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/rwsem.h b/include/asm-i386/rwsem.h
index 2f07601..43113f5 100644
--- a/include/asm-i386/rwsem.h
+++ b/include/asm-i386/rwsem.h
@@ -111,8 +111,8 @@
" jmp 1b\n"
LOCK_SECTION_END
"# ending down_read\n\t"
- : "=m"(sem->count)
- : "a"(sem), "m"(sem->count)
+ : "+m" (sem->count)
+ : "a" (sem)
: "memory", "cc");
}
@@ -133,8 +133,8 @@
" jnz 1b\n\t"
"2:\n\t"
"# ending __down_read_trylock\n\t"
- : "+m"(sem->count), "=&a"(result), "=&r"(tmp)
- : "i"(RWSEM_ACTIVE_READ_BIAS)
+ : "+m" (sem->count), "=&a" (result), "=&r" (tmp)
+ : "i" (RWSEM_ACTIVE_READ_BIAS)
: "memory", "cc");
return result>=0 ? 1 : 0;
}
@@ -161,8 +161,8 @@
" jmp 1b\n"
LOCK_SECTION_END
"# ending down_write"
- : "=m"(sem->count), "=d"(tmp)
- : "a"(sem), "1"(tmp), "m"(sem->count)
+ : "+m" (sem->count), "=d" (tmp)
+ : "a" (sem), "1" (tmp)
: "memory", "cc");
}
@@ -205,8 +205,8 @@
" jmp 1b\n"
LOCK_SECTION_END
"# ending __up_read\n"
- : "=m"(sem->count), "=d"(tmp)
- : "a"(sem), "1"(tmp), "m"(sem->count)
+ : "+m" (sem->count), "=d" (tmp)
+ : "a" (sem), "1" (tmp)
: "memory", "cc");
}
@@ -231,8 +231,8 @@
" jmp 1b\n"
LOCK_SECTION_END
"# ending __up_write\n"
- : "=m"(sem->count)
- : "a"(sem), "i"(-RWSEM_ACTIVE_WRITE_BIAS), "m"(sem->count)
+ : "+m" (sem->count)
+ : "a" (sem), "i" (-RWSEM_ACTIVE_WRITE_BIAS)
: "memory", "cc", "edx");
}
@@ -256,8 +256,8 @@
" jmp 1b\n"
LOCK_SECTION_END
"# ending __downgrade_write\n"
- : "=m"(sem->count)
- : "a"(sem), "i"(-RWSEM_WAITING_BIAS), "m"(sem->count)
+ : "+m" (sem->count)
+ : "a" (sem), "i" (-RWSEM_WAITING_BIAS)
: "memory", "cc");
}
@@ -268,8 +268,8 @@
{
__asm__ __volatile__(
LOCK_PREFIX "addl %1,%0"
- : "=m"(sem->count)
- : "ir"(delta), "m"(sem->count));
+ : "+m" (sem->count)
+ : "ir" (delta));
}
/*
@@ -280,10 +280,9 @@
int tmp = delta;
__asm__ __volatile__(
-LOCK_PREFIX "xadd %0,(%2)"
- : "+r"(tmp), "=m"(sem->count)
- : "r"(sem), "m"(sem->count)
- : "memory");
+LOCK_PREFIX "xadd %0,%1"
+ : "+r" (tmp), "+m" (sem->count)
+ : : "memory");
return tmp+delta;
}