diff options
Diffstat (limited to 'arch/x86/lib/semaphore_32.S')
| -rw-r--r-- | arch/x86/lib/semaphore_32.S | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/arch/x86/lib/semaphore_32.S b/arch/x86/lib/semaphore_32.S new file mode 100644 index 00000000..06691daa --- /dev/null +++ b/arch/x86/lib/semaphore_32.S @@ -0,0 +1,124 @@ +/* + * i386 semaphore implementation. + * + * (C) Copyright 1999 Linus Torvalds + * + * Portions Copyright 1999 Red Hat, Inc. + * + * 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. + * + * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org> + */ + +#include <linux/linkage.h> +#include <asm/rwlock.h> +#include <asm/alternative-asm.h> +#include <asm/frame.h> +#include <asm/dwarf2.h> + +/* + * The semaphore operations have a special calling sequence that + * allow us to do a simpler in-line version of them. These routines + * need to convert that sequence back into the C sequence when + * there is contention on the semaphore. + * + * %eax contains the semaphore pointer on entry. Save the C-clobbered + * registers (%eax, %edx and %ecx) except %eax whish is either a return + * value or just clobbered.. + */ + .section .sched.text, "ax" + +/* + * rw spinlock fallbacks + */ +#ifdef CONFIG_SMP +ENTRY(__write_lock_failed) + CFI_STARTPROC + FRAME +2: LOCK_PREFIX + addl $ RW_LOCK_BIAS,(%eax) +1: rep; nop + cmpl $ RW_LOCK_BIAS,(%eax) + jne 1b + LOCK_PREFIX + subl $ RW_LOCK_BIAS,(%eax) + jnz 2b + ENDFRAME + ret + CFI_ENDPROC + ENDPROC(__write_lock_failed) + +ENTRY(__read_lock_failed) + CFI_STARTPROC + FRAME +2: LOCK_PREFIX + incl (%eax) +1: rep; nop + cmpl $1,(%eax) + js 1b + LOCK_PREFIX + decl (%eax) + js 2b + ENDFRAME + ret + CFI_ENDPROC + ENDPROC(__read_lock_failed) + +#endif + +#ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM + +/* Fix up special calling conventions */ +ENTRY(call_rwsem_down_read_failed) + CFI_STARTPROC + pushl_cfi %ecx + CFI_REL_OFFSET ecx,0 + pushl_cfi %edx + CFI_REL_OFFSET edx,0 + call rwsem_down_read_failed + popl_cfi %edx + popl_cfi %ecx + ret + CFI_ENDPROC + ENDPROC(call_rwsem_down_read_failed) + +ENTRY(call_rwsem_down_write_failed) + CFI_STARTPROC + pushl_cfi %ecx + CFI_REL_OFFSET ecx,0 + calll rwsem_down_write_failed + popl_cfi %ecx + ret + CFI_ENDPROC + ENDPROC(call_rwsem_down_write_failed) + +ENTRY(call_rwsem_wake) + CFI_STARTPROC + decw %dx /* do nothing if still outstanding active readers */ + jnz 1f + pushl_cfi %ecx + CFI_REL_OFFSET ecx,0 + call rwsem_wake + popl_cfi %ecx +1: ret + CFI_ENDPROC + ENDPROC(call_rwsem_wake) + +/* Fix up special calling conventions */ +ENTRY(call_rwsem_downgrade_wake) + CFI_STARTPROC + pushl_cfi %ecx + CFI_REL_OFFSET ecx,0 + pushl_cfi %edx + CFI_REL_OFFSET edx,0 + call rwsem_downgrade_wake + popl_cfi %edx + popl_cfi %ecx + ret + CFI_ENDPROC + ENDPROC(call_rwsem_downgrade_wake) + +#endif |