On 5/15/18 9:41 PM, Jakub Kicinski wrote:
On Tue, 15 May 2018 16:45:21 -0700, Yonghong Song wrote:
The new command "bpftool perf [show]" will traverse
all processes under /proc, and if any fd is associated
with a perf event, it will print out related perf event
information.

Below is an example to show the results using bcc commands.
Running the following 4 bcc commands:
   kprobe:     trace.py '__x64_sys_nanosleep'
   kretprobe:  trace.py 'r::__x64_sys_nanosleep'
   tracepoint: trace.py 't:syscalls:sys_enter_nanosleep'
   uprobe:     trace.py 'p:/home/yhs/a.out:main'

The bpftool command line and result:

   $ bpftool perf
   21711: prog_id 5 kprobe func __x64_sys_write offset 0
   21765: prog_id 7 kretprobe func __x64_sys_nanosleep offset 0
   21767: prog_id 8 tracepoint sys_enter_nanosleep
   21800: prog_id 9 uprobe filename /home/yhs/a.out offset 1159

   $ bpftool -j perf
   
{"pid":21711,"prog_id":5,"prog_info":"kprobe","func":"__x64_sys_write","offset":0},
 \
   
{"pid":21765,"prog_id":7,"prog_info":"kretprobe","func":"__x64_sys_nanosleep","offset":0},
 \
   
{"pid":21767,"prog_id":8,"prog_info":"tracepoint","tracepoint":"sys_enter_nanosleep"},
 \
   
{"pid":21800,"prog_id":9,"prog_info":"uprobe","filename":"/home/yhs/a.out","offset":1159}

You need to wrap the objects inside an array, so

        if (json_output)
                jsonw_start_array(json_wtr);
        nftw();
        if (json_output)
                jsonw_end_array(json_wtr);

otherwise output will not be a valid JSON.  To validate JSON try:

$ bpftool -j perf | python -m json.tool

Thanks for detailed review! All of your comments make sense.
I will address them in next revision after getting some feedback
for other patches.


   $ bpftool prog
   5: kprobe  name probe___x64_sys  tag e495a0c82f2c7a8d  gpl
          loaded_at 2018-05-15T04:46:37-0700  uid 0
          xlated 200B  not jited  memlock 4096B  map_ids 4
   7: kprobe  name probe___x64_sys  tag f2fdee479a503abf  gpl
          loaded_at 2018-05-15T04:48:32-0700  uid 0
          xlated 200B  not jited  memlock 4096B  map_ids 7
   8: tracepoint  name tracepoint__sys  tag 5390badef2395fcf  gpl
          loaded_at 2018-05-15T04:48:48-0700  uid 0
          xlated 200B  not jited  memlock 4096B  map_ids 8
   9: kprobe  name probe_main_1  tag 0a87bdc2e2953b6d  gpl
          loaded_at 2018-05-15T04:49:52-0700  uid 0
          xlated 200B  not jited  memlock 4096B  map_ids 9

   $ ps ax | grep "python ./trace.py"
   21711 pts/0    T      0:03 python ./trace.py __x64_sys_write
   21765 pts/0    S+     0:00 python ./trace.py r::__x64_sys_nanosleep
   21767 pts/2    S+     0:00 python ./trace.py t:syscalls:sys_enter_nanosleep
   21800 pts/3    S+     0:00 python ./trace.py p:/home/yhs/a.out:main
   22374 pts/1    S+     0:00 grep --color=auto python ./trace.py

Signed-off-by: Yonghong Song <y...@fb.com>
---
  tools/bpf/bpftool/main.c |   3 +-
  tools/bpf/bpftool/main.h |   1 +
  tools/bpf/bpftool/perf.c | 188 +++++++++++++++++++++++++++++++++++++++++++++++

Would you be able to also extend the Documentation/ and bash
completions?

