From: Michael Matz <matz@suse.de>
To: Jeff Law <law@redhat.com>
Cc: 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: <alpine.LSU.2.21.1807021743390.15410@wotan.suse.de> (raw)
In-Reply-To: <6c555c05-e6d7-f37a-577f-4e0559c36f76@redhat.com>
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.
Ciao,
Michael.
next prev parent reply other threads:[~2018-07-02 15:48 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 ` Florian Weimer
2018-01-01 0:00 ` Michael Matz [this message]
2018-01-01 0:00 ` Jakub Jelinek
2018-01-01 0:00 ` Michael Matz
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 ` Florian Weimer
2018-01-01 0:00 ` Jakub Jelinek
2018-01-01 0:00 ` Nathan Sidwell
2018-01-01 0:00 ` Jakub Jelinek
2018-01-01 0:00 ` Florian Weimer
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