| /* |
| * 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> |
| |
| #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 %ecx |
| |
| #define restore_common_regs \ |
| popl %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 %rdi; \ |
| pushq %rsi; \ |
| pushq %rcx; \ |
| pushq %r8; \ |
| pushq %r9; \ |
| pushq %r10; \ |
| pushq %r11 |
| |
| #define restore_common_regs \ |
| popq %r11; \ |
| popq %r10; \ |
| popq %r9; \ |
| popq %r8; \ |
| popq %rcx; \ |
| popq %rsi; \ |
| popq %rdi |
| |
| #endif |
| |
| /* Fix up special calling conventions */ |
| ENTRY(call_rwsem_down_read_failed) |
| save_common_regs |
| __ASM_SIZE(push,) %__ASM_REG(dx) |
| movq %rax,%rdi |
| call rwsem_down_read_failed |
| __ASM_SIZE(pop,) %__ASM_REG(dx) |
| restore_common_regs |
| ret |
| ENDPROC(call_rwsem_down_read_failed) |
| |
| ENTRY(call_rwsem_down_write_failed) |
| save_common_regs |
| movq %rax,%rdi |
| call rwsem_down_write_failed |
| restore_common_regs |
| ret |
| ENDPROC(call_rwsem_down_write_failed) |
| |
| ENTRY(call_rwsem_wake) |
| /* 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 |
| ENDPROC(call_rwsem_wake) |
| |
| ENTRY(call_rwsem_downgrade_wake) |
| save_common_regs |
| __ASM_SIZE(push,) %__ASM_REG(dx) |
| movq %rax,%rdi |
| call rwsem_downgrade_wake |
| __ASM_SIZE(pop,) %__ASM_REG(dx) |
| restore_common_regs |
| ret |
| ENDPROC(call_rwsem_downgrade_wake) |
