perf/urgent fixes

Hi Ingo,

Please consider pulling,

- Arnaldo

The following changes since commit 275ae411e56f8f900fa364da29c4706f9af4e1f3:

perf/x86/intel/rapl: Fix pmus free during cleanup (2016-05-25 10:56:43 +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-20160527

for you to fetch changes up to 5ea5888b2fbf5b230da62b2a21c8247bebb6c9cf:

perf ctf: Convert invalid chars in a string before set value (2016-05-27 12:08:40 -0300)

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

- Fix kptr_restrict=2 related 'perf record' segfault (Wang Nan)

- Fix CTF/libbabeltrace handling of chinese COMM strings (Wang Nan)

----------------------------------------------------------------
Wang Nan (3):
perf symbols: Check kptr_restrict for root
perf record: Fix crash when kptr is restricted perf ctf: Convert invalid chars in a string before set value

 tools/perf/util/data-convert-bt.c | 41 +++++++++++++++++++++++++++++++++++++--
 tools/perf/util/event.c           |  2 ++
 tools/perf/util/symbol.c          | 16 +++++++--------
 3 files changed, 49 insertions(+), 10 deletions(-)

From: Wang Nan <[email protected]>

If kptr_restrict is set to 2, even root is not allowed to see pointers. This patch checks kptr_restrict even if euid == 0. For root, report error if kptr_restrict is 2.

---
 tools/perf/util/symbol.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

index 20f9cb32b703..54c4ff2b1cee 100644
@@ -1933,17 +1933,17 @@ int setup_intlist(struct intlist **list, const char *list_str,
 static bool symbol__read_kptr_restrict(void)
 {
 	bool value = false;
+	FILE *fp = fopen("/proc/sys/kernel/kptr_restrict", "r");
 
-	if (geteuid() != 0) {
-		FILE *fp = fopen("/proc/sys/kernel/kptr_restrict", "r");
-		if (fp != NULL) {
-			char line[8];
+	if (fp != NULL) {
+		char line[8];
 
-			if (fgets(line, sizeof(line), fp) != NULL)
-				value = atoi(line) != 0;
+		if (fgets(line, sizeof(line), fp) != NULL)
+			value = (geteuid() != 0) ?
+					(atoi(line) != 0) :
+					(atoi(line) == 2);
 
-			fclose(fp);
-		}
+		fclose(fp);
 	}
 
 	return value;

2.5.5

From: Wang Nan <[email protected]>

Before this patch, a simple 'perf record' could fail if kptr_restrict is set to 1 (for normal user) or 2 (for root):

  # perf record ls
  WARNING: Kernel address maps (/proc/{kallsyms,modules}) are restricted,
  check /proc/sys/kernel/kptr_restrict.

Samples in kernel functions may not be resolved if a suitable vmlinux file is not found in the buildid cache or in the vmlinux path.

Samples in kernel modules won't be resolved at all.

If some relocation was applied (e.g. kexec) symbols may be misresolved even with a suitable vmlinux or kallsyms file.

Segmentation fault (core dumped)

This patch skips perf_event__synthesize_kernel_mmap() when kptr is not available.

---
 tools/perf/util/event.c | 2 ++
 1 file changed, 2 insertions(+)

index f6fcc6832949..9b141f12329e 100644
@@ -673,6 +673,8 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 	int err;
 	union perf_event *event;
 
+	if (symbol_conf.kptr_restrict)
+		return -1;
 	if (map == NULL)
 		return -1;
 

2.5.5

From: Wang Nan <[email protected]>

We observed some crazy apps on Android set their comm to unprintable string. For example:

  # cat /proc/10607/task/*/comm
  tencent.qqmusic
  ...
  Binder_2
  日志输出线  <-- Chinese word 'log output thread'
  WifiManager
  ...

'perf data convert' fails to convert perf.data with such string to CTF format.

For example:

  # cat << EOF > ./badguy.c
  #include <sys/prctl.h>
  int main(int argc, char *argv[])
  {
         prctl(PR_SET_NAME, "\xe6\x97\xa5\xe5\xbf\x97\xe8\xbe\x93\xe5\x87\xba\xe7\xba\xbf");
         while(1)
                 sleep(1);
         return 0;
  }
  EOF
  # gcc ./badguy.c
  # perf record -e sched:* ./a.out
  # perf data convert --to-ctf ./bad.ctf
  CTF stream 4 flush failed
  [ perf data convert: Converted 'perf.data' into CTF data './bad.ctf' ]
  [ perf data convert: Converted and wrote 0.008 MB (78 samples)  ]
  # babeltrace ./bad.ctf/
  [error] Packet size (18446744073709551615 bits) is larger than remaining file size (262144 bits).
  [error] Stream index creation error.
  [error] Open file stream error.
  [warning] [Context] Cannot open_trace of format ctf at path ./bad.ctf.
  [warning] [Context] cannot open trace "./bad.ctf" from ./bad.ctf/ for reading.
  [error] Cannot open any trace for reading.

