/* * x86 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/alternative-asm.h> #include <asm/dwarf2.h> #define __ASM_HALF_REG(reg) __ASM_SEL(reg, e##reg) #define __ASM_HALF_SIZE(inst) __ASM_SEL(inst##w, inst##l) #ifdef CONFIG_X86_32 /* * 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.. */ #define save_common_regs \ pushl_cfi %ecx; CFI_REL_OFFSET ecx, 0 #define restore_common_regs \ popl_cfi %ecx; CFI_RESTORE ecx /* Avoid uglifying the argument copying x86-64 needs to do. */ .macro movq src, dst .endm #else /* * x86-64 rwsem wrappers * * This interfaces the inline asm code to the slow-path * C routines. We need to save the call-clobbered regs * that the asm does not mark as clobbered, and move the * argument from %rax to %rdi. * * NOTE! We don't need to save %rax, because the functions * will always return the semaphore pointer in %rax (which * is also the input argument to these helpers) * * The following can clobber %rdx because the asm clobbers it: * call_rwsem_down_write_failed * call_rwsem_wake * but %rdi, %rsi, %rcx, %r8-r11 always need saving. */ #define save_common_regs \ pushq_cfi %rdi; CFI_REL_OFFSET rdi, 0; \ pushq_cfi %rsi; CFI_REL_OFFSET rsi, 0; \ pushq_cfi %rcx; CFI_REL_OFFSET rcx, 0; \ pushq_cfi %r8; CFI_REL_OFFSET r8, 0; \ pushq_cfi %r9; CFI_REL_OFFSET r9, 0; \ pushq_cfi %r10; CFI_REL_OFFSET r10, 0; \ pushq_cfi %r11; CFI_REL_OFFSET r11, 0 #define restore_common_regs \ popq_cfi %r11; CFI_RESTORE r11; \ popq_cfi %r10; CFI_RESTORE r10; \ popq_cfi %r9; CFI_RESTORE r9; \ popq_cfi %r8; CFI_RESTORE r8; \ popq_cfi %rcx; CFI_RESTORE rcx; \ popq_cfi %rsi; CFI_RESTORE rsi; \ popq_cfi %rdi; CFI_RESTORE rdi #endif /* Fix up special calling conventions */ ENTRY(call_rwsem_down_read_failed) CFI_STARTPROC save_common_regs __ASM_SIZE(push,_cfi) %__ASM_REG(dx) CFI_REL_OFFSET __ASM_REG(dx), 0 movq %rax,%rdi call rwsem_down_read_failed __ASM_SIZE(pop,_cfi) %__ASM_REG(dx) CFI_RESTORE __ASM_REG(dx) restore_common_regs ret CFI_ENDPROC ENDPROC(call_rwsem_down_read_failed) ENTRY(call_rwsem_down_write_failed) CFI_STARTPROC save_common_regs movq %rax,%rdi call rwsem_down_write_failed restore_common_regs ret CFI_ENDPROC ENDPROC(call_rwsem_down_write_failed) ENTRY(call_rwsem_wake) CFI_STARTPROC /* do nothing if still outstanding active readers */ __ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx) jnz 1f save_common_regs movq %rax,%rdi call rwsem_wake restore_common_regs 1: ret CFI_ENDPROC ENDPROC(call_rwsem_wake) ENTRY(call_rwsem_downgrade_wake) CFI_STARTPROC save_common_regs __ASM_SIZE(push,_cfi) %__ASM_REG(dx) CFI_REL_OFFSET __ASM_REG(dx), 0 movq %rax,%rdi call rwsem_downgrade_wake __ASM_SIZE(pop,_cfi) %__ASM_REG(dx) CFI_RESTORE __ASM_REG(dx) restore_common_regs ret CFI_ENDPROC ENDPROC(call_rwsem_downgrade_wake)