  3 files changed, 191 insertions(+), 1 deletion(-)
  create mode 100644 tools/bpf/bpftool/perf.c

diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 1ec852d..eea7f14 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -87,7 +87,7 @@ static int do_help(int argc, char **argv)
                "       %s batch file FILE\n"
                "       %s version\n"
                "\n"
-               "       OBJECT := { prog | map | cgroup }\n"
+               "       OBJECT := { prog | map | cgroup | perf }\n"
                "       " HELP_SPEC_OPTIONS "\n"
                "",
                bin_name, bin_name, bin_name);
@@ -216,6 +216,7 @@ static const struct cmd cmds[] = {
        { "prog",     do_prog },
        { "map",      do_map },
        { "cgroup",   do_cgroup },
+       { "perf",     do_perf },
        { "version",  do_version },
        { 0 }
  };
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 6173cd9..63fdb31 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -119,6 +119,7 @@ int do_prog(int argc, char **arg);
  int do_map(int argc, char **arg);
  int do_event_pipe(int argc, char **argv);
  int do_cgroup(int argc, char **arg);
+int do_perf(int argc, char **arg);
int prog_parse_fd(int *argc, char ***argv);
  int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 
*info_len);
diff --git a/tools/bpf/bpftool/perf.c b/tools/bpf/bpftool/perf.c
new file mode 100644
index 0000000..6d676e4
--- /dev/null
+++ b/tools/bpf/bpftool/perf.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright (C) 2018 Facebook
+// Author: Yonghong Song <y...@fb.com>
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <ftw.h>
+
+#include <bpf.h>
+
+#include "main.h"
+
+static void print_perf_json(int pid, __u32 prog_id, __u32 prog_info,
+                           char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+       jsonw_start_object(json_wtr);
+       jsonw_int_field(json_wtr, "pid", pid);
+       jsonw_uint_field(json_wtr, "prog_id", prog_id);
+       switch (prog_info) {
+       case BPF_PERF_INFO_TP_NAME:
+               jsonw_string_field(json_wtr, "prog_info", "tracepoint");
+               jsonw_string_field(json_wtr, "tracepoint", buf);
+               break;
+       case BPF_PERF_INFO_KPROBE:
+               jsonw_string_field(json_wtr, "prog_info", "kprobe");
+               if (buf[0] != '\0') {
+                       jsonw_string_field(json_wtr, "func", buf);
+                       jsonw_lluint_field(json_wtr, "offset", probe_offset);
+               } else {
+                       jsonw_lluint_field(json_wtr, "addr", probe_addr);
+               }
+               break;
+       case BPF_PERF_INFO_KRETPROBE:
+               jsonw_string_field(json_wtr, "prog_info", "kretprobe");
+               if (buf[0] != '\0') {
+                       jsonw_string_field(json_wtr, "func", buf);
+                       jsonw_lluint_field(json_wtr, "offset", probe_offset);
+               } else {
+                       jsonw_lluint_field(json_wtr, "addr", probe_addr);
+               }
+               break;
+       case BPF_PERF_INFO_UPROBE:
+               jsonw_string_field(json_wtr, "prog_info", "uprobe");
+               jsonw_string_field(json_wtr, "filename", buf);
+               jsonw_lluint_field(json_wtr, "offset", probe_offset);
+               break;
+       case BPF_PERF_INFO_URETPROBE:
+               jsonw_string_field(json_wtr, "prog_info", "uretprobe");
+               jsonw_string_field(json_wtr, "filename", buf);
+               jsonw_lluint_field(json_wtr, "offset", probe_offset);
+               break;
+       }
+       jsonw_end_object(json_wtr);
+}
+
+static void print_perf_plain(int pid, __u32 prog_id, __u32 prog_info,
+                           char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+       printf("%d: prog_id %u ", pid, prog_id);

nit: for consistency with prog and map listings consider using double
spaces after prog_id (i.e. between fields).  Not a hard requirement,
though, perhaps I'm the only one who finds that more readable :)

