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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 422 | giacomo | 1 | /* include/asm-i386/rwlock.h |
| 2 | * |
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| 3 | * Helpers used by both rw spinlocks and rw semaphores. |
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| 4 | * |
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| 5 | * Based in part on code from semaphore.h and |
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| 6 | * spinlock.h Copyright 1996 Linus Torvalds. |
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| 7 | * |
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| 8 | * Copyright 1999 Red Hat, Inc. |
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| 9 | * |
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| 10 | * Written by Benjamin LaHaise. |
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| 11 | * |
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| 12 | * This program is free software; you can redistribute it and/or |
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| 13 | * modify it under the terms of the GNU General Public License |
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| 14 | * as published by the Free Software Foundation; either version |
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| 15 | * 2 of the License, or (at your option) any later version. |
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| 16 | */ |
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| 17 | #ifndef _ASM_I386_RWLOCK_H |
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| 18 | #define _ASM_I386_RWLOCK_H |
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| 19 | |||
| 20 | #define RW_LOCK_BIAS 0x01000000 |
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| 21 | #define RW_LOCK_BIAS_STR "0x01000000" |
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| 22 | |||
| 23 | #define __build_read_lock_ptr(rw, helper) \ |
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| 24 | asm volatile(LOCK "subl $1,(%0)\n\t" \ |
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| 25 | "js 2f\n" \ |
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| 26 | "1:\n" \ |
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| 27 | LOCK_SECTION_START("") \ |
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| 28 | "2:\tcall " helper "\n\t" \ |
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| 29 | "jmp 1b\n" \ |
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| 30 | LOCK_SECTION_END \ |
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| 31 | ::"a" (rw) : "memory") |
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| 32 | |||
| 33 | #define __build_read_lock_const(rw, helper) \ |
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| 34 | asm volatile(LOCK "subl $1,%0\n\t" \ |
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| 35 | "js 2f\n" \ |
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| 36 | "1:\n" \ |
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| 37 | LOCK_SECTION_START("") \ |
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| 38 | "2:\tpushl %%eax\n\t" \ |
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| 39 | "leal %0,%%eax\n\t" \ |
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| 40 | "call " helper "\n\t" \ |
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| 41 | "popl %%eax\n\t" \ |
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| 42 | "jmp 1b\n" \ |
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| 43 | LOCK_SECTION_END \ |
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| 44 | :"=m" (*(volatile int *)rw) : : "memory") |
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| 45 | |||
| 46 | #define __build_read_lock(rw, helper) do { \ |
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| 47 | if (__builtin_constant_p(rw)) \ |
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| 48 | __build_read_lock_const(rw, helper); \ |
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| 49 | else \ |
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| 50 | __build_read_lock_ptr(rw, helper); \ |
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| 51 | } while (0) |
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| 52 | |||
| 53 | #define __build_write_lock_ptr(rw, helper) \ |
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| 54 | asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \ |
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| 55 | "jnz 2f\n" \ |
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| 56 | "1:\n" \ |
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| 57 | LOCK_SECTION_START("") \ |
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| 58 | "2:\tcall " helper "\n\t" \ |
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| 59 | "jmp 1b\n" \ |
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| 60 | LOCK_SECTION_END \ |
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| 61 | ::"a" (rw) : "memory") |
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| 62 | |||
| 63 | #define __build_write_lock_const(rw, helper) \ |
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| 64 | asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",%0\n\t" \ |
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| 65 | "jnz 2f\n" \ |
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| 66 | "1:\n" \ |
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| 67 | LOCK_SECTION_START("") \ |
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| 68 | "2:\tpushl %%eax\n\t" \ |
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| 69 | "leal %0,%%eax\n\t" \ |
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| 70 | "call " helper "\n\t" \ |
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| 71 | "popl %%eax\n\t" \ |
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| 72 | "jmp 1b\n" \ |
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| 73 | LOCK_SECTION_END \ |
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| 74 | :"=m" (*(volatile int *)rw) : : "memory") |
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| 75 | |||
| 76 | #define __build_write_lock(rw, helper) do { \ |
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| 77 | if (__builtin_constant_p(rw)) \ |
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| 78 | __build_write_lock_const(rw, helper); \ |
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| 79 | else \ |
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| 80 | __build_write_lock_ptr(rw, helper); \ |
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| 81 | } while (0) |
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| 82 | |||
| 83 | #endif |