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Diffstat (limited to 'kernel/arch/x86/lib/cmpxchg8b_emu.S')
-rw-r--r--kernel/arch/x86/lib/cmpxchg8b_emu.S55
1 files changed, 55 insertions, 0 deletions
diff --git a/kernel/arch/x86/lib/cmpxchg8b_emu.S b/kernel/arch/x86/lib/cmpxchg8b_emu.S
new file mode 100644
index 000000000..b4807fce5
--- /dev/null
+++ b/kernel/arch/x86/lib/cmpxchg8b_emu.S
@@ -0,0 +1,55 @@
+/*
+ * 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/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)
+#
+ pushfl_cfi
+ cli
+
+ cmpl (%esi), %eax
+ jne .Lnot_same
+ cmpl 4(%esi), %edx
+ jne .Lhalf_same
+
+ movl %ebx, (%esi)
+ movl %ecx, 4(%esi)
+
+ CFI_REMEMBER_STATE
+ popfl_cfi
+ ret
+
+ CFI_RESTORE_STATE
+.Lnot_same:
+ movl (%esi), %eax
+.Lhalf_same:
+ movl 4(%esi), %edx
+
+ popfl_cfi
+ ret
+
+CFI_ENDPROC
+ENDPROC(cmpxchg8b_emu)