at the very end of the function after the stack frame has been destroyed. This is an inherent limitation of frame pointers. -b) 100% reliable stack traces for DWARF enabled kernels - - (NOTE: This is not yet implemented) - - As an alternative to frame pointers, DWARF Call Frame Information - (CFI) metadata can be used to walk the stack. Unlike frame pointers, - CFI metadata is out of band. So it doesn't affect runtime - performance and it can be reliable even when interrupts or exceptions - are involved. - - For C code, gcc automatically generates DWARF CFI metadata. But for - asm code, generating CFI is a tedious manual approach which requires - manually placed .cfi assembler macros to be scattered throughout the - code. It's clumsy and very easy to get wrong, and it makes the real - code harder to read. - - Stacktool will improve this situation in several ways. For code - which already has CFI annotations, it will validate them. For code - which doesn't have CFI annotations, it will generate them. So an - architecture can opt to strip out all the manual .cfi annotations - from their asm code and have objtool generate them instead. +b) ORC (Oops Rewind Capability) unwind table generation - We might also add a runtime stack validation debug option where we - periodically walk the stack from schedule() and/or an NMI to ensure - that the stack metadata is sane and that we reach the bottom of the - stack. + An alternative to frame pointers and DWARF, ORC unwind data can be + used to walk the stack. Unlike frame pointers, ORC data is out of + band. So it doesn't affect runtime performance and it can be + reliable even when interrupts or exceptions are involved. - So the benefit of objtool here will be that external tooling should - always show perfect stack traces. And the same will be true for - kernel warning/oops traces if the architecture has a runtime DWARF - unwinder. + For more details, see Documentation/x86/orc-unwinder.txt. c) Higher live patching compatibility rate @@ -211,7 +189,7 @@ they mean, and suggestions for how to fix them. function, add proper frame pointer logic using the FRAME_BEGIN and FRAME_END macros. Otherwise, if it's not a callable function, remove its ELF function annotation by changing ENDPROC to END, and instead - use the manual CFI hint macros in asm/undwarf.h. + use the manual unwind hint macros in asm/unwind_hints.h. If it's a GCC-compiled .c file, the error may be because the function uses an inline asm() statement which has a "call" instruction. An @@ -231,8 +209,8 @@ they mean, and suggestions for how to fix them. If the error is for an asm file, and the instruction is inside (or reachable from) a callable function, the function should be annotated with the ENTRY/ENDPROC macros (ENDPROC is the important one). - Otherwise, the code should probably be annotated with the CFI hint - macros in asm/undwarf.h so objtool and the unwinder can know the + Otherwise, the code should probably be annotated with the unwind hint + macros in asm/unwind_hints.h so objtool and the unwinder can know the stack state associated with the code. If you're 100% sure the code won't affect stack traces, or if you're @@ -258,7 +236,7 @@ they mean, and suggestions for how to fix them. instructions aren't allowed in a callable function, and are most likely part of the kernel entry code. They should usually not have the callable function annotation (ENDPROC) and should always be - annotated with the CFI hint macros in asm/undwarf.h. + annotated with the unwind hint macros in asm/unwind_hints.h. 6. file.o: warning: objtool: func()+0x26: sibling call from callable instruction with modified stack frame @@ -272,7 +250,7 @@ they mean, and suggestions for how to fix them. If the instruction is not actually in a callable function (e.g. kernel entry code), change ENDPROC to END and annotate manually with - the CFI hint macros in asm/undwarf.h. + the unwind hint macros in asm/unwind_hints.h. 7. file: warning: objtool: func()+0x5c: stack state mismatch @@ -288,8 +266,8 @@ they mean, and suggestions for how to fix them. Another possibility is that the code has some asm or inline asm which does some unusual things to the stack or the frame pointer. In such - cases it's probably appropriate to use the CFI hint macros in - asm/undwarf.h. + cases it's probably appropriate to use the unwind hint macros in + asm/unwind_hints.h. 8. file.o: warning: objtool: funcA() falls through to next function funcB() diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile index 0e2765e243c0..6976c73e60c4 100644 --- a/tools/objtool/Makefile +++ b/tools/objtool/Makefile @@ -25,7 +25,8 @@ OBJTOOL_IN := $(OBJTOOL)-in.o all: $(OBJTOOL) INCLUDES := -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi -CFLAGS += -Wall -Werror $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -fomit-frame-pointer -O2 -g $(INCLUDES) +WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed +CFLAGS += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES) LDFLAGS += -lelf $(LIBSUBCMD) # Allow old libelf to be used: @@ -52,6 +53,9 @@ $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN) diff -I'^#include' arch/x86/insn/inat.h ../../arch/x86/include/asm/inat.h >/dev/null && \ diff -I'^#include' arch/x86/insn/inat_types.h ../../arch/x86/include/asm/inat_types.h >/dev/null) \ || echo "warning: objtool: x86 instruction decoder differs from kernel" >&2 )) || true + @(test -d ../../kernel -a -d ../../tools -a -d ../objtool && (( \ + diff ../../arch/x86/include/asm/orc_types.h