From: Greg Ungerer <gerg@uclinux.org>
To: Waldemar Brodkorb <mail@waldemar-brodkorb.de>,
Waldemar Brodkorb <wbx@openadk.org>
Cc: linux-kernel@vger.kernel.org,
Denys Vlasenko <vda.linux@googlemail.com>,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
Gustavo Zacarias <gustavo@zacarias.com.ar>
Subject: Re: qemu m68k/mcf5208: problem with signal handler
Date: Mon, 9 May 2016 23:57:01 +1000 [thread overview]
Message-ID: <5730972D.8050409@uclinux.org> (raw)
In-Reply-To: <20160509085815.GB13502@waldemar-brodkorb.de>
Hi Waldemar,
On 09/05/16 18:58, Waldemar Brodkorb wrote:
> Hi,
>
> forgot to add Greg in CC.
> And sorry for the whitespace fuckup in the example code.
>
> Waldemar Brodkorb wrote,
>
>> Dear kernel hackers,
>>
>> I have a problem with the signal handling under qemu-system-m68k
>> emulating coldfire mcf5208 evalboard. Following example code
>> provided by Busybox maintainer Denys Vlasenko
>> shows the problem when running on qemu:
>
> [ .. ]
>
>> You can generate a bootable image with latest buildroot, which shows the issue:
>> $ git clone git://git.buildroot.net/buildroot
>> $ cd buildroot; make qemu_m68k_mcf5208_defconfig; make
>> $ qemu-system-m68k -M mcf5208evb -cpu m5208 -kernel output/images/vmlinux -nographic
>>
>> Every command forked from busybox hush shell will lead into a segmentation fault.
>>
>> I added following printk to start investigating the problem:
>> diff -Nur linux-4.5.3.orig/arch/m68k/kernel/signal.c linux-4.5.3/arch/m68k/kernel/signal.c
>> --- linux-4.5.3.orig/arch/m68k/kernel/signal.c 2016-05-04 23:50:38.000000000 +0200
>> +++ linux-4.5.3/arch/m68k/kernel/signal.c 2016-05-09 04:24:53.885199544 +0200
>> @@ -595,6 +595,7 @@
>> void __user *fp)
>> {
>> int fsize = frame_extra_sizes(formatvec >> 12);
>> + printk("avoid broken signal handler...\n");
>> if (fsize < 0) {
>> /*
>> * user process trying to return with weird frame format
>>
>> But now the problem disappeared. :/
>>
>> What do you think? Is it a Kernel bug or a C library problem?
What version of linux kernel?
What version of gcc?
This sounds a lot like the problem I fixed in linux commit a9551799
("m68k: Use conventional function parameters for do_sigreturn").
Definitely try that first.
Regards
Greg
>> Busybox hush otherwise works fine for other noMMU targets as stm32
>> evalboard with cortex-m4. It also works in Qemu M68k emulating Q800
>> full MMU system.
>>
>> Thanks for any ideas,
>> Waldemar
>>
>> http://lists.busybox.net/pipermail/busybox/2014-September/081659.html
>>
>
next prev parent reply other threads:[~2016-05-09 13:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-09 6:39 qemu m68k/mcf5208: problem with signal handler Waldemar Brodkorb
2016-05-09 8:58 ` Waldemar Brodkorb
2016-05-09 13:57 ` Greg Ungerer [this message]
2016-05-09 16:29 ` Waldemar Brodkorb
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=5730972D.8050409@uclinux.org \
--to=gerg@uclinux.org \
--cc=gustavo@zacarias.com.ar \
--cc=linux-kernel@vger.kernel.org \
--cc=mail@waldemar-brodkorb.de \
--cc=thomas.petazzoni@free-electrons.com \
--cc=vda.linux@googlemail.com \
--cc=wbx@openadk.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.