Re: [kvm-unit-tests PATCH v2 0/4] Better backtraces for leaf functions

Mathias Krause
2025-11-18T01:47:42Z

On 18.11.25 02:33, Mathias Krause wrote:
> On 17.11.25 23:19, Sean Christopherson wrote:
>> On Sat, Nov 15, 2025, Mathias Krause wrote:
>>> On 14.11.25 19:25, Sean Christopherson wrote:
>>>> On Mon, 15 Sep 2025 23:54:28 +0200, Mathias Krause wrote:
>>>>> This is v2 of [1], trying to enhance backtraces involving leaf
>>>>> functions.
>>>>>
>>>>> This version fixes backtraces on ARM and ARM64 as well, as ARM currently
>>>>> fails hard for leaf functions lacking a proper stack frame setup, making
>>>>> it dereference invalid pointers. ARM64 just skips frames, much like x86
>>>>> does.
>>>>>
>>>>> [...]
>>>>
>>>> Applied to kvm-x86 next, thanks!
>>>
>>> Thanks a lot, Sean!
>>>
>>>> P.S. This also prompted me to get pretty_print_stacks.py working in my
>>>> environment, so double thanks!
>>>
>>> Haha, you're welcome! :D
>>>
>>>>
>>>> [1/4] Makefile: Provide a concept of late CFLAGS
>>>> https://github.com/kvm-x86/kvm-unit-tests/commit/816fe2d45aed
>>>> [2/4] x86: Better backtraces for leaf functions
>>>> https://github.com/kvm-x86/kvm-unit-tests/commit/f01ea38a385a
>>
>> Spoke too soon :-(
>>
>> The x86 change breaks the realmode test. I didn't try hard to debug, as that
>> test is brittle, e.g. see https://lore.kernel.org/all/20240604143507.1041901-1-pbonzini@redhat.com.

Bleh, I just noticed, f01ea38a385a ("x86: Better backtraces for leaf
functions") broke vmx_sipi_signal_test too :(

Looking into it!

Mathias