Threads share map_groups, all map events are merged into it.

Thus we could send mmaps only for thread group leader.  Otherwise it
took ages to attach and record something from processes with many vmas
and threads.

Thread group leader could be already dead, but it seems perf cannot
handle this case anyway.

Testing dummy:

  #include <stdio.h>
  #include <stdlib.h>
  #include <sys/mman.h>
  #include <pthread.h>
  #include <unistd.h>

  void *thread(void *arg) {
          pause();
  }

  int main(int argc, char **argv) {
        int threads = 10000;
        int vmas = 50000;
        pthread_t th;
        for (int i = 0; i < threads; i++)
                pthread_create(&th, NULL, thread, NULL);
        for (int i = 0; i < vmas; i++)
                mmap(NULL, 4096, (i & 1) ? PROT_READ : PROT_WRITE,
                     MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
        sleep(60);
        return 0;
  }

Comment by Jiri Olsa:

We actualy synthesize the group leader (if we found one) for the thread
even if it's not present in the thread_map, so the process maps are
always in data.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/153363294102.396323.6277944760215058174.stgit@buzzSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We just check that the evsel is the one we associated with the
bpf-output event associated with the "__augmented_syscalls__" eBPF map,
to show that the formatting is done properly:

  # perf trace -e perf/tools/perf/examples/bpf/augmented_syscalls.c,openat cat /etc/passwd > /dev/null
     0.000 (         ): __augmented_syscalls__:dfd: CWD, filename: 0x43e06da8, flags: CLOEXEC
     0.006 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x43e06da8, flags: CLOEXEC
     0.007 ( 0.004 ms): cat/11486 openat(dfd: CWD, filename: 0x43e06da8, flags: CLOEXEC                 ) = 3
     0.029 (         ): __augmented_syscalls__:dfd: CWD, filename: 0x4400ece0, flags: CLOEXEC
     0.030 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x4400ece0, flags: CLOEXEC
     0.031 ( 0.004 ms): cat/11486 openat(dfd: CWD, filename: 0x4400ece0, flags: CLOEXEC                 ) = 3
     0.249 (         ): __augmented_syscalls__:dfd: CWD, filename: 0xc3700d6
     0.250 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0xc3700d6
     0.252 ( 0.003 ms): cat/11486 openat(dfd: CWD, filename: 0xc3700d6                                  ) = 3
  #

Now we just need to get the full blown enter/exit handlers to check if the
evsel being processed is the augmented_syscalls one to go pick the pointer
payloads from the end of the payload.

We also need to state somehow what is the layout for multi pointer arg syscalls.

Also handy would be to have a BTF file with the struct definitions used in
syscalls, compact, generated at kernel built time and available for use in eBPF
programs.

Till we get there we can go on doing some manual coupling of the most relevant
syscalls with some hand built beautifiers.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-r6ba5izrml82nwfmwcp7jpkm@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The payload that is put in place by the eBPF script attached to
syscalls:sys_enter_openat (and other syscalls with pointers, in the
future) can be consumed by the existing sys_enter beautifiers if
evsel->priv is setup with a struct syscall_tp with struct tp_fields for
the 'syscall_id' and 'args' fields expected by the beautifiers, this
patch does just that.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-xfjyog8oveg2fjys9r1yy1es@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We're calling it to setup that event, and we'll need it later to decide
if the bpf-output event we're handling is the one setup for a specific
purpose, return it using ERR_PTR, etc.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-zhachv7il2n1lopt9aonwhu7@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add an example BPF script that writes syscalls:sys_enter_openat raw
tracepoint payloads augmented with the first 64 bytes of the "filename"
syscall pointer arg.

