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Commit 8aef36d

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Al Viro
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x86: don't reload after cmpxchg in unsafe_atomic_op2() loop
lock cmpxchg leaves the current value in eax; no need to reload it. Signed-off-by: Al Viro <[email protected]>
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arch/x86/include/asm/futex.h

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -34,17 +34,17 @@ do { \
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do { \
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int oldval = 0, ret, tem; \
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asm volatile("1:\tmovl %2, %0\n" \
37-
"\tmovl\t%0, %3\n" \
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"2:\tmovl\t%0, %3\n" \
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"\t" insn "\n" \
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"2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \
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"\tjnz\t1b\n" \
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"3:\n" \
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"3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \
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"\tjnz\t2b\n" \
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"4:\n" \
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"\t.section .fixup,\"ax\"\n" \
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"4:\tmov\t%5, %1\n" \
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"\tjmp\t3b\n" \
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"5:\tmov\t%5, %1\n" \
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"\tjmp\t4b\n" \
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"\t.previous\n" \
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_ASM_EXTABLE_UA(1b, 4b) \
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_ASM_EXTABLE_UA(2b, 4b) \
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_ASM_EXTABLE_UA(1b, 5b) \
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_ASM_EXTABLE_UA(3b, 5b) \
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: "=&a" (oldval), "=&r" (ret), \
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"+m" (*uaddr), "=&r" (tem) \
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: "r" (oparg), "i" (-EFAULT), "1" (0)); \

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