From: Al Viro Date: Thu, 26 Mar 2020 21:34:40 +0000 (-0400) Subject: x86: don't reload after cmpxchg in unsafe_atomic_op2() loop X-Git-Tag: Ubuntu-5.13.0-19.19~6410^2~4^2~2 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=8aef36dacb3a932cb77da8bb7eb21a154babd0b8;p=mirror_ubuntu-jammy-kernel.git 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 --- diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h index 53c07ab63762..5ff7626a333d 100644 --- a/arch/x86/include/asm/futex.h +++ b/arch/x86/include/asm/futex.h @@ -34,17 +34,17 @@ do { \ do { \ int oldval = 0, ret, tem; \ asm volatile("1:\tmovl %2, %0\n" \ - "\tmovl\t%0, %3\n" \ + "2:\tmovl\t%0, %3\n" \ "\t" insn "\n" \ - "2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \ - "\tjnz\t1b\n" \ - "3:\n" \ + "3:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \ + "\tjnz\t2b\n" \ + "4:\n" \ "\t.section .fixup,\"ax\"\n" \ - "4:\tmov\t%5, %1\n" \ - "\tjmp\t3b\n" \ + "5:\tmov\t%5, %1\n" \ + "\tjmp\t4b\n" \ "\t.previous\n" \ - _ASM_EXTABLE_UA(1b, 4b) \ - _ASM_EXTABLE_UA(2b, 4b) \ + _ASM_EXTABLE_UA(1b, 5b) \ + _ASM_EXTABLE_UA(3b, 5b) \ : "=&a" (oldval), "=&r" (ret), \ "+m" (*uaddr), "=&r" (tem) \ : "r" (oparg), "i" (-EFAULT), "1" (0)); \