Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* include/asm-i386/rwlock.h |
2 | * | |
3 | * Helpers used by both rw spinlocks and rw semaphores. | |
4 | * | |
5 | * Based in part on code from semaphore.h and | |
6 | * spinlock.h Copyright 1996 Linus Torvalds. | |
7 | * | |
8 | * Copyright 1999 Red Hat, Inc. | |
9 | * | |
10 | * Written by Benjamin LaHaise. | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version | |
15 | * 2 of the License, or (at your option) any later version. | |
16 | */ | |
17 | #ifndef _ASM_I386_RWLOCK_H | |
18 | #define _ASM_I386_RWLOCK_H | |
19 | ||
20 | #define RW_LOCK_BIAS 0x01000000 | |
21 | #define RW_LOCK_BIAS_STR "0x01000000" | |
22 | ||
23 | #define __build_read_lock_ptr(rw, helper) \ | |
24 | asm volatile(LOCK "subl $1,(%0)\n\t" \ | |
25 | "jns 1f\n" \ | |
26 | "call " helper "\n\t" \ | |
27 | "1:\n" \ | |
28 | ::"a" (rw) : "memory") | |
29 | ||
30 | #define __build_read_lock_const(rw, helper) \ | |
31 | asm volatile(LOCK "subl $1,%0\n\t" \ | |
32 | "jns 1f\n" \ | |
33 | "pushl %%eax\n\t" \ | |
34 | "leal %0,%%eax\n\t" \ | |
35 | "call " helper "\n\t" \ | |
36 | "popl %%eax\n\t" \ | |
37 | "1:\n" \ | |
38 | :"=m" (*(volatile int *)rw) : : "memory") | |
39 | ||
40 | #define __build_read_lock(rw, helper) do { \ | |
41 | if (__builtin_constant_p(rw)) \ | |
42 | __build_read_lock_const(rw, helper); \ | |
43 | else \ | |
44 | __build_read_lock_ptr(rw, helper); \ | |
45 | } while (0) | |
46 | ||
47 | #define __build_write_lock_ptr(rw, helper) \ | |
48 | asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \ | |
49 | "jz 1f\n" \ | |
50 | "call " helper "\n\t" \ | |
51 | "1:\n" \ | |
52 | ::"a" (rw) : "memory") | |
53 | ||
54 | #define __build_write_lock_const(rw, helper) \ | |
55 | asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",%0\n\t" \ | |
56 | "jz 1f\n" \ | |
57 | "pushl %%eax\n\t" \ | |
58 | "leal %0,%%eax\n\t" \ | |
59 | "call " helper "\n\t" \ | |
60 | "popl %%eax\n\t" \ | |
61 | "1:\n" \ | |
62 | :"=m" (*(volatile int *)rw) : : "memory") | |
63 | ||
64 | #define __build_write_lock(rw, helper) do { \ | |
65 | if (__builtin_constant_p(rw)) \ | |
66 | __build_write_lock_const(rw, helper); \ | |
67 | else \ | |
68 | __build_write_lock_ptr(rw, helper); \ | |
69 | } while (0) | |
70 | ||
71 | #endif |