Messages in this thread | | | Subject | Re: qemu m68k/mcf5208: problem with signal handler | From | Greg Ungerer <> | Date | Mon, 9 May 2016 23:57:01 +1000 |
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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 >> >
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