Kernel 4.13 is broken on m68k

Kernel 4.13 is broken on m68k

[John Paul Adrian Glaubitz]

Hi!

While working on updated installation images for m68k, I ran into a serious
problem with shell-scripts which makes booting Linux on m68k impossible.

With debian-installer, the problem manifests with the script /sbin/reopen-console
which fails with:

/sbin/reopen-console: line 74: syntax error: unterminated quoted string

with reopen-console coming from [1].

In order to rule out a problem with debian-installer, I dist-upgraded an
existing system which also upgraded the kernel from 4.12 to 4.13.

And, indeed, after upgrading the system, the boot fails with:

[    0.520000] ADB mouse at 3, handler 1
[    0.520000]
[    0.520000] input: ADB mouse as /devices/virtual/input/input1
[    0.520000] adb: finished probe task...
Loading, please wait...
/init: line 69: syntax error: missing '}'
[    0.610000] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000200
[    0.610000]
[    0.610000] CPU: 0 PID: 1 Comm: init Not tainted 4.13.0-1-m68k #1 Debian 4.13.4-1
[    0.610000] Stack from 3dc35f48:
[    0.610000]         3dc35f48 00355ab1 0002c9bc 000002ff 0004bea0 0028ede6 00000000 3dc33390
[    0.610000]         0038643c 00000000 3dc35fb0 0002e63c 00322d0f 00000200 00000200 000000f7
[    0.610000]         00000000 00000000 00000000 00000000 d00b0140 d00b1404 c0154000 00000001
[    0.610000]         3dc35fa8 3dc35fa8 efe128c8 0002e9d4 00000200 00000002 0002e9e8 00000200
[    0.610000]         00002934 00000002 00000002 000000f7 00000000 00000000 d00b1008 efe128e0
[    0.610000]         d00b1408 000000f7 000000f7 00000000 0000c00b c04e0080
[    0.610000] Call Trace: [<0002c9bc>] panic+0xa6/0x22e
[    0.610000]  [<0004bea0>] up_read+0x0/0x6
[    0.610000]  [<0028ede6>] down_read+0x0/0x6
[    0.610000]  [<0002e63c>] do_exit+0x490/0x75c
[    0.610000]  [<0002e9d4>] SyS_exit_group+0x0/0x14
[    0.610000]  [<0002e9e8>] __wake_up_parent+0x0/0x24
[    0.610000]  [<00002934>] syscall+0x8/0xc
[    0.610000]  [<0000c00b>] mac_hwclk+0x501/0x62c
[    0.610000] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000200
[    0.610000]

I can trigger the problem by switching between 4.12 and 4.13, 4.12 is fin while 4.13 is broken.

Adrian

> [1] https://anonscm.debian.org/cgit/d-i/rootskel.git/tree/src/sbin/reopen-console-linux

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

Re: Kernel 4.13 is broken on m68k

[John Paul Adrian Glaubitz]

On 10/04/2017 11:49 PM, John Paul Adrian Glaubitz wrote:
> I can trigger the problem by switching between 4.12 and 4.13, 4.12 is fin while 4.13 is broken.

Ok, switching just the initrd to the one from 4.13 while keeping the 4.12 kernel
image results in the same crash. Maybe the glibc is broken?

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

Re: Kernel 4.13 is broken on m68k

[John Paul Adrian Glaubitz]

On 10/04/2017 11:56 PM, John Paul Adrian Glaubitz wrote:
> On 10/04/2017 11:49 PM, John Paul Adrian Glaubitz wrote:
>> I can trigger the problem by switching between 4.12 and 4.13, 4.12 is fin while 4.13 is broken.
> 
> Ok, switching just the initrd to the one from 4.13 while keeping the 4.12 kernel
> image results in the same crash. Maybe the glibc is broken?

I have tracked it down to busybox which was recently upgraded to 1.27.2 in Debian [1].

busybox_1:1.22.0-17:

root@pacman:~/rootskel/src/sbin# ls -l /root/sh
lrwxrwxrwx 1 root root 12 Oct  5 00:18 /root/sh -> /bin/busybox
root@pacman:~/rootskel/src/sbin# /root/sh ./reopen-console-linux
./reopen-console-linux: exec: line 74: /sbin/steal-ctty: not found
root@pacman:~/rootskel/src/sbin#

Despite the error messages, the above behavior is correct.

busybox_1:1.27.2-1:

root@pacman:~/rootskel/src/sbin# /root/sh ./reopen-console-linux
./reopen-console-linux: line 74: syntax error: unterminated quoted string
root@pacman:~/rootskel/src/sbin#

Now we need to find out whether busybox was either miscompiled or
whether the new upstream version is broken. I will recompile the
old version with gcc-7 next.

Adrian

> [1] https://packages.qa.debian.org/b/busybox/news/20170917T171907Z.html

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

Re: Kernel 4.13 is broken on m68k

[Andreas Schwab]

On Okt 04 2017, John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> wrote:

> Ok, switching just the initrd to the one from 4.13 while keeping the 4.12 kernel
> image results in the same crash. Maybe the glibc is broken?

It's busybox.  Try setting BUSYBOX=n in
/etc/initramfs-tools/initramfs.conf (or deinstall busybox).

$ busybox ash -c 'echo ${x}'
ash: syntax error: missing '}'

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: Kernel 4.13 is broken on m68k

[John Paul Adrian Glaubitz]

On 10/05/2017 12:43 AM, Andreas Schwab wrote:
> On Okt 04 2017, John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> wrote:
> 
>> Ok, switching just the initrd to the one from 4.13 while keeping the 4.12 kernel
>> image results in the same crash. Maybe the glibc is broken?
> 
> It's busybox.  Try setting BUSYBOX=n in
> /etc/initramfs-tools/initramfs.conf (or deinstall busybox).

Indeed. I also just found that out.

> $ busybox ash -c 'echo ${x}'
> ash: syntax error: missing '}'

Thanks. That's a very handy testcase.

busybox has gotten new maintainers in Debian and they have stripped
"-O2" from CFLAGS so that it's building with "-Os" now [1].

Maybe that caused the code to be miscompiled. I hope I won't have
to bisect busybox.

Adrian

> [1] https://anonscm.debian.org/cgit/d-i/busybox.git/commit/?id=8a115a910fb3cd7a525972e150a32f8aeb1da492

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

Re: Kernel 4.13 is broken on m68k

[John Paul Adrian Glaubitz]

On 10/05/2017 12:49 AM, John Paul Adrian Glaubitz wrote:
> busybox has gotten new maintainers in Debian and they have stripped
> "-O2" from CFLAGS so that it's building with "-Os" now [1].
> 
> Maybe that caused the code to be miscompiled. I hope I won't have
> to bisect busybox.

Reverting the commit from [1] fixes the problem for me:

root@pacman:~# busybox ash -c 'echo ${x}'

root@pacman:~#

Adrian

>> [1] https://anonscm.debian.org/cgit/d-i/busybox.git/commit/?id=8a115a910fb3cd7a525972e150a32f8aeb1da49

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913