From: "wcohen at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: systemtap@sourceware.org
Subject: [Bug translator/25972] New: stap -v -L misses probe points
Date: Mon, 11 May 2020 15:32:03 +0000 [thread overview]
Message-ID: <bug-25972-6586@http.sourceware.org/bugzilla/> (raw)
https://sourceware.org/bugzilla/show_bug.cgi?id=25972
Bug ID: 25972
Summary: stap -v -L misses probe points
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: translator
Assignee: systemtap at sourceware dot org
Reporter: wcohen at redhat dot com
Target Milestone: ---
Created attachment 12525
--> https://sourceware.org/bugzilla/attachment.cgi?id=12525&action=edit
Reproducer for stap missing statement lines
When debugging pr25549 I noticed that there were some cases where it appeared
systemtap missed listing lines for instruction that had multiple debuginfo
views for the same instruction. this can be replicated on fedora 32 with the
$ rpm -q gcc systemtap elfutils
gcc-10.1.1-1.fc32.x86_64
systemtap-4.3-0.20200211git91ffb97ad335.fc32.x86_64
elfutils-0.179-2.fc32pr25549.x86_64
$ gcc -O2 -g pr25549b.cxx -o pr25549b
$ stap -v -L 'process("./pr25549b").statement("*@*:*")'
Pass 1: parsed user script and 502 library scripts using
442584virt/211916res/12772shr/199236data kb, in 450usr/70sys/554real ms.
process("/home/wcohen/pr25549b").statement("main@/home/wcohen/pr25549b.cxx:10")
/* pc=.absolute+0x1040 */ $argc:int $argv:char**
process("/home/wcohen/pr25549b").statement("main@/home/wcohen/pr25549b.cxx:12")
/* pc=.absolute+0x104e */ $argc:int $argv:char**
Pass 2: analyzed script: 2 probes, 0 functions, 0 embeds, 0 globals using
451284virt/222188res/13700shr/207936data kb, in 60usr/0sys/69real ms.
However, there are multiple views for the instructions:
$ readelf --debug-dump=decodedline pr25549b
Contents of the .debug_line section:
CU: pr25549b.cxx:
File name Line number Starting address View
Stmt
pr25549b.cxx 10 0x401040
x
pr25549b.cxx 11 0x401040 1
x
pr25549b.cxx 3 0x401040 2
x
pr25549b.cxx 5 0x401040 3
x
pr25549b.cxx 10 0x401040 4
pr25549b.cxx 5 0x401044
pr25549b.cxx 5 0x401049
pr25549b.cxx 6 0x40104e
x
pr25549b.cxx 12 0x40104e 1
x
pr25549b.cxx 13 0x40104e 2
pr25549b.cxx 13 0x401055
gdb allows setting breakpoints at those alternative view for the instructions.
I would expect that systemtap would also allow probe points at those points.
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