From: Namhyung Kim <namhyung....@lge.com>

The ftrace show subcommand is for viewing recorded ftrace files.  It
enters perf.data.dir directory and open perf.header file to find out
necessary information.  And then read out per-cpu trace records using
kbuffer helper and print them to stdout in time order.

It only shows its basic form so function graph doesn't show duration/
overhead and no leaf entry handling is provided yet.  Maybe it can be
handled by a proper plugin in the libtraceevent.

Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Signed-off-by: Namhyung Kim <namhy...@kernel.org>
---
 tools/perf/builtin-ftrace.c | 435 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 433 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 52bb8137daf2..3a12fb9d4b94 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -13,6 +13,7 @@
 #include <signal.h>
 #include <fcntl.h>
 #include <dirent.h>
+#include <sys/mman.h>
 
 #include "util/debug.h"
 #include "util/parse-options.h"
@@ -21,6 +22,8 @@
 #include "util/thread_map.h"
 #include "util/cpumap.h"
 #include "util/trace-event.h"
+#include "../lib/traceevent/kbuffer.h"
+#include "../lib/traceevent/event-parse.h"
 
 
 #define DEFAULT_TRACER  "function_graph"
@@ -31,6 +34,7 @@ struct perf_ftrace {
        struct perf_target target;
        const char *tracer;
        const char *dirname;
+       struct pevent *pevent;
 };
 
