Messages in this thread | | | Date | Tue, 16 Oct 2018 14:52:04 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 3/3] perf report: don't crash on invalid inline debug information |
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Em Tue, Oct 16, 2018 at 02:49:23PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Mon, Oct 15, 2018 at 10:51:36PM +0200, Milian Wolff escreveu: > > On Donnerstag, 11. Oktober 2018 21:39:20 CEST Arnaldo Carvalho de Melo wrote: > > > Em Thu, Oct 11, 2018 at 08:23:31PM +0200, Milian Wolff escreveu: > > > > On Donnerstag, 27. September 2018 21:10:37 CEST Arnaldo Carvalho de Melo > > > > > > > > wrote: > > > > > Em Wed, Sep 26, 2018 at 03:52:07PM +0200, Milian Wolff escreveu: > > > > > > When the function name for an inline frame is invalid, we must > > > > > > not try to demangle this symbol, otherwise we crash with: > > > > > > > > > > > > #0 0x0000555555895c01 in bfd_demangle () > > > > > > #1 0x0000555555823262 in demangle_sym (dso=0x555555d92b90, > > > > > > elf_name=0x0, > > > > > > kmodule=0) at util/symbol-elf.c:215 #2 dso__demangle_sym > > > > > > (dso=dso@entry=0x555555d92b90, kmodule=<optimized out>, > > > > > > kmodule@entry=0, > > > > > > elf_name=elf_name@entry=0x0) at util/symbol-elf.c:400 #3 > > > > > > 0x00005555557fef4b in new_inline_sym (funcname=0x0, > > > > > > base_sym=0x555555d92b90, dso=0x555555d92b90) at util/srcline.c:89 #4 > > > > > > inline_list__append_dso_a2l (dso=dso@entry=0x555555c7bb00, > > > > > > node=node@entry=0x555555e31810, sym=sym@entry=0x555555d92b90) at > > > > > > util/srcline.c:264 #5 0x00005555557ff27f in addr2line > > > > > > (dso_name=dso_name@entry=0x555555d92430 > > > > > > "/home/milian/.debug/.build-id/f7/186d14bb94f3c6161c010926da66033d24fc > > > > > > e5/ > > > > > > elf", addr=addr@entry=2888, file=file@entry=0x0,> > > > > > > > > > > > > line=line@entry=0x0, dso=dso@entry=0x555555c7bb00, > > > > > > unwind_inlines=unwind_inlines@entry=true, node=0x555555e31810, > > > > > > sym=0x555555d92b90) at util/srcline.c:313> > > > > > > > > > > > > #6 0x00005555557ffe7c in addr2inlines (sym=0x555555d92b90, > > > > > > dso=0x555555c7bb00, addr=2888, dso_name=0x555555d92430 > > > > > > "/home/milian/.debug/.build-id/f7/186d14bb94f3c6161c010926da66033d24fc > > > > > > e5/ > > > > > > elf")> > > > > > > > > > > > > at util/srcline.c:358 > > > > > > > > > > > > So instead handle the case where we get invalid function names > > > > > > for inlined frames and use a fallback '??' function name instead. > > > > > > > > > > > > While this crash was originally reported by Hadrien for rust code, > > > > > > I can now also reproduce it with trivial C++ code. Indeed, it seems > > > > > > like libbfd fails to interpret the debug information for the inline > > > > > > frame symbol name: > > > > > > > > > > > > $ addr2line -e > > > > > > /home/milian/.debug/.build-id/f7/186d14bb94f3c6161c010926da66033d24fce > > > > > > 5/e > > > > > > lf -if b48 main > > > > > > /usr/include/c++/8.2.1/complex:610 > > > > > > ?? > > > > > > /usr/include/c++/8.2.1/complex:618 > > > > > > ?? > > > > > > /usr/include/c++/8.2.1/complex:675 > > > > > > ?? > > > > > > /usr/include/c++/8.2.1/complex:685 > > > > > > main > > > > > > /home/milian/projects/kdab/rnd/hotspot/tests/test-clients/cpp-inlining > > > > > > /mai > > > > > > n.cpp:39 > > > > > > > > > > > > I've reported this bug upstream and also attached a patch there > > > > > > which should fix this issue: > > > > > > https://sourceware.org/bugzilla/show_bug.cgi?id=23715 > > > > > > > > > > Millian, what about this one, which is the cset it is fixing? > > > > > > > > Hey Arnaldo, > > > > > > > > just noticed this email and that the corresponding patch hasn't landed in > > > > perf/core yet. The patch set which introduced this is a64489c56c307 ("perf > > > > report: Find the inline stack for a given address"). Note that the code > > > > was > > > > introduced by this patch, but then subsequently touched and moved by > > > > follow up patches. So, is this the patch you want to see referenced? > > > > Otherwise, the latest patch which gets fixed is afaik: 7285cf3325b4a > > > > ("perf srcline: Show correct function name for srcline of callchains"). > > > > > > > > Can you please pick either of these patches and amend the commit message > > > > of my patch and push it to perf/urgent and perf/core? > > > > > > I'll reread all this later or tomorrow and continue, going AFK now. > > > > Ping? > > Applied, seems simple enough, makes this code a bit more robust. > > With regards to the cset where the problem originally was introduced, > i.e. not checking if a2l->funcname was NULL before either passing it to > strdup() or all the way to bfd_demangle(), that would cause the crash in > either place, I think this is the cset: > > commit a64489c56c307bf0955f0489158c5ecf6aa10fe2 > Author: Jin Yao <yao.jin@linux.intel.com> > Date: Sun Mar 26 04:34:26 2017 +0800 > > perf report: Find the inline stack for a given address > >> Agreed?
But I'm not sure this will be worth for doing backports, as before applying this patch a series of other patches touching this code would have to be applied :-\
I can leave it there, so that we know when the problem was introduced, i.e. I _guess_ that if this rust or C++ reproducers would be used with perf built with a64489c56c307bf0955f0489158c5ecf6aa10fe2 as head, we would see a crash as well.
- Arnaldo
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