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 >