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-rw-r--r--tools/perf/util/header.c42
1 files changed, 31 insertions, 11 deletions
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 3724707425e..6a9c041134b 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1703,21 +1703,41 @@ int perf_file_header__read(struct perf_file_header *header,
bitmap_zero(header->adds_features, HEADER_FEAT_BITS);
else
return -1;
+ } else if (ph->needs_swap) {
+ unsigned int i;
+ /*
+ * feature bitmap is declared as an array of unsigned longs --
+ * not good since its size can differ between the host that
+ * generated the data file and the host analyzing the file.
+ *
+ * We need to handle endianness, but we don't know the size of
+ * the unsigned long where the file was generated. Take a best
+ * guess at determining it: try 64-bit swap first (ie., file
+ * created on a 64-bit host), and check if the hostname feature
+ * bit is set (this feature bit is forced on as of fbe96f2).
+ * If the bit is not, undo the 64-bit swap and try a 32-bit
+ * swap. If the hostname bit is still not set (e.g., older data
+ * file), punt and fallback to the original behavior --
+ * clearing all feature bits and setting buildid.
+ */
+ for (i = 0; i < BITS_TO_LONGS(HEADER_FEAT_BITS); ++i)
+ header->adds_features[i] = bswap_64(header->adds_features[i]);
+
+ if (!test_bit(HEADER_HOSTNAME, header->adds_features)) {
+ for (i = 0; i < BITS_TO_LONGS(HEADER_FEAT_BITS); ++i) {
+ header->adds_features[i] = bswap_64(header->adds_features[i]);
+ header->adds_features[i] = bswap_32(header->adds_features[i]);
+ }
+ }
+
+ if (!test_bit(HEADER_HOSTNAME, header->adds_features)) {
+ bitmap_zero(header->adds_features, HEADER_FEAT_BITS);
+ set_bit(HEADER_BUILD_ID, header->adds_features);
+ }
}
memcpy(&ph->adds_features, &header->adds_features,
sizeof(ph->adds_features));
- /*
- * FIXME: hack that assumes that if we need swap the perf.data file
- * may be coming from an arch with a different word-size, ergo different
- * DEFINE_BITMAP format, investigate more later, but for now its mostly
- * safe to assume that we have a build-id section. Trace files probably
- * have several other issues in this realm anyway...
- */
- if (ph->needs_swap) {
- memset(&ph->adds_features, 0, sizeof(ph->adds_features));
- perf_header__set_feat(ph, HEADER_BUILD_ID);
- }
ph->event_offset = header->event_types.offset;
ph->event_size = header->event_types.size;