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authorJan Beulich <JBeulich@novell.com>2011-07-19 12:59:51 +0100
committerIngo Molnar <mingo@elte.hu>2011-07-21 09:03:31 +0200
commit4625cd637919edfb562e0d62abf94f52e9321335 (patch)
tree88c4cf965722fb54731a6e8f632ec6ef6e83e194 /arch/x86/lib/rwlock.S
parentdd2897bf0f4d523238e87dabb23e9634ea9ba73d (diff)
downloadop-kernel-dev-4625cd637919edfb562e0d62abf94f52e9321335.zip
op-kernel-dev-4625cd637919edfb562e0d62abf94f52e9321335.tar.gz
x86: Unify rwlock assembly implementation
Rather than having two functionally identical implementations for 32- and 64-bit configurations, extend the existing assembly abstractions enough to fold the two rwlock implementations into a shared one. Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4E258DD7020000780004E3EA@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/lib/rwlock.S')
-rw-r--r--arch/x86/lib/rwlock.S44
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/x86/lib/rwlock.S b/arch/x86/lib/rwlock.S
new file mode 100644
index 0000000..fca1782
--- /dev/null
+++ b/arch/x86/lib/rwlock.S
@@ -0,0 +1,44 @@
+/* Slow paths of read/write spinlocks. */
+
+#include <linux/linkage.h>
+#include <asm/alternative-asm.h>
+#include <asm/frame.h>
+#include <asm/rwlock.h>
+
+#ifdef CONFIG_X86_32
+# define __lock_ptr eax
+#else
+# define __lock_ptr rdi
+#endif
+
+ENTRY(__write_lock_failed)
+ CFI_STARTPROC
+ FRAME
+0: LOCK_PREFIX
+ addl $RW_LOCK_BIAS, (%__lock_ptr)
+1: rep; nop
+ cmpl $RW_LOCK_BIAS, (%__lock_ptr)
+ jne 1b
+ LOCK_PREFIX
+ subl $RW_LOCK_BIAS, (%__lock_ptr)
+ jnz 0b
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+END(__write_lock_failed)
+
+ENTRY(__read_lock_failed)
+ CFI_STARTPROC
+ FRAME
+0: LOCK_PREFIX
+ incl (%__lock_ptr)
+1: rep; nop
+ cmpl $1, (%__lock_ptr)
+ js 1b
+ LOCK_PREFIX
+ decl (%__lock_ptr)
+ js 0b
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+END(__read_lock_failed)
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