i386: improve and correct inline asm memory constraints
Use "+m" rather than a combination of "=m" and "m" for improved clarity
and consistency.
This also fixes some inlines that incorrectly didn't tell the compiler
that they read the old value at all, potentially causing the compiler to
generate bogus code. It appear that all of those potential bugs were
hidden by the use of extra "volatile" specifiers on the data structures
in question, though.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/asm-i386/futex.h b/include/asm-i386/futex.h
index 7b8ceef..946d97c 100644
--- a/include/asm-i386/futex.h
+++ b/include/asm-i386/futex.h
@@ -20,8 +20,8 @@
.align 8\n\
.long 1b,3b\n\
.previous" \
- : "=r" (oldval), "=r" (ret), "=m" (*uaddr) \
- : "i" (-EFAULT), "m" (*uaddr), "0" (oparg), "1" (0))
+ : "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
+ : "i" (-EFAULT), "0" (oparg), "1" (0))
#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg) \
__asm__ __volatile ( \
@@ -38,9 +38,9 @@
.align 8\n\
.long 1b,4b,2b,4b\n\
.previous" \
- : "=&a" (oldval), "=&r" (ret), "=m" (*uaddr), \
+ : "=&a" (oldval), "=&r" (ret), "+m" (*uaddr), \
"=&r" (tem) \
- : "r" (oparg), "i" (-EFAULT), "m" (*uaddr), "1" (0))
+ : "r" (oparg), "i" (-EFAULT), "1" (0))
static inline int
futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
@@ -123,7 +123,7 @@
" .long 1b,3b \n"
" .previous \n"
- : "=a" (oldval), "=m" (*uaddr)
+ : "=a" (oldval), "+m" (*uaddr)
: "i" (-EFAULT), "r" (newval), "0" (oldval)
: "memory"
);