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a866374aec
Introduce pagefault_{disable,enable}() and use these where previously we did
manual preempt increments/decrements to make the pagefault handler do the
atomic thing.
Currently they still rely on the increased preempt count, but do not rely on
the disabled preemption, this might go away in the future.
(NOTE: the extra barrier() in pagefault_disable might fix some holes on
machines which have too many registers for their own good)
[heiko.carstens@de.ibm.com: s390 fix]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <npiggin@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
126 lines
2.9 KiB
C
126 lines
2.9 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/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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.quad 1b,3b\n\
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.previous" \
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: "=r" (oldval), "=r" (ret), "=m" (*uaddr) \
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: "i" (-EFAULT), "m" (*uaddr), "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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.quad 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), "m" (*uaddr), "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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pagefault_disable();
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switch (op) {
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case FUTEX_OP_SET:
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__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
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break;
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case FUTEX_OP_ADD:
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__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
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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, 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, ~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, 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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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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" .quad 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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