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authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>2008-08-15 12:56:59 -0400
committerH. Peter Anvin <hpa@zytor.com>2008-08-15 15:51:11 -0400
commit5bbd4c3724008c93cf3efdfc38a3402e245ab506 (patch)
tree5b74f2b70396f2cf808b368d415ae444fe94bfac /include/asm-x86/spinlock.h
parent1f49a2c2aeb22d5abc6d4ea574ff63d37ca55fbe (diff)
x86: spinlock use LOCK_PREFIX
Since we are now using DS prefixes instead of NOP to remove LOCK prefixes, there is no longer any problems with instruction boundaries moving around. * Linus Torvalds (torvalds@linux-foundation.org) wrote: > > > On Thu, 14 Aug 2008, Mathieu Desnoyers wrote: > > > > Changing the 0x90 (single-byte nop) currently used into a 0x3E DS segment > > override prefix should fix this issue. Since the default of the atomic > > instructions is to use the DS segment anyway, it should not affect the > > behavior. > > Ok, so I think this is an _excellent_ patch, but I'd like to also then use > LOCK_PREFIX in include/asm-x86/futex.h. > > See commit 9d55b9923a1b7ea8193b8875c57ec940dc2ff027. > > Linus Unless there a rationale for this, I think these be changed to LOCK_PREFIX too. grep "lock ;" include/asm-x86/spinlock.h "lock ; cmpxchgw %w1,%2\n\t" asm volatile("lock ; xaddl %0, %1\n" "lock ; cmpxchgl %1,%2\n\t" Applies to 2.6.27-rc2. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: H. Peter Anvin <hpa@zytor.com> CC: Jeremy Fitzhardinge <jeremy@goop.org> CC: Roland McGrath <roland@redhat.com> CC: Ingo Molnar <mingo@elte.hu> Cc: Steven Rostedt <rostedt@goodmis.org> CC: Steven Rostedt <srostedt@redhat.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Peter Zijlstra <peterz@infradead.org> CC: Andrew Morton <akpm@linux-foundation.org> CC: David Miller <davem@davemloft.net> CC: Ulrich Drepper <drepper@redhat.com> CC: Rusty Russell <rusty@rustcorp.com.au> CC: Gregory Haskins <ghaskins@novell.com> CC: Arnaldo Carvalho de Melo <acme@redhat.com> CC: "Luis Claudio R. Goncalves" <lclaudio@uudg.org> CC: Clark Williams <williams@redhat.com> CC: Christoph Lameter <cl@linux-foundation.org> CC: Andi Kleen <andi@firstfloor.org> CC: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'include/asm-x86/spinlock.h')
-rw-r--r--include/asm-x86/spinlock.h6
1 files changed, 3 insertions, 3 deletions
diff --git a/include/asm-x86/spinlock.h b/include/asm-x86/spinlock.h
index 4f9a9861799a..0b4d59a93d23 100644
--- a/include/asm-x86/spinlock.h
+++ b/include/asm-x86/spinlock.h
@@ -97,7 +97,7 @@ static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock)
97 "jne 1f\n\t" 97 "jne 1f\n\t"
98 "movw %w0,%w1\n\t" 98 "movw %w0,%w1\n\t"
99 "incb %h1\n\t" 99 "incb %h1\n\t"
100 "lock ; cmpxchgw %w1,%2\n\t" 100 LOCK_PREFIX "cmpxchgw %w1,%2\n\t"
101 "1:" 101 "1:"
102 "sete %b1\n\t" 102 "sete %b1\n\t"
103 "movzbl %b1,%0\n\t" 103 "movzbl %b1,%0\n\t"
@@ -135,7 +135,7 @@ static __always_inline void __ticket_spin_lock(raw_spinlock_t *lock)
135 int inc = 0x00010000; 135 int inc = 0x00010000;
136 int tmp; 136 int tmp;
137 137
138 asm volatile("lock ; xaddl %0, %1\n" 138 asm volatile(LOCK_PREFIX "xaddl %0, %1\n"
139 "movzwl %w0, %2\n\t" 139 "movzwl %w0, %2\n\t"
140 "shrl $16, %0\n\t" 140 "shrl $16, %0\n\t"
141 "1:\t" 141 "1:\t"
@@ -162,7 +162,7 @@ static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock)
162 "cmpl %0,%1\n\t" 162 "cmpl %0,%1\n\t"
163 "jne 1f\n\t" 163 "jne 1f\n\t"
164 "addl $0x00010000, %1\n\t" 164 "addl $0x00010000, %1\n\t"
165 "lock ; cmpxchgl %1,%2\n\t" 165 LOCK_PREFIX "cmpxchgl %1,%2\n\t"
166 "1:" 166 "1:"
167 "sete %b1\n\t" 167 "sete %b1\n\t"
168 "movzbl %b1,%0\n\t" 168 "movzbl %b1,%0\n\t"