orc_types.h >/dev/null) \ + || echo "warning: objtool: orc_types.h differs from kernel" >&2 )) || true $(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@ diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h index 21aeca874edb..b0d7dc3d71b5 100644 --- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -31,8 +31,9 @@ #define INSN_RETURN 6 #define INSN_CONTEXT_SWITCH 7 #define INSN_STACK 8 -#define INSN_NOP 9 -#define INSN_OTHER 10 +#define INSN_BUG 9 +#define INSN_NOP 10 +#define INSN_OTHER 11 #define INSN_LAST INSN_OTHER enum op_dest_type { diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index a36c2eba64e7..7841e5d31973 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -271,7 +271,7 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, case 0x8d: if (rex == 0x48 && modrm == 0x65) { - /* lea -disp(%rbp), %rsp */ + /* lea disp(%rbp), %rsp */ *type = INSN_STACK; op->src.type = OP_SRC_ADD; op->src.reg = CFI_BP; @@ -281,6 +281,30 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, break; } + if (rex == 0x48 && (modrm == 0xa4 || modrm == 0x64) && + sib == 0x24) { + + /* lea disp(%rsp), %rsp */ + *type = INSN_STACK; + op->src.type = OP_SRC_ADD; + op->src.reg = CFI_SP; + op->src.offset = insn.displacement.value; + op->dest.type = OP_DEST_REG; + op->dest.reg = CFI_SP; + break; + } + + if (rex == 0x48 && modrm == 0x2c && sib == 0x24) { + + /* lea (%rsp), %rbp */ + *type = INSN_STACK; + op->src.type = OP_SRC_REG; + op->src.reg = CFI_SP; + op->dest.type = OP_DEST_REG; + op->dest.reg = CFI_BP; + break; + } + if (rex == 0x4c && modrm == 0x54 && sib == 0x24 && insn.displacement.value == 8) { @@ -382,20 +406,27 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, case 0x0f: - if (op2 >= 0x80 && op2 <= 0x8f) + if (op2 >= 0x80 && op2 <= 0x8f) { + *type = INSN_JUMP_CONDITIONAL; - else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 || - op2 == 0x35) + + } else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 || + op2 == 0x35) { /* sysenter, sysret */ *type = INSN_CONTEXT_SWITCH; - else if (op2 == 0x0d || op2 == 0x1f) + } else if (op2 == 0x0b || op2 == 0xb9) { + + /* ud2 */ + *type = INSN_BUG; + + } else if (op2 == 0x0d || op2 == 0x1f) { /* nopl/nopw */ *type = INSN_NOP; - else if (op2 == 0xa0 || op2 == 0xa8) { + } else if (op2 == 0xa0 || op2 == 0xa8) { /* push fs/gs */ *type = INSN_STACK; diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index 365c34ecab26..57254f5b2779 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -29,7 +29,7 @@ #include "builtin.h" #include "check.h" -bool nofp; +bool no_fp, no_unreachable; static const char * const check_usage[] = { "objtool check [<options>] file.o", @@ -37,7 +37,8 @@ static const char * const check_usage[] = { }; const struct option check_options[] = { - OPT_BOOLEAN('f', "no-fp", &nofp, "Skip frame pointer validation"), + OPT_BOOLEAN('f', "no-fp", &no_fp, "Skip frame pointer validation"), + OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"), OPT_END(), }; @@ -52,5 +53,5 @@ int cmd_check(int argc, const char **argv) objname = argv[0]; - return check(objname, nofp); + return check(objname, no_fp, no_unreachable, false); } diff --git a/tools/objtool/builtin-orc.c b/tools/objtool/builtin-orc.c new file mode 100644 index 000000000000..4c6b5c9ef073 --- /dev/null +++ b/tools/objtool/builtin-orc.c @@ -0,0 +1,70 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +/* + * objtool orc: + * + * This command analyzes a .o file and adds .orc_unwind and .orc_unwind_ip + * sections to it, which is used by the in-kernel ORC unwinder. + * + * This command is a superset of "objtool check". + */ + +#include <string.h> +#include <subcmd/parse-options.h> +#include "builtin.h" +#include "check.h" + + +static const char *orc_usage[] = { + "objtool orc generate [<options>] file.o", + "objtool orc dump file.o", + NULL, +}; + +extern const struct option check_options[]; +extern bool no_fp, no_unreachable; + +int cmd_orc(int argc, const char **argv) +{ + const char *objname; + + argc--; argv++; + if (!strncmp(argv[0], "gen", 3)) { + argc = parse_options(argc, argv, check_options, orc_usage, 0); + if (argc != 1) + usage_with_options(orc_usage, check_options); + + objname = argv[0]; + + return check(objname, no_fp, no_unreachable, true); + + } + + if (!strcmp(argv[0], "dump")) { + if (argc != 2) + usage_with_options(orc_usage, check_options); + + objname = argv[1]; + + return orc_dump(objname); + } + + usage_with_options(orc_usage, check_options); + + return 0; +} diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h index 34d2ba78a616..dd526067fed5 100644 --- a/tools/objtool/builtin.h +++ b/tools/objtool/builtin.h @@ -18,5 +18,6 @@ #define _BUILTIN_H extern int cmd_check(int argc, const char **argv); +extern int cmd_orc(int argc, const char **argv); #endif /* _BUILTIN_H */ diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 2c6d74880403..4f0c4aea8f6f 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -33,11 +33,11 @@ struct alternative { }; const char *objname; -static bool nofp; +static bool no_fp; struct cfi_state initial_func_cfi; -static struct instruction *find_insn(struct objtool_file *file, - struct section *sec, unsigned long offset) +struct instruction *find_insn(struct objtool_file *file, + struct section *sec, unsigned long offset) { struct instruction *insn; @@ -59,19 +59,6 @@ static struct instruction *next_insn_same_sec(struct objtool_file *file, return next; } -static bool gcov_enabled(struct objtool_file *file) -{ - struct section *sec; - struct