Initial commit

arch/x86/lib/cmpxchg8b_emu.S

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+/*
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; version 2
+ *	of the License.
+ *
+ */
+
+#include <linux/linkage.h>
+#include <asm/alternative-asm.h>
+#include <asm/frame.h>
+#include <asm/dwarf2.h>
+
+
+.text
+
+/*
+ * Inputs:
+ * %esi : memory location to compare
+ * %eax : low 32 bits of old value
+ * %edx : high 32 bits of old value
+ * %ebx : low 32 bits of new value
+ * %ecx : high 32 bits of new value
+ */
+ENTRY(cmpxchg8b_emu)
+CFI_STARTPROC
+
+#
+# Emulate 'cmpxchg8b (%esi)' on UP except we don't
+# set the whole ZF thing (caller will just compare
+# eax:edx with the expected value)
+#
+cmpxchg8b_emu:
+	pushfl
+	cli
+
+	cmpl  (%esi), %eax
+	jne not_same
+	cmpl 4(%esi), %edx
+	jne half_same
+
+	movl %ebx,  (%esi)
+	movl %ecx, 4(%esi)
+
+	popfl
+	ret
+
+ not_same:
+	movl  (%esi), %eax
+ half_same:
+	movl 4(%esi), %edx
+
+	popfl
+	ret
+
+CFI_ENDPROC
+ENDPROC(cmpxchg8b_emu)