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SubjectRe: [PATCH] perf symbol: Fix kernel symbol address display
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On 4/20/20 10:46 PM, Arnaldo Carvalho de Melo wrote:
> Em Wed, Apr 15, 2020 at 09:07:44AM +0200, Thomas Richter escreveu:
>> Running commands
>>
>> ./perf record -e rb0000 -- find .
>> ./perf report -v
>
> Or when pressing 'V' in the TUI.
>
>> reveals symbol names and its addresses. There is a mismatch between
>
> Yeah, an address that at some point was put there to help with debugging
> the symbol resolution, IIRC how it looked like when looking at
>
> readelf -sW vmlinux
>
> Or any other DSO, for instance, for a glibc symbol here:
>
> Using 'perf report -s pid,dso,sym' then pressing 'V':
>
> 1.55% 20325:perf /usr/lib64/libc-2.30.so 0x161825 B [.] __strlen_avx2
>
> [acme@five perf]$ readelf -sW /usr/lib64/libc-2.30.so | grep strlen_avx2
> 24371: 0000000000161810 414 FUNC LOCAL DEFAULT 15 __strlen_avx2
> [acme@five perf]$
>
> Can you check if doing in /lib/modules/.../build/vmlinux produces what
> appears when 'V' is in place?
>

Yes, I used latest 5.7.0rc2 and did
./perf record -e rb0000 -- find
./perf report -s pid,dso,sym
and pressed 'V' in the TUI.

This gives
6.06% 9986:find /lib/modules/5.7 0x1f0c86 v [k] check_chain_key
and
[root@m35lp76 ~]# readelf -sW /lib/modules/5.7.0-rc2d-perf+/build/vmlinux | fgrep check_chain_key
20698: 00000000001f0c70 486 FUNC LOCAL DEFAULT 1 check_chain_key
[root@m35lp76 ~]#

which is perfectly good and in the range.

> And perhaps we can also show the DSO offset and the rip as it gets laid
> out in memory in the end? So we have all the informations?
>
> - Arnaldo
>

I do not follow you here, do you mean something like DSO-name+offset
for example libc-2.30.so+0x123?

Thanks

--
Thomas Richter, Dept 3252, IBM s390 Linux Development, Boeblingen, Germany
--
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294

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