linux-kernel - [PATCH 13/15] perf trace: Make --(min,max}-stack imply "--call-graph dwarf"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 15 Apr 2016 18:50:59 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
	Milian Wolff <milian.wolff@...b.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Wang Nan <wangnan0@...wei.com>
Subject: [PATCH 13/15] perf trace: Make --(min,max}-stack imply "--call-graph dwarf"

From: Arnaldo Carvalho de Melo <acme@...hat.com>

If one uses:

  # perf trace --min-stack 16

Then it implicitly means that callgraphs should be enabled, and the best
option in terms of widespread availability is "dwarf".

Further work needed to choose a better alternative, LBR, in capable
systems.

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Milian Wolff <milian.wolff@...b.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-xtjmnpkyk42npekxz3kynzmx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/Documentation/perf-trace.txt |  6 ++++++
 tools/perf/builtin-trace.c              | 13 ++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/perf/Documentation/perf-trace.txt b/tools/perf/Documentation/perf-trace.txt
index 4e8baa75a32e..146c6db21cbf 100644
--- a/tools/perf/Documentation/perf-trace.txt
+++ b/tools/perf/Documentation/perf-trace.txt
@@ -136,12 +136,18 @@ the thread executes on the designated CPUs. Default is to monitor all CPUs.
         not limiting, the overhead of callchains needs to be set via the
         knobs in --call-graph dwarf.
 
+        Implies '--call-graph dwarf' when --call-graph not present on the
+        command line, on systems where DWARF unwinding was built in.
+
         Default: 127
 
 --min-stack::
         Set the stack depth limit when parsing the callchain, anything
         below the specified depth will be ignored. Disabled by default.
 
+        Implies '--call-graph dwarf' when --call-graph not present on the
+        command line, on systems where DWARF unwinding was built in.
+
 --proc-map-timeout::
 	When processing pre-existing threads /proc/XXX/mmap, it may take a long time,
 	because the file may be huge. A time out is needed in such cases.
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 6a64cb1344c7..19f5100acc1d 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -3047,7 +3047,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 		.show_comm = true,
 		.trace_syscalls = true,
 		.kernel_syscallchains = false,
-		.max_stack = PERF_MAX_STACK_DEPTH,
+		.max_stack = UINT_MAX,
 	};
 	const char *output_name = NULL;
 	const char *ev_qualifier_str = NULL;
@@ -3109,6 +3109,7 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 			"per thread proc mmap processing timeout in ms"),
 	OPT_END()
 	};
+	bool max_stack_user_set = true;
 	const char * const trace_subcommands[] = { "record", NULL };
 	int err;
 	char bf[BUFSIZ];
@@ -3142,6 +3143,16 @@ int cmd_trace(int argc, const char **argv, const char *prefix __maybe_unused)
 		trace.opts.sample_time = true;
 	}
 
+	if (trace.max_stack == UINT_MAX) {
+		trace.max_stack = PERF_MAX_STACK_DEPTH;
+		max_stack_user_set = false;
+	}
+
+#ifdef HAVE_DWARF_UNWIND_SUPPORT
+	if ((trace.min_stack || max_stack_user_set) && !trace.opts.callgraph_set)
+		record_opts__parse_callchain(&trace.opts, &callchain_param, "dwarf", false);
+#endif
+
 	if (trace.opts.callgraph_set)
 		symbol_conf.use_callchain = true;
 
-- 
2.5.5