diff mbox series

[bpf-next,v2,7/7] tools/bpftool: add perf subcommand

Message ID 20180518050310.2814608-8-yhs@fb.com
State Changes Requested, archived
Delegated to: BPF Maintainers
Headers show
Series bpf: implement BPF_TASK_FD_QUERY | expand

Commit Message

Yonghong Song May 18, 2018, 5:03 a.m. UTC 
The new command "bpftool perf [show | list]" will traverse
all processes under /proc, and if any fd is associated
with a perf event, it will print out related perf event
information. Documentation is also added.

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

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

  $ 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 <yhs@fb.com>
---
 tools/bpf/bpftool/Documentation/bpftool-perf.rst |  81 +++++++++
 tools/bpf/bpftool/Documentation/bpftool.rst      |   5 +-
 tools/bpf/bpftool/bash-completion/bpftool        |   9 +
 tools/bpf/bpftool/main.c                         |   3 +-
 tools/bpf/bpftool/main.h                         |   1 +
 tools/bpf/bpftool/perf.c                         | 200 +++++++++++++++++++++++
 6 files changed, 297 insertions(+), 2 deletions(-)
 create mode 100644 tools/bpf/bpftool/Documentation/bpftool-perf.rst
 create mode 100644 tools/bpf/bpftool/perf.c

Comments

Jakub Kicinski May 18, 2018, 8:51 p.m. UTC | #1 
On Thu, 17 May 2018 22:03:10 -0700, Yonghong Song wrote:
> The new command "bpftool perf [show | list]" will traverse
> all processes under /proc, and if any fd is associated
> with a perf event, it will print out related perf event
> information. Documentation is also added.

Thanks for the changes, it looks good with some minor nits which can be
addressed as follow up if there is no other need to respin.  Please
consider it:

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>

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

nit: this is now an array

>   $ 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 <yhs@fb.com>

> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
> index b301c9b..3680ad4 100644
> --- a/tools/bpf/bpftool/bash-completion/bpftool
> +++ b/tools/bpf/bpftool/bash-completion/bpftool
> @@ -448,6 +448,15 @@ _bpftool()
>                      ;;
>              esac
>              ;;
> +        cgroup)

s/cgroup/perf/ :)

> +            case $command in
> +                *)
> +                    [[ $prev == $object ]] && \
> +                        COMPREPLY=( $( compgen -W 'help \
> +                            show list' -- "$cur" ) )
> +                    ;;
> +            esac
> +            ;;
>      esac
>  } &&
>  complete -F _bpftool bpftool

> +static int show_proc(const char *fpath, const struct stat *sb,
> +		     int tflag, struct FTW *ftwbuf)
> +{
> +	__u64 probe_offset, probe_addr;
> +	__u32 prog_id, attach_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 (isdigit(*pch)) {
> +		pid = pid * 10 + *pch - '0';
> +		pch++;
> +	}
> +	if (*pch == '\0')
> +		return 0;
> +	if (*pch != '/')
> +		return FTW_SKIP_SUBTREE;
> +
> +	/* check /proc/<pid>/fd directory */
> +	pch++;
> +	if (strncmp(pch, "fd", 2))
> +		return FTW_SKIP_SUBTREE;
> +	pch += 2;
> +	if (*pch == '\0')
> +		return 0;
> +	if (*pch != '/')
> +		return FTW_SKIP_SUBTREE;
> +
> +	/* check /proc/<pid>/fd/<fd_num> */
> +	pch++;
> +	while (isdigit(*pch)) {
> +		fd = fd * 10 + *pch - '0';
> +		pch++;
> +	}
> +	if (*pch != '\0')
> +		return FTW_SKIP_SUBTREE;
> +
> +	/* query (pid, fd) for potential perf events */
> +	err = bpf_task_fd_query(pid, fd, 0, buf, sizeof(buf), &prog_id,
> +				&attach_info, &probe_offset, &probe_addr);
> +	if (err < 0)
> +		return 0;

nit: it could be nice from user perspective to detect whether kernel
     supports the command and fail if not.  Otherwise user is not sure
     if there is no output because kernel lacks support or because
     there were really no attached progs.  Just a thought, not really
     a requirement.

