From: Raoni Fassina Firmino <raoni@linux.ibm.com>
To: Rich Felker <dalias@libc.org>
Cc: Florian Weimer <fweimer@redhat.com>,
musl@lists.openwall.com, libc-alpha@sourceware.org,
linuxppc-dev@lists.ozlabs.org,
Nicholas Piggin <npiggin@gmail.com>,
Alan Modra <amodra@gmail.com>
Subject: Re: [musl] Re: [PATCH v2] powerpc/64/signal: balance return predictor stack in signal trampoline
Date: Fri, 22 Jan 2021 15:19:22 -0300 [thread overview]
Message-ID: <20210122181922.pcxyomeg5xcf2umu@work-tp> (raw)
In-Reply-To: <20210122144402.GP23432@brightrain.aerifal.cx>
On Fri, Jan 22, 2021 at 09:44:05AM -0500, Rich Felker wrote:
> Maybe I'm missing something but I don't see how this would break musl;
> we just inspect the PC in the mcontext, which I don't see any changes
> to and which should still point to the next instruction of the
> interrupted context. I don't have a test environment though so I'll
> have to wait for feedback from ppc users to be sure. Are there any
> further details on how it's breaking glibc?
For glibc, backtrace() compares the return-address from each stack frame
to the value of `__kernel_sigtramp_rt64` to identify the frame with the
mcontext information, but now the return-address is not the start of the
routine, but the middle of it, so it fails to catch this special frame.
o/
Raoni Fassina
next prev parent reply other threads:[~2021-01-22 18:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200511101952.1463138-1-npiggin@gmail.com>
2021-01-22 11:27 ` Florian Weimer
2021-01-22 14:44 ` Rich Felker
2021-01-22 18:19 ` Raoni Fassina Firmino [this message]
2021-01-22 18:31 ` Rich Felker
2021-01-22 18:50 ` Raoni Fassina Firmino
2021-01-22 18:13 ` Raoni Fassina Firmino
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210122181922.pcxyomeg5xcf2umu@work-tp \
--to=raoni@linux.ibm.com \
--cc=amodra@gmail.com \
--cc=dalias@libc.org \
--cc=fweimer@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=musl@lists.openwall.com \
--cc=npiggin@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).