[PATCH 11/15] perf report: Properly handle branch count in match_chain()

Arnaldo Carvalho de Melo
2017-10-25T16:02:08Z

Some of the code paths I introduced before returned too early without
running the code to handle a node's branch count. By refactoring
match_chain to only have one exit point, this can be remedied.

Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1707691.qaJ269GSZW@agathebauer
Link: http://lkml.kernel.org/r/20171018185350.14893-2-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/callchain.c | 140 ++++++++++++++++++++++++--------------------
1 file changed, 78 insertions(+), 62 deletions(-)

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 35a920f09503..19bfcadcf891 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -666,83 +666,99 @@ static enum match_result match_chain_strings(const char *left,
return ret;
}

-static enum match_result match_chain(struct callchain_cursor_node *node,
- struct callchain_list *cnode)
+/*
+ * We need to always use relative addresses because we're aggregating
+ * callchains from multiple threads, i.e. different address spaces, so
+ * comparing absolute addresses make no sense as a symbol in a DSO may end up
+ * in a different address when used in a different binary or even the same
+ * binary but with some sort of address randomization technique, thus we need
+ * to compare just relative addresses. -acme
+ */
+static enum match_result match_chain_dso_addresses(struct map *left_map, u64 left_ip,
+ struct map *right_map, u64 right_ip)
{
- struct symbol *sym = node->sym;
- u64 left, right;
- struct dso *left_dso = NULL;
- struct dso *right_dso = NULL;
+ struct dso *left_dso = left_map ? left_map->dso : NULL;
+ struct dso *right_dso = right_map ? right_map->dso : NULL;

- if (callchain_param.key == CCKEY_SRCLINE) {
- enum match_result match = match_chain_strings(cnode->srcline,
- node->srcline);
+ if (left_dso != right_dso)
+ return left_dso < right_dso ? MATCH_LT : MATCH_GT;

- /* if no srcline is available, fallback to symbol name */
- if (match == MATCH_ERROR && cnode->ms.sym && node->sym)
- match = match_chain_strings(cnode->ms.sym->name,
- node->sym->name);
+ if (left_ip != right_ip)
+ return left_ip < right_ip ? MATCH_LT : MATCH_GT;

- if (match != MATCH_ERROR)
- return match;
+ return MATCH_EQ;
+}

- /* otherwise fall-back to IP-based comparison below */
- }
+static enum match_result match_chain(struct callchain_cursor_node *node,
+ struct callchain_list *cnode)
+{
+ enum match_result match = MATCH_ERROR;

- if (cnode->ms.sym && sym && callchain_param.key == CCKEY_FUNCTION) {
- /*
- * Compare inlined frames based on their symbol name because
- * different inlined frames will have the same symbol start
- */
- if (cnode->ms.sym->inlined || node->sym->inlined)
- return match_chain_strings(cnode->ms.sym->name,
- node->sym->name);
-
- left = cnode->ms.sym->start;
- right = sym->start;
- left_dso = cnode->ms.map->dso;
- right_dso = node->map->dso;
- } else {
- left = cnode->ip;
- right = node->ip;
+ switch (callchain_param.key) {
+ case CCKEY_SRCLINE:
+ match = match_chain_strings(cnode->srcline, node->srcline);
+ if (match != MATCH_ERROR)
+ break;
+ /* otherwise fall-back to symbol-based comparison below */
+ __fallthrough;
+ case CCKEY_FUNCTION:
+ if (node->sym && cnode->ms.sym) {
+ /*
+ * Compare inlined frames based on their symbol name
+ * because different inlined frames will have the same
+ * symbol start. Otherwise do a faster comparison based
+ * on the symbol start address.
+ */
+ if (cnode->ms.sym->inlined || node->sym->inlined) {
+ match = match_chain_strings(cnode->ms.sym->name,
+ node->sym->name);
+ if (match != MATCH_ERROR)
+ break;
+ } else {
+ match = match_chain_dso_addresses(cnode->ms.map, cnode->ms.sym->start,
+ node->map, node->sym->start);
+ break;
+ }
+ }
+ /* otherwise fall-back to IP-based comparison below */
+ __fallthrough;
+ case CCKEY_ADDRESS:
+ default:
+ match = match_chain_dso_addresses(cnode->ms.map, cnode->ip, node->map, node->ip);
+ break;
}

- if (left == right && left_dso == right_dso) {
- if (node->branch) {
- cnode->branch_count++;
+ if (match == MATCH_EQ && node->branch) {
+ cnode->branch_count++;

- if (node->branch_from) {
- /*
- * It's "to" of a branch
- */
- cnode->brtype_stat.branch_to = true;
+ if (node->branch_from) {
+ /*
+ * It's "to" of a branch
+ */
+ cnode->brtype_stat.branch_to = true;

- if (node->branch_flags.predicted)
- cnode->predicted_count++;
+ if (node->branch_flags.predicted)
+ cnode->predicted_count++;

- if (node->branch_flags.abort)
- cnode->abort_count++;
+ if (node->branch_flags.abort)
+ cnode->abort_count++;

- branch_type_count(&cnode->brtype_stat,
- &node->branch_flags,
- node->branch_from,
- node->ip);
- } else {
- /*
- * It's "from" of a branch
- */
- cnode->brtype_stat.branch_to = false;
- cnode->cycles_count +=
- node->branch_flags.cycles;
- cnode->iter_count += node->nr_loop_iter;
- cnode->iter_cycles += node->iter_cycles;
- }
+ branch_type_count(&cnode->brtype_stat,
+ &node->branch_flags,
+ node->branch_from,
+ node->ip);
+ } else {
+ /*
+ * It's "from" of a branch
+ */
+ cnode->brtype_stat.branch_to = false;
+ cnode->cycles_count += node->branch_flags.cycles;
+ cnode->iter_count += node->nr_loop_iter;
+ cnode->iter_cycles += node->iter_cycles;
}
-
- return MATCH_EQ;
}

- return left > right ? MATCH_GT : MATCH_LT;
+ return match;
}

/*
--
2.13.6