Commit-ID: 69237f94e65d3d7f539f1adb98ef68685c595004 Gitweb: http://git.kernel.org/tip/69237f94e65d3d7f539f1adb98ef68685c595004 Author: Eric Dumazet <eric.dumazet@xxxxxxxxx> AuthorDate: Fri, 3 Jul 2009 13:26:41 +0200 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Fri, 3 Jul 2009 13:26:41 +0200 x86: atomic64: Improve cmpxchg8b() Rewrite cmpxchg8b() to not use %edi register but a generic "+m" constraint, to increase compiler freedom in code generation and possibly better code. Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: David Howells <dhowells@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> LKML-Reference: <alpine.LFD.2.01.0907021653030.3210@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- arch/x86/lib/atomic64_32.c | 19 +++++++------------ 1 files changed, 7 insertions(+), 12 deletions(-) diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c index afa5d44..5fc1e2c 100644 --- a/arch/x86/lib/atomic64_32.c +++ b/arch/x86/lib/atomic64_32.c @@ -6,19 +6,14 @@ static inline u64 cmpxchg8b(u64 *ptr, u64 old, u64 new) { - asm volatile( - - LOCK_PREFIX "cmpxchg8b (%[ptr])\n" - - : "=A" (old) - - : [ptr] "D" (ptr), - "A" (old), - "b" (ll_low(new)), - "c" (ll_high(new)) - - : "memory"); + u32 low = new; + u32 high = new >> 32; + asm volatile( + LOCK_PREFIX "cmpxchg8b %1\n" + : "+A" (old), "+m" (*ptr) + : "b" (low), "c" (high) + ); return old; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html