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
>
