| /* |
| * 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; version 2 |
| * of the License. |
| * |
| */ |
| #include <linux/linkage.h> |
| #include <asm/alternative-asm.h> |
| #include <asm/frame.h> |
| #include <asm/dwarf2.h> |
| |
| #ifdef CONFIG_SMP |
| #define SEG_PREFIX %gs: |
| #else |
| #define SEG_PREFIX |
| #endif |
| |
| .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) |
| CFI_STARTPROC |
| |
| # |
| # 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). |
| # |
| this_cpu_cmpxchg16b_emu: |
| pushf |
| cli |
| |
| cmpq SEG_PREFIX(%rsi), %rax |
| jne not_same |
| cmpq SEG_PREFIX 8(%rsi), %rdx |
| jne not_same |
| |
| movq %rbx, SEG_PREFIX(%rsi) |
| movq %rcx, SEG_PREFIX 8(%rsi) |
| |
| popf |
| mov $1, %al |
| ret |
| |
| not_same: |
| popf |
| xor %al,%al |
| ret |
| |
| CFI_ENDPROC |
| |
| ENDPROC(this_cpu_cmpxchg16b_emu) |