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

nit: reverse xmas tree

> +	if (json_output)
> +		jsonw_start_array(json_wtr);
> +	if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
> +		p_err("%s", strerror(errno));
> +		err = -1;
> +	}
> +	if (json_output)
> +		jsonw_end_array(json_wtr);
> +
> +	return err;
> +}
Y Song May 18, 2018, 10:13 p.m. UTC | #2 
On Fri, May 18, 2018 at 1:51 PM, Jakub Kicinski
<jakub.kicinski@netronome.com> wrote:
> On Thu, 17 May 2018 22:03:10 -0700, Yonghong Song wrote:
>> The new command "bpftool perf [show | list]" will traverse
>> all processes under /proc, and if any fd is associated
>> with a perf event, it will print out related perf event
>> information. Documentation is also added.
>
> Thanks for the changes, it looks good with some minor nits which can be
> addressed as follow up if there is no other need to respin.  Please
> consider it:
>
> Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>

Most likely will need respin. Will make suggested changes then.

>
>> 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
>>   pid 21711  fd 5: prog_id 5  kprobe  func __x64_sys_write  offset 0
>>   pid 21765  fd 5: prog_id 7  kretprobe  func __x64_sys_nanosleep  offset 0
>>   pid 21767  fd 5: prog_id 8  tracepoint  sys_enter_nanosleep
>>   pid 21800  fd 5: prog_id 9  uprobe  filename /home/yhs/a.out  offset 1159
>>
>>   $ bpftool -j perf
>>   {"pid":21711,"fd":5,"prog_id":5,"attach_info":"kprobe","func":"__x64_sys_write","offset":0}, \
>>   {"pid":21765,"fd":5,"prog_id":7,"attach_info":"kretprobe","func":"__x64_sys_nanosleep","offset":0}, \
>>   {"pid":21767,"fd":5,"prog_id":8,"attach_info":"tracepoint","tracepoint":"sys_enter_nanosleep"}, \
>>   {"pid":21800,"fd":5,"prog_id":9,"attach_info":"uprobe","filename":"/home/yhs/a.out","offset":1159}
>
> nit: this is now an array

Sorry, this is probably updated in middle of work. Will make the change in
the next revision.

>
>>   $ 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 <yhs@fb.com>
>
>> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
>> index b301c9b..3680ad4 100644
>> --- a/tools/bpf/bpftool/bash-completion/bpftool
>> +++ b/tools/bpf/bpftool/bash-completion/bpftool
>> @@ -448,6 +448,15 @@ _bpftool()
>>                      ;;
>>              esac
>>              ;;
>> +        cgroup)
>
> s/cgroup/perf/ :)

A mistake in my side to consolidate different version of code.
I did have "perf" in one of my versions and tested it properly.

>
>> +            case $command in
>> +                *)
>> +                    [[ $prev == $object ]] && \
>> +                        COMPREPLY=( $( compgen -W 'help \
>> +                            show list' -- "$cur" ) )
>> +                    ;;
>> +            esac
>> +            ;;
>>      esac
>>  } &&
>>  complete -F _bpftool bpftool
>
>> +static int show_proc(const char *fpath, const struct stat *sb,
>> +                  int tflag, struct FTW *ftwbuf)
>> +{
>> +     __u64 probe_offset, probe_addr;
>> +     __u32 prog_id, attach_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 (isdigit(*pch)) {
>> +             pid = pid * 10 + *pch - '0';
>> +             pch++;
>> +     }
>> +     if (*pch == '\0')
>> +             return 0;
>> +     if (*pch != '/')
>> +             return FTW_SKIP_SUBTREE;
>> +
>> +     /* check /proc/<pid>/fd directory */
>> +     pch++;
>> +     if (strncmp(pch, "fd", 2))
>> +             return FTW_SKIP_SUBTREE;
>> +     pch += 2;
>> +     if (*pch == '\0')
>> +             return 0;
>> +     if (*pch != '/')
>> +             return FTW_SKIP_SUBTREE;
>> +
>> +     /* check /proc/<pid>/fd/<fd_num> */
>> +     pch++;
>> +     while (isdigit(*pch)) {
>> +             fd = fd * 10 + *pch - '0';
>> +             pch++;
>> +     }
>> +     if (*pch != '\0')
>> +             return FTW_SKIP_SUBTREE;
>> +
>> +     /* query (pid, fd) for potential perf events */
>> +     err = bpf_task_fd_query(pid, fd, 0, buf, sizeof(buf), &prog_id,
>> +                             &attach_info, &probe_offset, &probe_addr);
>> +     if (err < 0)
>> +             return 0;
>
> nit: it could be nice from user perspective to detect whether kernel
>      supports the command and fail if not.  Otherwise user is not sure
>      if there is no output because kernel lacks support or because
>      there were really no attached progs.  Just a thought, not really
>      a requirement.

