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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-16 11:22:41 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-16 11:22:41 -0400
commit79d8a8f736151b12129984b1250fd708440e742c (patch)
treef67eebe2bafca8820955ee9f851985a41fb32e66 /arch/x86/lib
parentbd2895eeade5f11f3e5906283c630bbdb4b57454 (diff)
parentb9ec40af0e18fb7d02106be148036c2ea490fdf9 (diff)
Merge branch 'for-2.6.39' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-2.6.39' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu, x86: Add arch-specific this_cpu_cmpxchg_double() support percpu: Generic support for this_cpu_cmpxchg_double() alpha: use L1_CACHE_BYTES for cacheline size in the linker script percpu: align percpu readmostly subsection to cacheline Fix up trivial conflict in arch/x86/kernel/vmlinux.lds.S due to the percpu alignment having changed ("x86: Reduce back the alignment of the per-CPU data section")
Diffstat (limited to 'arch/x86/lib')
-rw-r--r--arch/x86/lib/Makefile1
-rw-r--r--arch/x86/lib/cmpxchg16b_emu.S59
2 files changed, 60 insertions, 0 deletions
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index e10cf070ede0..f2479f19ddde 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -42,4 +42,5 @@ else
42 lib-y += memmove_64.o memset_64.o 42 lib-y += memmove_64.o memset_64.o
43 lib-y += copy_user_64.o rwlock_64.o copy_user_nocache_64.o 43 lib-y += copy_user_64.o rwlock_64.o copy_user_nocache_64.o
44 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem_64.o 44 lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem_64.o
45 lib-y += cmpxchg16b_emu.o
45endif 46endif
diff --git a/arch/x86/lib/cmpxchg16b_emu.S b/arch/x86/lib/cmpxchg16b_emu.S
new file mode 100644
index 000000000000..3e8b08a6de2b
--- /dev/null
+++ b/arch/x86/lib/cmpxchg16b_emu.S
@@ -0,0 +1,59 @@
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 */
24ENTRY(this_cpu_cmpxchg16b_emu)
25CFI_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#
36this_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
57CFI_ENDPROC
58
59ENDPROC(this_cpu_cmpxchg16b_emu)