Subject: x86: replace LOCK_PREFIX in futex.h From: Thomas Gleixner Date: Thu, 07 Feb 2008 13:05:19 +0100 The exception fixup for the futex macros __futex_atomic_op1/2 and futex_atomic_cmpxchg_inatomic() is missing an entry when the lock prefix is replaced by a NOP via SMP alternatives. Chuck Ebert tracked this down from the information provided in: https://bugzilla.redhat.com/show_bug.cgi?id=429412 A possible solution would be to add another fixup after the LOCK_PREFIX, so both the LOCK and NOP case have their own entry in the exception table, but it's not really worth the trouble. Simply replace LOCK_PREFIX with lock and keep those untouched by SMP alternatives. Signed-off-by: Thomas Gleixner Index: linux-2.6.23/include/asm-i386/futex.h =================================================================== --- linux-2.6.23.orig/include/asm-i386/futex.h 2008-02-07 13:08:03.000000000 +0100 +++ linux-2.6.23/include/asm-i386/futex.h 2008-02-07 13:09:39.000000000 +0100 @@ -28,7 +28,7 @@ "1: movl %2, %0\n\ movl %0, %3\n" \ insn "\n" \ -"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\ +"2: lock cmpxchgl %3, %2\n\ jnz 1b\n\ 3: .section .fixup,\"ax\"\n\ 4: mov %5, %1\n\ @@ -68,7 +68,7 @@ futex_atomic_op_inuser (int encoded_op, #endif switch (op) { case FUTEX_OP_ADD: - __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, + __futex_atomic_op1("lock xaddl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_OR: @@ -111,7 +111,7 @@ futex_atomic_cmpxchg_inatomic(int __user return -EFAULT; __asm__ __volatile__( - "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n" + "1: lock cmpxchgl %3, %1 \n" "2: .section .fixup, \"ax\" \n" "3: mov %2, %0 \n" Index: linux-2.6.23/include/asm-x86_64/futex.h =================================================================== --- linux-2.6.23.orig/include/asm-x86_64/futex.h 2008-02-07 13:08:03.000000000 +0100 +++ linux-2.6.23/include/asm-x86_64/futex.h 2008-02-07 13:09:39.000000000 +0100 @@ -27,7 +27,7 @@ "1: movl %2, %0\n\ movl %0, %3\n" \ insn "\n" \ -"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\ +"2: "lock cmpxchgl %3, %2\n\ jnz 1b\n\ 3: .section .fixup,\"ax\"\n\ 4: mov %5, %1\n\ @@ -62,7 +62,7 @@ futex_atomic_op_inuser (int encoded_op, __futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval, + __futex_atomic_op1("lock xaddl %0, %2", ret, oldval, uaddr, oparg); break; case FUTEX_OP_OR: @@ -101,7 +101,7 @@ futex_atomic_cmpxchg_inatomic(int __user return -EFAULT; __asm__ __volatile__( - "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n" + "1: lock cmpxchgl %3, %1 \n" "2: .section .fixup, \"ax\" \n" "3: mov %2, %0 \n"