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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Arnaldo Carvalho de Melo <acme@redhat.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        David Ahern <dsahern@gmail.com>,
        Hendrick Brueckner <brueckner@linux.vnet.ibm.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Thomas Richter <tmricht@linux.vnet.ibm.com>,
        Wang Nan <wangnan0@huawei.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 026/161] perf callchain: Fix
 attr.sample_max_stack setting
Thread-Topic: [PATCH AUTOSEL for 4.14 026/161] perf callchain: Fix
 attr.sample_max_stack setting
Thread-Index: AQHTz5iBslZfCXPnjEisBrc21d1Ezw==
Date:   Mon, 9 Apr 2018 00:20:03 +0000
Message-ID: <20180409001936.162706-26-alexander.levin@microsoft.com>
References: <20180409001936.162706-1-alexander.levin@microsoft.com>
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From: Arnaldo Carvalho de Melo <acme@redhat.com>

[ Upstream commit 249d98e567e25dd03e015e2d31e1b7b9648f34df ]

When setting the "dwarf" unwinder for a specific event and not
specifying the max-stack, the attr.sample_max_stack ended up using an
uninitialized callchain_param.max_stack, fix it by using designated
initializers for that callchain_param variable, zeroing all non
explicitely initialized struct members.

Here is what happened:

  # perf trace -vv --no-syscalls --max-stack 4 -e probe_libc:inet_pton/call=
-graph=3Ddwarf/ ping -6 -c 1 ::1
  callchain: type DWARF
  callchain: stack dump size 8192
  perf_event_attr:
    type                             2
    size                             112
    config                           0x730
    { sample_period, sample_freq }   1
    sample_type                      IP|TID|TIME|ADDR|CALLCHAIN|CPU|PERIOD|=
RAW|REGS_USER|STACK_USER|DATA_SRC
    exclude_callchain_user           1
    { wakeup_events, wakeup_watermark } 1
    sample_regs_user                 0xff0fff
    sample_stack_user                8192
    sample_max_stack                 50656
  sys_perf_event_open failed, error -75
  Value too large for defined data type
  # perf trace -vv --no-syscalls --max-stack 4 -e probe_libc:inet_pton/call=
-graph=3Ddwarf/ ping -6 -c 1 ::1
  callchain: type DWARF
  callchain: stack dump size 8192
  perf_event_attr:
    type                             2
    size                             112
    config                           0x730
    sample_type                      IP|TID|TIME|ADDR|CALLCHAIN|CPU|PERIOD|=
RAW|REGS_USER|STACK_USER|DATA_SRC
    exclude_callchain_user           1
    sample_regs_user                 0xff0fff
    sample_stack_user                8192
    sample_max_stack                 30448
  sys_perf_event_open failed, error -75
  Value too large for defined data type
  #

Now the attr.sample_max_stack is set to zero and the above works as
expected:

  # perf trace --no-syscalls --max-stack 4 -e probe_libc:inet_pton/call-gra=
ph=3Ddwarf/ ping -6 -c 1 ::1
  PING ::1(::1) 56 data bytes
  64 bytes from ::1: icmp_seq=3D1 ttl=3D64 time=3D0.072 ms

  --- ::1 ping statistics ---
  1 packets transmitted, 1 received, 0% packet loss, time 0ms
  rtt min/avg/max/mdev =3D 0.072/0.072/0.072/0.000 ms
       0.000 probe_libc:inet_pton:(7feb7a998350))
                                         __inet_pton (inlined)
                                         gaih_inet.constprop.7 (/usr/lib64/=
libc-2.26.so)
                                         __GI_getaddrinfo (inlined)
                                         [0xffffaa39b6108f3f] (/usr/bin/pin=
g)
  #

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hendrick Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-is9tramondqa9jlxxsgcm9iz@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 tools/perf/util/evsel.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 1f6beb3d0c68..4c31a22bbaa0 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -722,14 +722,14 @@ static void apply_config_terms(struct perf_evsel *evs=
el,
 	struct perf_evsel_config_term *term;
 	struct list_head *config_terms =3D &evsel->config_terms;
 	struct perf_event_attr *attr =3D &evsel->attr;
-	struct callchain_param param;
+	/* callgraph default */
+	struct callchain_param param =3D {
+		.record_mode =3D callchain_param.record_mode,
+	};
 	u32 dump_size =3D 0;
 	int max_stack =3D 0;
 	const char *callgraph_buf =3D NULL;
=20
-	/* callgraph default */
-	param.record_mode =3D callchain_param.record_mode;
-
 	list_for_each_entry(term, config_terms, list) {
 		switch (term->type) {
 		case PERF_EVSEL__CONFIG_TERM_PERIOD:
--=20
2.15.1