306a82881b
Richard Henderson pointed out that the powerpc __futex_atomic_op has a bug: it will write the wrong value if the stwcx. fails and it has to retry the lwarx/stwcx. loop, since 'oparg' will have been overwritten by the result from the first time around the loop. This happens because it uses the same register for 'oparg' (an input) as it uses for the result. This fixes it by using separate registers for 'oparg' and 'ret'. Cc: stable@kernel.org Signed-off-by: Paul Mackerras <paulus@samba.org>
117 lines
2.8 KiB
C
117 lines
2.8 KiB
C
#ifndef _ASM_POWERPC_FUTEX_H
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#define _ASM_POWERPC_FUTEX_H
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#ifdef __KERNEL__
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#include <linux/futex.h>
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#include <linux/uaccess.h>
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#include <asm/errno.h>
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#include <asm/synch.h>
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#include <asm/asm-compat.h>
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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
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__asm__ __volatile ( \
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LWSYNC_ON_SMP \
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"1: lwarx %0,0,%2\n" \
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insn \
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PPC405_ERR77(0, %2) \
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"2: stwcx. %1,0,%2\n" \
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"bne- 1b\n" \
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"li %1,0\n" \
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"3: .section .fixup,\"ax\"\n" \
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"4: li %1,%3\n" \
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"b 3b\n" \
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".previous\n" \
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".section __ex_table,\"a\"\n" \
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".align 3\n" \
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PPC_LONG "1b,4b,2b,4b\n" \
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".previous" \
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: "=&r" (oldval), "=&r" (ret) \
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: "b" (uaddr), "i" (-EFAULT), "r" (oparg) \
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: "cr0", "memory")
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static inline int futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
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{
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int op = (encoded_op >> 28) & 7;
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int cmp = (encoded_op >> 24) & 15;
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int oparg = (encoded_op << 8) >> 20;
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int cmparg = (encoded_op << 20) >> 20;
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int oldval = 0, ret;
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if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
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oparg = 1 << oparg;
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if (! access_ok (VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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pagefault_disable();
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switch (op) {
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case FUTEX_OP_SET:
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__futex_atomic_op("mr %1,%4\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ADD:
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__futex_atomic_op("add %1,%0,%4\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_OR:
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__futex_atomic_op("or %1,%0,%4\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ANDN:
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__futex_atomic_op("andc %1,%0,%4\n", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_XOR:
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__futex_atomic_op("xor %1,%0,%4\n", ret, oldval, uaddr, oparg);
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break;
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default:
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ret = -ENOSYS;
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}
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pagefault_enable();
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if (!ret) {
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switch (cmp) {
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case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break;
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case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break;
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case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break;
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case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break;
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case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break;
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case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break;
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default: ret = -ENOSYS;
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}
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}
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return ret;
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}
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static inline int
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futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
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{
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int prev;
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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__asm__ __volatile__ (
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LWSYNC_ON_SMP
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"1: lwarx %0,0,%2 # futex_atomic_cmpxchg_inatomic\n\
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cmpw 0,%0,%3\n\
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bne- 3f\n"
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PPC405_ERR77(0,%2)
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"2: stwcx. %4,0,%2\n\
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bne- 1b\n"
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ISYNC_ON_SMP
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"3: .section .fixup,\"ax\"\n\
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4: li %0,%5\n\
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b 3b\n\
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.previous\n\
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.section __ex_table,\"a\"\n\
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.align 3\n\
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" PPC_LONG "1b,4b,2b,4b\n\
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.previous" \
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: "=&r" (prev), "+m" (*uaddr)
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: "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT)
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: "cc", "memory");
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return prev;
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}
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_FUTEX_H */
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