[PATCH v6 08/17] perf ftrace: add support for tracing option 'func_stack_trace'

[Changbin Du]

This adds support to display call trace for function tracer. To do this,
just specify a '--func-opts call-graph' option.

$ sudo perf ftrace -T vfs_read --func-opts call-graph
 iio-sensor-prox-855   [003]   6168.369657: vfs_read <-ksys_read
 iio-sensor-prox-855   [003]   6168.369677: <stack trace>
 => vfs_read
 => ksys_read
 => __x64_sys_read
 => do_syscall_64
 => entry_SYSCALL_64_after_hwframe
 ...

Signed-off-by: Changbin Du <changbin...@gmail.com>

---
v3: switch to uniform option --func-opts.
v2: option name '-s' -> '--func-call-graph'
---
 tools/perf/Documentation/perf-ftrace.txt |  4 +++
 tools/perf/builtin-ftrace.c              | 42 ++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/tools/perf/Documentation/perf-ftrace.txt 
b/tools/perf/Documentation/perf-ftrace.txt
index 3eee073a7042..5a5069306141 100644
--- a/tools/perf/Documentation/perf-ftrace.txt
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -74,6 +74,10 @@ OPTIONS
        (or glob patterns).  It will be passed to 'set_ftrace_notrace'
        in tracefs.
 
+--func-opts::
+       List of options allowed to set:
+         call-graph - Display kernel stack trace for function tracer.
+
 -G::
 --graph-funcs=::
        Set graph filter on the given function (or a glob pattern).
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 765ebd56e05f..e7c8697294f0 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -27,6 +27,7 @@
 #include "util/cap.h"
 #include "util/config.h"
 #include "util/units.h"
+#include "util/parse-sublevel-options.h"
 
 struct perf_ftrace {
        struct evlist           *evlist;
@@ -40,6 +41,7 @@ struct perf_ftrace {
        int                     graph_depth;
        unsigned long           percpu_buffer_size;
        bool                    inherit;
+       int                     func_stack_trace;
 };
 
 struct filter_entry {
@@ -200,6 +202,7 @@ static void reset_tracing_filters(void);
 static void reset_tracing_options(struct perf_ftrace *ftrace __maybe_unused)
 {
        write_tracing_option_file("function-fork", "0");
+       write_tracing_option_file("func_stack_trace", "0");
 }
 
 static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
@@ -276,6 +279,17 @@ static int set_tracing_cpu(struct perf_ftrace *ftrace)
        return set_tracing_cpumask(cpumap);
 }
 
+static int set_tracing_func_stack_trace(struct perf_ftrace *ftrace)
+{
+       if (!ftrace->func_stack_trace)
+               return 0;
+
+       if (write_tracing_option_file("func_stack_trace", "1") < 0)
+               return -1;
+
+       return 0;
+}
+
 static int reset_tracing_cpu(void)
 {
        struct perf_cpu_map *cpumap = perf_cpu_map__new(NULL);
@@ -424,6 +438,11 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int 
argc, const char **argv)
                goto out_reset;
        }
 
+       if (set_tracing_func_stack_trace(ftrace) < 0) {
+               pr_err("failed to set tracing option func_stack_trace\n");
+               goto out_reset;
+       }
+
        if (set_tracing_filters(ftrace) < 0) {
                pr_err("failed to set tracing filters\n");
                goto out_reset;
@@ -597,6 +616,26 @@ static int parse_buffer_size(const struct option *opt,
        return -1;
 }
 
+static int parse_func_tracer_opts(const struct option *opt,
+                                 const char *str, int unset)
+{
+       int ret;
+       struct perf_ftrace *ftrace = (struct perf_ftrace *) opt->value;
+       struct sublevel_option func_tracer_opts[] = {
+               { .name = "call-graph", .value_ptr = &ftrace->func_stack_trace 
},
+               { .name = NULL, }
+       };
+
+       if (unset)
+               return 0;
+
+       ret = perf_parse_sublevel_options(str, func_tracer_opts);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
 int cmd_ftrace(int argc, const char **argv)
 {
        int ret;
@@ -627,6 +666,9 @@ int cmd_ftrace(int argc, const char **argv)
                     parse_filter_func),
        OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
                     "do not trace given functions", parse_filter_func),
+       OPT_CALLBACK(0, "func-opts", &ftrace, "options",
+                    "function tracer options, available options: call-graph",
+                    parse_func_tracer_opts),
        OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
                     "trace given functions using function_graph tracer",
                     parse_filter_func),
-- 
2.25.1