From: Jakub Jelinek <jakub@redhat.com>
To: Michael Matz <matz@suse.de>
Cc: Jeff Law <law@redhat.com>, Florian Weimer <fweimer@redhat.com>,
GCC <gcc@gcc.gnu.org>,
GNU C Library <libc-alpha@sourceware.org>,
Binutils <binutils@sourceware.org>,
gnu-gabi@sourceware.org
Subject: Re: Invalid program counters and unwinding
Date: Mon, 01 Jan 2018 00:00:00 -0000 [thread overview]
Message-ID: <20180702155448.GW7166@tucnak> (raw)
In-Reply-To: <alpine.LSU.2.21.1807021743390.15410@wotan.suse.de>
On Mon, Jul 02, 2018 at 05:48:32PM +0200, Michael Matz wrote:
> Hi,
>
> On Thu, 28 Jun 2018, Jeff Law wrote:
>
> > I believe "dumb" is referring to the fact that we're already in a bit of
> > a weird state as evidenced by the NULL FDE. Blindly trying to read the
> > contents of the PC that we couldn't map to an FDE is, IMHO, dumb.
> >
> > One might even be able to argue in this day and age that we should have
> > suitable descriptors for everything. If no suitable descriptor is found
> > then backtracing should stop. Lack of suitable descriptors in any code
> > would be considered a bug in that scenario.
>
> I disagree. ASM code often lacks unwind descriptors (now less than in the
> past, but still). My rule of thumb is always: no descriptor -> has to be
> a framepointer-using routine with standard calling sequence. (I.e.
> declare the combination of no descriptor and no fp to be a bug). Some of
> the callee-saved register will temporarily be wrong but unwinding can
> continue.
Doesn't that clash with the x86-64 ABI which says what kind of FDE use by
default if none is found (essentially a standard leaf routine that doesn't
change sp, nor save any registers)?
Jakub
next prev parent reply other threads:[~2018-07-02 15:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-01 0:00 Florian Weimer
2018-01-01 0:00 ` Jeff Law
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Jeff Law
2018-01-01 0:00 ` Michael Matz
2018-01-01 0:00 ` Jakub Jelinek [this message]
2018-01-01 0:00 ` Michael Matz
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Nathan Sidwell
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Jakub Jelinek
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Nathan Sidwell
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Nathan Sidwell
2018-01-01 0:00 ` Florian Weimer
2018-01-01 0:00 ` Nathan Sidwell
2018-01-01 0:00 ` Jakub Jelinek
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=20180702155448.GW7166@tucnak \
--to=jakub@redhat.com \
--cc=binutils@sourceware.org \
--cc=fweimer@redhat.com \
--cc=gcc@gcc.gnu.org \
--cc=gnu-gabi@sourceware.org \
--cc=law@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=matz@suse.de \
/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.
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 read-only IMAP folder(s) and NNTP newsgroup(s).