[PATCH] perf record: Add support to collect callchains from kernel or user space only.

[ufo19890607]

From: yuzhoujian <yuzhoujian@xxxxxxxxxxxxxxx>

One can just record callchains in the kernel or user space with
this new options. We can use it together with "--all-kernel" options.
This two options is used just like print_stack(sys) or print_ustack(usr)
for systemtap.

Show below is the usage of this new option combined with "--all-kernel"
options.
	1. Configure all used events to run in kernel space and just
collect kernel callchains.
	$ perf record -a -g --all-kernel --kernel-callchains
	2. Configure all used events to run in kernel space and just
collect user callchains.
	$ perf record -a -g --all-kernel --user-callchains

Signed-off-by: yuzhoujian <yuzhoujian@xxxxxxxxxxxxxxx>
---
 tools/perf/Documentation/perf-record.txt | 6 ++++++
 tools/perf/builtin-record.c              | 4 ++++
 tools/perf/perf.h                        | 2 ++
 tools/perf/util/evsel.c                  | 4 ++++
 4 files changed, 16 insertions(+)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index de269430720a..b647eb3db0c6 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -490,6 +490,12 @@ Configure all used events to run in kernel space.
 --all-user::
 Configure all used events to run in user space.
 
+--kernel-callchains::
+Collect callchains from kernel space.
+
+--user-callchains::
+Collect callchains from user space.
+
 --timestamp-filename
 Append timestamp to output file name.
 
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index e2c3a585a61e..dca55997934e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -2191,6 +2191,10 @@ static struct option __record_options[] = {
 	OPT_BOOLEAN_FLAG(0, "all-user", &record.opts.all_user,
 			 "Configure all used events to run in user space.",
 			 PARSE_OPT_EXCLUSIVE),
+	OPT_BOOLEAN(0, "kernel-callchains", &record.opts.kernel_callchains,
+		    "collect kernel callchains"),
+	OPT_BOOLEAN(0, "user-callchains", &record.opts.user_callchains,
+		    "collect user callchains"),
 	OPT_STRING(0, "clang-path", &llvm_param.clang_path, "clang path",
 		   "clang binary to use for compiling BPF scriptlets"),
 	OPT_STRING(0, "clang-opt", &llvm_param.clang_opt, "clang options",
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index d59dee61b64d..711e009381ec 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -61,6 +61,8 @@ struct record_opts {
 	bool	     record_switch_events;
 	bool	     all_kernel;
 	bool	     all_user;
+	bool	     kernel_callchains;
+	bool	     user_callchains;
 	bool	     tail_synthesize;
 	bool	     overwrite;
 	bool	     ignore_missing_thread;
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index a6f572a40deb..a606b2833e27 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -680,6 +680,10 @@ static void __perf_evsel__config_callchain(struct perf_evsel *evsel,
 
 	attr->sample_max_stack = param->max_stack;
 
+	if (opts->kernel_callchains)
+		attr->exclude_callchain_user = 1;
+	if (opts->user_callchains)
+		attr->exclude_callchain_kernel = 1;
 	if (param->record_mode == CALLCHAIN_LBR) {
 		if (!opts->branch_stack) {
 			if (attr->exclude_user) {
-- 
2.14.1