From 8e4bff4cab0ddac6060645b0715210484d02ff40 Mon Sep 17 00:00:00 2001
From: Yuval Adam <_@yuv.al>
Date: Wed, 30 Aug 2017 08:25:59 +0000
Subject: Initial file dump from open source release

---
 arch/x86/lib/rwlock.S | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 arch/x86/lib/rwlock.S

(limited to 'arch/x86/lib/rwlock.S')

diff --git a/arch/x86/lib/rwlock.S b/arch/x86/lib/rwlock.S
new file mode 100644
index 00000000..1cad2213
--- /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)
-- 
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