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authorDavid Ahern <dsahern@gmail.com>2011-10-18 17:34:01 -0600
committerArnaldo Carvalho de Melo <acme@redhat.com>2011-10-19 13:14:35 -0200
commitd327fa435996c3e559b55e254bad6ed801a92f89 (patch)
tree120b8e58623ba82d82fcc99bc8a2bd36b118b763 /tools
parente77b15bd849fc85b0228e95da9b7559aa6d31f40 (diff)
perf tools: handle endianness of feature bitmap
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. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1318980841-12616-1-git-send-email-dsahern@gmail.com Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-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;