b862f3b099
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>
136 lines
3 KiB
C
136 lines
3 KiB
C
#ifndef _ASM_FUTEX_H
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#define _ASM_FUTEX_H
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#ifdef __KERNEL__
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#include <linux/futex.h>
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#include <asm/errno.h>
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#include <asm/system.h>
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#include <asm/processor.h>
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#include <asm/uaccess.h>
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#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg) \
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__asm__ __volatile ( \
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"1: " insn "\n" \
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"2: .section .fixup,\"ax\"\n\
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3: mov %3, %1\n\
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jmp 2b\n\
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.previous\n\
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.section __ex_table,\"a\"\n\
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.align 8\n\
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.long 1b,3b\n\
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.previous" \
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: "=r" (oldval), "=r" (ret), "+m" (*uaddr) \
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: "i" (-EFAULT), "0" (oparg), "1" (0))
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#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg) \
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__asm__ __volatile ( \
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"1: movl %2, %0\n\
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movl %0, %3\n" \
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insn "\n" \
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"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\
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jnz 1b\n\
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3: .section .fixup,\"ax\"\n\
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4: mov %5, %1\n\
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jmp 3b\n\
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.previous\n\
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.section __ex_table,\"a\"\n\
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.align 8\n\
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.long 1b,4b,2b,4b\n\
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.previous" \
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: "=&a" (oldval), "=&r" (ret), "+m" (*uaddr), \
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"=&r" (tem) \
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: "r" (oparg), "i" (-EFAULT), "1" (0))
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static inline int
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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, tem;
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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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inc_preempt_count();
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if (op == FUTEX_OP_SET)
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__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
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else {
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#ifndef CONFIG_X86_BSWAP
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if (boot_cpu_data.x86 == 3)
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ret = -ENOSYS;
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else
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#endif
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switch (op) {
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case FUTEX_OP_ADD:
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__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret,
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oldval, uaddr, oparg);
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break;
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case FUTEX_OP_OR:
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__futex_atomic_op2("orl %4, %3", ret, oldval, uaddr,
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oparg);
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break;
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case FUTEX_OP_ANDN:
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__futex_atomic_op2("andl %4, %3", ret, oldval, uaddr,
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~oparg);
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break;
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case FUTEX_OP_XOR:
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__futex_atomic_op2("xorl %4, %3", ret, oldval, uaddr,
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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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}
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dec_preempt_count();
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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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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
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return -EFAULT;
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__asm__ __volatile__(
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"1: " LOCK_PREFIX "cmpxchgl %3, %1 \n"
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"2: .section .fixup, \"ax\" \n"
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"3: mov %2, %0 \n"
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" jmp 2b \n"
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" .previous \n"
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" .section __ex_table, \"a\" \n"
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" .align 8 \n"
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" .long 1b,3b \n"
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" .previous \n"
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: "=a" (oldval), "+m" (*uaddr)
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: "i" (-EFAULT), "r" (newval), "0" (oldval)
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: "memory"
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);
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return oldval;
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}
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#endif
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#endif
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