diff options
Diffstat (limited to 'arch/x86/lib/cmpxchg8b_emu.S')
| -rw-r--r-- | arch/x86/lib/cmpxchg8b_emu.S | 81 |
1 files changed, 66 insertions, 15 deletions
diff --git a/arch/x86/lib/cmpxchg8b_emu.S b/arch/x86/lib/cmpxchg8b_emu.S index 6a912d58fecc..d4bb24347ff8 100644 --- a/arch/x86/lib/cmpxchg8b_emu.S +++ b/arch/x86/lib/cmpxchg8b_emu.S @@ -1,11 +1,17 @@ /* SPDX-License-Identifier: GPL-2.0-only */ +#include <linux/export.h> #include <linux/linkage.h> -#include <asm/export.h> +#include <asm/percpu.h> +#include <asm/processor-flags.h> .text +#ifndef CONFIG_X86_CX8 + /* + * Emulate 'cmpxchg8b (%esi)' on UP + * * Inputs: * %esi : memory location to compare * %eax : low 32 bits of old value @@ -15,32 +21,77 @@ */ SYM_FUNC_START(cmpxchg8b_emu) -# -# Emulate 'cmpxchg8b (%esi)' on UP except we don't -# set the whole ZF thing (caller will just compare -# eax:edx with the expected value) -# pushfl cli - cmpl (%esi), %eax - jne .Lnot_same - cmpl 4(%esi), %edx - jne .Lhalf_same + cmpl (%esi), %eax + jne .Lnot_same + cmpl 4(%esi), %edx + jne .Lnot_same + + movl %ebx, (%esi) + movl %ecx, 4(%esi) - movl %ebx, (%esi) - movl %ecx, 4(%esi) + orl $X86_EFLAGS_ZF, (%esp) popfl RET .Lnot_same: - movl (%esi), %eax -.Lhalf_same: - movl 4(%esi), %edx + movl (%esi), %eax + movl 4(%esi), %edx + + andl $(~X86_EFLAGS_ZF), (%esp) popfl RET SYM_FUNC_END(cmpxchg8b_emu) EXPORT_SYMBOL(cmpxchg8b_emu) + +#endif + +#ifndef CONFIG_UML + +/* + * Emulate 'cmpxchg8b %fs:(%rsi)' + * + * Inputs: + * %esi : memory location to compare + * %eax : low 32 bits of old value + * %edx : high 32 bits of old value + * %ebx : low 32 bits of new value + * %ecx : high 32 bits of new value + * + * Notably this is not LOCK prefixed and is not safe against NMIs + */ +SYM_FUNC_START(this_cpu_cmpxchg8b_emu) + + pushfl + cli + + cmpl __percpu (%esi), %eax + jne .Lnot_same2 + cmpl __percpu 4(%esi), %edx + jne .Lnot_same2 + + movl %ebx, __percpu (%esi) + movl %ecx, __percpu 4(%esi) + + orl $X86_EFLAGS_ZF, (%esp) + + popfl + RET + +.Lnot_same2: + movl __percpu (%esi), %eax + movl __percpu 4(%esi), %edx + + andl $(~X86_EFLAGS_ZF), (%esp) + + popfl + RET + +SYM_FUNC_END(this_cpu_cmpxchg8b_emu) + +#endif |