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[PATCH] lightweight robust futexes: i386
i386: add the futex_atomic_cmpxchg_inuser() assembly implementation, and wire up the new syscalls. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Acked-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -310,3 +310,5 @@ ENTRY(sys_call_table)
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.long sys_pselect6
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.long sys_ppoll
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.long sys_unshare /* 310 */
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.long sys_set_robust_list
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.long sys_get_robust_list
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@ -107,7 +107,28 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
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static inline int
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futex_atomic_cmpxchg_inuser(int __user *uaddr, int oldval, int newval)
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{
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return -ENOSYS;
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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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@ -316,8 +316,10 @@
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#define __NR_pselect6 308
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#define __NR_ppoll 309
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#define __NR_unshare 310
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#define __NR_set_robust_list 311
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#define __NR_get_robust_list 312
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#define NR_syscalls 311
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#define NR_syscalls 313
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/*
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* user-visible error numbers are in the range -1 - -128: see
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