On 20.02.2024 08:46, David Gow wrote:
> On Wed, 14 Feb 2024 at 20:41, Paul Heidekrüger <[email protected]>
> wrote:
> >
> > Hi!
> >
> > I was running some KASan tests with kunit.py recently and noticed that
> > when KASan is run in hw tags mode, we manually have to add the required
> > `mte=on` option to kunit_tool's qemu invocation, as the tests will
> > otherwise crash.
> >
> > To make life easier, I was looking into ways for kunit.py to recognise
> > when MTE support was required and set the option automatically.
> >
> > All solutions I could come up with for having kunit_tool conditionally
> > pass `mte=on` to qemu, either entailed duplicate code or required
> > parsing of kernel's config file again. I was working under the
> > assumption that only after configuring the kernel we would know whether
> > the 'mte=on' option was necessary, as CONFIG_ARM64_MTE is not visible
> > before.
> >
> > Only afterwads did I realise that the qemu arm64 config that kunit_tool
> > falls back on, uses the `virt` machine, which supports MTE in any case.
> > So, could it be as easy as just adding the `mte=on` option to
> > kunit_tool's arm64 config? Would this be a welcome addition?
> >
> > What do you think?
> >
> > Many thanks,
> > Paul
> >
> > Signed-off-by: Paul Heidekrüger <[email protected]>
> > ---
>
> I think this is fine. I'd be a little bit concerned if this were only
> supported in newer qemu versions, but it seems to go back to 6.2, so
> should be okay. I think it's better to just enable it unconditionally
> by default rather than trying to parse the config.
>
> The KASAN tests seemed to work fine with HW tags in my testing here. I
> do wonder if there's a way to make the tests skip themselves if MTE
> isn't available: is there a way of doing a runtime check for this?
Huh, interesting. Even though "mte=on" isn't set on your side?
I get the following output without the MTE patch.
➜ ./tools/testing/kunit/kunit.py run
--kunitconfig=mm/kasan/.kunitconfig --arch=arm64
[14:08:11] Configuring KUnit Kernel ...
[14:08:11] Building KUnit Kernel ...
Populating config with:
$ make ARCH=arm64 O=.kunit olddefconfig
Building with:
$ make ARCH=arm64 O=.kunit --jobs=8
[14:08:23] Starting KUnit Kernel (1/1)...
[14:08:23] ============================================================
Running tests with:
$ qemu-system-aarch64 -nodefaults -m 1024 -kernel
.kunit/arch/arm64/boot/Image.gz -append 'kunit.enable=1 console=ttyAMA0
kunit_shutdown=reboot' -no-reboot -nographic -serial stdio -machine virt -cpu
max,pauth-impdef=on
[14:08:23] kasan: test: Can't run KASAN tests with KASAN disabled
[14:08:23] # kasan: # failed to initialize (-1)
[14:08:23] [FAILED] kasan
[14:08:23] ============================================================
[14:08:23] Testing complete. Ran 1 tests: failed: 1
[14:08:24] Elapsed time: 12.374s total, 0.001s configuring, 11.937s
building, 0.382s running
Where the mentioned .kunitconfig has the following options set for KASan.
CONFIG_KUNIT=y
CONFIG_KUNIT_ALL_TESTS=n
CONFIG_FTRACE=y
CONFIG_STACK_TRACER=y
CONFIG_KASAN=y
CONFIG_KASAN_HW_TAGS=y
CONFIG_KASAN_KUNIT_TEST=y
With the MTE patch from my previous email, everything works just fine.
Based on that, do you have a guess why it's working for you and why it isn't
for
me?
> Regardless, this is:
> Reviewed-by: David Gow <[email protected]>
Thanks! I'll be sending a non-RFC patch shortly.
Many thanks,
Paul
