/* * 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 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 #ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM /* Fix up special calling conventions */ ENTRY(call_rwsem_down_read_failed) CFI_STARTPROC push %ecx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ecx,0 push %edx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET edx,0 call rwsem_down_read_failed pop %edx CFI_ADJUST_CFA_OFFSET -4 pop %ecx CFI_ADJUST_CFA_OFFSET -4 ret CFI_ENDPROC END(call_rwsem_down_read_failed) ENTRY(call_rwsem_down_write_failed) CFI_STARTPROC push %ecx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ecx,0 calll rwsem_down_write_failed pop %ecx CFI_ADJUST_CFA_OFFSET -4 ret CFI_ENDPROC END(call_rwsem_down_write_failed) ENTRY(call_rwsem_wake) CFI_STARTPROC decw %dx /* do nothing if still outstanding active readers */ jnz 1f push %ecx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ecx,0 call rwsem_wake pop %ecx CFI_ADJUST_CFA_OFFSET -4 1: ret CFI_ENDPROC END(call_rwsem_wake) /* Fix up special calling conventions */ ENTRY(call_rwsem_downgrade_wake) CFI_STARTPROC push %ecx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET ecx,0 push %edx CFI_ADJUST_CFA_OFFSET 4 CFI_REL_OFFSET edx,0 call rwsem_downgrade_wake pop %edx CFI_ADJUST_CFA_OFFSET -4 pop %ecx CFI_ADJUST_CFA_OFFSET -4 ret CFI_ENDPROC END(call_rwsem_downgrade_wake) #endif