Messages in this thread Patch in this message | | | From | Uros Bizjak <> | Subject | [PATCH 1/6] locking/atomic/x86: Introduce arch_atomic64_try_cmpxchg to x86_32 | Date | Tue, 9 Apr 2024 12:03:52 +0200 |
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Introduce arch_atomic64_try_cmpxchg for 32-bit targets to use optimized target specific implementation instead of a generic one. This implementation eliminates dual-word compare after cmpxchg8b instruction and improves generated asm code from:
2273: f0 0f c7 0f lock cmpxchg8b (%edi) 2277: 8b 74 24 2c mov 0x2c(%esp),%esi 227b: 89 d3 mov %edx,%ebx 227d: 89 c2 mov %eax,%edx 227f: 89 5c 24 10 mov %ebx,0x10(%esp) 2283: 8b 7c 24 30 mov 0x30(%esp),%edi 2287: 89 44 24 1c mov %eax,0x1c(%esp) 228b: 31 f2 xor %esi,%edx 228d: 89 d0 mov %edx,%eax 228f: 89 da mov %ebx,%edx 2291: 31 fa xor %edi,%edx 2293: 09 d0 or %edx,%eax 2295: 0f 85 a5 00 00 00 jne 2340 <...>
to:
2270: f0 0f c7 0f lock cmpxchg8b (%edi) 2274: 0f 85 a6 00 00 00 jne 2320 <...>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> --- arch/x86/include/asm/atomic64_32.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/atomic64_32.h b/arch/x86/include/asm/atomic64_32.h index d510405e4e1d..11e817dab44a 100644 --- a/arch/x86/include/asm/atomic64_32.h +++ b/arch/x86/include/asm/atomic64_32.h @@ -61,12 +61,18 @@ ATOMIC64_DECL(add_unless); #undef __ATOMIC64_DECL #undef ATOMIC64_EXPORT -static __always_inline s64 arch_atomic64_cmpxchg(atomic64_t *v, s64 o, s64 n) +static __always_inline s64 arch_atomic64_cmpxchg(atomic64_t *v, s64 old, s64 new) { - return arch_cmpxchg64(&v->counter, o, n); + return arch_cmpxchg64(&v->counter, old, new); } #define arch_atomic64_cmpxchg arch_atomic64_cmpxchg +static __always_inline bool arch_atomic64_try_cmpxchg(atomic64_t *v, s64 *old, s64 new) +{ + return arch_try_cmpxchg64(&v->counter, old, new); +} +#define arch_atomic64_try_cmpxchg arch_atomic64_try_cmpxchg + static __always_inline s64 arch_atomic64_xchg(atomic64_t *v, s64 n) { s64 o; -- 2.44.0
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