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-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 00000000000..1cad22139c8
--- /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
+ WRITE_LOCK_ADD($RW_LOCK_BIAS) (%__lock_ptr)
+1: rep; nop
+ cmpl $WRITE_LOCK_CMP, (%__lock_ptr)
+ jne 1b
+ LOCK_PREFIX
+ WRITE_LOCK_SUB($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
+ READ_LOCK_SIZE(inc) (%__lock_ptr)
+1: rep; nop
+ READ_LOCK_SIZE(cmp) $1, (%__lock_ptr)
+ js 1b
+ LOCK_PREFIX
+ READ_LOCK_SIZE(dec) (%__lock_ptr)
+ js 0b
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+END(__read_lock_failed)