Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1396615 > unrolled thread
| Started by | Waldemar Brodkorb <wbx@openadk.org> |
|---|---|
| First post | 2016-05-09 08:50 +0200 |
| Last post | 2016-05-09 18:30 +0200 |
| Articles | 4 — 2 participants |
Back to article view | Back to linux.kernel
qemu m68k/mcf5208: problem with signal handler Waldemar Brodkorb <wbx@openadk.org> - 2016-05-09 08:50 +0200
Re: qemu m68k/mcf5208: problem with signal handler Waldemar Brodkorb <wbx@openadk.org> - 2016-05-09 11:00 +0200
Re: qemu m68k/mcf5208: problem with signal handler Greg Ungerer <gerg@uclinux.org> - 2016-05-09 16:00 +0200
Re: qemu m68k/mcf5208: problem with signal handler Waldemar Brodkorb <wbx@openadk.org> - 2016-05-09 18:30 +0200
| From | Waldemar Brodkorb <wbx@openadk.org> |
|---|---|
| Date | 2016-05-09 08:50 +0200 |
| Subject | qemu m68k/mcf5208: problem with signal handler |
| Message-ID | <rwNaW-7n5-13@gated-at.bofh.it> |
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:
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
static void sighandler(int sig)
{
write(1, "SIGNAL\n", 7);
}
int main()
{
int pid;
write(1, "VFORK1\n", 7);
pid = vfork();
if (pid == 0) {
write(1, "EXIT1\n", 6);
_exit(1);
}
wait(NULL);
signal(SIGCHLD, sighandler);
write(1, "VFORK2\n", 7);
pid = vfork();
if (pid == 0) {
write(1, "EXIT2\n", 6);
_exit(1);
}
wait(NULL);
write(1, "EXIT\n", 5);
return 0;
}
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
[toc] | [next] | [standalone]
| From | Waldemar Brodkorb <wbx@openadk.org> |
|---|---|
| Date | 2016-05-09 11:00 +0200 |
| Message-ID | <rwPcK-1Kc-21@gated-at.bofh.it> |
| In reply to | #1396615 |
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
>
[toc] | [prev] | [next] | [standalone]
| From | Greg Ungerer <gerg@uclinux.org> |
|---|---|
| Date | 2016-05-09 16:00 +0200 |
| Message-ID | <rwTT4-6II-7@gated-at.bofh.it> |
| In reply to | #1396863 |
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
>>
>
[toc] | [prev] | [next] | [standalone]
| From | Waldemar Brodkorb <wbx@openadk.org> |
|---|---|
| Date | 2016-05-09 18:30 +0200 |
| Message-ID | <rwWef-RF-23@gated-at.bofh.it> |
| In reply to | #1397074 |
Hi Greg,
Greg Ungerer wrote,
> >>What do you think? Is it a Kernel bug or a C library problem?
>
> What version of linux kernel?
4.5.3
> What version of gcc?
4.9.3
> 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.
Jackpot. Thanks a lot. This works!
May be some candidate for LTS kernels.
best regards
Waldemar
[toc] | [prev] | [standalone]
Back to top | Article view | linux.kernel
csiph-web