perf/urgent fixes

Hi Ingo,

Please consider pulling,

- Arnaldo

Test results at the end of this message, as usual.

The following changes since commit 49cf4a4b3f5a8b02556dd4f45c5cee598d4fc799:

Merge tag 'perf-urgent-for-mingo-4.17-20180507' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent (2018-05-10 20:09:00 +0200)

are available in the Git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git tags/perf-urgent-for-mingo-4.17-20180514

for you to fetch changes up to c23080a6e4e853cff2834436e3cf33eae7723900:

perf tools: Add missing newline when parsing empty BPF proggie (2018-05-11 12:10:02 -0300)

----------------------------------------------------------------
perf/urgent fixes:

- Fix segfault when processing unknown threads in cs-etm (Leo Yan)

- Fix "perf test inet_pton" on s390 failing due to missing inline (Thomas Richter)

- Display all available events on 'perf annotate --stdio' (Jin Yao)

- Add missing newline when parsing empty BPF proggie (Arnaldo Carvalho de Melo)

----------------------------------------------------------------
Arnaldo Carvalho de Melo (1):
perf tools: Add missing newline when parsing empty BPF proggie

Jin Yao (1):
perf annotate: Display all available events on --stdio

Leo Yan (2):
perf cs-etm: Support unknown_thread in cs_etm_auxtrace perf cs-etm: Remove redundant space

Thomas Richter (1):
perf test: "probe libc's inet_pton" fails on s390 due to missing inline

 .../tests/shell/record+probe_libc_inet_pton.sh     |  2 +-
 tools/perf/util/annotate.c                         |  3 +++
 tools/perf/util/cs-etm.c                           | 28 ++++++++++++++++++----
 tools/perf/util/parse-events.c                     |  2 +-
 4 files changed, 29 insertions(+), 6 deletions(-)

Test results:

The first ones are container (docker) based builds of tools/perf with and without libelf support. Where clang is available, it is also used to build perf with/without libelf, and building with LIBCLANGLLVM=1 (built-in clang) with gcc and clang when clang and its devel libraries are installed.

The objtool and samples/bpf/ builds are disabled now that I'm switching from using the sources in a local volume to fetching them from a http server to build it inside the container, to make it easier to build in a container cluster. Those will come back later.

Several are cross builds, the ones with -x-ARCH and the android one, and those may not have all the features built, due to lack of multi-arch devel packages, available and being used so far on just a few, like debian:experimental-x-{arm64,mipsel}.

The 'perf test' one will perform a variety of tests exercising tools/perf/util/, tools/lib/{bpf,traceevent,etc}, as well as run perf commands with a variety of command line event specifications to then intercept the sys_perf_event syscall to check that the perf_event_attr fields are set up as expected, among a variety of other unit tests.

Then there is the 'make -C tools/perf build-test' ones, that build tools/perf/ with a variety of feature sets, exercising the build with an incomplete set of features as well as with a complete one. It is planned to have it run on each of the containers mentioned above, using some container orchestration infrastructure. Get in contact if interested in helping having this in place.

