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| author | Will Deacon <will.deacon@arm.com> | 2011-09-23 17:34:12 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-09-26 15:36:47 +0400 |
| commit | df77abcafc8dc881b6c9347548651777088e4b27 (patch) | |
| tree | 1311e860f1c86371852175c582d111ce565d411d /arch/arm | |
| parent | d8e89b47e00ee80e920761145144640aac4cf71a (diff) | |
| download | linux-df77abcafc8dc881b6c9347548651777088e4b27.tar.xz | |
ARM: 7099/1: futex: preserve oldval in SMP __futex_atomic_op
The SMP implementation of __futex_atomic_op clobbers oldval with the
status flag from the exclusive store. This causes it to always read as
zero when performing the FUTEX_OP_CMP_* operation.
This patch updates the ARM __futex_atomic_op implementations to take a
tmp argument, allowing us to store the strex status flag without
overwriting the register containing oldval.
Cc: stable@kernel.org
Reported-by: Minho Ban <mhban@samsung.com>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/include/asm/futex.h | 34 |
1 files changed, 17 insertions, 17 deletions
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 8c73900da9ed..253cc86318bf 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -25,17 +25,17 @@ #ifdef CONFIG_SMP -#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ +#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \ smp_mb(); \ __asm__ __volatile__( \ - "1: ldrex %1, [%2]\n" \ + "1: ldrex %1, [%3]\n" \ " " insn "\n" \ - "2: strex %1, %0, [%2]\n" \ - " teq %1, #0\n" \ + "2: strex %2, %0, [%3]\n" \ + " teq %2, #0\n" \ " bne 1b\n" \ " mov %0, #0\n" \ - __futex_atomic_ex_table("%4") \ - : "=&r" (ret), "=&r" (oldval) \ + __futex_atomic_ex_table("%5") \ + : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \ : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ : "cc", "memory") @@ -73,14 +73,14 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, #include <linux/preempt.h> #include <asm/domain.h> -#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \ +#define __futex_atomic_op(insn, ret, oldval, tmp, uaddr, oparg) \ __asm__ __volatile__( \ - "1: " T(ldr) " %1, [%2]\n" \ + "1: " T(ldr) " %1, [%3]\n" \ " " insn "\n" \ - "2: " T(str) " %0, [%2]\n" \ + "2: " T(str) " %0, [%3]\n" \ " mov %0, #0\n" \ - __futex_atomic_ex_table("%4") \ - : "=&r" (ret), "=&r" (oldval) \ + __futex_atomic_ex_table("%5") \ + : "=&r" (ret), "=&r" (oldval), "=&r" (tmp) \ : "r" (uaddr), "r" (oparg), "Ir" (-EFAULT) \ : "cc", "memory") @@ -117,7 +117,7 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) int cmp = (encoded_op >> 24) & 15; int oparg = (encoded_op << 8) >> 20; int cmparg = (encoded_op << 20) >> 20; - int oldval = 0, ret; + int oldval = 0, ret, tmp; if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) oparg = 1 << oparg; @@ -129,19 +129,19 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) switch (op) { case FUTEX_OP_SET: - __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("mov %0, %4", ret, oldval, tmp, uaddr, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("add %0, %1, %4", ret, oldval, tmp, uaddr, oparg); break; case FUTEX_OP_OR: - __futex_atomic_op("orr %0, %1, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("orr %0, %1, %4", ret, oldval, tmp, uaddr, oparg); break; case FUTEX_OP_ANDN: - __futex_atomic_op("and %0, %1, %3", ret, oldval, uaddr, ~oparg); + __futex_atomic_op("and %0, %1, %4", ret, oldval, tmp, uaddr, ~oparg); break; case FUTEX_OP_XOR: - __futex_atomic_op("eor %0, %1, %3", ret, oldval, uaddr, oparg); + __futex_atomic_op("eor %0, %1, %4", ret, oldval, tmp, uaddr, oparg); break; default: ret = -ENOSYS; |