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The perf test "probe libc's inet_pton & backtrace it with ping" fails on
powerpc as below:
# perf test -v "probe libc's inet_pton & backtrace it with
ping"
85: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 96028
ping 96056 [002] 127271.101961: probe_libc:inet_pton: (7fffa1779a60)
7fffa1779a60 __GI___inet_pton+0x0 (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
7fffa172a73c getaddrinfo+0x121c (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
FAIL: expected backtrace entry
"gaih_inet.*\+0x[[:xdigit:]]+[[:space:]]\(/usr/lib64/glibc-hwcaps/power10/libc.so.6\)$"
got "7fffa172a73c getaddrinfo+0x121c (/usr/lib64/glibc-hwcaps/power10/libc.so.6)"
test child finished with -1
---- end ----
probe libc's inet_pton & backtrace it with ping: FAILED!
This test installs a probe on libc's inet_pton function, which will use
uprobes and then uses perf trace on a ping to localhost. It gets 3
levels deep backtrace and checks whether it is what we expected or not.
The test started failing from RHEL 9.4 where as it works in previous
distro version (RHEL 9.2). Test expects gaih_inet function to be part of
backtrace. But in the glibc version (2.34-86) which is part of distro
where it fails, this function is missing and hence the test is failing.
From nm and ping command output we can confirm that gaih_inet function
is not present in the expected backtrace for glibc version glibc-2.34-86
[root@xxx perf]# nm /usr/lib64/glibc-hwcaps/power10/libc.so.6 | grep gaih_inet
00000000001273e0 t gaih_inet_serv
00000000001cd8d8 r gaih_inet_typeproto
[root@xxx perf]# perf script -i /tmp/perf.data.6E8
ping 104048 [000] 128582.508976: probe_libc:inet_pton: (7fff83779a60)
7fff83779a60 __GI___inet_pton+0x0 (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
7fff8372a73c getaddrinfo+0x121c (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
11dc73534 [unknown] (/usr/bin/ping)
7fff8362a8c4 __libc_start_call_main+0x84 (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
FAIL: expected backtrace entry
"gaih_inet.*\+0x[[:xdigit:]]+[[:space:]]\(/usr/lib64/glibc-hwcaps/power10/libc.so.6\)$"
got "7fff9d52a73c getaddrinfo+0x121c (/usr/lib64/glibc-hwcaps/power10/libc.so.6)"
With version glibc-2.34-60 gaih_inet function is present as part of the
expected backtrace. So we cannot just remove the gaih_inet function from
the backtrace.
[root@xxx perf]# nm /usr/lib64/glibc-hwcaps/power10/libc.so.6 | grep gaih_inet
0000000000130490 t gaih_inet.constprop.0
000000000012e830 t gaih_inet_serv
00000000001d45e4 r gaih_inet_typeproto
[root@xxx perf]# ./perf script -i /tmp/perf.data.b6S
ping 67906 [000] 22699.591699: probe_libc:inet_pton_3: (7fffbdd80820) 7fffbdd80820 __GI___inet_pton+0x0
(/usr/lib64/glibc-hwcaps/power10/libc.so.6) 7fffbdd31160 gaih_inet.constprop.0+0xcd0
(/usr/lib64/glibc-hwcaps/power10/libc.so.6) 7fffbdd31c7c getaddrinfo+0x14c
(/usr/lib64/glibc-hwcaps/power10/libc.so.6) 1140d3558 [unknown] (/usr/bin/ping)
This patch solves this issue by doing a conditional skip. If there is a
gaih_inet function present in the libc then it will be added to the
expected backtrace else the function will be skipped from being added
to the expected backtrace.
Output with the patch
[root@xxx perf]# ./perf test -v "probe libc's inet_pton & backtrace it
with ping"
83: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 102662
ping 102692 [000] 127935.549973: probe_libc:inet_pton: (7fff93379a60)
7fff93379a60 __GI___inet_pton+0x0 (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
7fff9332a73c getaddrinfo+0x121c (/usr/lib64/glibc-hwcaps/power10/libc.so.6)
11ef03534 [unknown] (/usr/bin/ping)
test child finished with 0
---- end ----
probe libc's inet_pton & backtrace it with ping: Ok
Reported-by: Disha Goel <disgoel@linux.ibm.com>
Reviewed-by: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Likhitha Korrapati <likhitha@linux.ibm.com>
Tested-by: Disha Goel <disgoel@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Disha Goel <disgoel@linux.vnet.ibm.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20231126070914.175332-1-likhitha@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.