linux/include/asm-i386/futex.h
Linus Torvalds b862f3b099 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>
2006-07-08 15:24:18 -07:00

135 lines
3 KiB
C

#ifndef _ASM_FUTEX_H
#define _ASM_FUTEX_H
#ifdef __KERNEL__
#include <linux/futex.h>
#include <asm/errno.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg) \
__asm__ __volatile ( \
"1: " insn "\n" \
"2: .section .fixup,\"ax\"\n\
3: mov %3, %1\n\
jmp 2b\n\
.previous\n\
.section __ex_table,\"a\"\n\
.align 8\n\
.long 1b,3b\n\
.previous" \
: "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
: "i" (-EFAULT), "0" (oparg), "1" (0))
#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg) \
__asm__ __volatile ( \
"1: movl %2, %0\n\
movl %0, %3\n" \
insn "\n" \
"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\
jnz 1b\n\
3: .section .fixup,\"ax\"\n\
4: mov %5, %1\n\
jmp 3b\n\
.previous\n\
.section __ex_table,\"a\"\n\
.align 8\n\
.long 1b,4b,2b,4b\n\
.previous" \
: "=&a" (oldval), "=&r" (ret), "+m" (*uaddr), \
"=&r" (tem) \
: "r" (oparg), "i" (-EFAULT), "1" (0))
static inline int
futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
{
int op = (encoded_op >> 28) & 7;
int cmp = (encoded_op >> 24) & 15;
int oparg = (encoded_op << 8) >> 20;
int cmparg = (encoded_op << 20) >> 20;
int oldval = 0, ret, tem;
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
oparg = 1 << oparg;
if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
return -EFAULT;
inc_preempt_count();
if (op == FUTEX_OP_SET)
__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
else {
#ifndef CONFIG_X86_BSWAP
if (boot_cpu_data.x86 == 3)
ret = -ENOSYS;
else
#endif
switch (op) {
case FUTEX_OP_ADD:
__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret,
oldval, uaddr, oparg);
break;
case FUTEX_OP_OR:
__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr,
oparg);
break;
case FUTEX_OP_ANDN:
__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr,
~oparg);
break;
case FUTEX_OP_XOR:
__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr,
oparg);
break;
default:
ret = -ENOSYS;
}
}
dec_preempt_count();
if (!ret) {
switch (cmp) {
case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
default: ret = -ENOSYS;
}
}
return ret;
}
static inline int
futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
{
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
#endif