[PATCH v2] perf/test: perf test 86 fails on s390

From: Thomas Richter
Date: Tue Oct 01 2024 - 08:43:22 EST


Command perf test 86 fails on s390:
# perf test -F 86
ping 868299 [007] 28248.013596: probe_libc:inet_pton_1: (3ff95948020)
3ff95948020 inet_pton+0x0 (inlined)
3ff9595e6e7 text_to_binary_address+0x1007 (inlined)
3ff9595e6e7 gaih_inet+0x1007 (inlined)
FAIL: expected backtrace entry \
"main\+0x[[:xdigit:]]+[[:space:]]\(.*/bin/ping.*\)$"
got "3ff9595e6e7 gaih_inet+0x1007 (inlined)"
86: probe libc's inet_pton & backtrace it with ping : FAILED!
#

The root cause is a new stack layout, two functions have been added
as seen below.

# perf script | tac | grep -m1 '^ping' -B9 | tac
ping 866856 [007] 25979.494921: probe_libc:inet_pton: (3ff8ec48020)
3ff8ec48020 inet_pton+0x0 (inlined)
new --> 3ff8ec5e6e7 text_to_binary_address+0x1007 (inlined)
new --> 3ff8ec5e6e7 gaih_inet+0x1007 (inlined)
3ff8ec5e6e7 getaddrinfo+0x1007 (/usr/lib64/libc.so.6)
2aa3fe04bf5 main+0xff5 (/usr/bin/ping)
3ff8eb34a5b __libc_start_call_main+0x8b (/usr/lib64/libc.so.6)
3ff8eb34b5d __libc_start_main@GLIBC_2.2+0xad (inlined)
2aa3fe06a1f [unknown] (/usr/bin/ping)

#

The new functions in the call chain are:
- text_to_binary_address()
- gaih_inet().

Both functions are inlined and do not show up in the output
of the nm command:

# nm -a /usr/lib64/libc.so.6 | \
grep -E '(text_to_binary_address|gaih_inet)$'
#

There is no possibility to add these 2 functions depending on their
existance in the C library.

Add text_to_binary_address() and gaih_inet() to the list of
expected functions in an compatible way and extend the regular
expression. On s390 the backtrace can now be

Before After
probe_libc:inet_pton probe_libc:inet_pton
inet_pton inet_pton
getaddrinfo getaddrinfo | text_to_binary_address
main main | gaih_inet

Output after:
# perf test -F 86
86: probe libc's inet_pton & backtrace it with ping : Ok
#

Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxx>
---
tools/perf/tests/shell/record+probe_libc_inet_pton.sh | 4 ++--
1 file changed, 2 insertions(+), 2 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 f38c8ead0b03..47a26f25db9f 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -40,8 +40,8 @@ trace_libc_inet_pton_backtrace() {
case "$(uname -m)" in
s390x)
eventattr='call-graph=dwarf,max-stack=4'
- echo "(__GI_)?getaddrinfo\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
- echo "main\+0x[[:xdigit:]]+[[:space:]]\(.*/bin/ping.*\)$" >> $expected
+ echo "((__GI_)?getaddrinfo|text_to_binary_address)\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
+ echo "(gaih_inet|main)\+0x[[:xdigit:]]+[[:space:]]\(inlined|.*/bin/ping.*\)$" >> $expected
;;
ppc64|ppc64le)
eventattr='max-stack=4'
--
2.46.2