  # dm
   1 alpine:3.4                    : Ok   gcc (Alpine 5.3.0) 5.3.0
   2 alpine:3.5                    : Ok   gcc (Alpine 6.2.1) 6.2.1 20160822
   3 alpine:3.6                    : Ok   gcc (Alpine 6.3.0) 6.3.0
   4 alpine:3.7                    : Ok   gcc (Alpine 6.4.0) 6.4.0
   5 alpine:edge                   : Ok   gcc (Alpine 6.4.0) 6.4.0
   6 amazonlinux:1                 : Ok   gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11)
   7 amazonlinux:2                 : Ok   gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
   8 android-ndk:r12b-arm          : Ok   arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
   9 android-ndk:r15c-arm          : Ok   arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
  10 centos:5                      : Ok   gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-55)
  11 centos:6                      : Ok   gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
  12 centos:7                      : Ok   gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-16)
  13 debian:7                      : Ok   gcc (Debian 4.7.2-5) 4.7.2
  14 debian:8                      : Ok   gcc (Debian 4.9.2-10+deb8u1) 4.9.2
  15 debian:9                      : Ok   gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
  16 debian:experimental           : Ok   gcc (Debian 7.3.0-15) 7.3.0
  17 debian:experimental-x-arm64   : Ok   aarch64-linux-gnu-gcc (Debian 7.3.0-15) 7.3.0
  18 debian:experimental-x-mips    : Ok   mips-linux-gnu-gcc (Debian 7.3.0-12) 7.3.0
  19 debian:experimental-x-mips64  : Ok   mips64-linux-gnuabi64-gcc (Debian 7.3.0-12) 7.3.0
  20 debian:experimental-x-mipsel  : Ok   mipsel-linux-gnu-gcc (Debian 7.3.0-12) 7.3.0
  21 fedora:20                     : Ok   gcc (GCC) 4.8.3 20140911 (Red Hat 4.8.3-7)
  22 fedora:21                     : Ok   gcc (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6)
  23 fedora:22                     : Ok   gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6)
  24 fedora:23                     : Ok   gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6)
  25 fedora:24                     : Ok   gcc (GCC) 6.3.1 20161221 (Red Hat 6.3.1-1)
  26 fedora:24-x-ARC-uClibc        : Ok   arc-linux-gcc (ARCompact ISA Linux uClibc toolchain 2017.09-rc2) 7.1.1 20170710
  27 fedora:25                     : Ok   gcc (GCC) 6.4.1 20170727 (Red Hat 6.4.1-1)
  28 fedora:26                     : Ok   gcc (GCC) 7.3.1 20180130 (Red Hat 7.3.1-2)
  29 fedora:27                     : Ok   gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
  30 fedora:28                     : Ok   gcc (GCC) 8.0.1 20180324 (Red Hat 8.0.1-0.20)
  31 fedora:rawhide                : Ok   gcc (GCC) 8.0.1 20180324 (Red Hat 8.0.1-0.20)
  32 gentoo-stage3-amd64:latest    : Ok   gcc (Gentoo 6.4.0-r1 p1.3) 6.4.0
  33 mageia:5                      : Ok   gcc (GCC) 4.9.2
  34 mageia:6                      : Ok   gcc (Mageia 5.5.0-1.mga6) 5.5.0
  35 opensuse:42.1                 : Ok   gcc (SUSE Linux) 4.8.5
  36 opensuse:42.2                 : Ok   gcc (SUSE Linux) 4.8.5
  37 opensuse:42.3                 : Ok   gcc (SUSE Linux) 4.8.5
  38 opensuse:tumbleweed           : Ok   gcc (SUSE Linux) 7.3.1 20180323 [gcc-7-branch revision 258812]
  39 oraclelinux:6                 : Ok   gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-18)
  40 oraclelinux:7                 : Ok   gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28.0.1)
  41 ubuntu:12.04.5                : Ok   gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
  42 ubuntu:14.04.4                : Ok   gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
  43 ubuntu:14.04.4-x-linaro-arm64 : Ok   aarch64-linux-gnu-gcc (Linaro GCC 5.4-2017.05) 5.4.1 20170404
  44 ubuntu:15.04                  : Ok   gcc (Ubuntu 4.9.2-10ubuntu13) 4.9.2
  45 ubuntu:16.04                  : Ok   gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  46 ubuntu:16.04-x-arm            : Ok   arm-linux-gnueabihf-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  47 ubuntu:16.04-x-arm64          : Ok   aarch64-linux-gnu-gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  48 ubuntu:16.04-x-powerpc        : Ok   powerpc-linux-gnu-gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  49 ubuntu:16.04-x-powerpc64	   : Ok   powerpc64-linux-gnu-gcc (Ubuntu/IBM 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  50 ubuntu:16.04-x-powerpc64el    : Ok   powerpc64le-linux-gnu-gcc (Ubuntu/IBM 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  51 ubuntu:16.04-x-s390           : Ok   s390x-linux-gnu-gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
  52 ubuntu:16.10                  : Ok   gcc (Ubuntu 6.2.0-5ubuntu12) 6.2.0 20161005
  53 ubuntu:17.04                  : Ok   gcc (Ubuntu 6.3.0-12ubuntu2) 6.3.0 20170406
  54 ubuntu:17.10                  : Ok   gcc (Ubuntu 7.2.0-8ubuntu3.2) 7.2.0
  55 ubuntu:18.04                  : Ok   gcc (Ubuntu 7.3.0-16ubuntu3) 7.3.0