I agree with you. it is good to output an error if the kernel does not
support the syscall (e.g., either non-root or new subcommand is not
supported).

>
>> +     if (json_output)
>> +             print_perf_json(pid, fd, prog_id, attach_info, buf, probe_offset,
>> +                             probe_addr);
>> +     else
>> +             print_perf_plain(pid, fd, prog_id, attach_info, buf, probe_offset,
>> +                              probe_addr);
>> +
>> +     return 0;
>> +}
>> +
>> +static int do_show(int argc, char **argv)
>> +{
>> +     int err = 0, nopenfd = 16;
>> +     int flags = FTW_ACTIONRETVAL | FTW_PHYS;
>
> nit: reverse xmas tree

Will make the change in the next revision.

>
>> +     if (json_output)
>> +             jsonw_start_array(json_wtr);
>> +     if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
>> +             p_err("%s", strerror(errno));
>> +             err = -1;
>> +     }
>> +     if (json_output)
>> +             jsonw_end_array(json_wtr);
>> +
>> +     return err;
>> +}
diff mbox series

Patch

diff --git a/tools/bpf/bpftool/Documentation/bpftool-perf.rst b/tools/bpf/bpftool/Documentation/bpftool-perf.rst
new file mode 100644
index 0000000..3e65375
--- /dev/null
+++ b/tools/bpf/bpftool/Documentation/bpftool-perf.rst
@@ -0,0 +1,81 @@ 
+================
+bpftool-perf
+================
+-------------------------------------------------------------------------------
+tool for inspection of perf related bpf prog attachments
+-------------------------------------------------------------------------------
+
+:Manual section: 8
+
+SYNOPSIS
+========
+
+	**bpftool** [*OPTIONS*] **perf** *COMMAND*
+
+	*OPTIONS* := { [{ **-j** | **--json** }] [{ **-p** | **--pretty** }] }
+
+	*COMMANDS* :=
+	{ **show** | **list** | **help** }
+
+PERF COMMANDS
+=============
+
+|	**bpftool** **perf { show | list }**
+|	**bpftool** **perf help**
+
+DESCRIPTION
+===========
+	**bpftool perf { show | list }**
+		  List all raw_tracepoint, tracepoint, kprobe attachment in the system.
+
+		  Output will start with process id and file descriptor in that process,
+		  followed by bpf program id, attachment information, and attachment point.
+		  The attachment point for raw_tracepoint/tracepoint is the trace probe name.
+		  The attachment point for k[ret]probe is either symbol name and offset,
+		  or a kernel virtual address.
+		  The attachment point for u[ret]probe is the file name and the file offset.
+
+	**bpftool perf help**
+		  Print short help message.
+
+OPTIONS
+=======
+	-h, --help
+		  Print short generic help message (similar to **bpftool help**).
+
+	-v, --version
+		  Print version number (similar to **bpftool version**).
+
+	-j, --json
+		  Generate JSON output. For commands that cannot produce JSON, this
+		  option has no effect.
+
+	-p, --pretty
+		  Generate human-readable JSON output. Implies **-j**.
+
+EXAMPLES
+========
+
+| **# bpftool perf**
+
+::
+
+      pid 21711  fd 5: prog_id 5  kprobe  func __x64_sys_write  offset 0
+      pid 21765  fd 5: prog_id 7  kretprobe  func __x64_sys_nanosleep  offset 0
+      pid 21767  fd 5: prog_id 8  tracepoint  sys_enter_nanosleep
+      pid 21800  fd 5: prog_id 9  uprobe  filename /home/yhs/a.out  offset 1159
+
+|
+| **# bpftool -j perf**
+
+::
+
+    [{"pid":21711,"fd":5,"prog_id":5,"attach_info":"kprobe","func":"__x64_sys_write","offset":0}, \
+     {"pid":21765,"fd":5,"prog_id":7,"attach_info":"kretprobe","func":"__x64_sys_nanosleep","offset":0}, \
+     {"pid":21767,"fd":5,"prog_id":8,"attach_info":"tracepoint","tracepoint":"sys_enter_nanosleep"}, \
+     {"pid":21800,"fd":5,"prog_id":9,"attach_info":"uprobe","filename":"/home/yhs/a.out","offset":1159}]
+
+
+SEE ALSO
+========
+	**bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-map**\ (8)
diff --git a/tools/bpf/bpftool/Documentation/bpftool.rst b/tools/bpf/bpftool/Documentation/bpftool.rst
index 564cb0d..b6f5d56 100644
--- a/tools/bpf/bpftool/Documentation/bpftool.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool.rst
@@ -16,7 +16,7 @@  SYNOPSIS
 