Then catch it and print it just like with things written to the
"__bpf_stdout__" map associated with a PERF_COUNT_SW_BPF_OUTPUT software
event, by just letting the default tracepoint handler in 'perf trace',
trace__event_handler(), to use bpf_output__fprintf(trace, sample), just
like it does with all other PERF_COUNT_SW_BPF_OUTPUT events, i.e. just
do a dump on the payload, so that we can check if what is being printed
has at least the first 64 bytes of the "filename" arg:

The augmented_syscalls.c eBPF script:

  # cat tools/perf/examples/bpf/augmented_syscalls.c
  // SPDX-License-Identifier: GPL-2.0

  #include <stdio.h>

  struct bpf_map SEC("maps") __augmented_syscalls__ = {
       .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
       .key_size = sizeof(int),
       .value_size = sizeof(u32),
       .max_entries = __NR_CPUS__,
  };

  struct syscall_enter_openat_args {
	unsigned long long common_tp_fields;
	long		   syscall_nr;
	long		   dfd;
	char		   *filename_ptr;
	long		   flags;
	long		   mode;
  };

  struct augmented_enter_openat_args {
	struct syscall_enter_openat_args args;
	char				 filename[64];
  };

  int syscall_enter(openat)(struct syscall_enter_openat_args *args)
  {
	struct augmented_enter_openat_args augmented_args;

	probe_read(&augmented_args.args, sizeof(augmented_args.args), args);
	probe_read_str(&augmented_args.filename, sizeof(augmented_args.filename), args->filename_ptr);
	perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU,
			  &augmented_args, sizeof(augmented_args));
	return 1;
  }

  license(GPL);
  #

So it will just prepare a raw_syscalls:sys_enter payload for the
"openat" syscall.

This will eventually be done for all syscalls with pointer args,
globally or just when the user asks, using some spec, which args of
which syscalls it wants "expanded" this way, we'll probably start with
just all the syscalls that have char * pointers with familiar names, the
ones we already handle with the probe:vfs_getname kprobe if it is in
place hooking the kernel getname_flags() function used to copy from user
the paths.

Running it we get:

  # perf trace -e perf/tools/perf/examples/bpf/augmented_syscalls.c,openat cat /etc/passwd > /dev/null
     0.000 (         ): __augmented_syscalls__:X?.C......................`\..................../etc/ld.so.cache..#......,....ao.k...............k......1.".........
     0.006 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x5c600da8, flags: CLOEXEC
     0.008 ( 0.005 ms): cat/31292 openat(dfd: CWD, filename: 0x5c600da8, flags: CLOEXEC                 ) = 3
     0.036 (         ): __augmented_syscalls__:X?.C.......................\..................../lib64/libc.so.6......... .\....#........?.......=.C..../.".........
     0.037 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0x5c808ce0, flags: CLOEXEC
     0.039 ( 0.007 ms): cat/31292 openat(dfd: CWD, filename: 0x5c808ce0, flags: CLOEXEC                 ) = 3
     0.323 (         ): __augmented_syscalls__:X?.C.....................P....................../etc/passwd......>.C....@................>.C.....,....ao.>.C........
     0.325 (         ): syscalls:sys_enter_openat:dfd: CWD, filename: 0xe8be50d6
     0.327 ( 0.004 ms): cat/31292 openat(dfd: CWD, filename: 0xe8be50d6                                 ) = 3
  #

We need to go on optimizing this to avoid seding trash or zeroes in the
pointer content payload, using the return from bpf_probe_read_str(), but
to keep things simple at this stage and make incremental progress, lets
leave it at that for now.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-g360n1zbj6bkbk6q0qo11c28@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Will be used shortly in the augmented syscalls work together with a
PERF_COUNT_SW_BPF_OUTPUT software event to insert syscalls + pointer
contents in the perf ring buffer, to be consumed by 'perf trace'
beautifiers.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ajlkpz4cd688ulx1u30htkj3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

That is just bpf__strerror_setup_stdout() renamed to the more general
"setup_output_event" method, keep the existing stdout() as a wrapper.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-nwnveo428qn0b48axj50vkc7@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We will use it to set up other bpf-output events, for instance to
generate augmented syscall entry tracepoints with pointer contents.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4r7kw0nsyi4vyz6xm1tzx6a3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

