The following commit has been merged into the locking/core branch of tip:
Commit-ID: 276b893049e4cdc2f33c009706a75ec18a114485
Gitweb: https://git.kernel.org/tip/276b893049e4cdc2f33c009706a75ec18a114485
Author: Uros Bizjak <ubizjak@xxxxxxxxx>
AuthorDate: Wed, 10 Apr 2024 08:29:33 +02:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Wed, 10 Apr 2024 15:04:54 +02:00
locking/atomic/x86: Introduce arch_atomic64_try_cmpxchg() to x86_32
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@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240410062957.322614-1-ubizjak@xxxxxxxxx
---
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 3486d91..ec217aa 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;
|