2023-08-30 17:31:07 +02:00
|
|
|
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
|
|
|
#include <linux/linkage.h>
|
|
|
|
|
#include <asm/percpu.h>
|
2023-10-24 12:59:35 +02:00
|
|
|
#include <asm/processor-flags.h>
|
2023-08-30 17:31:07 +02:00
|
|
|
|
|
|
|
|
.text
|
|
|
|
|
|
|
|
|
|
/*
|
2023-10-24 12:59:35 +02:00
|
|
|
* Emulate 'cmpxchg16b %gs:(%rsi)'
|
|
|
|
|
*
|
2023-08-30 17:31:07 +02:00
|
|
|
* Inputs:
|
|
|
|
|
* %rsi : memory location to compare
|
|
|
|
|
* %rax : low 64 bits of old value
|
|
|
|
|
* %rdx : high 64 bits of old value
|
|
|
|
|
* %rbx : low 64 bits of new value
|
|
|
|
|
* %rcx : high 64 bits of new value
|
2023-10-24 12:59:35 +02:00
|
|
|
*
|
|
|
|
|
* Notably this is not LOCK prefixed and is not safe against NMIs
|
2023-08-30 17:31:07 +02:00
|
|
|
*/
|
|
|
|
|
SYM_FUNC_START(this_cpu_cmpxchg16b_emu)
|
|
|
|
|
|
|
|
|
|
pushfq
|
|
|
|
|
cli
|
|
|
|
|
|
2023-10-24 12:59:35 +02:00
|
|
|
/* if (*ptr == old) */
|
|
|
|
|
cmpq PER_CPU_VAR(0(%rsi)), %rax
|
|
|
|
|
jne .Lnot_same
|
|
|
|
|
cmpq PER_CPU_VAR(8(%rsi)), %rdx
|
|
|
|
|
jne .Lnot_same
|
2023-08-30 17:31:07 +02:00
|
|
|
|
2023-10-24 12:59:35 +02:00
|
|
|
/* *ptr = new */
|
|
|
|
|
movq %rbx, PER_CPU_VAR(0(%rsi))
|
|
|
|
|
movq %rcx, PER_CPU_VAR(8(%rsi))
|
|
|
|
|
|
|
|
|
|
/* set ZF in EFLAGS to indicate success */
|
|
|
|
|
orl $X86_EFLAGS_ZF, (%rsp)
|
2023-08-30 17:31:07 +02:00
|
|
|
|
|
|
|
|
popfq
|
|
|
|
|
RET
|
|
|
|
|
|
|
|
|
|
.Lnot_same:
|
2023-10-24 12:59:35 +02:00
|
|
|
/* *ptr != old */
|
|
|
|
|
|
|
|
|
|
/* old = *ptr */
|
|
|
|
|
movq PER_CPU_VAR(0(%rsi)), %rax
|
|
|
|
|
movq PER_CPU_VAR(8(%rsi)), %rdx
|
|
|
|
|
|
|
|
|
|
/* clear ZF in EFLAGS to indicate failure */
|
|
|
|
|
andl $(~X86_EFLAGS_ZF), (%rsp)
|
|
|
|
|
|
2023-08-30 17:31:07 +02:00
|
|
|
popfq
|
|
|
|
|
RET
|
|
|
|
|
|
|
|
|
|
SYM_FUNC_END(this_cpu_cmpxchg16b_emu)
|