[error] opening trace "./bad.ctf/" for reading.

[error] none of the specified trace paths could be opened.

This patch converts unprintable characters to hexadecimal word.

After applying this patch the above test works correctly:

# ~/perf data convert --to-ctf ./good.ctf
[ perf data convert: Converted 'perf.data' into CTF data './good.ctf' ] [ perf data convert: Converted and wrote 0.008 MB (78 samples) ]

  # babeltrace ./good.ctf
  ..
  [23:14:35.491665268] (+0.000001100) sched:sched_wakeup: { cpu_id = 4 }, { perf_ip = 0xFFFFFFFF810AEF33, perf_tid = 0, perf_pid = 0, perf_id = 5123, perf_period = 1, common_type = 270, common_flags = 45, common_preempt_count = 4, common_pid = 0, comm = "\xe6\x97\xa5\xe5\xbf\x97\xe8\xbe\x93\xe5\x87\xba\xe7\xba\xbf", pid = 1057, prio = 120, success = 1, target_cpu = 4 }
  [23:14:35.491666230] (+0.000000962) sched:sched_wakeup: { cpu_id = 4 }, { perf_ip = 0xFFFFFFFF810AEF33, perf_tid = 0, perf_pid = 0, perf_id = 5122, perf_period = 1, common_type = 270, common_flags = 45, common_preempt_count = 4, common_pid = 0, comm = "\xe6\x97\xa5\xe5\xbf\x97\xe8\xbe\x93\xe5\x87\xba\xe7\xba\xbf", pid = 1057, prio = 120, success = 1, target_cpu = 4 }
  ..

Committer note:

To build perf with libabeltrace, use:

  $ mkdir -p /tmp/build/perf
  $ make LIBBABELTRACE=1 LIBBABELTRACE_DIR=/usr/local O=/tmp/build/perf -C tools/perf install-bin

Or equivalent (no O=, fixup LIBBABELTRACE_DIR, etc).

---
 tools/perf/util/data-convert-bt.c | 41 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

index bbf69d248ec5..9f53020c3269 100644
@@ -204,6 +204,44 @@ static unsigned long long adjust_signedness(unsigned long long value_int, int si
 	return (value_int & value_mask) | ~value_mask;
 }
 
+static int string_set_value(struct bt_ctf_field *field, const char *string)
+{
+	char *buffer = NULL;
+	size_t len = strlen(string), i, p;
+	int err;
+
+	for (i = p = 0; i < len; i++, p++) {
+		if (isprint(string[i])) {
+			if (!buffer)
+				continue;
+			buffer[p] = string[i];
+		} else {
+			char numstr[5];
+
+			snprintf(numstr, sizeof(numstr), "\\x%02x",
+				 (unsigned int)(string[i]) & 0xff);
+
+			if (!buffer) {
+				buffer = zalloc(i + (len - i) * 4 + 2);
+				if (!buffer) {
+					pr_err("failed to set unprintable string '%s'\n", string);
+					return bt_ctf_field_string_set_value(field, "UNPRINTABLE-STRING");
+				}
+				if (i > 0)
+					strncpy(buffer, string, i);
+			}
+			strncat(buffer + p, numstr, 4);
+			p += 3;
+		}
+	}
+
+	if (!buffer)
+		return bt_ctf_field_string_set_value(field, string);
+	err = bt_ctf_field_string_set_value(field, buffer);
+	free(buffer);
+	return err;
+}
+
 static int add_tracepoint_field_value(struct ctf_writer *cw,
 				      struct bt_ctf_event_class *event_class,
 				      struct bt_ctf_event *event,

@@ -270,8 +308,7 @@ static int add_tracepoint_field_value(struct ctf_writer *cw,
 		}
 
 		if (flags & FIELD_IS_STRING)
-			ret = bt_ctf_field_string_set_value(field,
-					data + offset + i * len);
+			ret = string_set_value(field, data + offset + i * len);
 		else {
 			unsigned long long value_int;
 

2.5.5