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Diffstat (limited to 'arch/i386/lib/semaphore.S')
| -rw-r--r-- | arch/i386/lib/semaphore.S | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/arch/i386/lib/semaphore.S b/arch/i386/lib/semaphore.S new file mode 100644 index 000000000000..e16ff1696390 --- /dev/null +++ b/arch/i386/lib/semaphore.S @@ -0,0 +1,154 @@ +/* + * 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/config.h> +#include <linux/linkage.h> +#include <asm/rwlock.h> +#include <asm/alternative-asm.i> +#include <asm/frame.i> +#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 +ENTRY(__down_failed) + CFI_STARTPROC + FRAME + pushl %edx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET edx,0 + pushl %ecx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET ecx,0 + call __down + popl %ecx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE ecx + popl %edx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE edx + ENDFRAME + ret + CFI_ENDPROC + END(__down_failed) + +ENTRY(__down_failed_interruptible) + CFI_STARTPROC + FRAME + pushl %edx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET edx,0 + pushl %ecx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET ecx,0 + call __down_interruptible + popl %ecx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE ecx + popl %edx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE edx + ENDFRAME + ret + CFI_ENDPROC + END(__down_failed_interruptible) + +ENTRY(__down_failed_trylock) + CFI_STARTPROC + FRAME + pushl %edx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET edx,0 + pushl %ecx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET ecx,0 + call __down_trylock + popl %ecx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE ecx + popl %edx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE edx + ENDFRAME + ret + CFI_ENDPROC + END(__down_failed_trylock) + +ENTRY(__up_wakeup) + CFI_STARTPROC + FRAME + pushl %edx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET edx,0 + pushl %ecx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET ecx,0 + call __up + popl %ecx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE ecx + popl %edx + CFI_ADJUST_CFA_OFFSET -4 + CFI_RESTORE edx + ENDFRAME + ret + CFI_ENDPROC + END(__up_wakeup) + +/* + * rw spinlock fallbacks + */ +#ifdef CONFIG_SMP +ENTRY(__write_lock_failed) + CFI_STARTPROC simple + 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 + END(__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 + END(__read_lock_failed) + +#endif |