  # uname -a
  Linux jouet 4.17.0-rc3-00034-gf4ef6a438cee #18 SMP Thu May 3 11:49:35 -03 2018 x86_64 x86_64 x86_64 GNU/Linux
  # perf test
   1: vmlinux symtab matches kallsyms                       : Ok
   2: Detect openat syscall event                           : Ok
   3: Detect openat syscall event on all cpus               : Ok
   4: Read samples using the mmap interface                 : Ok
   5: Test data source output                               : Ok
   6: Parse event definition strings                        : Ok
   7: Simple expression parser                              : Ok
   8: PERF_RECORD_* events & perf_sample fields             : Ok
   9: Parse perf pmu format                                 : Ok
  10: DSO data read                                         : Ok
  11: DSO data cache                                        : Ok
  12: DSO data reopen                                       : Ok
  13: Roundtrip evsel->name                                 : Ok
  14: Parse sched tracepoints fields                        : Ok
  15: syscalls:sys_enter_openat event fields                : Ok
  16: Setup struct perf_event_attr                          : Ok
  17: Match and link multiple hists                         : Ok
  18: 'import perf' in python                               : Ok
  19: Breakpoint overflow signal handler                    : Ok
  20: Breakpoint overflow sampling                          : Ok
  21: Breakpoint accounting                                 : Ok
  22: Number of exit events of a simple workload            : Ok
  23: Software clock events period values                   : Ok
  24: Object code reading                                   : Ok
  25: Sample parsing                                        : Ok
  26: Use a dummy software event to keep tracking           : Ok
  27: Parse with no sample_id_all bit set                   : Ok
  28: Filter hist entries                                   : Ok
  29: Lookup mmap thread                                    : Ok
  30: Share thread mg                                       : Ok
  31: Sort output of hist entries                           : Ok
  32: Cumulate child hist entries                           : Ok
  33: Track with sched_switch                               : Ok
  34: Filter fds with revents mask in a fdarray             : Ok
  35: Add fd to a fdarray, making it autogrow               : Ok
  36: kmod_path__parse                                      : Ok
  37: Thread map                                            : Ok
  38: LLVM search and compile                               :
  38.1: Basic BPF llvm compile                              : Ok
  38.2: kbuild searching                                    : Ok
  38.3: Compile source for BPF prologue generation          : Ok
  38.4: Compile source for BPF relocation                   : Ok
  39: Session topology                                      : Ok
  40: BPF filter                                            :
  40.1: Basic BPF filtering                                 : Ok
  40.2: BPF pinning                                         : Ok
  40.3: BPF prologue generation                             : Ok
  40.4: BPF relocation checker                              : Ok
  41: Synthesize thread map                                 : Ok
  42: Remove thread map                                     : Ok
  43: Synthesize cpu map                                    : Ok
  44: Synthesize stat config                                : Ok
  45: Synthesize stat                                       : Ok
  46: Synthesize stat round                                 : Ok
  47: Synthesize attr update                                : Ok
  48: Event times                                           : Ok
  49: Read backward ring buffer                             : Ok
  50: Print cpu map                                         : Ok
  51: Probe SDT events                                      : Ok
  52: is_printable_array                                    : Ok
  53: Print bitmap                                          : Ok
  54: perf hooks                                            : Ok
  55: builtin clang support                                 : Skip (not compiled in)
  56: unit_number__scnprintf                                : Ok
  57: mem2node                                              : Ok
  58: x86 rdpmc                                             : Ok
  59: Convert perf time to TSC                              : Ok
  60: DWARF unwind                                          : Ok
  61: x86 instruction decoder - new instructions            : Ok
  62: Use vfs_getname probe to get syscall args filenames   : Ok
  63: Check open filename arg using perf trace + vfs_getname: Ok
  64: probe libc's inet_pton & backtrace it with ping       : Ok
  65: Add vfs_getname probe to get syscall args filenames   : Ok
  #