symbol *sym; - - for_each_sec(file, sec) - list_for_each_entry(sym, &sec->symbol_list, list) - if (!strncmp(sym->name, "__gcov_.", 8)) - return true; - - return false; -} - #define func_for_each_insn(file, func, insn) \ for (insn = find_insn(file, func->sec, func->offset); \ insn && &insn->list != &file->insn_list && \ @@ -100,7 +87,6 @@ static bool gcov_enabled(struct objtool_file *file) static bool ignore_func(struct objtool_file *file, struct symbol *func) { struct rela *rela; - struct instruction *insn; /* check for STACK_FRAME_NON_STANDARD */ if (file->whitelist && file->whitelist->rela) @@ -113,11 +99,6 @@ static bool ignore_func(struct objtool_file *file, struct symbol *func) return true; } - /* check if it has a context switching instruction */ - func_for_each_insn(file, func, insn) - if (insn->type == INSN_CONTEXT_SWITCH) - return true; - return false; } @@ -259,6 +240,11 @@ static int decode_instructions(struct objtool_file *file) if (!(sec->sh.sh_flags & SHF_EXECINSTR)) continue; + if (strcmp(sec->name, ".altinstr_replacement") && + strcmp(sec->name, ".altinstr_aux") && + strncmp(sec->name, ".discard.", 9)) + sec->text = true; + for (offset = 0; offset < sec->len; offset += insn->len) { insn = malloc(sizeof(*insn)); if (!insn) { @@ -310,7 +296,7 @@ static int decode_instructions(struct objtool_file *file) } /* - * Find all uses of the unreachable() macro, which are code path dead ends. + * Mark "ud2" instructions and manually annotated dead ends. */ static int add_dead_ends(struct objtool_file *file) { @@ -319,9 +305,20 @@ static int add_dead_ends(struct objtool_file *file) struct instruction *insn; bool found; + /* + * By default, "ud2" is a dead end unless otherwise annotated, because + * GCC 7 inserts it for certain divide-by-zero cases. + */ + for_each_insn(file, insn) + if (insn->type == INSN_BUG) + insn->dead_end = true; + + /* + * Check for manually annotated dead ends. + */ sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); if (!sec) - return 0; + goto reachable; list_for_each_entry(rela, &sec->rela_list, list) { if (rela->sym->type != STT_SECTION) { @@ -354,6 +351,48 @@ static int add_dead_ends(struct objtool_file *file) insn->dead_end = true; } +reachable: + /* + * These manually annotated reachable checks are needed for GCC 4.4, + * where the Linux unreachable() macro isn't supported. In that case + * GCC doesn't know the "ud2" is fatal, so it generates code as if it's + * not a dead end. + */ + sec = find_section_by_name(file->elf, ".rela.discard.reachable"); + if (!sec) + return 0; + + list_for_each_entry(rela, &sec->rela_list, list) { + if (rela->sym->type != STT_SECTION) { + WARN("unexpected relocation symbol type in %s", sec->name); + return -1; + } + insn = find_insn(file, rela->sym->sec, rela->addend); + if (insn) + insn = list_prev_entry(insn, list); + else if (rela->addend == rela->sym->sec->len) { + found = false; + list_for_each_entry_reverse(insn, &file->insn_list, list) { + if (insn->sec == rela->sym->sec) { + found = true; + break; + } + } + + if (!found) { + WARN("can't find reachable insn at %s+0x%x", + rela->sym->sec->name, rela->addend); + return -1; + } + } else { + WARN("can't find reachable insn at %s+0x%x", + rela->sym->sec->name, rela->addend); + return -1; + } + + insn->dead_end = false; + } + return 0; } @@ -874,6 +913,99 @@ static int add_switch_table_alts(struct objtool_file *file) return 0; } +static int read_unwind_hints(struct objtool_file *file) +{ + struct section *sec, *relasec; + struct rela *rela; + struct unwind_hint *hint; + struct instruction *insn; + struct cfi_reg *cfa; + int i; + + sec = find_section_by_name(file->elf, ".discard.unwind_hints"); + if (!sec) + return 0; + + relasec = sec->rela; + if (!relasec) { + WARN("missing .rela.discard.unwind_hints section"); + return -1; + } + + if (sec->len % sizeof(struct unwind_hint)) { + WARN("struct unwind_hint size mismatch"); + return -1; + } + + file->hints = true; + + for (i = 0; i < sec->len / sizeof(struct unwind_hint); i++) { + hint = (struct unwind_hint *)sec->data->d_buf + i; + + rela = find_rela_by_dest(sec, i * sizeof(*hint)); + if (!rela) { + WARN("can't find rela for unwind_hints[%d]", i); + return -1; + } + + insn = find_insn(file, rela->sym->sec, rela->addend); + if (!insn) { + WARN("can't find insn for unwind_hints[%d]", i); + return -1; + } + + cfa = &insn->state.cfa; + + if (hint->type == UNWIND_HINT_TYPE_SAVE) { + insn->save = true; + continue; + + } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) { + insn->restore = true; + insn->hint = true; + continue; + } + + insn->hint = true; + + switch (hint->sp_reg) { + case ORC_REG_UNDEFINED: + cfa->base = CFI_UNDEFINED; + break; + case ORC_REG_SP: + cfa->base = CFI_SP; + break; + case ORC_REG_BP: + cfa->base = CFI_BP; + break; + case ORC_REG_SP_INDIRECT: + cfa->base = CFI_SP_INDIRECT; + break; + case ORC_REG_R10: + cfa->base = CFI_R10; + break; + case ORC_REG_R13: + cfa->base = CFI_R13; + break; + case ORC_REG_DI: + cfa->base = CFI_DI; + break; + case ORC_REG_DX: + cfa->base = CFI_DX; + break; + default: + WARN_FUNC("unsupported unwind_hint sp base reg %d", + insn->sec, insn->offset, hint->sp_reg); + return -1; + } + + cfa->offset = hint->sp_offset; + insn->state.type = hint->type; + } + + return 0; +} + static int decode_sections(struct objtool_file *file) { int ret; @@ -904,6 +1036,10 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; + ret = read_unwind_hints(file); + if (ret) + return ret; + return 0; } @@ -947,6 +1083,30 @@ static