diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2025-04-03 14:50:45 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-04-03 16:28:38 +0200 |
| commit | fc1cd60042b3df1d162278461c7a87f0362502b8 (patch) | |
| tree | 58aae61aab0315a6cfa84515cee6e010a13bb3d5 | |
| parent | a17b37a3f416c9e385bbd2b5fc603d337eab76eb (diff) | |
x86/idle: Use MONITOR and MWAIT mnemonics in <asm/mwait.h>
Current minimum required version of binutils is 2.25,
which supports MONITOR and MWAIT instruction mnemonics.
Replace the byte-wise specification of MONITOR and
MWAIT with these proper mnemonics.
No functional change intended.
Note: LLVM assembler is not able to assemble correct forms of MONITOR
and MWAIT instructions with explicit operands and reports:
error: invalid operand for instruction
monitor %rax,%ecx,%edx
^~~~
# https://lore.kernel.org/oe-kbuild-all/202504030802.2lEVBSpN-lkp@intel.com/
Use instruction mnemonics with implicit operands to
work around this issue.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250403125111.429805-1-ubizjak@gmail.com
| -rw-r--r-- | arch/x86/include/asm/mwait.h | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h index 44d3bb2a259d..dd2b129b0418 100644 --- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -27,9 +27,11 @@ static __always_inline void __monitor(const void *eax, u32 ecx, u32 edx) { - /* "monitor %eax, %ecx, %edx;" */ - asm volatile(".byte 0x0f, 0x01, 0xc8;" - :: "a" (eax), "c" (ecx), "d"(edx)); + /* + * Use the instruction mnemonic with implicit operands, as the LLVM + * assembler fails to assemble the mnemonic with explicit operands: + */ + asm volatile("monitor" :: "a" (eax), "c" (ecx), "d" (edx)); } static __always_inline void __monitorx(const void *eax, u32 ecx, u32 edx) @@ -43,9 +45,11 @@ static __always_inline void __mwait(u32 eax, u32 ecx) { mds_idle_clear_cpu_buffers(); - /* "mwait %eax, %ecx;" */ - asm volatile(".byte 0x0f, 0x01, 0xc9;" - :: "a" (eax), "c" (ecx)); + /* + * Use the instruction mnemonic with implicit operands, as the LLVM + * assembler fails to assemble the mnemonic with explicit operands: + */ + asm volatile("mwait" :: "a" (eax), "c" (ecx)); } /* @@ -95,9 +99,8 @@ static __always_inline void __mwaitx(u32 eax, u32 ebx, u32 ecx) static __always_inline void __sti_mwait(u32 eax, u32 ecx) { mds_idle_clear_cpu_buffers(); - /* "mwait %eax, %ecx;" */ - asm volatile("sti; .byte 0x0f, 0x01, 0xc9;" - :: "a" (eax), "c" (ecx)); + + asm volatile("sti; mwait" :: "a" (eax), "c" (ecx)); } /* |