  $ make -C tools/perf build-test
  make: Entering directory '/home/acme/git/perf/tools/perf'
  - tarpkg: ./tests/perf-targz-src-pkg .
  make_no_libdw_dwarf_unwind_O: make NO_LIBDW_DWARF_UNWIND=1
         make_with_clangllvm_O: make LIBCLANGLLVM=1
       make_util_pmu_bison_o_O: make util/pmu-bison.o
             make_no_libperl_O: make NO_LIBPERL=1
                   make_tags_O: make tags
                make_no_gtk2_O: make NO_GTK2=1
              make_no_libelf_O: make NO_LIBELF=1
         make_install_prefix_O: make install prefix=/tmp/krava
           make_no_libunwind_O: make NO_LIBUNWIND=1
              make_clean_all_O: make clean all
                  make_no_ui_O: make NO_NEWT=1 NO_SLANG=1 NO_GTK2=1
           make_no_libbionic_O: make NO_LIBBIONIC=1
        make_with_babeltrace_O: make LIBBABELTRACE=1
                    make_doc_O: make doc
            make_no_libaudit_O: make NO_LIBAUDIT=1
           make_no_backtrace_O: make NO_BACKTRACE=1
                   make_help_O: make help
            make_no_auxtrace_O: make NO_AUXTRACE=1
              make_no_libbpf_O: make NO_LIBBPF=1
             make_no_libnuma_O: make NO_LIBNUMA=1
                 make_static_O: make LDFLAGS=-static
           make_no_libpython_O: make NO_LIBPYTHON=1
                   make_pure_O: make
             make_no_scripts_O: make NO_LIBPYTHON=1 NO_LIBPERL=1
                 make_perf_o_O: make perf.o
            make_no_demangle_O: make NO_DEMANGLE=1
   make_install_prefix_slash_O: make install prefix=/tmp/krava/
            make_install_bin_O: make install-bin
             make_util_map_o_O: make util/map.o
                make_no_newt_O: make NO_NEWT=1
                  make_debug_O: make DEBUG=1
                make_minimal_O: make NO_LIBPERL=1 NO_LIBPYTHON=1 NO_NEWT=1 NO_GTK2=1 NO_DEMANGLE=1 NO_LIBELF=1 NO_LIBUNWIND=1 NO_BACKTRACE=1 NO_LIBNUMA=1 NO_LIBAUDIT=1 NO_LIBBIONIC=1 NO_LIBDW_DWARF_UNWIND=1 NO_AUXTRACE=1 NO_LIBBPF=1 NO_LIBCRYPTO=1 NO_SDT=1 NO_JVMTI=1
                make_install_O: make install
               make_no_slang_O: make NO_SLANG=1
  OK
  make: Leaving directory '/home/acme/git/perf/tools/perf'
  $

From: Thomas Richter <[email protected]>

perf test "probe libc's inet_pton & backtrace it with ping" fails on 4.17.0rc3 on s/390. It turned out that function __inet_pton is reported as inline:

[root@s8360047 perf]# ./perf script -i /tmp/perf.data.111 ping 12457 [000] 1584.478959: probe_libc:inet_pton: (3ffb5a347e8)

                    1347e8 __inet_pton (inlined)
                     f19d7 gaih_inet.constprop.5 (/usr/lib64/libc-2.24.so)
                     f4c3f __GI_getaddrinfo (inlined)
                      410b main (/usr/bin/ping)

Allow __inet_pton listed as inline.