 	**bpftool** **version**
 
-	*OBJECT* := { **map** | **program** | **cgroup** }
+	*OBJECT* := { **map** | **program** | **cgroup** | **perf** }
 
 	*OPTIONS* := { { **-V** | **--version** } | { **-h** | **--help** }
 	| { **-j** | **--json** } [{ **-p** | **--pretty** }] }
@@ -30,6 +30,8 @@  SYNOPSIS
 
 	*CGROUP-COMMANDS* := { **show** | **list** | **attach** | **detach** | **help** }
 
+	*PERF-COMMANDS* := { **show** | **list** | **help** }
+
 DESCRIPTION
 ===========
 	*bpftool* allows for inspection and simple modification of BPF objects
@@ -56,3 +58,4 @@  OPTIONS
 SEE ALSO
 ========
 	**bpftool-map**\ (8), **bpftool-prog**\ (8), **bpftool-cgroup**\ (8)
+        **bpftool-perf**\ (8)
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index b301c9b..3680ad4 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -448,6 +448,15 @@  _bpftool()
                     ;;
             esac
             ;;
+        cgroup)
+            case $command in
+                *)
+                    [[ $prev == $object ]] && \
+                        COMPREPLY=( $( compgen -W 'help \
+                            show list' -- "$cur" ) )
+                    ;;
+            esac
+            ;;
     esac
 } &&
 complete -F _bpftool bpftool
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..baa4bbe
--- /dev/null
+++ b/tools/bpf/bpftool/perf.c
@@ -0,0 +1,200 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright (C) 2018 Facebook
+// Author: Yonghong Song <yhs@fb.com>
+
+#define _GNU_SOURCE
+#include <ctype.h>
+#include <errno.h>
+#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, int fd, __u32 prog_id, __u32 attach_info,
+			    char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+	jsonw_start_object(json_wtr);
+	jsonw_int_field(json_wtr, "pid", pid);
+	jsonw_int_field(json_wtr, "fd", fd);
+	jsonw_uint_field(json_wtr, "prog_id", prog_id);
+	switch (attach_info) {
+	case BPF_ATTACH_RAW_TRACEPOINT:
+		jsonw_string_field(json_wtr, "attach_info", "raw_tracepoint");
+		jsonw_string_field(json_wtr, "tracepoint", buf);
+		break;
+	case BPF_ATTACH_TRACEPOINT:
+		jsonw_string_field(json_wtr, "attach_info", "tracepoint");
+		jsonw_string_field(json_wtr, "tracepoint", buf);
+		break;
+	case BPF_ATTACH_KPROBE:
+		jsonw_string_field(json_wtr, "attach_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_ATTACH_KRETPROBE:
+		jsonw_string_field(json_wtr, "attach_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_ATTACH_UPROBE:
+		jsonw_string_field(json_wtr, "attach_info", "uprobe");
+		jsonw_string_field(json_wtr, "filename", buf);