 static bool done;
@@ -819,6 +823,379 @@ out_reset:
 }
 
 static int
+function_handler(struct trace_seq *s, struct pevent_record *record,
+                struct event_format *event, void *context __maybe_unused)
+{
+       struct pevent *pevent = event->pevent;
+       unsigned long long function;
+       const char *func;
+
+       if (pevent_get_field_val(s, event, "ip", record, &function, 1))
+               return trace_seq_putc(s, '!');
+
+       func = pevent_find_function(pevent, function);
+       if (func)
+               trace_seq_printf(s, "%s <-- ", func);
+       else
+               trace_seq_printf(s, "0x%llx", function);
+
+       if (pevent_get_field_val(s, event, "parent_ip", record, &function, 1))
+               return trace_seq_putc(s, '!');
+
+       func = pevent_find_function(pevent, function);
+       if (func)
+               trace_seq_printf(s, "%s", func);
+       else
+               trace_seq_printf(s, "0x%llx", function);
+
+       trace_seq_putc(s, '\n');
+       return 0;
+}
+
+#define TRACE_GRAPH_INDENT  2
+
+static int
+fgraph_ent_handler(struct trace_seq *s, struct pevent_record *record,
+                  struct event_format *event, void *context __maybe_unused)
+{
+       unsigned long long depth;
+       unsigned long long val;
+       const char *func;
+       int i;
+
+       if (pevent_get_field_val(s, event, "depth", record, &depth, 1))
+               return trace_seq_putc(s, '!');
+
+       /* Function */
+       for (i = 0; i < (int)(depth * TRACE_GRAPH_INDENT); i++)
+               trace_seq_putc(s, ' ');
+
+       if (pevent_get_field_val(s, event, "func", record, &val, 1))
+               return trace_seq_putc(s, '!');
+
+       func = pevent_find_function(event->pevent, val);
+
+       if (func)
+               trace_seq_printf(s, "%s() {", func);
+       else
+               trace_seq_printf(s, "%llx() {", val);
+
+       trace_seq_putc(s, '\n');
+       return 0;
+}
+
+static int
+fgraph_ret_handler(struct trace_seq *s, struct pevent_record *record,
+                  struct event_format *event, void *context __maybe_unused)
+{
+       unsigned long long depth;
+       int i;
+
+       if (pevent_get_field_val(s, event, "depth", record, &depth, 1))
+               return trace_seq_putc(s, '!');
+
+       /* Function */
+       for (i = 0; i < (int)(depth * TRACE_GRAPH_INDENT); i++)
+               trace_seq_putc(s, ' ');
+
+       trace_seq_puts(s, "}\n");
+       return 0;
+}
+
+struct perf_ftrace_report {
+       struct perf_ftrace *ftrace;
+       struct perf_tool tool;
+};
+
+struct ftrace_report_arg {
+       struct list_head node;
+       struct pevent_record *record;
+       struct kbuffer *kbuf;
+       void *map;
+       int cpu;
+       int fd;
+       int done;
+       off_t offset;
+       off_t size;
+};
+
+static LIST_HEAD(ftrace_cpu_buffers);
+
+static int process_sample_event(struct perf_tool *tool,
+                               union perf_event * event __maybe_unused,
+                               struct perf_sample *sample,
+                               struct perf_evsel *evsel __maybe_unused,
+                               struct machine *machine __maybe_unused)
+{
+       struct perf_ftrace *ftrace;
+       struct perf_ftrace_report *report;
+       struct ftrace_report_arg *fra;
+       struct stat statbuf;
+       enum kbuffer_long_size long_size;
+       enum kbuffer_endian endian;
+       char buf[PATH_MAX];
+
+       report = container_of(tool, struct perf_ftrace_report, tool);
+       ftrace = report->ftrace;
+
+       if (perf_target__has_cpu(&ftrace->target)) {
+               int i;
+               bool found = false;
+
+               for (i = 0; i < cpu_map__nr(ftrace->evlist->cpus); i++) {
+                       if ((int)sample->cpu == ftrace->evlist->cpus->map[i]) {
+                               found = true;
+                               break;
+                       }
+               }
+               if (!found)
+                       return 0;
+       }
+
+       fra = zalloc(sizeof(*fra));
+       if (fra == NULL)
+               return -1;
+
+       fra->cpu = sample->cpu;
+
+       scnprintf(buf, sizeof(buf), "%s.dir/trace-cpu%d.buf",
+                 ftrace->dirname, fra->cpu);
+
+       fra->fd = open(buf, O_RDONLY);
+       if (fra->fd < 0)
+               goto out;
+
+       if (fstat(fra->fd, &statbuf) < 0)
+               goto out_close;
+
+       fra->size = statbuf.st_size;
+       if (fra->size == 0) {
+               /* skip zero-size buffers */
+               close(fra->fd);
+               free(fra);
+               return 0;
+       }
+
+       /*
+        * FIXME: What if pevent->page_size is smaller than current page size?
+        */
+       fra->map = mmap(NULL, pevent_get_page_size(ftrace->pevent),
+                       PROT_READ, MAP_PRIVATE, fra->fd, fra->offset);
+       if (fra->map == MAP_FAILED)
+               goto out_close;
+
+       fra->offset = 0;
+
+       if (pevent_is_file_bigendian(ftrace->pevent))
+               endian = KBUFFER_ENDIAN_BIG;
+       else
+               endian = KBUFFER_ENDIAN_LITTLE;
+
+       if (pevent_get_long_size(ftrace->pevent) == 8)
+               long_size = KBUFFER_LSIZE_8;
+       else
+               long_size = KBUFFER_LSIZE_4;
+
+       fra->kbuf = kbuffer_alloc(long_size, endian);
+       if (fra->kbuf == NULL)
+               goto out_unmap;
+
+       if (ftrace->pevent->old_format)
+               kbuffer_set_old_format(fra->kbuf);
+
+       kbuffer_load_subbuffer(fra->kbuf, fra->map);
+
+       pr_debug2("setup kbuffer for cpu%d\n", fra->cpu);
+       list_add_tail(&fra->node, &ftrace_cpu_buffers);
+       return 0;
+
+out_unmap:
+       munmap(fra->map, pevent_get_page_size(ftrace->pevent));
+out_close:
+       close(fra->fd);
+out:
