From dfd4e3ec246355274c9cf62c6b04a1ee6fa3caba Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 27 Mar 2006 01:16:25 -0800 Subject: [PATCH] lightweight robust futexes: i386 i386: add the futex_atomic_cmpxchg_inuser() assembly implementation, and wire up the new syscalls. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Arjan van de Ven Acked-by: Ulrich Drepper Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-i386/futex.h | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) (limited to 'include/asm-i386/futex.h') diff --git a/include/asm-i386/futex.h b/include/asm-i386/futex.h index 1f39ad9d52a..41184a31885 100644 --- a/include/asm-i386/futex.h +++ b/include/asm-i386/futex.h @@ -107,7 +107,28 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr) static inline int futex_atomic_cmpxchg_inuser(int __user *uaddr, int oldval, int newval) { - return -ENOSYS; + if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int))) + return -EFAULT; + + __asm__ __volatile__( + "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n" + + "2: .section .fixup, \"ax\" \n" + "3: mov %2, %0 \n" + " jmp 2b \n" + " .previous \n" + + " .section __ex_table, \"a\" \n" + " .align 8 \n" + " .long 1b,3b \n" + " .previous \n" + + : "=a" (oldval), "=m" (*uaddr) + : "i" (-EFAULT), "r" (newval), "0" (oldval) + : "memory" + ); + + return oldval; } #endif -- cgit v1.2.3