| /* SPDX-License-Identifier: GPL-2.0-only */ |
| #include <linux/linkage.h> |
| #include <asm/percpu.h> |
| |
| .text |
| |
| /* |
| * 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 |
| * %al : Operation successful |
| */ |
| ENTRY(this_cpu_cmpxchg16b_emu) |
| |
| # |
| # Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not |
| # via the ZF. Caller will access %al to get result. |
| # |
| # Note that this is only useful for a cpuops operation. Meaning that we |
| # do *not* have a fully atomic operation but just an operation that is |
| # *atomic* on a single cpu (as provided by the this_cpu_xx class of |
| # macros). |
| # |
| pushfq |
| cli |
| |
| cmpq PER_CPU_VAR((%rsi)), %rax |
| jne .Lnot_same |
| cmpq PER_CPU_VAR(8(%rsi)), %rdx |
| jne .Lnot_same |
| |
| movq %rbx, PER_CPU_VAR((%rsi)) |
| movq %rcx, PER_CPU_VAR(8(%rsi)) |
| |
| popfq |
| mov $1, %al |
| ret |
| |
| .Lnot_same: |
| popfq |
| xor %al,%al |
| ret |
| |
| ENDPROC(this_cpu_cmpxchg16b_emu) |
