| 1 | #
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| 2 | # Copyright (c) 2001-2004 Jakub Jermar
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| 3 | # All rights reserved.
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| 4 | #
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| 5 | # Redistribution and use in source and binary forms, with or without
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| 6 | # modification, are permitted provided that the following conditions
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| 7 | # are met:
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| 8 | #
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| 9 | # - Redistributions of source code must retain the above copyright
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| 10 | # notice, this list of conditions and the following disclaimer.
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| 11 | # - Redistributions in binary form must reproduce the above copyright
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| 12 | # notice, this list of conditions and the following disclaimer in the
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| 13 | # documentation and/or other materials provided with the distribution.
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| 14 | # - The name of the author may not be used to endorse or promote products
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| 15 | # derived from this software without specific prior written permission.
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| 16 | #
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| 17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | #
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| 28 |
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| 29 | #include <abi/asmtool.h>
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| 30 |
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| 31 | .text
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| 32 |
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| 33 | #ifdef CONFIG_SMP
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| 34 |
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| 35 | #
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| 36 | # This is a bus-and-hyperthreading-friendly implementation of spinlock
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| 37 | #
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| 38 | FUNCTION_BEGIN(spinlock_arch)
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| 39 | pushl %eax
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| 40 | pushl %ebx
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| 41 |
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| 42 | movl 12(%esp),%ebx
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| 43 |
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| 44 | 0:
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| 45 | pause # Pentium 4's with HT love this instruction
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| 46 | movl (%ebx),%eax
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| 47 | testl %eax,%eax
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| 48 | jnz 0b # lightweight looping while it is locked
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| 49 | incl %eax
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| 50 | xchgl %eax,(%ebx) # now use the atomic operation
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| 51 | testl %eax,%eax
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| 52 | jnz 0b
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| 53 |
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| 54 | popl %ebx
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| 55 | popl %eax
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| 56 | ret
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| 57 | FUNCTION_END(spinlock_arch)
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| 58 |
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| 59 | #endif
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