bool has_valid_stack_frame(struct insn_state *state) return false; } +static int update_insn_state_regs(struct instruction *insn, struct insn_state *state) +{ + struct cfi_reg *cfa = &state->cfa; + struct stack_op *op = &insn->stack_op; + + if (cfa->base != CFI_SP) + return 0; + + /* push */ + if (op->dest.type == OP_DEST_PUSH) + cfa->offset += 8; + + /* pop */ + if (op->src.type == OP_SRC_POP) + cfa->offset -= 8; + + /* add immediate to sp */ + if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD && + op->dest.reg == CFI_SP && op->src.reg == CFI_SP) + cfa->offset -= op->src.offset; + + return 0; +} + static void save_reg(struct insn_state *state, unsigned char reg, int base, int offset) { @@ -1032,6 +1192,9 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) return 0; } + if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET) + return update_insn_state_regs(insn, state); + switch (op->dest.type) { case OP_DEST_REG: @@ -1051,7 +1214,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) regs[CFI_BP].base = CFI_BP; regs[CFI_BP].offset = -state->stack_size; state->bp_scratch = false; - } else if (!nofp) { + } else if (!no_fp) { WARN_FUNC("unknown stack-related register move", insn->sec, insn->offset); @@ -1222,7 +1385,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) } /* detect when asm code uses rbp as a scratch register */ - if (!nofp && insn->func && op->src.reg == CFI_BP && + if (!no_fp && insn->func && op->src.reg == CFI_BP && cfa->base != CFI_BP) state->bp_scratch = true; break; @@ -1323,6 +1486,10 @@ static bool insn_state_match(struct instruction *insn, struct insn_state *state) break; } + } else if (state1->type != state2->type) { + WARN_FUNC("stack state mismatch: type1=%d type2=%d", + insn->sec, insn->offset, state1->type, state2->type); + } else if (state1->drap != state2->drap || (state1->drap && state1->drap_reg != state2->drap_reg)) { WARN_FUNC("stack state mismatch: drap1=%d(%d) drap2=%d(%d)", @@ -1346,7 +1513,7 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, struct insn_state state) { struct alternative *alt; - struct instruction *insn; + struct instruction *insn, *next_insn; struct section *sec; struct symbol *func = NULL; int ret; @@ -1361,6 +1528,8 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, } while (1) { + next_insn = next_insn_same_sec(file, insn); + if (file->c_file && insn->func) { if (func && func != insn->func) { WARN("%s() falls through to next function %s()", @@ -1378,13 +1547,54 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, } if (insn->visited) { - if (!!insn_state_match(insn, &state)) + if (!insn->hint && !insn_state_match(insn, &state)) return 1; return 0; } - insn->state = state; + if (insn->hint) { + if (insn->restore) { + struct instruction *save_insn, *i; + + i = insn; + save_insn = NULL; + func_for_each_insn_continue_reverse(file, func, i) { + if (i->save) { + save_insn = i; + break; + } + } + + if (!save_insn) { + WARN_FUNC("no corresponding CFI save for CFI restore", + sec, insn->offset); + return 1; + } + + if (!save_insn->visited) { + /* + * Oops, no state to copy yet. + * Hopefully we can reach this + * instruction from another branch + * after the save insn has been + * visited. + */ + if (insn == first) + return 0; + + WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo", + sec, insn->offset); + return 1; + } + + insn->state = save_insn->state; + } + + state = insn->state; + + } else + insn->state = state; insn->visited = true; @@ -1423,7 +1633,7 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, /* fallthrough */ case INSN_CALL_DYNAMIC: - if (!nofp && func && !has_valid_stack_frame(&state)) { + if (!no_fp && func && !has_valid_stack_frame(&state)) { WARN_FUNC("call without frame pointer save/setup", sec, insn->offset); return 1; @@ -1461,6 +1671,14 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, return 0; + case INSN_CONTEXT_SWITCH: + if (func && (!next_insn || !next_insn->hint)) { + WARN_FUNC("unsupported instruction in callable function", + sec, insn->offset); + return 1; + } + return 0; + case INSN_STACK: if (update_insn_state(insn, &state)) return -1; @@ -1474,7 +1692,7 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, if (insn->dead_end) return 0; - insn = next_insn_same_sec(file, insn); + insn = next_insn; if (!insn) { WARN("%s: unexpected end of section", sec->name); return 1; @@ -1484,6 +1702,27 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, return 0; } +static int validate_unwind_hints(struct objtool_file *file) +{ + struct instruction *insn; + int ret, warnings = 0; + struct insn_state state; + + if (!file->hints) + return 0; + + clear_insn_state(&state); + + for_each_insn(file, insn) { + if (insn->hint && !insn->visited) { + ret = validate_branch(file, insn, state); + warnings += ret; + } + } + + return warnings; +} + static bool is_kasan_insn(struct instruction *insn) { return (insn->type == INSN_CALL && @@ -1507,8 +1746,13 @@ static bool ignore_unreachable_insn(struct instruction *insn) /* * Ignore any unused exceptions. This can happen when a whitelisted * function has an exception table entry. + * + * Also ignore alternative replacement instructions. This can happen + * when a whitelisted function uses one of the ALTERNATIVE macros. */ - if (!strcmp(insn->sec->name, ".fixup")) + if (!strcmp(insn->sec->name, ".fixup") || + !strcmp(insn->sec->name, ".altinstr_replacement") || + !strcmp(insn->sec->name, ".altinstr_aux")) return true; /* @@ -1580,15 +1824,6 @@ static int validate_reachable_instructions(struct