From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Blue Swirl <blauwirbel@gmail.com>, TeLeMan <geleman@gmail.com>,
Jan Kiszka <jan.kiszka@web.de>,
qemu-devel <qemu-devel@nongnu.org>,
David Gilbert <david.gilbert@linaro.org>
Subject: Re: [Qemu-devel] [PATCH] tcg: Reload local variables after return from longjmp
Date: Thu, 11 Aug 2011 14:16:11 +0200 [thread overview]
Message-ID: <4E43C80B.1050300@redhat.com> (raw)
In-Reply-To: <CAFEAcA81p4F836+cX_y6sdoERC3ewFQzrPDtao=xTRHuV7--UA@mail.gmail.com>
On 08/11/2011 01:30 PM, Peter Maydell wrote:
>> > Recent compilers look deep into cpu_exec, find longjmp as a noreturn
>> > function and decide to smash some stack variables as they won't be used
>> > again. This may lead to env becoming invalid after return from setjmp,
>> > causing crashes. Fix it by reloading env from cpu_single_env in that
>> > case.
> Can you give more details of what compiler/platform this was
> a problem for? My reading of the C standard is that the compiler
> isn't allowed to trash env across this longjmp, because it's
> a variable of automatic scope which isn't modified between the
> setjmp and the longjmp...
longjmp can destroy any non-volatile variable (-Wclobbered warns about
this).
Paolo
next prev parent reply other threads:[~2011-08-11 12:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-30 16:47 [Qemu-devel] "cpu-exec.c: avoid AREG0 use" breaks x86 emulation on x86-64 Jan Kiszka
2011-06-30 21:17 ` Stefan Weil
2011-07-01 1:44 ` TeLeMan
2011-07-01 20:15 ` Blue Swirl
2011-07-02 7:50 ` [Qemu-devel] [PATCH] tcg: Reload local variables after return from longjmp Jan Kiszka
2011-07-02 9:08 ` Blue Swirl
2011-07-02 9:43 ` Jan Kiszka
2011-07-03 14:09 ` Paolo Bonzini
2011-07-12 20:56 ` Blue Swirl
2011-08-11 11:30 ` Peter Maydell
2011-08-11 12:16 ` Paolo Bonzini [this message]
2011-08-11 12:40 ` Peter Maydell
2011-08-11 13:13 ` Paolo Bonzini
2011-08-11 13:31 ` Peter Maydell
2011-08-11 14:10 ` Paolo Bonzini
2011-08-11 14:12 ` David Gilbert
2011-08-11 14:24 ` Peter Maydell
2011-08-11 14:32 ` Paolo Bonzini
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=4E43C80B.1050300@redhat.com \
--to=pbonzini@redhat.com \
--cc=blauwirbel@gmail.com \
--cc=david.gilbert@linaro.org \
--cc=geleman@gmail.com \
--cc=jan.kiszka@web.de \
--cc=peter.maydell@linaro.org \
--cc=qemu-devel@nongnu.org \
/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 NNTP newsgroup(s).