---
 tools/perf/tests/shell/record+probe_libc_inet_pton.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 016882dbbc16..ee86473643be 100755
@@ -16,7 +16,7 @@ nm -g $libc 2>/dev/null | fgrep -q inet_pton || exit 254
 trace_libc_inet_pton_backtrace() {
 	idx=0
 	expected[0]="ping[][0-9 \.:]+probe_libc:inet_pton: \([[:xdigit:]]+\)"
-	expected[1]=".*inet_pton[[:space:]]\($libc\)$"
+	expected[1]=".*inet_pton[[:space:]]\($libc|inlined\)$"
 	case "$(uname -m)" in
 	s390x)
 		eventattr='call-graph=dwarf,max-stack=4'

2.14.3

From: Jin Yao <[email protected]>

When we perform the following command lines:

  $ perf record -e "{cycles,branches}" ./div
  $ perf annotate main --stdio

The output shows only the first event, "cycles" and the displaying format is not correct.

   Percent         |      Source code & Disassembly of div for cycles (44550 samples)
  -----------------------------------------------------------------------------------
                   :
                   :
                   :
                   :            Disassembly of section .text:
                   :
                   :            00000000004004b0 <main>:
                   :            main():
                   :
                   :                    return i;
                   :            }
                   :
                   :            int main(void)
                   :            {
      0.00 :   4004b0:       push   %rbx
                   :                    int i;
                   :                    int flag;
                   :                    volatile double x = 1212121212, y = 121212;
                   :
                   :                    s_randseed = time(0);
      0.00 :   4004b1:       xor    %edi,%edi
                   :                    srand(s_randseed);
      0.00 :   4004b3:       mov    $0x77359400,%ebx
                   :
                   :                    return i;
                   :            }

The issue is that the value of the 'nr_percent' variable is hardcoded to
1. This patch fixes it.

With this patch, the output is:

   Percent         |      Source code & Disassembly of div for cycles (44550 samples)
  -----------------------------------------------------------------------------------
                   :
                   :
                   :
                   :            Disassembly of section .text:
                   :
                   :            00000000004004b0 <main>:
                   :            main():
                   :
                   :                    return i;
                   :            }
                   :
                   :            int main(void)
                   :            {
      0.00    0.00 :   4004b0:       push   %rbx
                   :                    int i;
                   :                    int flag;
                   :                    volatile double x = 1212121212, y = 121212;
                   :
                   :                    s_randseed = time(0);
      0.00    0.00 :   4004b1:       xor    %edi,%edi
                   :                    srand(s_randseed);
      0.00    0.00 :   4004b3:       mov    $0x77359400,%ebx
                   :
                   :                    return i;
                   :            }

---
 tools/perf/util/annotate.c | 3 +++
 1 file changed, 3 insertions(+)

index 536ee148bff8..5d74a30fe00f 100644
@@ -1263,6 +1263,9 @@ annotation_line__print(struct annotation_line *al, struct symbol *sym, u64 start
 				max_percent = sample->percent;
 		}
 
+		if (al->samples_nr > nr_percent)
+			nr_percent = al->samples_nr;
+
 		if (max_percent < min_pcnt)
 			return -1;
 

2.14.3

From: Leo Yan <[email protected]>

CoreSight doesn't allocate thread structure for unknown_thread in ETM auxtrace, so unknown_thread is NULL pointer. If the perf data doesn't contain valid tid and then cs_etm__mem_access() uses unknown_thread instead as thread handler, this results in a segmentation fault when thread__find_addr_map() accesses the thread handler.

This commit creates a new thread data which is used by unknown_thread, so CoreSight tracing can roll back to use unknown_thread if perf data doesn't include valid thread info. This commit also releases thread data for initialization failure case and for normal auxtrace free flow.

