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
