linux-kernel - Re: [PATCH] perf tests: Fix regex for record+probe_libc_inet

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Date:   Fri, 18 May 2018 12:21:07 +0200
From:   Thomas-Mich Richter <tmricht@...ux.ibm.com>
To:     Sandipan Das <sandipan@...ux.vnet.ibm.com>, acme@...nel.org,
        jolsa@...hat.com
Cc:     linux-kernel@...r.kernel.org, ravi.bangoria@...ux.ibm.com,
        naveen.n.rao@...ux.vnet.ibm.com,
        Hendrik Brueckner <brueckner@...ux.vnet.ibm.com>
Subject: Re: [PATCH] perf tests: Fix regex for record+probe_libc_inet_pton.sh

On 05/18/2018 09:24 AM, Sandipan Das wrote:
> This test currently fails because the regular expressions for
> matching the output of perf script do not consider the symbol
> offsets to be part of the output.
> 
> The symbol offsets are seen because of the default behaviour
> introduced by commit 4140d2ea74b3 ("perf script: Show symbol
> offsets by default").
> 
> Before applying this patch:
> 
>   # perf test -v "probe libc's inet_pton & backtrace it with ping"
> 
>   62: probe libc's inet_pton & backtrace it with ping       :
>   --- start ---
>   test child forked, pid 30389
>   ping 30406 [002] 307144.280983: probe_libc:inet_pton: (7f4117adf220)
>   7f4117adf220 __GI___inet_pton+0x0 (/usr/lib64/libc-2.25.so)
>   FAIL: expected backtrace entry 1 ".*inet_pton[[:space:]]\(/usr/lib64/libc-2.25.so|inlined\)$" got "7f4117adf220 __GI___inet_pton+0x0 (/usr/lib64/libc-2.25.so)"
>   test child finished with -1
>   ---- end ----
>   probe libc's inet_pton & backtrace it with ping: FAILED!
> 
> After applying this patch:
> 
>   # perf test -v "probe libc's inet_pton & backtrace it with ping"
> 
>   62: probe libc's inet_pton & backtrace it with ping       :
>   --- start ---
>   test child forked, pid 30539
>   ping 30556 [003] 307254.313217: probe_libc:inet_pton: (7fe19ab10220)
>   7fe19ab10220 __GI___inet_pton+0x0 (/usr/lib64/libc-2.25.so)
>   7fe19aad5ebd getaddrinfo+0x11d (/usr/lib64/libc-2.25.so)
>   56351e3c1c71 main+0x891 (/usr/bin/ping)
>   test child finished with 0
>   ---- end ----
>   probe libc's inet_pton & backtrace it with ping: Ok
> 
> Signed-off-by: Sandipan Das <sandipan@...ux.vnet.ibm.com>
> ---
>  tools/perf/tests/shell/record+probe_libc_inet_pton.sh | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 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 ee86473643be..650b208f700f 100755
> --- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> +++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
> @@ -16,18 +16,18 @@ nm -g $libc 2>/dev/null | fgrep -q inet_pton || exit 254
>  trace_libc_inet_pton_backtrace() {
>  	idx=0
>  	expected[0]="ping[][0-9 \.:]+probe_libc:inet_pton: \([[:xdigit:]]+\)"
> -	expected[1]=".*inet_pton[[:space:]]\($libc|inlined\)$"
> +	expected[1]=".*inet_pton\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$"
>  	case "$(uname -m)" in
>  	s390x)
>  		eventattr='call-graph=dwarf,max-stack=4'
> -		expected[2]="gaih_inet.*[[:space:]]\($libc|inlined\)$"
> -		expected[3]="(__GI_)?getaddrinfo[[:space:]]\($libc|inlined\)$"
> -		expected[4]="main[[:space:]]\(.*/bin/ping.*\)$"
> +		expected[2]="gaih_inet.*\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$"
> +		expected[3]="(__GI_)?getaddrinfo\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$"
> +		expected[4]="main\+0x[[:xdigit:]]+[[:space:]]\(.*/bin/ping.*\)$"
>  		;;
>  	*)
>  		eventattr='max-stack=3'
> -		expected[2]="getaddrinfo[[:space:]]\($libc\)$"
> -		expected[3]=".*\(.*/bin/ping.*\)$"
> +		expected[2]="getaddrinfo\+0x[[:xdigit:]]+[[:space:]]\($libc\)$"
> +		expected[3]=".*\+0x[[:xdigit:]]+[[:space:]]\(.*/bin/ping.*\)$"
>  		;;
>  	esac
>  
> 

This patch fails on s390. I used 4.17.0rc5 + fedora 27 and I get this output:


[root@...lp27 perf]# ./perf test 59
59: probe libc's inet_pton & backtrace it with ping       : Ok
[root@...lp27 linux]# cd ~/linux; patch -p1 < ../inet_pton1 
(Stripping trailing CRs from patch; use --binary to disable.)
patching file tools/perf/tests/shell/record+probe_libc_inet_pton.sh
[root@...lp27 linux]# cd -; 
[root@...lp27 perf]# ./perf test 59
59: probe libc's inet_pton & backtrace it with ping       : FAILED!
[root@...lp27 perf]#

Debugging revealed this line as cause of failure:


FAIL: expected backtrace entry 2 "gaih_inet.*\+0x[[:xdigit:]]+[[:space:]]\(/usr/lib64/libc-2.26.so|inlined\)$" got "fdcb1 gaih_inet.constprop.7 (/usr/lib64/libc-2.26.so)"

Here is the output of the trace file

[root@...lp27 perf]# perf script 
ping 87291 [001] 96936.231618: probe_libc:inet_pton: (3ff96342378)
                  142378 __inet_pton (inlined)
                   fdcb1 gaih_inet.constprop.7 (/usr/lib64/libc-2.26.so)
                  100189 __GI_getaddrinfo (inlined)
                    398d main (/usr/bin/ping)
                   2303d __libc_start_main (/usr/lib64/libc-2.26.so)
                    457b [unknown] (/usr/bin/ping)

[root@...lp27 perf]# 

Hope this helps
-- 
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
--
Vorsitzende des Aufsichtsrats: Martina Koederitz 
Geschäftsführung: Dirk Wittkopp
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