From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751752AbcEII6T (ORCPT ); Mon, 9 May 2016 04:58:19 -0400 Received: from helium.openadk.org ([89.238.66.15]:35250 "EHLO helium.openadk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750951AbcEII6R (ORCPT ); Mon, 9 May 2016 04:58:17 -0400 Date: Mon, 9 May 2016 10:58:15 +0200 From: Waldemar Brodkorb To: Waldemar Brodkorb Cc: linux-kernel@vger.kernel.org, Denys Vlasenko , Thomas Petazzoni , Gustavo Zacarias , Greg Ungerer Subject: Re: qemu m68k/mcf5208: problem with signal handler Message-ID: <20160509085815.GB13502@waldemar-brodkorb.de> Reply-To: Waldemar Brodkorb References: <20160509063902.GL26720@waldemar-brodkorb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20160509063902.GL26720@waldemar-brodkorb.de> X-Operating-System: Linux 3.16.0-4-amd64 x86_64 User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > > 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 >