+       free(fra);
+       return -1;
+}
+
+static struct pevent_record *
+get_next_ftrace_event_record(struct perf_ftrace *ftrace,
+                            struct ftrace_report_arg *fra)
+{
+       struct pevent_record *record;
+       unsigned long long ts;
+       void *data;
+
+retry:
+       data = kbuffer_read_event(fra->kbuf, &ts);
+       if (data) {
+               record = zalloc(sizeof(*record));
+               if (record == NULL) {
+                       pr_err("memory allocation failure\n");
+                       return NULL;
+               }
+
+               record->ts = ts;
+               record->cpu = fra->cpu;
+               record->data = data;
+               record->size = kbuffer_event_size(fra->kbuf);
+               record->record_size = kbuffer_curr_size(fra->kbuf);
+               record->offset = kbuffer_curr_offset(fra->kbuf);
+               record->missed_events = kbuffer_missed_events(fra->kbuf);
+               record->ref_count = 1;
+
+               kbuffer_next_event(fra->kbuf, NULL);
+               return record;
+       }
+
+       if (fra->done)
+               return NULL;
+
+       munmap(fra->map, pevent_get_page_size(ftrace->pevent));
+       fra->map = NULL;
+
+       fra->offset += pevent_get_page_size(ftrace->pevent);
+       if (fra->offset >= fra->size) {
+               /* EOF */
+               fra->done = 1;
+               return NULL;
+       }
+
+       fra->map = mmap(NULL, pevent_get_page_size(ftrace->pevent),
+                       PROT_READ, MAP_PRIVATE, fra->fd, fra->offset);
+       if (fra->map == MAP_FAILED) {
+               pr_err("memory mapping failed\n");
+               return NULL;
+       }
+
+       kbuffer_load_subbuffer(fra->kbuf, fra->map);
+
+       goto retry;
+}
+
+static struct pevent_record *
+get_ftrace_event_record(struct perf_ftrace *ftrace,
+                       struct ftrace_report_arg *fra)
+{
+       if (fra->record == NULL)
+               fra->record = get_next_ftrace_event_record(ftrace, fra);
+
+       return fra->record;
+}
+
+static struct pevent_record *get_ordered_record(struct perf_ftrace *ftrace)
+{
+       struct ftrace_report_arg *fra = NULL;
+       struct ftrace_report_arg *tmp;
+       struct pevent_record *record;
+       unsigned long long min_ts = LLONG_MAX;
+
+       list_for_each_entry(tmp, &ftrace_cpu_buffers, node) {
+               record = get_ftrace_event_record(ftrace, tmp);
+               if (record && record->ts < min_ts) {
+                       min_ts = record->ts;
+                       fra = tmp;
+               }
+       }
+
+       if (fra) {
+               record = fra->record;
+               fra->record = NULL;
+               return record;
+       }
+       return NULL;
+}
+
+static void free_ftrace_report_args(struct perf_ftrace *ftrace)
+{
+       struct ftrace_report_arg *fra, *tmp;
+
+       list_for_each_entry_safe(fra, tmp, &ftrace_cpu_buffers, node) {
+               list_del(&fra->node);
+
+               /* don't care about the errors */
+               munmap(fra->map, pevent_get_page_size(ftrace->pevent));
+               kbuffer_free(fra->kbuf);
+               free(fra->record);
+               close(fra->fd);
+               free(fra);
+       }
+}
+
+static int do_ftrace_show(struct perf_ftrace *ftrace)
+{
+       int ret = 0;
+       char buf[PATH_MAX];
+       struct perf_session *session;
+       struct pevent_record *record;
+       struct trace_seq seq;
+       struct perf_ftrace_report show = {
+               .ftrace = ftrace,
+               .tool = {
+                       .sample = process_sample_event,
+               },
+       };
+
+       canonicalize_directory_name(ftrace->dirname);
+
+       scnprintf(buf, sizeof(buf), "%s.dir/perf.header", ftrace->dirname);
+
+       session = perf_session__new(buf, O_RDONLY, false, false, &show.tool);
+       if (session == NULL) {
+               pr_err("failed to create a session\n");
+               return -1;
+       }
+
+       ftrace->pevent = session->pevent;
+
+       pevent_register_event_handler(ftrace->pevent, -1,
+                                     "ftrace", "function",
+                                     function_handler, NULL);
+       pevent_register_event_handler(ftrace->pevent, -1,
+                                     "ftrace", "funcgraph_entry",
+                                     fgraph_ent_handler, NULL);
+       pevent_register_event_handler(ftrace->pevent, -1,
+                                     "ftrace", "funcgraph_exit",
+                                     fgraph_ret_handler, NULL);
+
+       if (perf_session__process_events(session, &show.tool) < 0) {
+               pr_err("failed to process events\n");
+               ret = -1;
+               goto out;
+       }
+
+       trace_seq_init(&seq);
+
+       record = get_ordered_record(ftrace);
+       while (record) {
+               int type;
+               struct event_format *event;
+
+               type = pevent_data_type(ftrace->pevent, record);
+               event = pevent_find_event(ftrace->pevent, type);
+               if (!event) {
+                       pr_warning("no event found for type %d", type);
+                       continue;
+               }
+
+               pevent_print_event(ftrace->pevent, &seq, record);
+               trace_seq_do_printf(&seq);
+
+               trace_seq_reset(&seq);
+
+               free(record);
+               record = get_ordered_record(ftrace);
+       }
+
+       trace_seq_destroy(&seq);
+
+out:
+       free_ftrace_report_args(ftrace);
+       perf_session__delete(session);
+       return ret;
+}
+
+static int
 __cmd_ftrace_live(struct perf_ftrace *ftrace, int argc, const char **argv)
 {
        int ret = -1;
@@ -949,6 +1326,58 @@ out:
        return ret;
 }
 
