37a9d912b2
The cmpxchg_futex_value_locked API was funny in that it returned either
the original, user-exposed futex value OR an error code such as -EFAULT.
This was confusing at best, and could be a source of livelocks in places
that retry the cmpxchg_futex_value_locked after trying to fix the issue
by running fault_in_user_writeable().
This change makes the cmpxchg_futex_value_locked API more similar to the
get_futex_value_locked one, returning an error code and updating the
original value through a reference argument.
Signed-off-by: Michel Lespinasse <walken@google.com>
Acked-by: Chris Metcalf <cmetcalf@tilera.com> [tile]
Acked-by: Tony Luck <tony.luck@intel.com> [ia64]
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michal Simek <monstr@monstr.eu> [microblaze]
Acked-by: David Howells <dhowells@redhat.com> [frv]
Cc: Darren Hart <darren@dvhart.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110311024851.GC26122@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
206 lines
5.1 KiB
C
206 lines
5.1 KiB
C
/*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License. See the file "COPYING" in the main directory of this archive
|
|
* for more details.
|
|
*
|
|
* Copyright (c) 2006 Ralf Baechle (ralf@linux-mips.org)
|
|
*/
|
|
#ifndef _ASM_FUTEX_H
|
|
#define _ASM_FUTEX_H
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
#include <linux/futex.h>
|
|
#include <linux/uaccess.h>
|
|
#include <asm/barrier.h>
|
|
#include <asm/errno.h>
|
|
#include <asm/war.h>
|
|
|
|
#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
|
|
{ \
|
|
if (cpu_has_llsc && R10000_LLSC_WAR) { \
|
|
__asm__ __volatile__( \
|
|
" .set push \n" \
|
|
" .set noat \n" \
|
|
" .set mips3 \n" \
|
|
"1: ll %1, %4 # __futex_atomic_op \n" \
|
|
" .set mips0 \n" \
|
|
" " insn " \n" \
|
|
" .set mips3 \n" \
|
|
"2: sc $1, %2 \n" \
|
|
" beqzl $1, 1b \n" \
|
|
__WEAK_LLSC_MB \
|
|
"3: \n" \
|
|
" .set pop \n" \
|
|
" .set mips0 \n" \
|
|
" .section .fixup,\"ax\" \n" \
|
|
"4: li %0, %6 \n" \
|
|
" j 3b \n" \
|
|
" .previous \n" \
|
|
" .section __ex_table,\"a\" \n" \
|
|
" "__UA_ADDR "\t1b, 4b \n" \
|
|
" "__UA_ADDR "\t2b, 4b \n" \
|
|
" .previous \n" \
|
|
: "=r" (ret), "=&r" (oldval), "=R" (*uaddr) \
|
|
: "0" (0), "R" (*uaddr), "Jr" (oparg), "i" (-EFAULT) \
|
|
: "memory"); \
|
|
} else if (cpu_has_llsc) { \
|
|
__asm__ __volatile__( \
|
|
" .set push \n" \
|
|
" .set noat \n" \
|
|
" .set mips3 \n" \
|
|
"1: ll %1, %4 # __futex_atomic_op \n" \
|
|
" .set mips0 \n" \
|
|
" " insn " \n" \
|
|
" .set mips3 \n" \
|
|
"2: sc $1, %2 \n" \
|
|
" beqz $1, 1b \n" \
|
|
__WEAK_LLSC_MB \
|
|
"3: \n" \
|
|
" .set pop \n" \
|
|
" .set mips0 \n" \
|
|
" .section .fixup,\"ax\" \n" \
|
|
"4: li %0, %6 \n" \
|
|
" j 3b \n" \
|
|
" .previous \n" \
|
|
" .section __ex_table,\"a\" \n" \
|
|
" "__UA_ADDR "\t1b, 4b \n" \
|
|