By passing a 'name' arg, that will eventually be used to setup more
"bpf-output" events, e.g. to create a event where to create raw_syscalls
like events that in addition to the syscall arguments will also copy the
pointer contents being passed from/to userspace.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-talrnxps9p3qozk3aeh91fgv@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

That, together with the map __bpf_output__ that is already handled by
'perf trace' to print that event's contents as strings provides a
debugging facility, to show it in use, print a simple string everytime
the syscalls:sys_enter_openat() syscall tracepoint is hit:

  # cat tools/perf/examples/bpf/hello.c
  #include <stdio.h>

  int syscall_enter(openat)(void *args)
  {
	  puts("Hello, world\n");
	  return 0;
  }

  license(GPL);
  #
  # perf trace -e openat,tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
     0.016 (         ): __bpf_stdout__:Hello, world
     0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
     0.057 (         ): __bpf_stdout__:Hello, world
     0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3
     0.417 (         ): __bpf_stdout__:Hello, world
     0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd) = 3
  #

This is part of an ongoing experimentation on making eBPF scripts as
consumed by perf to be as concise as possible and using familiar
concepts such as stdio.h functions, that end up just wrapping the
existing BPF functions, trying to hide as much boilerplate as possible
while using just conventions and C preprocessor tricks.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4tiaqlx5crf0fwpe7a6j84x7@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

A helper structure used by eBPF C program to describe map attributes to
elf_bpf loader, to be used initially by the special __bpf_stdout__ map
used to print strings into the perf ring buffer in BPF scripts, e.g.:

Using the upcoming stdio.h and puts() macros to use the __bpf_stdout__
map to add strings to the ring buffer:

  # cat tools/perf/examples/bpf/hello.c
  #include <stdio.h>

  int syscall_enter(openat)(void *args)
  {
	  puts("Hello, world\n");
	  return 0;
  }

  license(GPL);
  #
  # cat ~/.perfconfig
  [llvm]
	dump-obj = true
  # perf trace -e openat,tools/perf/examples/bpf/hello.c/call-graph=dwarf/ cat /etc/passwd > /dev/null
  LLVM: dumping tools/perf/examples/bpf/hello.o
     0.016 (         ): __bpf_stdout__:Hello, world
     0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC           ) = 3
     0.057 (         ): __bpf_stdout__:Hello, world
     0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC           ) = 3
     0.417 (         ): __bpf_stdout__:Hello, world
     0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd                                ) = 3
  #
  # file tools/perf/examples/bpf/hello.o
  tools/perf/examples/bpf/hello.o: ELF 64-bit LSB relocatable, *unknown arch 0xf7* version 1 (SYSV), not stripped
   # readelf -SW tools/perf/examples/bpf/hello.o
  There are 10 section headers, starting at offset 0x208:

  Section Headers:
    [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
    [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
    [ 1] .strtab           STRTAB          0000000000000000 000188 00007f 00      0   0  1
    [ 2] .text             PROGBITS        0000000000000000 000040 000000 00  AX  0   0  4
    [ 3] syscalls:sys_enter_openat PROGBITS        0000000000000000 000040 000088 00  AX  0   0  8
    [ 4] .relsyscalls:sys_enter_openat REL             0000000000000000 000178 000010 10      9   3  8
    [ 5] maps              PROGBITS        0000000000000000 0000c8 00001c 00  WA  0   0  4
    [ 6] .rodata.str1.1    PROGBITS        0000000000000000 0000e4 00000e 01 AMS  0   0  1
    [ 7] license           PROGBITS        0000000000000000 0000f2 000004 00  WA  0   0  1
    [ 8] version           PROGBITS        0000000000000000 0000f8 000004 00  WA  0   0  4
    [ 9] .symtab           SYMTAB          0000000000000000 000100 000078 18      1   1  8
  Key to Flags:
    W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
    L (link order), O (extra OS processing required), G (group), T (TLS),
    C (compressed), x (unknown), o (OS specific), E (exclude),
    p (processor specific)
    # readelf -s tools/perf/examples/bpf/hello.o

