diff options
Diffstat (limited to 'include/asm-i386/rwlock.h')
| -rw-r--r-- | include/asm-i386/rwlock.h | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/include/asm-i386/rwlock.h b/include/asm-i386/rwlock.h new file mode 100644 index 000000000..ac9e8f36b --- /dev/null +++ b/include/asm-i386/rwlock.h @@ -0,0 +1,86 @@ +/* include/asm-i386/rwlock.h + * + * Helpers used by both rw spinlocks and rw semaphores. + * + * Based in part on code from semaphore.h and + * spinlock.h Copyright 1996 Linus Torvalds. + * + * Copyright 1999 Red Hat, Inc. + * + * Written by Benjamin LaHaise. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#ifndef _ASM_I386_RWLOCK_H +#define _ASM_I386_RWLOCK_H + +typedef struct { unsigned long a[100]; } __dummy_lock_t; +#define __dummy_lock(lock) (*(__dummy_lock_t *)(lock)) + +#define RW_LOCK_BIAS 0x01000000 +#define RW_LOCK_BIAS_STR "0x01000000" + +#define __build_read_lock_ptr(rw, helper) \ + asm volatile(LOCK "subl $1,(%0)\n\t" \ + "js 2f\n" \ + "1:\n" \ + ".section .text.lock,\"ax\"\n" \ + "2:\tcall " helper "\n\t" \ + "jmp 1b\n" \ + ".previous" \ + ::"a" (rw) : "memory") + +#define __build_read_lock_const(rw, helper) \ + asm volatile(LOCK "subl $1,%0\n\t" \ + "js 2f\n" \ + "1:\n" \ + ".section .text.lock,\"ax\"\n" \ + "2:\tpushl %%eax\n\t" \ + "leal %0,%%eax\n\t" \ + "call " helper "\n\t" \ + "popl %%eax\n\t" \ + "jmp 1b\n" \ + ".previous" \ + :"=m" (__dummy_lock(rw))) + +#define __build_read_lock(rw, helper) do { \ + if (__builtin_constant_p(rw)) \ + __build_read_lock_const(rw, helper); \ + else \ + __build_read_lock_ptr(rw, helper); \ + } while (0) + +#define __build_write_lock_ptr(rw, helper) \ + asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \ + "jnz 2f\n" \ + "1:\n" \ + ".section .text.lock,\"ax\"\n" \ + "2:\tcall " helper "\n\t" \ + "jmp 1b\n" \ + ".previous" \ + ::"a" (rw) : "memory") + +#define __build_write_lock_const(rw, helper) \ + asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \ + "jnz 2f\n" \ + "1:\n" \ + ".section .text.lock,\"ax\"\n" \ + "2:\tpushl %%eax\n\t" \ + "leal %0,%%eax\n\t" \ + "call " helper "\n\t" \ + "popl %%eax\n\t" \ + "jmp 1b\n" \ + ".previous" \ + :"=m" (__dummy_lock(rw))) + +#define __build_write_lock(rw, helper) do { \ + if (__builtin_constant_p(rw)) \ + __build_write_lock_const(rw, helper); \ + else \ + __build_write_lock_ptr(rw, helper); \ + } while (0) + +#endif |