+       switch (prog_info) {
+       case BPF_PERF_INFO_TP_NAME:
+               printf("tracepoint %s\n", buf);
+               break;
+       case BPF_PERF_INFO_KPROBE:
+               if (buf[0] != '\0')
+                       printf("kprobe func %s offset %llu\n", buf,
+                              probe_offset);
+               else
+                       printf("kprobe addr %llu\n", probe_addr);
+               break;
+       case BPF_PERF_INFO_KRETPROBE:
+               if (buf[0] != '\0')
+                       printf("kretprobe func %s offset %llu\n", buf,
+                              probe_offset);
+               else
+                       printf("kretprobe addr %llu\n", probe_addr);
+               break;
+       case BPF_PERF_INFO_UPROBE:
+               printf("uprobe filename %s offset %llu\n", buf, probe_offset);
+               break;
+       case BPF_PERF_INFO_URETPROBE:
+               printf("uretprobe filename %s offset %llu\n", buf,
+                      probe_offset);
+               break;
+       }
+}
+
+static int show_proc(const char *fpath, const struct stat *sb,
+                    int tflag, struct FTW *ftwbuf)
+{
+       __u64 probe_offset, probe_addr;
+       __u32 prog_id, prog_info;
+       int err, pid = 0, fd = 0;
+       const char *pch;
+       char buf[4096];
+
+       /* prefix always /proc */
+       pch = fpath + 5;
+       if (*pch == '\0')
+               return 0;
+
+       /* pid should be all numbers */
+       pch++;
+       while (*pch >= '0' && *pch <= '9') {

nit: isdigit()?  strtoul() with its endptr also an option.  That said
      the code is actually quite readable as is, so I'm not sure if it's
      worth complicating it.

+               pid = pid * 10 + *pch - '0';
+               pch++;
+       }
+       if (*pch == '\0')
+               return 0;
+       if (*pch != '/')
+               return FTW_SKIP_SUBTREE;
+
+       /* check /proc/<pid>/fd directory */
+       pch++;
+       if (*pch == '\0' || *pch != 'f')
+               return FTW_SKIP_SUBTREE;

but == '\0' implies != 'f'

+       pch++;
+       if (*pch == '\0' || *pch != 'd')
+               return FTW_SKIP_SUBTREE;

nit: possibly just:
      if (strncmp(pch, "fd", 2))
           return FTW_SKIP_SUBTREE;
      pch += 2;

+       pch++;
+       if (*pch == '\0')
+               return 0;
+       if (*pch != '/')
+               return FTW_SKIP_SUBTREE;
+
+       /* check /proc/<pid>/fd/<fd_num> */
+       pch++;
+       while (*pch >= '0' && *pch <= '9') {
+               fd = fd * 10 + *pch - '0';
+               pch++;
+       }
+       if (*pch != '\0')
+               return FTW_SKIP_SUBTREE;
+
+       /* query (pid, fd) for potential perf events */
+       err = bpf_trace_event_query(pid, fd, buf, sizeof(buf),
+               &prog_id, &prog_info, &probe_offset, &probe_addr);

nit: continuation line not aligned with opening bracket

+       if (err < 0)
+               return 0;
+
+       if (json_output)
+               print_perf_json(pid, prog_id, prog_info, buf, probe_offset,
+                               probe_addr);
+       else
+               print_perf_plain(pid, prog_id, prog_info, buf, probe_offset,
+                                probe_addr);
+
+       return 0;
+}
+
+static int do_show(int argc, char **argv)
+{
+       int nopenfd = 16;
+       int flags = FTW_ACTIONRETVAL | FTW_PHYS;

nit: reverse christmas tree networking style if you don't mind

+       if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
+               perror("nftw");

nit: p_err("%s", strerror(errno)); would also show up in JSON output

+               return -1;
+       }
+
+       return 0;
+}
+
+static int do_help(int argc, char **argv)
+{
+       fprintf(stderr,
+               "Usage: %s %s { show | help }\n"
+               "",
+               bin_name, argv[-2]);
+
+       return 0;
+}
+
+static const struct cmd cmds[] = {
+       { "show",     do_show },

Other commands alias show and list, so could you add:

        { "list",     do_show },

and list to help output?

+       { "help",     do_help },
+       { 0 }
+};
+
+int do_perf(int argc, char **argv)
+{
+       return cmd_select(cmds, argc, argv, do_help);
+}

Thanks a lot for adding bpftool support, and with JSON output included!

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