]>
Commit | Line | Data |
---|---|---|
b9ec40af CL |
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) |