powerpc: use __NO_LWSYNC__ check to use appropriate lwsync/sync opcode

[urcu.git] / urcu / arch / ppc.h

diff --git a/urcu/arch/ppc.h b/urcu/arch/ppc.h
index d7317bb327c72afa48f087f50251cbe311a2ff62..2fcbf5660958a12d2ad6dd957838ed73da4f2bec 100644 (file)
--- a/urcu/arch/ppc.h
+++ b/urcu/arch/ppc.h
@@ -32,7 +32,30 @@ extern "C" {
 /* Include size of POWER5+ L3 cache lines: 256 bytes */
 #define CAA_CACHE_LINE_SIZE    256
 
-#define cmm_mb()    asm volatile("sync":::"memory")
+#ifdef __NO_LWSYNC__
+#define LWSYNC_OPCODE  "sync\n"
+#else
+#define LWSYNC_OPCODE  "lwsync\n"
+#endif
+
+/*
+ * Use sync for all cmm_mb/rmb/wmb barriers because lwsync does not
+ * preserve ordering of cacheable vs. non-cacheable accesses, so it
+ * should not be used to order with respect to MMIO operations.  An
+ * eieio+lwsync pair is also not enough for cmm_rmb, because it will
+ * order cacheable and non-cacheable memory operations separately---i.e.
+ * not the latter against the former.
+ */
+#define cmm_mb()         asm volatile("sync":::"memory")
+
+/*
+ * lwsync orders loads in cacheable memory with respect to other loads,
+ * and stores in cacheable memory with respect to other stores.
+ * Therefore, use it for barriers ordering accesses to cacheable memory
+ * only.
+ */
+#define cmm_smp_rmb()    asm volatile(LWSYNC_OPCODE:::"memory")
+#define cmm_smp_wmb()    asm volatile(LWSYNC_OPCODE:::"memory")
 
 #define mftbl()                                                \
        ({                                              \
@@ -48,11 +71,24 @@ extern "C" {
                rval;                                   \
        })
 
+#define mftb()                                         \
+       ({                                              \
+               unsigned long long rval;                \
+               asm volatile("mftb %0" : "=r" (rval));  \
+               rval;                                   \
+       })
+
 typedef unsigned long long cycles_t;
 
-static inline cycles_t caa_get_cycles (void)
+#ifdef __powerpc64__
+static inline cycles_t caa_get_cycles(void)
 {
-       long h, l;
+       return (cycles_t) mftb();
+}
+#else
+static inline cycles_t caa_get_cycles(void)
+{
+       unsigned long h, l;
 
        for (;;) {
                h = mftbu();
@@ -63,6 +99,7 @@ static inline cycles_t caa_get_cycles (void)
                        return (((cycles_t) h) << 32) + l;
        }
 }
+#endif
 
 #ifdef __cplusplus 
 }