| Christoph Lameter | b9ec40a | 2011-02-28 11:02:24 +0100 | [diff] [blame^] | 1 | /* |
| 2 | * This program is free software; you can redistribute it and/or |
| 3 | * modify it under the terms of the GNU General Public License |
| 4 | * as published by the Free Software Foundation; version 2 |
| 5 | * of the License. |
| 6 | * |
| 7 | */ |
| 8 | #include <linux/linkage.h> |
| 9 | #include <asm/alternative-asm.h> |
| 10 | #include <asm/frame.h> |
| 11 | #include <asm/dwarf2.h> |
| 12 | |
| 13 | .text |
| 14 | |
| 15 | /* |
| 16 | * Inputs: |
| 17 | * %rsi : memory location to compare |
| 18 | * %rax : low 64 bits of old value |
| 19 | * %rdx : high 64 bits of old value |
| 20 | * %rbx : low 64 bits of new value |
| 21 | * %rcx : high 64 bits of new value |
| 22 | * %al : Operation successful |
| 23 | */ |
| 24 | ENTRY(this_cpu_cmpxchg16b_emu) |
| 25 | CFI_STARTPROC |
| 26 | |
| 27 | # |
| 28 | # Emulate 'cmpxchg16b %gs:(%rsi)' except we return the result in %al not |
| 29 | # via the ZF. Caller will access %al to get result. |
| 30 | # |
| 31 | # Note that this is only useful for a cpuops operation. Meaning that we |
| 32 | # do *not* have a fully atomic operation but just an operation that is |
| 33 | # *atomic* on a single cpu (as provided by the this_cpu_xx class of |
| 34 | # macros). |
| 35 | # |
| 36 | this_cpu_cmpxchg16b_emu: |
| 37 | pushf |
| 38 | cli |
| 39 | |
| 40 | cmpq %gs:(%rsi), %rax |
| 41 | jne not_same |
| 42 | cmpq %gs:8(%rsi), %rdx |
| 43 | jne not_same |
| 44 | |
| 45 | movq %rbx, %gs:(%rsi) |
| 46 | movq %rcx, %gs:8(%rsi) |
| 47 | |
| 48 | popf |
| 49 | mov $1, %al |
| 50 | ret |
| 51 | |
| 52 | not_same: |
| 53 | popf |
| 54 | xor %al,%al |
| 55 | ret |
| 56 | |
| 57 | CFI_ENDPROC |
| 58 | |
| 59 | ENDPROC(this_cpu_cmpxchg16b_emu) |