+		jsonw_lluint_field(json_wtr, "offset", probe_offset);
+		break;
+	case BPF_ATTACH_URETPROBE:
+		jsonw_string_field(json_wtr, "attach_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, int fd, __u32 prog_id, __u32 attach_info,
+			    char *buf, __u64 probe_offset, __u64 probe_addr)
+{
+	printf("pid %d  fd %d: prog_id %u  ", pid, fd, prog_id);
+	switch (attach_info) {
+	case BPF_ATTACH_RAW_TRACEPOINT:
+		printf("raw_tracepoint  %s\n", buf);
+		break;
+	case BPF_ATTACH_TRACEPOINT:
+		printf("tracepoint  %s\n", buf);
+		break;
+	case BPF_ATTACH_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_ATTACH_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_ATTACH_UPROBE:
+		printf("uprobe  filename %s  offset %llu\n", buf, probe_offset);
+		break;
+	case BPF_ATTACH_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, attach_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 (isdigit(*pch)) {
+		pid = pid * 10 + *pch - '0';
+		pch++;
+	}
+	if (*pch == '\0')
+		return 0;
+	if (*pch != '/')
+		return FTW_SKIP_SUBTREE;
+
+	/* check /proc/<pid>/fd directory */
+	pch++;
+	if (strncmp(pch, "fd", 2))
+		return FTW_SKIP_SUBTREE;
+	pch += 2;
+	if (*pch == '\0')
+		return 0;
+	if (*pch != '/')
+		return FTW_SKIP_SUBTREE;
+
+	/* check /proc/<pid>/fd/<fd_num> */
+	pch++;
+	while (isdigit(*pch)) {
+		fd = fd * 10 + *pch - '0';
+		pch++;
+	}
+	if (*pch != '\0')
+		return FTW_SKIP_SUBTREE;
+
+	/* query (pid, fd) for potential perf events */
+	err = bpf_task_fd_query(pid, fd, 0, buf, sizeof(buf), &prog_id,
+				&attach_info, &probe_offset, &probe_addr);
+	if (err < 0)
+		return 0;
+
+	if (json_output)
+		print_perf_json(pid, fd, prog_id, attach_info, buf, probe_offset,
+				probe_addr);
+	else
+		print_perf_plain(pid, fd, prog_id, attach_info, buf, probe_offset,
+				 probe_addr);
+
+	return 0;
+}
+
+static int do_show(int argc, char **argv)
+{
+	int err = 0, nopenfd = 16;
+	int flags = FTW_ACTIONRETVAL | FTW_PHYS;
+
+	if (json_output)
+		jsonw_start_array(json_wtr);
+	if (nftw("/proc", show_proc, nopenfd, flags) == -1) {
+		p_err("%s", strerror(errno));
+		err = -1;
+	}
+	if (json_output)
+		jsonw_end_array(json_wtr);
+
+	return err;
+}
+
+static int do_help(int argc, char **argv)
+{
+	fprintf(stderr,
+		"Usage: %s %s { show | list | help }\n"
+		"",
+		bin_name, argv[-2]);
+
+	return 0;
+}
+
+static const struct cmd cmds[] = {
+	{ "show",	do_show },
+	{ "list",	do_show },
+	{ "help",	do_help },
+	{ 0 }
+};
+
+int do_perf(int argc, char **argv)
+{
+	return cmd_select(cmds, argc, argv, do_help);
+}