objtool_file *file) if (insn->visited || ignore_unreachable_insn(insn)) continue; - /* - * gcov produces a lot of unreachable instructions. If we get - * an unreachable warning and the file has gcov enabled, just - * ignore it, and all other such warnings for the file. Do - * this here because this is an expensive function. - */ - if (gcov_enabled(file)) - return 0; - WARN_FUNC("unreachable instruction", insn->sec, insn->offset); return 1; } @@ -1613,15 +1848,15 @@ static void cleanup(struct objtool_file *file) elf_close(file->elf); } -int check(const char *_objname, bool _nofp) +int check(const char *_objname, bool _no_fp, bool no_unreachable, bool orc) { struct objtool_file file; int ret, warnings = 0; objname = _objname; - nofp = _nofp; + no_fp = _no_fp; - file.elf = elf_open(objname); + file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY); if (!file.elf) return 1; @@ -1629,8 +1864,9 @@ int check(const char *_objname, bool _nofp) hash_init(file.insn_hash); file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard"); file.rodata = find_section_by_name(file.elf, ".rodata"); - file.ignore_unreachables = false; file.c_file = find_section_by_name(file.elf, ".comment"); + file.ignore_unreachables = no_unreachable; + file.hints = false; arch_initial_func_cfi_state(&initial_func_cfi); @@ -1647,6 +1883,11 @@ int check(const char *_objname, bool _nofp) goto out; warnings += ret; + ret = validate_unwind_hints(&file); + if (ret < 0) + goto out; + warnings += ret; + if (!warnings) { ret = validate_reachable_instructions(&file); if (ret < 0) @@ -1654,6 +1895,20 @@ int check(const char *_objname, bool _nofp) warnings += ret; } + if (orc) { + ret = create_orc(&file); + if (ret < 0) + goto out; + + ret = create_orc_sections(&file); + if (ret < 0) + goto out; + + ret = elf_write(file.elf); + if (ret < 0) + goto out; + } + out: cleanup(&file); diff --git a/tools/objtool/check.h b/tools/objtool/check.h index da85f5b00ec6..c9af11f0c8af 100644 --- a/tools/objtool/check.h +++ b/tools/objtool/check.h @@ -22,12 +22,14 @@ #include "elf.h" #include "cfi.h" #include "arch.h" +#include "orc.h" #include <linux/hashtable.h> struct insn_state { struct cfi_reg cfa; struct cfi_reg regs[CFI_NUM_REGS]; int stack_size; + unsigned char type; bool bp_scratch; bool drap; int drap_reg; @@ -41,13 +43,14 @@ struct instruction { unsigned int len; unsigned char type; unsigned long immediate; - bool alt_group, visited, dead_end, ignore; + bool alt_group, visited, dead_end, ignore, hint, save, restore; struct symbol *call_dest; struct instruction *jump_dest; struct list_head alts; struct symbol *func; struct stack_op stack_op; struct insn_state state; + struct orc_entry orc; }; struct objtool_file { @@ -55,12 +58,22 @@ struct objtool_file { struct list_head insn_list; DECLARE_HASHTABLE(insn_hash, 16); struct section *rodata, *whitelist; - bool ignore_unreachables, c_file; + bool ignore_unreachables, c_file, hints; }; -int check(const char *objname, bool nofp); +int check(const char *objname, bool no_fp, bool no_unreachable, bool orc); + +struct instruction *find_insn(struct objtool_file *file, + struct section *sec, unsigned long offset); #define for_each_insn(file, insn) \ list_for_each_entry(insn, &file->insn_list, list) +#define sec_for_each_insn(file, sec, insn) \ + for (insn = find_insn(file, sec, 0); \ + insn && &insn->list != &file->insn_list && \ + insn->sec == sec; \ + insn = list_next_entry(insn, list)) + + #endif /* _CHECK_H */ diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 1a7e8aa2af58..6e9f980a7d26 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -30,16 +30,6 @@ #include "elf.h" #include "warn.h" -/* - * Fallback for systems without this "read, mmaping if possible" cmd. - */ -#ifndef ELF_C_READ_MMAP -#define ELF_C_READ_MMAP ELF_C_READ -#endif - -#define WARN_ELF(format, ...) \ - WARN(format ": %s", ##__VA_ARGS__, elf_errmsg(-1)) - struct section *find_section_by_name(struct elf *elf, const char *name) { struct section *sec; @@ -349,9 +339,10 @@ static int read_relas(struct elf *elf) return 0; } -struct elf *elf_open(const char *name) +struct elf *elf_open(const char *name, int flags) { struct elf *elf; + Elf_Cmd cmd; elf_version(EV_CURRENT); @@ -364,13 +355,20 @@ struct elf *elf_open(const char *name) INIT_LIST_HEAD(&elf->sections); - elf->fd = open(name, O_RDONLY); + elf->fd = open(name, flags); if (elf->fd == -1) { perror("open"); goto err; } - elf->elf = elf_begin(elf->fd, ELF_C_READ_MMAP, NULL); + if ((flags & O_ACCMODE) == O_RDONLY) + cmd = ELF_C_READ_MMAP; + else if ((flags & O_ACCMODE) == O_RDWR) + cmd = ELF_C_RDWR; + else /* O_WRONLY */ + cmd = ELF_C_WRITE; + + elf->elf = elf_begin(elf->fd, cmd, NULL); if (!elf->elf) { WARN_ELF("elf_begin"); goto err; @@ -397,6 +395,194 @@ err: return NULL; } +struct section *elf_create_section(struct elf *elf, const char *name, + size_t entsize, int nr) +{ + struct section *sec, *shstrtab; + size_t size = entsize * nr; + struct Elf_Scn *s; + Elf_Data *data; + + sec = malloc(sizeof(*sec)); + if (!sec) { + perror("malloc"); + return NULL; + } + memset(sec, 0, sizeof(*sec)); + + INIT_LIST_HEAD(&sec->symbol_list); + INIT_LIST_HEAD(&sec->rela_list); + hash_init(sec->rela_hash); + hash_init(sec->symbol_hash); + + list_add_tail(&sec->list, &elf->sections); + + s = elf_newscn(elf->elf); + if (!s) { + WARN_ELF("elf_newscn"); + return NULL; + } + + sec->name = strdup(name); + if (!sec->name) { + perror("strdup"); + return NULL; + } + + sec->idx = elf_ndxscn(s); + sec->len = size; + sec->changed = true; + + sec->data = elf_newdata(s); + if (!sec->data) { + WARN_ELF("elf_newdata"); + return NULL; + } + + sec->data->d_size = size; + sec->data->d_align = 1; + + if (size) { + sec->data->d_buf = malloc(size); + if (!sec->data->d_buf) { + perror("malloc"); + return NULL; + } + memset(sec->data->d_buf, 0, size); + } + + if (!gelf_getshdr(s, &sec->sh)) { + WARN_ELF("gelf_getshdr"); + return NULL; + } + + sec->sh.sh_size = size; + sec->sh.sh_entsize = entsize; + sec->sh.sh_type = SHT_PROGBITS; + sec->sh.sh_addralign = 1; + sec->sh.sh_flags = SHF_ALLOC; + + + /* Add section name to .shstrtab */ + shstrtab = find_section_by_name(elf, ".shstrtab"); + if (!shstrtab) { + WARN("can't find .shstrtab section"); + return NULL; + } + + s = elf_getscn(elf->elf, shstrtab->idx); + if (!s) { + WARN_ELF("elf_getscn"); + return NULL; + } + + data = elf_newdata(s); + if (!data) { + WARN_ELF("elf_newdata"); + return NULL; + } + + data->d_buf = sec->name; + data->d_size = strlen(name) + 1; + data->d_align = 1; + + sec->sh.sh_name = shstrtab->len; + + shstrtab->len += strlen(name) + 1; + shstrtab->changed = true; + + return sec; +} + +struct section *elf_create_rela_section(struct elf *elf, struct section *base) +{ + char *relaname; + struct section *sec; + + relaname = malloc(strlen(base->name) + strlen(".rela") + 1); + if (!relaname) { + perror("malloc"); + return NULL; + } + strcpy(relaname, ".rela"); + strcat(relaname, base->name); + + sec = elf_create_section(elf, relaname, sizeof(GElf_Rela), 0); + if (!sec) + return NULL; + + base->rela = sec; + sec->base = base; + + sec->sh.sh_type = SHT_RELA; + sec->sh.sh_addralign = 8; + sec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx; + sec->sh.sh_info = base->idx; + sec->sh.sh_flags = SHF_INFO_LINK; + + return sec; +} + +int elf_rebuild_rela_section(struct section *sec) +{ + struct rela *rela; + int nr, idx = 0, size; + GElf_Rela *relas; + + nr = 0; + list_for_each_entry(rela, &sec->rela_list, list) + nr++; + + size = nr * sizeof(*relas); + relas = malloc(size); + if (!relas) { + perror("malloc"); + return -1; + } + + sec->data->d_buf = relas; + sec->data->d_size = size; + + sec->sh.sh_size = size; + + idx = 0; + list_for_each_entry(rela, &sec->rela_list, list) { + relas[idx].r_offset = rela->offset; + relas[idx].r_addend = rela->addend; + relas[idx].r_info = GELF_R_INFO(rela->sym->idx, rela->type); + idx++; + } + + return 0; +} + +int elf_write(struct elf *elf) +{ + struct section *sec; + Elf_Scn *s; + + list_for_each_entry(sec, &elf->sections, list) { + if (sec->changed) { + s = elf_getscn(elf->elf, sec->idx); + if (!s) { + WARN_ELF("elf_getscn"); + return -1; + } + if (!gelf_update_shdr (s, &sec->sh)) { + WARN_ELF("gelf_update_shdr"); + return -1; + } + } + } + + if (elf_update(elf->elf, ELF_C_WRITE) < 0) { + WARN_ELF("elf_update"); + return -1; + } + + return 0; +} + void elf_close(struct elf *elf) { struct section *sec, *tmpsec; diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index 343968b778cb..d86e2ff14466 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -28,6 +28,13 @@ # define elf_getshdrstrndx elf_getshstrndx #endif +/* + * Fallback for systems without this "read, mmaping if possible" cmd. + */ +#ifndef ELF_C_READ_MMAP +#define ELF_C_READ_MMAP ELF_C_READ +#endif + struct section { struct list_head list; GElf_Shdr sh; @@ -41,6 +48,7 @@ struct section { char *name; int idx; unsigned int len; + bool changed, text; }; struct symbol { @@ -75,7 +83,7 @@ struct elf { }; -struct elf *elf_open(const char *name); +struct elf *elf_open(const char *name, int flags); struct section *find_section_by_name(struct elf *elf, const char *name); struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset); struct symbol *find_symbol_containing(struct section *sec, unsigned long offset); @@ -83,6 +91,11 @@ struct rela *find_rela_by_dest(struct section *sec, unsigned long offset); struct rela *find_rela_by_dest_range(struct section *sec, unsigned long offset, unsigned int len); struct symbol *find_containing_func(struct section *sec, unsigned long offset); +struct section *elf_create_section(struct elf *elf, const char *name, size_t + entsize, int nr); +struct section *elf_create_rela_section(struct elf *elf, struct section *base); +int elf_rebuild_rela_section(struct section *sec); +int elf_write(struct elf *elf); void elf_close(struct elf *elf); #define for_each_sec(file, sec) \ diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c index ecc5b1b5d15d..31e0f9143840 100644 --- a/tools/objtool/objtool.c +++ b/tools/objtool/objtool.c @@ -42,10 +42,11 @@ struct cmd_struct { }; static const char objtool_usage_string[] = - "objtool [OPTIONS] COMMAND [ARGS]"; + "objtool COMMAND [ARGS]"; static struct cmd_struct objtool_cmds[] = { {"check", cmd_check, "Perform stack metadata validation on an object file" }, + {"orc", cmd_orc, "Generate in-place ORC unwind tables for an object file" }, }; bool help; diff --git a/tools/objtool/orc.h b/tools/objtool/orc.h new file mode 100644 index 000000000000..a4139e386ef3 --- /dev/null +++ b/tools/objtool/orc.h @@ -0,0 +1,30 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef _ORC_H +#define _ORC_H + +#include "orc_types.h" + +struct objtool_file; + +int create_orc(struct objtool_file *file); +int create_orc_sections(struct objtool_file *file); + +int orc_dump(const char *objname); + +#endif /* _ORC_H */ diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c new file mode 100644 index 000000000000..36c5bf6a2675 --- /dev/null +++ b/tools/objtool/orc_dump.c @@ -0,0 +1,212 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <unistd.h> +#include "orc.h" +#include "warn.h" + +static const char *reg_name(unsigned int reg) +{ + switch (reg) { + case ORC_REG_PREV_SP: + return "prevsp"; + case ORC_REG_DX: + return "dx"; + case ORC_REG_DI: + return "di"; + case ORC_REG_BP: + return "bp"; + case ORC_REG_SP: + return "sp"; + case ORC_REG_R10: + return "r10"; + case ORC_REG_R13: + return "r13"; + case ORC_REG_BP_INDIRECT: + return "bp(ind)"; + case ORC_REG_SP_INDIRECT: + return "sp(ind)"; + default: + return "?"; + } +} + +static const char *orc_type_name(unsigned int type) +{ + switch (type) { + case ORC_TYPE_CALL: + return "call"; + case ORC_TYPE_REGS: + return "regs"; + case ORC_TYPE_REGS_IRET: + return "iret"; + default: + return "?"; + } +} + +static void print_reg(unsigned int reg, int offset) +{ + if (reg == ORC_REG_BP_INDIRECT) + printf("(bp%+d)", offset); + else if (reg == ORC_REG_SP_INDIRECT) + printf("(sp%+d)", offset); + else if (reg == ORC_REG_UNDEFINED) + printf("(und)"); + else + printf("%s%+d", reg_name(reg), offset); +} + +int orc_dump(const char *_objname) +{ + int fd, nr_entries, i, *orc_ip = NULL, orc_size = 0; + struct orc_entry *orc = NULL; + char *name; + unsigned long nr_sections, orc_ip_addr = 0; + size_t shstrtab_idx; + Elf *elf; + Elf_Scn *scn; + GElf_Shdr sh; + GElf_Rela rela; + GElf_Sym sym; + Elf_Data *data, *symtab = NULL, *rela_orc_ip = NULL; + + + objname = _objname; + + elf_version(EV_CURRENT); + + fd = open(objname, O_RDONLY); + if (fd == -1) { + perror("open"); + return -1; + } + + elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); + if (!elf) { + WARN_ELF("elf_begin"); + return -1; + } + + if (elf_getshdrnum(elf, &nr_sections)) { + WARN_ELF("elf_getshdrnum"); + return -1; + } + + if (elf_getshdrstrndx(elf, &shstrtab_idx)) { + WARN_ELF("elf_getshdrstrndx"); + return -1; + } + + for (i = 0; i < nr_sections; i++) { + scn = elf_getscn(elf, i); + if (!scn) { + WARN_ELF("elf_getscn"); + return -1; + } + + if (!gelf_getshdr(scn, &sh)) { + WARN_ELF("gelf_getshdr"); + return -1; + } + + name = elf_strptr(elf, shstrtab_idx, sh.sh_name); + if (!name) { + WARN_ELF("elf_strptr"); + return -1; + } + + data = elf_getdata(scn, NULL); + if (!data) { + WARN_ELF("elf_getdata"); + return -1; + } + + if (!strcmp(name, ".symtab")) { + symtab = data; + } else if (!strcmp(name, ".orc_unwind")) { + orc = data->d_buf; + orc_size = sh.sh_size; + } else if (!strcmp(name, ".orc_unwind_ip")) { + orc_ip = data->d_buf; + orc_ip_addr = sh.sh_addr; + } else if (!strcmp(name, ".rela.orc_unwind_ip")) { + rela_orc_ip = data; + } + } + + if (!symtab || !orc || !orc_ip) + return 0; + + if (orc_size % sizeof(*orc) != 0) { + WARN("bad .orc_unwind section size"); + return -1; + } + + nr_entries = orc_size / sizeof(*orc); + for (i = 0; i < nr_entries; i++) { + if (rela_orc_ip) { + if (!gelf_getrela(rela_orc_ip, i, &rela)) { + WARN_ELF("gelf_getrela"); + return -1; + } + + if (!gelf_getsym(symtab, GELF_R_SYM(rela.r_info), &sym)) { + WARN_ELF("gelf_getsym"); + return -1; + } + + scn = elf_getscn(elf, sym.st_shndx); + if (!scn) { + WARN_ELF("elf_getscn"); + return -1; + } + + if (!gelf_getshdr(scn, &sh)) { + WARN_ELF("gelf_getshdr"); + return -1; + } + + name = elf_strptr(elf, shstrtab_idx, sh.sh_name); + if (!name || !*name) { + WARN_ELF("elf_strptr"); + return -1; + } + + printf("%s+%lx:", name, rela.r_addend); + + } else { + printf("%lx:", orc_ip_addr + (i * sizeof(int)) + orc_ip[i]); + } + + + printf(" sp:"); + + print_reg(orc[i].sp_reg, orc[i].sp_offset); + + printf(" bp:"); + + print_reg(orc[i].bp_reg, orc[i].bp_offset); + + printf(" type:%s\n", orc_type_name(orc[i].type)); + } + + elf_end(elf); + close(fd); + + return 0; +} diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c new file mode 100644 index 000000000000..e5ca31429c9b --- /dev/null +++ b/tools/objtool/orc_gen.c @@ -0,0 +1,214 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <stdlib.h> +#include <string.h> + +#include "orc.h" +#include "check.h" +#include "warn.h" + +int create_orc(struct objtool_file *file) +{ + struct instruction *insn; + + for_each_insn(file, insn) { + struct orc_entry *orc = &insn->orc; + struct cfi_reg *cfa = &insn->state.cfa; + struct cfi_reg *bp = &insn->state.regs[CFI_BP]; + + if (cfa->base == CFI_UNDEFINED) { + orc->sp_reg = ORC_REG_UNDEFINED; + continue; + } + + switch (cfa->base) { + case CFI_SP: + orc->sp_reg = ORC_REG_SP; + break; + case CFI_SP_INDIRECT: + orc->sp_reg = ORC_REG_SP_INDIRECT; + break; + case CFI_BP: + orc->sp_reg = ORC_REG_BP; + break; + case CFI_BP_INDIRECT: + orc->sp_reg = ORC_REG_BP_INDIRECT; + break; + case CFI_R10: + orc->sp_reg = ORC_REG_R10; + break; + case CFI_R13: + orc->sp_reg = ORC_REG_R13; + break; + case CFI_DI: + orc->sp_reg = ORC_REG_DI; + break; + case CFI_DX: + orc->sp_reg = ORC_REG_DX; + break; + default: + WARN_FUNC("unknown CFA base reg %d", + insn->sec, insn->offset, cfa->base); + return -1; + } + + switch(bp->base) { + case CFI_UNDEFINED: + orc->bp_reg = ORC_REG_UNDEFINED; + break; + case CFI_CFA: + orc->bp_reg = ORC_REG_PREV_SP; + break; + case CFI_BP: + orc->bp_reg = ORC_REG_BP; + break; + default: + WARN_FUNC("unknown BP base reg %d", + insn->sec, insn->offset, bp->base); + return -1; + } + + orc->sp_offset = cfa->offset; + orc->bp_offset = bp->offset; + orc->type = insn->state.type; + } + + return 0; +} + +static int create_orc_entry(struct section *u_sec, struct section *ip_relasec, + unsigned int idx, struct section *insn_sec, + unsigned long insn_off, struct orc_entry *o) +{ + struct orc_entry *orc; + struct rela *rela; + + /* populate ORC data */ + orc = (struct orc_entry *)u_sec->data->d_buf + idx; + memcpy(orc, o, sizeof(*orc)); + + /* populate rela for ip */ + rela = malloc(sizeof(*rela)); + if (!rela) { + perror("malloc"); + return -1; + } + memset(rela, 0, sizeof(*rela)); + + rela->sym = insn_sec->sym; + rela->addend = insn_off; + rela->type = R_X86_64_PC32; + rela->offset = idx * sizeof(int); + + list_add_tail(&rela->list, &ip_relasec->rela_list); + hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset); + + return 0; +} + +int create_orc_sections(struct objtool_file *file) +{ + struct instruction *insn, *prev_insn; + struct section *sec, *u_sec, *ip_relasec; + unsigned int idx; + + struct orc_entry empty = { + .sp_reg = ORC_REG_UNDEFINED, + .bp_reg = ORC_REG_UNDEFINED, + .type = ORC_TYPE_CALL, + }; + + sec = find_section_by_name(file->elf, ".orc_unwind"); + if (sec) { + WARN("file already has .orc_unwind section, skipping"); + return -1; + } + + /* count the number of needed orcs */ + idx = 0; + for_each_sec(file, sec) { + if (!sec->text) + continue; + + prev_insn = NULL; + sec_for_each_insn(file, sec, insn) { + if (!prev_insn || + memcmp(&insn->orc, &prev_insn->orc, + sizeof(struct orc_entry))) { + idx++; + } + prev_insn = insn; + } + + /* section terminator */ + if (prev_insn) + idx++; + } + if (!idx) + return -1; + + + /* create .orc_unwind_ip and .rela.orc_unwind_ip sections */ + sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx); + + ip_relasec = elf_create_rela_section(file->elf, sec); + if (!ip_relasec) + return -1; + + /* create .orc_unwind section */ + u_sec = elf_create_section(file->elf, ".orc_unwind", + sizeof(struct orc_entry), idx); + + /* populate sections */ + idx = 0; + for_each_sec(file, sec) { + if (!sec->text) + continue; + + prev_insn = NULL; + sec_for_each_insn(file, sec, insn) { + if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc, + sizeof(struct orc_entry))) { + + if (create_orc_entry(u_sec, ip_relasec, idx, + insn->sec, insn->offset, + &insn->orc)) + return -1; + + idx++; + } + prev_insn = insn; + } + + /* section terminator */ + if (prev_insn) { + if (create_orc_entry(u_sec, ip_relasec, idx, + prev_insn->sec, + prev_insn->offset + prev_insn->len, + &empty)) + return -1; + + idx++; + } + } + + if (elf_rebuild_rela_section(ip_relasec)) + return -1; + + return 0; +} diff --git a/tools/objtool/orc_types.h b/tools/objtool/orc_types.h new file mode 100644 index 000000000000..9c9dc579bd7d --- /dev/null +++ b/tools/objtool/orc_types.h @@ -0,0 +1,107 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#ifndef _ORC_TYPES_H +#define _ORC_TYPES_H + +#include <linux/types.h> +#include <linux/compiler.h> + +/* + * The ORC_REG_* registers are base registers which are used to find other + * registers on the stack. + * + * ORC_REG_PREV_SP, also known as DWARF Call Frame Address (CFA), is the + * address of the previous frame: the caller's SP before it called the current + * function. + * + * ORC_REG_UNDEFINED means the corresponding register's value didn't change in + * the current frame. + * + * The most commonly used base registers are SP and BP -- which the previous SP + * is usually based on -- and PREV_SP and UNDEFINED -- which the previous BP is + * usually based on. + * + * The rest of the base registers are needed for special cases like entry code + * and GCC realigned stacks. + */ +#define ORC_REG_UNDEFINED 0 +#define ORC_REG_PREV_SP 1 +#define ORC_REG_DX 2 +#define ORC_REG_DI 3 +#define ORC_REG_BP 4 +#define ORC_REG_SP 5 +#define ORC_REG_R10 6 +#define ORC_REG_R13 7 +#define ORC_REG_BP_INDIRECT 8 +#define ORC_REG_SP_INDIRECT 9 +#define ORC_REG_MAX 15 + +/* + * ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the + * caller's SP right before it made the call). Used for all callable + * functions, i.e. all C code and all callable asm functions. + * + * ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points + * to a fully populated pt_regs from a syscall, interrupt, or exception. + * + * ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset + * points to the iret return frame. + * + * The UNWIND_HINT macros are used only for the unwind_hint struct. They + * aren't used in struct orc_entry due to size and complexity constraints. + * Objtool converts them to real types when it converts the hints to orc + * entries. + */ +#define ORC_TYPE_CALL 0 +#define ORC_TYPE_REGS 1 +#define ORC_TYPE_REGS_IRET 2 +#define UNWIND_HINT_TYPE_SAVE 3 +#define UNWIND_HINT_TYPE_RESTORE 4 + +#ifndef __ASSEMBLY__ +/* + * This struct is more or less a vastly simplified version of the DWARF Call + * Frame Information standard. It contains only the necessary parts of DWARF + * CFI, simplified for ease of access by the in-kernel unwinder. It tells the + * unwinder how to find the previous SP and BP (and sometimes entry regs) on + * the stack for a given code address. Each instance of the struct corresponds + * to one or more code locations. + */ +struct orc_entry { + s16 sp_offset; + s16 bp_offset; + unsigned sp_reg:4; + unsigned bp_reg:4; + unsigned type:2; +} __packed; + +/* + * This struct is used by asm and inline asm code to manually annotate the + * location of registers on the stack for the ORC unwinder. + * + * Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*. + */ +struct unwind_hint { + u32 ip; + s16 sp_offset; + u8 sp_reg; + u8 type; +}; +#endif /* __ASSEMBLY__ */ + +#endif /* _ORC_TYPES_H */ |