  Symbol table '.symtab' contains 5 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    5 __bpf_stdout__
     2: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    7 _license
     3: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    8 _version
     4: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    3 syscall_enter_openat
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-81fg60om2ifnatsybzwmiga3@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Set annotation percent type from following choices:

  global-period, local-period, global-hits, local-hits

With following report option setup the percent type will be passed to
annotation browser:

  $ perf report --percent-type period-local

The local/global keywords set if the percentage is computed in the scope
of the function (local) or the whole data (global).  The period/hits
keywords set the base the percentage is computed on - the samples period
or the number of samples (hits).
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-21-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add --percent-type option to set annotation percent type from following
choices:

  global-period, local-period, global-hits, local-hits

Examples:

  $ perf annotate --percent-type period-local --stdio | head -1
   Percent         |      Source code ... es, percent: local period)
  $ perf annotate --percent-type hits-local --stdio | head -1
   Percent         |      Source code ... es, percent: local hits)
  $ perf annotate --percent-type hits-global --stdio | head -1
   Percent         |      Source code ... es, percent: global hits)
  $ perf annotate --percent-type period-global --stdio | head -1
   Percent         |      Source code ... es, percent: global period)

The local/global keywords set if the percentage is computed in the scope
of the function (local) or the whole data (global).

The period/hits keywords set the base the percentage is computed on -
the samples period or the number of samples (hits).
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-20-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

In following patches we will allow to switch percent type even for stdio
annotation outputs. Adding the percent type value into the annotation
outputs title.

  $ perf annotate --stdio
   Percent         |      Sou ... instructions:u } (2805 samples, percent: local period)
  --------------------------- ... ------------------------------------------------------
  ...

  $ perf annotate --stdio2
  Samples: 2K of events 'anon ...  count (approx.): 156525487, [percent: local period]
  safe_write.c() /usr/bin/yes
  Percent
  ...
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-19-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Currently we display the percentages in annotation output based on
number of samples hits. Switching it to period based percentage by
default, because it corresponds more to the time spent on the line.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-18-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add new key bindings to toggle percent type/base in annotation UI browser:

 'p' to switch between local and global percent type
 'b' to switch between hits and perdio percent base

Add the following help messages to the UI browser '?' window:

  ...
  p             Toggle percent type [local/global]
  b             Toggle percent base [period/hits]
  ...
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-17-jolsa@kernel.org
[ Moved percent_type to be the last arg to sym_title(), its an arg to what is being formmated (buf, size) ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Pass browser percent_type in annotate_browser__calc_percent().
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-16-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Pass 'struct annotation_options' to map_symbol__annotation_dump(), to
carry on and pass the percent_type value.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-15-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Pass struct annotation_options to symbol__calc_lines(), to carry on and
pass the percent_type value.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-14-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

It will be used to carry user selection of percent type for annotation
output.

Passing the percent_type to the annotation_line__print function as the
first step and making it default to current percentage type
(PERCENT_HITS_LOCAL) value.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-13-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Adding and computing global period percent value for annotation line.
Storing it in struct annotation_data percent array under new
PERCENT_PERIOD_GLOBAL index.

At the moment it's not displayed, it's coming in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-12-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Adding and computing local period percent value for annotation line.
Storing it in struct annotation_data percent array under new
PERCENT_PERIOD_LOCAL index.

At the moment it's not displayed, it's coming in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-11-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Adding and computing global hits percent value for annotation line.
Storing it in struct annotation_data percent array under new
PERCENT_HITS_GLOBAL index.

At the moment it's not displayed, it's coming in following patches.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-10-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

So we can hold multiple percent values for annotation line.

The first member of this array is current local hits percent value
(PERCENT_HITS_LOCAL index), so no functional change is expected.

Adding annotation_data__percent function to return requested percent
value from struct annotation_data.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-9-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We need to bring in 'struct hists' object and for that we need 'struct
perf_evsel' object in the scope.