" "__UA_ADDR "\t2b, 4b \n" \
|
|
" .previous \n" \
|
|
: "=r" (ret), "=&r" (oldval), "=R" (*uaddr) \
|
|
: "0" (0), "R" (*uaddr), "Jr" (oparg), "i" (-EFAULT) \
|
|
: "memory"); \
|
|
} else \
|
|
ret = -ENOSYS; \
|
|
}
|
|
|
|
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;
|
|
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
|
|
oparg = 1 << oparg;
|
|
|
|
if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
|
|
return -EFAULT;
|
|
|
|
pagefault_disable();
|
|
|
|
switch (op) {
|
|
case FUTEX_OP_SET:
|
|
__futex_atomic_op("move $1, %z5", ret, oldval, uaddr, oparg);
|
|
break;
|
|
|
|
case FUTEX_OP_ADD:
|
|
__futex_atomic_op("addu $1, %1, %z5",
|
|
ret, oldval, uaddr, oparg);
|
|
break;
|
|
case FUTEX_OP_OR:
|
|
__futex_atomic_op("or $1, %1, %z5",
|
|
ret, oldval, uaddr, oparg);
|
|
break;
|
|
case FUTEX_OP_ANDN:
|
|
__futex_atomic_op("and $1, %1, %z5",
|
|
ret, oldval, uaddr, ~oparg);
|
|
break;
|
|
case FUTEX_OP_XOR:
|
|
__futex_atomic_op("xor $1, %1, %z5",
|
|
ret, oldval, uaddr, oparg);
|
|
break;
|
|
default:
|
|
ret = -ENOSYS;
|
|
}
|
|
|
|
pagefault_enable();
|
|
|
|
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 *uval, int __user *uaddr,
|
|
int oldval, int newval)
|
|
{
|
|
int ret = 0, val;
|
|
|
|
if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
|
|
return -EFAULT;
|
|
|
|
if (cpu_has_llsc && R10000_LLSC_WAR) {
|
|
__asm__ __volatile__(
|
|
"# futex_atomic_cmpxchg_inatomic \n"
|
|
" .set push \n"
|
|
" .set noat \n"
|
|
" .set mips3 \n"
|
|
"1: ll %1, %3 \n"
|
|
" bne %1, %z4, 3f \n"
|
|
" .set mips0 \n"
|
|
" move $1, %z5 \n"
|
|
" .set mips3 \n"
|
|
"2: sc $1, %2 \n"
|
|
" beqzl $1, 1b \n"
|
|
__WEAK_LLSC_MB
|
|
"3: \n"
|
|
" .set pop \n"
|
|
" .section .fixup,\"ax\" \n"
|
|
"4: li %0, %6 \n"
|
|
" j 3b \n"
|
|
" .previous \n"
|
|
" .section __ex_table,\"a\" \n"
|
|
" "__UA_ADDR "\t1b, 4b \n"
|
|
" "__UA_ADDR "\t2b, 4b \n"
|
|
" .previous \n"
|
|
: "+r" (ret), "=&r" (val), "=R" (*uaddr)
|
|
: "R" (*uaddr), "Jr" (oldval), "Jr" (newval), "i" (-EFAULT)
|
|
: "memory");
|
|
} else if (cpu_has_llsc) {
|
|
__asm__ __volatile__(
|
|
"# futex_atomic_cmpxchg_inatomic \n"
|
|
" .set push \n"
|
|
" .set noat \n"
|
|
" .set mips3 \n"
|
|
"1: ll %1, %3 \n"
|
|
" bne %1, %z4, 3f \n"
|
|
" .set mips0 \n"
|
|
" move $1, %z5 \n"
|
|
" .set mips3 \n"
|
|
"2: sc $1, %2 \n"
|
|
" beqz $1, 1b \n"
|
|
__WEAK_LLSC_MB
|
|
"3: \n"
|
|
" .set pop \n"
|
|
" .section .fixup,\"ax\" \n"
|
|
"4: li %0, %6 \n"
|
|
" j 3b \n"
|
|
" .previous \n"
|
|
" .section __ex_table,\"a\" \n"
|
|
" "__UA_ADDR "\t1b, 4b \n"
|
|
" "__UA_ADDR "\t2b, 4b \n"
|
|
" .previous \n"
|
|
: "+r" (ret), "=&r" (val), "=R" (*uaddr)
|
|
: "R" (*uaddr), "Jr" (oldval), "Jr" (newval), "i" (-EFAULT)
|
|
: "memory");
|
|
} else
|
|
return -ENOSYS;
|
|
|
|
*uval = val;
|
|
return ret;
|
|
}
|
|
|
|
#endif
|
|
#endif /* _ASM_FUTEX_H */
|