1 files changed, 34 insertions, 0 deletions

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 4dcc8f3190cf..17c9ace445c4 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -481,6 +481,38 @@ static void perf_event__read_swap(union perf_event *event)
         event->read.id           = bswap_64(event->read.id);
 }
 
+static u8 revbyte(u8 b)
+{
+        int rev = (b >> 4) | ((b & 0xf) << 4);
+        rev = ((rev & 0xcc) >> 2) | ((rev & 0x33) << 2);
+        rev = ((rev & 0xaa) >> 1) | ((rev & 0x55) << 1);
+        return (u8) rev;
+}
+
+/*
+ * XXX this is hack in attempt to carry flags bitfield
+ * throught endian village. ABI says:
+ *
+ * Bit-fields are allocated from right to left (least to most significant)
+ * on little-endian implementations and from left to right (most to least
+ * significant) on big-endian implementations.
+ *
+ * The above seems to be byte specific, so we need to reverse each
+ * byte of the bitfield. 'Internet' also says this might be implementation
+ * specific and we probably need proper fix and carry perf_event_attr
+ * bitfield flags in separate data file FEAT_ section. Thought this seems
+ * to work for now.
+ */
+static void swap_bitfield(u8 *p, unsigned len)
+{
+        unsigned i;
+
+        for (i = 0; i < len; i++) {
+                *p = revbyte(*p);
+                p++;
+        }
+}
+
 /* exported for swapping attributes in file header */
 void perf_event__attr_swap(struct perf_event_attr *attr)
 {
@@ -494,6 +526,8 @@ void perf_event__attr_swap(struct perf_event_attr *attr)
         attr->bp_type           = bswap_32(attr->bp_type);
         attr->bp_addr           = bswap_64(attr->bp_addr);
         attr->bp_len            = bswap_64(attr->bp_len);
+
+        swap_bitfield((u8 *) (&attr->read_format + 1), sizeof(u64));
 }
 
 static void perf_event__hdr_attr_swap(union perf_event *event)