Add atomic_fcmpset_*() inlines for powerpc

Summary:
atomic_fcmpset_*() is analogous to atomic_cmpset(), but saves off the read value
from the target memory location into the 'old' pointer in the case of failure.

Requested by:	 mjg
Differential Revision: https://reviews.freebsd.org/D9325

1 files changed, 123 insertions, 0 deletions

diff --git a/sys/powerpc/include/atomic.h b/sys/powerpc/include/atomic.h
index c4db5ff68407..eb07f64fdb67 100644
--- a/sys/powerpc/include/atomic.h
+++ b/sys/powerpc/include/atomic.h
@@ -674,6 +674,129 @@ atomic_cmpset_rel_long(volatile u_long *p, u_long cmpval, u_long newval)
 #define	atomic_cmpset_rel_ptr	atomic_cmpset_rel_int
 #endif
 
+/*
+ * Atomically compare the value stored at *p with *cmpval and if the
+ * two values are equal, update the value of *p with newval. Returns
+ * zero if the compare failed and sets *cmpval to the read value from *p,
+ * nonzero otherwise.
+ */
+static __inline int
+atomic_fcmpset_int(volatile u_int *p, u_int *cmpval, u_int newval)
+{
+	int	ret;
+
+#ifdef __GNUCLIKE_ASM
+	__asm __volatile (
+		"1:\tlwarx %0, 0, %3\n\t"	/* load old value */
+		"cmplw %4, %0\n\t"		/* compare */
+		"bne 2f\n\t"			/* exit if not equal */
+		"stwcx. %5, 0, %3\n\t"      	/* attempt to store */
+		"bne- 1b\n\t"			/* spin if failed */
+		"li %0, 1\n\t"			/* success - retval = 1 */
+		"b 3f\n\t"			/* we've succeeded */
+		"2:\n\t"
+		"stwcx. %0, 0, %3\n\t"       	/* clear reservation (74xx) */
+		"stwx %0, 0, %7\n\t"
+		"li %0, 0\n\t"			/* failure - retval = 0 */
+		"3:\n\t"
+		: "=&r" (ret), "=m" (*p), "=m" (*cmpval)
+		: "r" (p), "r" (*cmpval), "r" (newval), "m" (*p), "r"(cmpval)
+		: "cr0", "memory");
+#endif
+
+	return (ret);
+}
+static __inline int
+atomic_fcmpset_long(volatile u_long *p, u_long *cmpval, u_long newval)
+{
+	int ret;
+
+#ifdef __GNUCLIKE_ASM
+	__asm __volatile (
+	    #ifdef __powerpc64__
+		"1:\tldarx %0, 0, %3\n\t"	/* load old value */
+		"cmpld %4, %0\n\t"		/* compare */
+		"bne 2f\n\t"			/* exit if not equal */
+		"stdcx. %5, 0, %3\n\t"		/* attempt to store */
+	    #else
+		"1:\tlwarx %0, 0, %3\n\t"	/* load old value */
+		"cmplw %4, %0\n\t"		/* compare */
+		"bne 2f\n\t"			/* exit if not equal */
+		"stwcx. %5, 0, %3\n\t"		/* attempt to store */
+	    #endif
+		"bne- 1b\n\t"			/* spin if failed */
+		"li %0, 1\n\t"			/* success - retval = 1 */
+		"b 3f\n\t"			/* we've succeeded */
+		"2:\n\t"
+	    #ifdef __powerpc64__
+		"stdcx. %0, 0, %3\n\t"		/* clear reservation (74xx) */
+		"stdx %0, 0, %7\n\t"
+	    #else
+		"stwcx. %0, 0, %3\n\t"		/* clear reservation (74xx) */
+		"stwx %0, 0, %7\n\t"
+	    #endif
+		"li %0, 0\n\t"			/* failure - retval = 0 */
+		"3:\n\t"
+		: "=&r" (ret), "=m" (*p), "=m" (*cmpval)
+		: "r" (p), "r" (*cmpval), "r" (newval), "m" (*p), "r"(cmpval)
+		: "cr0", "memory");
+#endif
+
+	return (ret);
+}
+
+static __inline int
+atomic_fcmpset_acq_int(volatile u_int *p, u_int *cmpval, u_int newval)
+{
+	int retval;
+
+	retval = atomic_fcmpset_int(p, cmpval, newval);
+	__ATOMIC_ACQ();
+	return (retval);
+}
+
+static __inline int
+atomic_fcmpset_rel_int(volatile u_int *p, u_int *cmpval, u_int newval)
+{
+	__ATOMIC_REL();
+	return (atomic_fcmpset_int(p, cmpval, newval));
+}
+
+static __inline int
+atomic_fcmpset_acq_long(volatile u_long *p, u_long *cmpval, u_long newval)
+{
+	u_long retval;
+
+	retval = atomic_fcmpset_long(p, cmpval, newval);
+	__ATOMIC_ACQ();
+	return (retval);
+}
+
+static __inline int
+atomic_fcmpset_rel_long(volatile u_long *p, u_long *cmpval, u_long newval)
+{
+	__ATOMIC_REL();
+	return (atomic_fcmpset_long(p, cmpval, newval));
+}
+
+#define	atomic_fcmpset_32	atomic_fcmpset_int
+#define	atomic_fcmpset_acq_32	atomic_fcmpset_acq_int
+#define	atomic_fcmpset_rel_32	atomic_fcmpset_rel_int
+
+#ifdef __powerpc64__
+#define	atomic_fcmpset_64	atomic_fcmpset_long
+#define	atomic_fcmpset_acq_64	atomic_fcmpset_acq_long
+#define	atomic_fcmpset_rel_64	atomic_fcmpset_rel_long
+
+#define	atomic_fcmpset_ptr	atomic_fcmpset_long
+#define	atomic_fcmpset_acq_ptr	atomic_fcmpset_acq_long
+#define	atomic_fcmpset_rel_ptr	atomic_fcmpset_rel_long
+#else
+#define	atomic_fcmpset_ptr	atomic_fcmpset_int
+#define	atomic_fcmpset_acq_ptr	atomic_fcmpset_acq_int
+#define	atomic_fcmpset_rel_ptr	atomic_fcmpset_rel_int
+#endif
+
 static __inline u_int
 atomic_fetchadd_int(volatile u_int *p, u_int v)
 {