| 1 | /*
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| 2 | * Copyright (C) 2005 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 | #ifndef __ia32_BARRIER_H__
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| 30 | #define __ia32_BARRIER_H__
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| 31 |
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| 32 | /*
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| 33 | * NOTE:
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| 34 | * No barriers for critical section (i.e. spinlock) on IA-32 are needed:
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| 35 | * - spinlock_lock() and spinlock_trylock() use serializing XCHG instruction
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| 36 | * - writes cannot pass reads on IA-32 => spinlock_unlock() needs no barriers
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| 37 | */
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| 38 |
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| 39 | /*
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| 40 | * Provisions are made to prevent compiler from reordering instructions itself.
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| 41 | */
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| 42 |
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| 43 | #define CS_ENTER_BARRIER() __asm__ volatile ("" ::: "memory")
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| 44 | #define CS_LEAVE_BARRIER() __asm__ volatile ("" ::: "memory")
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| 45 |
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| 46 | static inline void cpuid_serialization(void)
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| 47 | {
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| 48 | __asm__ volatile (
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| 49 | "xorl %%eax, %%eax\n"
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| 50 | "cpuid\n"
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| 51 | ::: "eax", "ebx", "ecx", "edx", "memory"
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| 52 | );
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| 53 | }
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| 54 |
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| 55 | #ifdef CONFIG_FENCES_P4
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| 56 | # define memory_barrier() __asm__ volatile ("mfence\n" ::: "memory")
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| 57 | # define read_barrier() __asm__ volatile ("lfence\n" ::: "memory")
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| 58 | # ifdef CONFIG_WEAK_MEMORY
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| 59 | # define write_barrier() __asm__ volatile ("sfence\n" ::: "memory")
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| 60 | # else
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| 61 | # define write_barrier() __asm__ volatile( "" ::: "memory");
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| 62 | # endif
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| 63 | #elif CONFIG_FENCES_P3
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| 64 | # define memory_barrier() cpuid_serialization()
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| 65 | # define read_barrier() cpuid_serialization()
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| 66 | # ifdef CONFIG_WEAK_MEMORY
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| 67 | # define write_barrier() __asm__ volatile ("sfence\n" ::: "memory")
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| 68 | # else
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| 69 | # define write_barrier() __asm__ volatile( "" ::: "memory");
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| 70 | # endif
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| 71 | #else
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| 72 | # define memory_barrier() cpuid_serialization()
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| 73 | # define read_barrier() cpuid_serialization()
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| 74 | # ifdef CONFIG_WEAK_MEMORY
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| 75 | # define write_barrier() cpuid_serialization()
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| 76 | # else
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| 77 | # define write_barrier() __asm__ volatile( "" ::: "memory");
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| 78 | # endif
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| 79 | #endif
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| 80 |
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| 81 | #endif
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