ppc64 qemu test failure since commit f9aa67142 ("powerpc/64s: Consolidate Alignment 0x600 interrupt")

[Guenter Roeck]

On 10/09/2016 10:49 PM, Nicholas Piggin wrote:
> On Sun, 9 Oct 2016 08:21:21 -0700
> Guenter Roeck <linux at roeck-us.net> wrote:
>
>> Nicholas,
>>
>> some of my qemu tests for ppc64 started failing on mainline (and -next).
>> You can find a test log at
>> http://kerneltests.org/builders/qemu-ppc64-master/builds/580/steps/qemubuildcommand/logs/stdio
>>
>> The scripts to run the test are available at
>> https://github.com/groeck/linux-build-test/tree/master/rootfs/ppc64
>>
>> Bisect points to commit f9aa67142ef26 ("powerpc/64s: Consolidate Alignment 0x600
>> interrupt"). Bisect log is attached.
>>
>> Since I don't have the means to run the code on a real system, I have no idea
>> if the problem is caused by qemu or by the code. It is interesting, though, that
>> only the 'mac99' tests are affected.
>>
>> Please let me know if there is anything I can do to help tracking down the
>> problem.
>
> Thanks for this. That patch just moves a small amount of code, so it's likely
> that it's caused something to get placed out of range of its caller, or the
> linker started generating a stub for some reason. I can't immediately see the
> problem, but it could be specific to your exact toolchain.
>
> Something that might help, would you be able to put the compiled vmlinux binaries
> from before/after the bad patch somewhere I can grab them?
>

http://server.roeck-us.net/qemu/ppc64/mac99/

'bad' is at f9aa67142ef26, 'good' is one commit earlier, 'tot' is from top of tree
(b66484cd7470, more specifically).

Key difference in System.map, from the bad case:

c000000000005c00 T __end_interrupts
c000000000007000 t end_virt_trampolines
c000000000008000 t 00000010.long_branch.power4_fixup_nap+0
c000000000008100 t fs_label
c000000000008100 t start_text

00000010.long_branch.power4_fixup_nap+0 does not exist in the good case,
and fs_label/start_text are at c000000000008000.

Toolchain is from poky 1.5.1, which uses gcc 4.8.1 and binutils 2.23.2.
I also tried with the toolchain from poky 1.6, using gcc 4.8.2 and binutils 2.24,
with the same result.

Guenter