Switching the group data loop with the evsel group loop.  It does the
same thing, but it brings evsel object, that we can use later get the
'struct hists' object.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-8-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We will need to bring in 'struct hists' variable in this scope, so it's
better we do this rename first.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-7-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Based on previous rename, changing also the local variable names to fit
properly.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-6-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

The name 'samples*' is little confusing because we have nested 'struct
sym_hist_entry' under annotation_line struct, which holds 'nr_samples'
as well.

Also the holding struct name is 'annotation_data' so the 'data' name
fits better.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-5-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

We have more current function tto get the title for annotation,
which is hists__scnprintf_title. They both have same output as
far as the annotation's header line goes.

They differ in counting of the nr_samples, hists__scnprintf_title
provides more accurate number based on the setup of the
symbol_conf.filter_relative variable.

Plus it also displays any uid/thread/dso/socket filters/zooms
if there are set any, which annotation__scnprintf_samples_period
does not.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-4-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

There's no outside user of it.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20180804130521.11408-3-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

There's no outside user of it.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lkml.kernel.org/r/20180804130521.11408-2-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Allowing one to hook into the syscalls:sys_enter_NAME tracepoints,
an example is provided that hooks into the 'openat' syscall.

Using it with the probe:vfs_getname probe into getname_flags to get the
filename args as it is copied from userspace:

  # perf probe -l
  probe:vfs_getname    (on getname_flags:73@acme/git/linux/fs/namei.c with pathname)
  # perf trace -e probe:*getname,tools/perf/examples/bpf/sys_enter_openat.c cat /etc/passwd > /dev/null
     0.000 probe:vfs_getname:(ffffffffbd2a8983) pathname="/etc/ld.so.preload"
     0.022 syscalls:sys_enter_openat:dfd: CWD, filename: 0xafbe8da8, flags: CLOEXEC
     0.027 probe:vfs_getname:(ffffffffbd2a8983) pathname="/etc/ld.so.cache"
     0.054 syscalls:sys_enter_openat:dfd: CWD, filename: 0xafdf0ce0, flags: CLOEXEC
     0.057 probe:vfs_getname:(ffffffffbd2a8983) pathname="/lib64/libc.so.6"
     0.316 probe:vfs_getname:(ffffffffbd2a8983) pathname="/usr/lib/locale/locale-archive"
     0.375 syscalls:sys_enter_openat:dfd: CWD, filename: 0xe2b2b0b4
     0.379 probe:vfs_getname:(ffffffffbd2a8983) pathname="/etc/passwd"
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-2po9jcqv1qgj0koxlg8kkg30@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

bitmap_zero() is called after bitmap_alloc() in perf code. But
bitmap_alloc() internally uses calloc() which guarantees that allocated
area is zeroed. So following bitmap_zero is unneeded. Drop it.

This happened because of confusing name for bitmap allocator. It
should has name bitmap_zalloc instead of bitmap_alloc.

This series:

  https://lkml.org/lkml/2018/6/18/841

introduces a new API for bitmap allocations in kernel, and functions
there are named correctly. Following patch propogates the API to tools,
and fixes naming issue.
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: David Carrillo-Cisneros <davidcc@google.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Link: http://lkml.kernel.org/r/20180623073502.16321-1-ynorov@caviumnetworks.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

This patch adds the Ampere Computing eMAG file.  This platform follows
the ARMv8 recommended IMPLEMENTATION DEFINED events, where applicable.
Signed-off-by: Sean V Kelley <seanvk.dev@oregontracks.org>
Reviewed-by: John Garry <john.garry@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: William Cohen <wcohen@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
LPU-Reference: 20180803041811.17065-1-seanvk.dev@oregontracks.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add support for s390 auxiliary trace support.

Use 'perf record -e rbd000 -- ls' to create the perf.data file.

Use 'perf report' to display the auxiliary trace data.

