1 files changed, 65 insertions, 0 deletions
diff --git a/roms/skiboot/include/cmpxchg.h b/roms/skiboot/include/cmpxchg.h
new file mode 100644
index 000000000..0304e9134
--- /dev/null
+++ b/roms/skiboot/include/cmpxchg.h
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+/* Copyright 2017 IBM Corp. */
+
+#ifndef __CMPXCHG_H
+#define __CMPXCHG_H
+
+#ifndef __TEST__
+/*
+ * Bare cmpxchg, no barriers.
+ */
+static inline uint32_t __cmpxchg32(uint32_t *mem, uint32_t old, uint32_t new)
+{
+	uint32_t prev;
+
+	asm volatile(
+		"# __cmpxchg32		\n"
+		"1:	lwarx	%0,0,%2	\n"
+		"	cmpw	%0,%3	\n"
+		"	bne-	2f	\n"
+		"	stwcx.	%4,0,%2	\n"
+		"	bne-	1b	\n"
+		"2:			\n"
+
+		: "=&r"(prev), "+m"(*mem)
+		: "r"(mem), "r"(old), "r"(new)
+		: "cr0");
+
+	return prev;
+}
+
+static inline uint64_t __cmpxchg64(uint64_t *mem, uint64_t old, uint64_t new)
+{
+	uint64_t prev;
+
+	asm volatile(
+		"# __cmpxchg64		\n"
+		"1:	ldarx	%0,0,%2	\n"
+		"	cmpd	%0,%3	\n"
+		"	bne-	2f	\n"
+		"	stdcx.	%4,0,%2	\n"
+		"	bne-	1b	\n"
+		"2:			\n"
+
+		: "=&r"(prev), "+m"(*mem)
+		: "r"(mem), "r"(old), "r"(new)
+		: "cr0");
+
+	return prev;
+}
+
+static inline uint32_t cmpxchg32(uint32_t *mem, uint32_t old, uint32_t new)
+{
+	uint32_t prev;
+
+	sync();
+	prev = __cmpxchg32(mem, old,new);
+	sync();
+
+	return prev;
+}
+#endif /* __TEST_ */
+
+#endif /* __CMPXCHG_H */
+
+