---
 tools/perf/util/cs-etm.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

index 40020b1ca54f..2bf28b5acc08 100644
@@ -239,6 +239,7 @@ static void cs_etm__free(struct perf_session *session)
 	for (i = 0; i < aux->num_cpu; i++)
 		zfree(&aux->metadata[i]);
 
+	thread__zput(aux->unknown_thread);
 	zfree(&aux->metadata);
 	zfree(&aux);
 }

@@ -1357,6 +1358,23 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
 	etm->auxtrace.free = cs_etm__free;
 	session->auxtrace = &etm->auxtrace;
 
+	etm->unknown_thread = thread__new(999999999, 999999999);
+	if (!etm->unknown_thread)
+		goto err_free_queues;
+
+	/*
+	 * Initialize list node so that at thread__zput() we can avoid
+	 * segmentation fault at list_del_init().
+	 */
+	INIT_LIST_HEAD(&etm->unknown_thread->node);
+
+	err = thread__set_comm(etm->unknown_thread, "unknown", 0);
+	if (err)
+		goto err_delete_thread;
+
+	if (thread__init_map_groups(etm->unknown_thread, etm->machine))
+		goto err_delete_thread;
+
 	if (dump_trace) {
 		cs_etm__print_auxtrace_info(auxtrace_info->priv, num_cpu);
 		return 0;

@@ -1371,16 +1389,18 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
 
 	err = cs_etm__synth_events(etm, session);
 	if (err)
-		goto err_free_queues;
+		goto err_delete_thread;
 
 	err = auxtrace_queues__process_index(&etm->queues, session);
 	if (err)
-		goto err_free_queues;
+		goto err_delete_thread;
 
 	etm->data_queued = etm->queues.populated;
 
 	return 0;
 
+err_delete_thread:
+	thread__zput(etm->unknown_thread);
 err_free_queues:
 	auxtrace_queues__free(&etm->queues);
 	session->auxtrace = NULL;

2.14.3

From: Leo Yan <[email protected]>

There have two spaces ahead function name cs_etm__set_pid_tid_cpu(), so remove one space and correct indentation.

---
 tools/perf/util/cs-etm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 2bf28b5acc08..bf16dc9ee507 100644
@@ -613,8 +613,8 @@ cs_etm__get_trace(struct cs_etm_buffer *buff, struct cs_etm_queue *etmq)
 	return buff->len;
 }
 
-static void  cs_etm__set_pid_tid_cpu(struct cs_etm_auxtrace *etm,
-				     struct auxtrace_queue *queue)
+static void cs_etm__set_pid_tid_cpu(struct cs_etm_auxtrace *etm,
+				    struct auxtrace_queue *queue)
 {
 	struct cs_etm_queue *etmq = queue->priv;
 

2.14.3

From: Arnaldo Carvalho de Melo <[email protected]>

This is not specific to BPF but was found when parsing a .c BPF proggie that while valid, had no events attached to tracepoints, kprobes, etc:

Very minimal file that perf's BPF code can compile:

  # cat empty.c
  char _license[] __attribute__((section("license"), used)) = "GPL";
  int _version __attribute__((section("version"), used)) = LINUX_VERSION_CODE;
  #

Before this patch:

  # perf trace -e empty.c
  WARNING: event parser found nothinginvalid or unsupported event: 'empty.c'
  Run 'perf list' for a list of valid events

Usage: perf trace [<options>] [<command>]
or: perf trace [<options>] -- <command> [<options>]
or: perf trace record [<options>] [<command>]
or: perf trace record [<options>] -- <command> [<options>]

-e, --event <event> event/syscall selector. use 'perf list' to list available events
#

After:

  # perf trace -e empty.c
  WARNING: event parser found nothing
  invalid or unsupported event: 'empty.c'
  Run 'perf list' for a list of valid events

Usage: perf trace [<options>] [<command>]
or: perf trace [<options>] -- <command> [<options>]
or: perf trace record [<options>] [<command>]
or: perf trace record [<options>] -- <command> [<options>]

-e, --event <event> event/syscall selector. use 'perf list' to list available events
#

---
 tools/perf/util/parse-events.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 2fb0272146d8..b8b8a9558d32 100644
@@ -1715,7 +1715,7 @@ int parse_events(struct perf_evlist *evlist, const char *str,
 		struct perf_evsel *last;
 
 		if (list_empty(&parse_state.list)) {
-			WARN_ONCE(true, "WARNING: event parser found nothing");
+			WARN_ONCE(true, "WARNING: event parser found nothing\n");
 			return -1;
 		}
 

2.14.3

Pulled, thanks a lot Arnaldo!

Ingo