Output before:

  [root@s35lp76 perf]# ./perf report --stdio
  0x128 [0x10]: failed to process type: 70
  Error:
  failed to process sample
  [root@s35lp76 perf]#

Output after:

  [root@s35lp76 perf]# ./perf report --stdio

      18.21%    18.21%  ls     [kernel.kallsyms]       [k] ftrace_likely_update
       9.52%     9.52%  ls     [kernel.kallsyms]       [k] lock_acquire
       9.38%     9.38%  ls     [kernel.kallsyms]       [k] lock_release
       3.45%     3.45%  ls     [kernel.kallsyms]       [k] lock_acquired
       2.88%     2.88%  ls     [kernel.kallsyms]       [k] link_path_walk
       2.63%     2.63%  ls     [kernel.kallsyms]       [k] __d_lookup
       2.38%     2.38%  ls     [kernel.kallsyms]       [k] __d_lookup_rcu
       2.04%     2.04%  ls     [kernel.kallsyms]       [k] ___might_sleep
       1.83%     1.83%  ls     [kernel.kallsyms]       [k] debug_lockdep_rcu_enabled
       1.44%     1.44%  ls     [kernel.kallsyms]       [k] dput
     ....
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180802074622.13641-4-tmricht@linux.ibm.com
[ Use PRI[xd]64 to fix the build on debian:experimental-x-mips (gcc 8.1.0) and others ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add support for s390 auxiliary trace support.

Use 'perf record -e rbd000' to create the perf.data file.  The event
also has the symbolic name SF_CYCLES_BASIC_DIAG, using 'perf record -e
SF_CYCLES_BASIC_DIAG' is equivalent.

Use 'perf report -D' to display the auxiliary trace data.

Output before:

 0 0 0x25a66 [0x30]: PERF_RECORD_AUXTRACE size: 0x40000
                 offset: 0  ref: 0  idx: 4  tid: -1  cpu: 4
     Nothing else

Output after:

 0 0 0x25a66 [0x30]: PERF_RECORD_AUXTRACE size: 0x40000
                  offset: 0  ref: 0  idx: 4  tid: -1  cpu: 4
 .
 . ... s390 AUX data: size 262144 bytes
    [00000000] Basic   Def:0001 Inst:0000 TW   AS:3 ASN:0xffff IA:0x0000000000c2f1bc
		CL:1 HPP:0x8000000000000000 GPP:000000000000000000
    [0x000020] Diag    Def:8005
    [0x0000bf] Basic   Def:0001 Inst:0000 TW   AS:3 ASN:0xffff IA:0x0000000000c2f1bc
		CL:1 HPP:0x8000000000000000 GPP:000000000000000000
    [0x0000df] Diag    Def:8005
    [0x00017e] Basic   Def:0001 Inst:0000 TW   AS:3 ASN:0xffff IA:0x0000000000c2f1bc
		CL:1 HPP:0x8000000000000000 GPP:000000000000000000
    ....
    [0x000fc0] Trailer F T bsdes:32 dsdes:159 Overflow:0 Time:0xd4ab59a8450fa108
		C:1 TOD:0xd4ab4ec98ceb3832 1:0x8000000000000000 2:0xd4ab4ec98ceb3832

This output is shown for every sampled data block. The
output contains the

 - basic-sampling data entry

 - diagnostic-sampling data entry

 - trailer entry

The basic sampling entry and diagnostic sampling entry sizes can be
extracted using the trailer entries in the SDB.  On older hardware these
values (bsdes and dsdes in the trailer entry) are reserved and zero.
Older hardware use hard coded values based on the s390 machine type.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: http://lkml.kernel.org/r/20180802074622.13641-3-tmricht@linux.ibm.com
Link: http://lkml.kernel.org/r/eda2632e-7919-5ffd-5f68-821e77d216fa@linux.ibm.com
[ Merged a fix for a 'tipe puned' problem reported by Michael Ellerman see last Link tag. ]
[ Removed __packed from two structs, they're already naturally packed and having that. ]
[ attribute breaks the build in gcc 8.1.1 mips, 4.4.7 x86_64, 7.1.1 ARCompact ISA, etc) ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add initial support for s390 auxiliary traces using the CPU-Measurement
Sampling Facility.

