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Starting with glibc 2.35 there are extra inet_pton() calls when doing a
IPv6 ping as in one of the 'perf test' entry, which makes it fail:
# perf test inet_pton
89: probe libc's inet_pton & backtrace it with ping : FAILED!
#
If we look at what this script is expecting (commenting out the removal
of the temporary files in it):
# cat /tmp/expected.aT6
ping[][0-9 \.:]+probe_libc:inet_pton: \([[:xdigit:]]+\)
.*inet_pton\+0x[[:xdigit:]]+[[:space:]]\(/usr/lib64/libc.so.6|inlined\)$
getaddrinfo\+0x[[:xdigit:]]+[[:space:]]\(/usr/lib64/libc.so.6\)$
.*(\+0x[[:xdigit:]]+|\[unknown\])[[:space:]]\(.*/bin/ping.*\)$
#
And looking at what we are getting out of 'perf script', to match with
the above:
# cat /tmp/perf.script.IUC
ping 623883 [006] 265438.471610: probe_libc:inet_pton: (7f32bcf314c0)
1314c0 __GI___inet_pton+0x0 (/usr/lib64/libc.so.6)
29510 __libc_start_call_main+0x80 (/usr/lib64/libc.so.6)
ping 623883 [006] 265438.471664: probe_libc:inet_pton: (7f32bcf314c0)
1314c0 __GI___inet_pton+0x0 (/usr/lib64/libc.so.6)
fa6c6 getaddrinfo+0x126 (/usr/lib64/libc.so.6)
491e [unknown] (/usr/bin/ping)
#
We see that its just the first call to inet_pton() that didn't came thru
getaddrinfo(), so if we ignore the first the script matches what it
expects, testing that using 'perf probe' + 'perf record' + 'perf script'
with callchains on userspace targets is producing the expected results.
Since we don't have a 'perf script --skip' to help us here, use tac +
grep to do that, resulting in a one liner that makes this script work on
both older glibc versions as well as with 2.35.
With it, on fedora 36, x86, glibc 2.35:
# perf test inet_pton
90: probe libc's inet_pton & backtrace it with ping : Ok
# perf test -v inet_pton
90: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 627197
ping 627220 1 267956.962402: probe_libc:inet_pton_1: (7f488bf314c0)
1314c0 __GI___inet_pton+0x0 (/usr/lib64/libc.so.6)
fa6c6 getaddrinfo+0x126 (/usr/lib64/libc.so.6)
491e n (/usr/bin/ping)
test child finished with 0
---- end ----
probe libc's inet_pton & backtrace it with ping: Ok
#
And on Ubuntu 22.04.1 LTS on a Libre Computer ROC-RK3399-PC arm64 system:
Before this patch it works (see that the script used has no 'tac' to
remove the first event):
root@roc-rk3399-pc:~# dpkg -l | grep libc-bin
ii libc-bin 2.35-0ubuntu3.1 arm64 GNU C Library: Binaries
root@roc-rk3399-pc:~# grep -w tac ~acme/libexec/perf-core/tests/shell/record+probe_libc_inet_pton.sh
root@roc-rk3399-pc:~# perf test inet_pton
86: probe libc's inet_pton & backtrace it with ping : Ok
root@roc-rk3399-pc:~# perf test -v inet_pton
86: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 1375
ping 1399 [000] 4114.417450: probe_libc:inet_pton: (ffffb3e26120)
106120 inet_pton+0x0 (/usr/lib/aarch64-linux-gnu/libc.so.6)
d18bc getaddrinfo+0xec (/usr/lib/aarch64-linux-gnu/libc.so.6)
2b68 [unknown] (/usr/bin/ping)
test child finished with 0
---- end ----
probe libc's inet_pton & backtrace it with ping: Ok
root@roc-rk3399-pc:~#
And after it continues to work:
root@roc-rk3399-pc:~# grep -w tac ~acme/libexec/perf-core/tests/shell/record+probe_libc_inet_pton.sh
perf script -i $perf_data | tac | grep -m1 ^ping -B9 | tac > $perf_script
root@roc-rk3399-pc:~# perf test inet_pton
86: probe libc's inet_pton & backtrace it with ping : Ok
root@roc-rk3399-pc:~# perf test -v inet_pton
86: probe libc's inet_pton & backtrace it with ping :
--- start ---
test child forked, pid 6995
ping 7019 [005] 4832.160741: probe_libc:inet_pton: (ffffa62e6120)
106120 inet_pton+0x0 (/usr/lib/aarch64-linux-gnu/libc.so.6)
d18bc getaddrinfo+0xec (/usr/lib/aarch64-linux-gnu/libc.so.6)
2b68 [unknown] (/usr/bin/ping)
test child finished with 0
---- end ----
probe libc's inet_pton & backtrace it with ping: Ok
root@roc-rk3399-pc:~#
Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: http://lore.kernel.org/lkml/Y7QyPkPlDYip3cZH@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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| README | ||
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.