diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2025-03-03 10:21:47 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-03-03 10:54:11 +0100 |
| commit | 73e8079be9e7ae5ed197d074e0ba6c43674c52f7 (patch) | |
| tree | 0cc3f337f5b8affbe4ccd0bc53eab19b6d0899f0 | |
| parent | dfebe7362f6f461d771cdb9ac2c5172a4721f064 (diff) | |
x86/ibt: Make cfi_bhi a constant for FINEIBT_BHI=n
Robot yielded a .config that tripped:
vmlinux.o: warning: objtool: do_jit+0x276: relocation to !ENDBR: .noinstr.text+0x6a60
This is the result of using __bhi_args[1] in unreachable code; make
sure the compiler is able to determine this is unreachable and trigger
DCE.
Closes: https://lore.kernel.org/oe-kbuild-all/202503030704.H9KFysNS-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250303094911.GL5880@noisy.programming.kicks-ass.net
| -rw-r--r-- | arch/x86/include/asm/cfi.h | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 7 |
2 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h index 2f6a01f098b5..3e51ba459154 100644 --- a/arch/x86/include/asm/cfi.h +++ b/arch/x86/include/asm/cfi.h @@ -100,7 +100,12 @@ enum cfi_mode { }; extern enum cfi_mode cfi_mode; + +#ifdef CONFIG_FINEIBT_BHI extern bool cfi_bhi; +#else +#define cfi_bhi (0) +#endif typedef u8 bhi_thunk[32]; extern bhi_thunk __bhi_args[]; diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 32e4b801db99..bf82c6f7d690 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -936,7 +936,10 @@ void __init_or_module apply_seal_endbr(s32 *start, s32 *end) { } #endif enum cfi_mode cfi_mode __ro_after_init = __CFI_DEFAULT; + +#ifdef CONFIG_FINEIBT_BHI bool cfi_bhi __ro_after_init = false; +#endif #ifdef CONFIG_CFI_CLANG struct bpf_insn; @@ -1070,11 +1073,15 @@ static __init int cfi_parse_cmdline(char *str) pr_err("Ignoring paranoid; depends on fineibt.\n"); } } else if (!strcmp(str, "bhi")) { +#ifdef CONFIG_FINEIBT_BHI if (cfi_mode == CFI_FINEIBT) { cfi_bhi = true; } else { pr_err("Ignoring bhi; depends on fineibt.\n"); } +#else + pr_err("Ignoring bhi; depends on FINEIBT_BHI=y.\n"); +#endif } else { pr_err("Ignoring unknown cfi option (%s).", str); } |