+static int
+__cmd_ftrace_show(struct perf_ftrace *ftrace, int argc, const char **argv)
+{
+       int ret = -1;
+       const char * const show_usage[] = {
+               "perf ftrace show [<options>]",
+               NULL
+       };
+       const struct option show_options[] = {
+       OPT_STRING('i', "input", &ftrace->dirname, "dirname",
+                  "input directory name to use (default: perf.data)"),
+       OPT_INCR('v', "verbose", &verbose,
+                "be more verbose"),
+       OPT_STRING('C', "cpu", &ftrace->target.cpu_list, "cpu",
+                   "list of cpus to monitor"),
+       OPT_END()
+       };
+
+       argc = parse_options(argc, argv, show_options, show_usage,
+                            PARSE_OPT_STOP_AT_NON_OPTION);
+       if (argc)
+               usage_with_options(show_usage, show_options);
+
+       ret = perf_target__validate(&ftrace->target);
+       if (ret) {
+               char errbuf[512];
+
+               perf_target__strerror(&ftrace->target, ret, errbuf, 512);
+               pr_err("%s\n", errbuf);
+               return -EINVAL;
+       }
+
+       ftrace->evlist = perf_evlist__new();
+       if (ftrace->evlist == NULL)
+               return -ENOMEM;
+
+       ret = perf_evlist__create_maps(ftrace->evlist, &ftrace->target);
+       if (ret < 0)
+               goto out;
+
+       if (ftrace->dirname == NULL)
+               ftrace->dirname = DEFAULT_DIRNAME;
+
+       ret = do_ftrace_show(ftrace);
+
+       perf_evlist__delete_maps(ftrace->evlist);
+out:
+       perf_evlist__delete(ftrace->evlist);
+
+       return ret;
+}
+
 int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused)
 {
        int ret;
@@ -956,8 +1385,8 @@ int cmd_ftrace(int argc, const char **argv, const char 
*prefix __maybe_unused)
                .target = { .uid = UINT_MAX, },
        };
        const char * const ftrace_usage[] = {
-               "perf ftrace {live|record} [<options>] [<command>]",
-               "perf ftrace {live|record} [<options>] -- <command> 
[<options>]",
+               "perf ftrace {live|record|show} [<options>] [<command>]",
+               "perf ftrace {live|record|show} [<options>] -- <command> 
[<options>]",
                NULL
        };
        const struct option ftrace_options[] = {
@@ -978,6 +1407,8 @@ int cmd_ftrace(int argc, const char **argv, const char 
*prefix __maybe_unused)
                ret = __cmd_ftrace_live(&ftrace, argc, argv);
        } else  if (strncmp(argv[0], "rec", 3) == 0) {
                ret = __cmd_ftrace_record(&ftrace, argc, argv);
+       } else  if (strcmp(argv[0], "show") == 0) {
+               ret = __cmd_ftrace_show(&ftrace, argc, argv);
        } else {
                usage_with_options(ftrace_usage, ftrace_options);
        }
-- 
1.7.11.7

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