Support and ignore PERF_REPORT_AUXTRACE_INFO records in the perf data
file. Later patches will show the contents of the auxiliary traces.

Setup the auxtrace queues and data structures for s390.  A raw dump of
the perf.data file now does not show an error when an auxtrace event is
encountered.

Output before:

  [root@s35lp76 perf]# ./perf report -D -i perf.data.auxtrace
  0x128 [0x10]: failed to process type: 70
  Error:
  failed to process sample

  0x128 [0x10]: event: 70
  .
  . ... raw event: size 16 bytes
  .  0000:  00 00 00 46 00 00 00 10 00 00 00 00 00 00 00 00  ...F............

  0x128 [0x10]: PERF_RECORD_AUXTRACE_INFO type: 0
  [root@s35lp76 perf]#

Output after:

   # ./perf report -D -i perf.data.auxtrace |fgrep PERF_RECORD_AUXTRACE
  0 0 0x128 [0x10]: PERF_RECORD_AUXTRACE_INFO type: 5
  0 0 0x25a66 [0x30]: PERF_RECORD_AUXTRACE size: 0x40000
	   offset: 0  ref: 0  idx: 4  tid: -1  cpu: 4
  ....

Additional notes about the underlying hardware and software
implementation, provided by Hendrik Brueckner (see Link: below).

=============================================================================

The CPU-Measurement Facility (CPU-MF) provides a set of functions to obtain
performance information on the mainframe.  Basically, it was introduced
with System z10 years ago for the z/Architecture, that means, 64-bit.
For Linux, there are two facilities of interest, counter facility and sampling
facility.  The counter facility provides hardware counters for instructions,
cycles, crypto-activities, and many more.

The sampling facility is a hardware sampler that when started will write
samples at a particular interval into a sampling buffer.  At some point,
for example, if a sample block is full, it generates an interrupt to collect
samples (while the sampler continues to run).

Few years ago, I started to provide the a perf PMU to use the counter
and sampling facilities.  Recently, the device driver was updated to also
"export" the sampling buffer into the AUX area.  Thomas now completed the
related perf work to interpret and process these AUX data.

If people are more interested in the sampling facility, they can have a
look into:

- The Load-Program-Parameter and the CPU-Measurement Facilities, SA23-2260-05
  http://www-01.ibm.com/support/docview.wss?uid=isg26fcd1cc32246f4c8852574ce0044734a

and to learn how-to use it for Linux on Z, have look at chapter 54,
"Using the CPU-measurement facilities" in the:

- Device Drivers, Features, and Commands, SC33-8411-34
  http://public.dhe.ibm.com/software/dw/linux390/docu/l416dd34.pdf

=============================================================================
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Link: http://lkml.kernel.org/r/20180803100758.GA28475@linux.ibm.com
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180802074622.13641-2-tmricht@linux.ibm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Now it looks just about the same as for the trace__sys_{enter,exit}.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-y59may7zx1eccnp4m3qm4u0b@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Mapping "__syscall_nr" to "id" and setting up "args" from the offset of
"__syscall_nr" + sizeof(u64), as the payload for syscalls:* is the same
as for raw_syscalls:*, just the fields have different names.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-ogeenrpviwcpwl3oy1l55f3m@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

To avoid having to ask libtraceevent to find a field by name when
handling each tracepoint event, we setup a struct syscall_tp with
a tp_field struct having an extractor function + the offset for the
"id", "args" and "ret" raw_syscalls:sys_{enter,exit} tracepoints.

Now that we want to do the same with syscalls:sys_{entry,exit}_NAME
individual syscall tracepoints, where we have "id" as "__syscall_nr" and
"args" as the actual series of per syscall parameters, we need more
flexibility from the routines that set up these pre-looked up syscall
tracepoint arg fields.

The next cset will use it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-v59q5e0jrlzkpl9a1c7t81ni@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>