linux-kernel - [PATCH v2] perf test: Adapt test case record+probe_libc_inet

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Message-Id: <20180423082428.7930-1-tmricht@linux.ibm.com>
Date:   Mon, 23 Apr 2018 10:24:28 +0200
From:   Thomas Richter <tmricht@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     brueckner@...ux.vnet.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, Thomas Richter <tmricht@...ux.ibm.com>
Subject: [PATCH v2] perf test: Adapt test case record+probe_libc_inet_pton.sh for s390

perf test case 58 (record+probe_libc_inet_pton.sh)
executed on s390x using kernel 4.16.0rc3
displays this result:
 # ./perf trace --no-syscalls
           -e probe_libc:inet_pton/call-graph=dwarf/ ping -6 -c 1 ::1
     probe_libc:inet_pton: (3ffa0240448)
	      __GI___inet_pton (/usr/lib64/libc-2.26.so)
	      gaih_inet (inlined)
	      __GI_getaddrinfo (inlined)
	      main (/usr/bin/ping)
	      __libc_start_main (/usr/lib64/libc-2.26.so)
	     _start (/usr/bin/ping)

After I installed kernel 4.16.0 the same tests uses
commands
 # perf record -e probe_libc:inet_pton/call-graph=dwarf/
      -o /tmp/perf.data.abc ping -6 -c 1 ::1
 # perf script -i /tmp/perf.data.abc
and displays:
 ping 39048 [006] 84230.381198: probe_libc:inet_pton: (3ffa0240448)
	       140448 __GI___inet_pton (/usr/lib64/libc-2.26.so)
	       fbde1 gaih_inet (inlined)
	       fe2b9 __GI_getaddrinfo (inlined)
	        398d main (/usr/bin/ping)

Nothing else changed including glibc elfutils and other libraries
picked up by the build.
The entries for __libc_start_main and _start are missing.

I bisected missing __libc_start_main and _start to commit
3d20c6246690219881786de10d2dda93f616d0ac
("perf unwind: Unwind with libdw doesn't take symfs into account")

When I undo this commit I get this call stack on s390:
 [root@...lp76 perf]# ./perf script  -i /tmp/perf.data.abc
 ping 39048 [006] 84230.381198: probe_libc:inet_pton: (3ffa0240448)
	140448 __GI___inet_pton (/usr/lib64/libc-2.26.so)
	 fbde1 gaih_inet (inlined)
	 fe2b9 __GI_getaddrinfo (inlined)
	  398d main (/usr/bin/ping)
	 22fbd __libc_start_main (/usr/lib64/libc-2.26.so)
	  457b _start (/usr/bin/ping)

Looks like dwarf functions dwfl_xxx  create different call back
stack trace when using file
/usr/lib/debug/usr/bin/ping-20161105-7.fc27.s390x.debug instead of
file /usr/bin/ping.

Fix this test case on s390 and do not expect any call back stack
entry after the main() function. Also be more robust and accept a
leading __GI_ prefix in front of getaddrinfo.

On x86 this test case shows the same call stack using
both kernel versions 4.16.0rc3 and 4.16.0 and also
stops at main:

[root@f27 perf]# ./perf script -i /tmp/perf.data.tmr
ping  4446 [000]   172.027088: probe_libc:inet_pton: (7fdfa08c93c0)
	           1393c0 __GI___inet_pton (/usr/lib64/libc-2.26.so)
	            fe60d getaddrinfo (/usr/lib64/libc-2.26.so)
	             2f40 main (/usr/bin/ping)

[root@f27 perf]#

Signed-off-by: Thomas Richter <tmricht@...ux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@...ux.ibm.com>
---
 tools/perf/tests/shell/record+probe_libc_inet_pton.sh | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
index 1ecc1f0ff84a..016882dbbc16 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -19,12 +19,10 @@ trace_libc_inet_pton_backtrace() {
 	expected[1]=".*inet_pton[[:space:]]\($libc\)$"
 	case "$(uname -m)" in
 	s390x)
-		eventattr='call-graph=dwarf'
+		eventattr='call-graph=dwarf,max-stack=4'
 		expected[2]="gaih_inet.*[[:space:]]\($libc|inlined\)$"
-		expected[3]="__GI_getaddrinfo[[:space:]]\($libc|inlined\)$"
+		expected[3]="(__GI_)?getaddrinfo[[:space:]]\($libc|inlined\)$"
 		expected[4]="main[[:space:]]\(.*/bin/ping.*\)$"
-		expected[5]="__libc_start_main[[:space:]]\($libc\)$"
-		expected[6]="_start[[:space:]]\(.*/bin/ping.*\)$"
 		;;
 	*)
 		eventattr='max-stack=3'
-- 
2.14.3