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authorAdrian Hunter <adrian.hunter@intel.com>2018-09-20 16:00:45 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-09-20 15:16:17 -0300
commit4d60e5e36aa6f11b4d9eadc5d2b94128f24870c7 (patch)
treecdd74e3a541925cdfb47f0e440d84c1fe2d45760 /tools/perf/util/thread-stack.c
parentff645daf30cafb6fa74bee9a73733700bac2aff7 (diff)
perf tools: Improve thread_stack__event() for trace begin / end
thread_stack__event() is used to create call stacks, by keeping track of calls and returns. Improve the handling of trace begin / end to allow for a trace that ends in a call. Previously, the Intel PT decoder would indicate begin / end by a branch from / to zero. That hides useful information, in particular when a trace ends with a call. Before remedying that, enhance the thread stack so that it does not expect to see the 'return' for a 'call' that ends the trace. Committer notes: Added this: return thread_stack__push(thread->ts, ret_addr, - flags && PERF_IP_FLAG_TRACE_END); + flags & PERF_IP_FLAG_TRACE_END); To fix problem spotted by: debian:9: clang version 3.8.1-24 (tags/RELEASE_381/final) debian:experimental: clang version 6.0.1-6 (tags/RELEASE_601/final) Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/20180920130048.31432-4-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/thread-stack.c')
-rw-r--r--tools/perf/util/thread-stack.c35
1 files changed, 30 insertions, 5 deletions
diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index dd17d6a38d3a..e3f7dfecafa9 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -36,6 +36,7 @@
* @branch_count: the branch count when the entry was created
* @cp: call path
* @no_call: a 'call' was not seen
+ * @trace_end: a 'call' but trace ended
*/
struct thread_stack_entry {
u64 ret_addr;
@@ -44,6 +45,7 @@ struct thread_stack_entry {
u64 branch_count;
struct call_path *cp;
bool no_call;
+ bool trace_end;
};
/**
@@ -112,7 +114,8 @@ static struct thread_stack *thread_stack__new(struct thread *thread,
return ts;
}
-static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
+static int thread_stack__push(struct thread_stack *ts, u64 ret_addr,
+ bool trace_end)
{
int err = 0;
@@ -124,6 +127,7 @@ static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
}
}
+ ts->stack[ts->cnt].trace_end = trace_end;
ts->stack[ts->cnt++].ret_addr = ret_addr;
return err;
@@ -150,6 +154,18 @@ static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
}
}
+static void thread_stack__pop_trace_end(struct thread_stack *ts)
+{
+ size_t i;
+
+ for (i = ts->cnt; i; ) {
+ if (ts->stack[--i].trace_end)
+ ts->cnt = i;
+ else
+ return;
+ }
+}
+
static bool thread_stack__in_kernel(struct thread_stack *ts)
{
if (!ts->cnt)
@@ -254,10 +270,19 @@ int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
ret_addr = from_ip + insn_len;
if (ret_addr == to_ip)
return 0; /* Zero-length calls are excluded */
- return thread_stack__push(thread->ts, ret_addr);
- } else if (flags & PERF_IP_FLAG_RETURN) {
- if (!from_ip)
- return 0;
+ return thread_stack__push(thread->ts, ret_addr,
+ flags & PERF_IP_FLAG_TRACE_END);
+ } else if (flags & PERF_IP_FLAG_TRACE_BEGIN) {
+ /*
+ * If the caller did not change the trace number (which would
+ * have flushed the stack) then try to make sense of the stack.
+ * Possibly, tracing began after returning to the current
+ * address, so try to pop that. Also, do not expect a call made
+ * when the trace ended, to return, so pop that.
+ */
+ thread_stack__pop(thread->ts, to_ip);
+ thread_stack__pop_trace_end(thread->ts);
+ } else if ((flags & PERF_IP_FLAG_RETURN) && from_ip) {
thread_stack__pop(thread->ts, to_ip);
}