Hi, On Thu, Jun 26, 2025 at 09:57:12PM +0200, Benjamin Berg wrote: > so I saw the UAPI testing framework patches and wondered whether I could > hack up a kunit test for userspace signal mcontext handling. I already > had some code, but never knew where to include it. Having it as a kunit > test in this way seems nice as it makes running the test really simple.
Nice to hear that you find it useful. > This is a very rough attempt with an extra patch to add sigaction > support as that is needed by the test. > > Note that this type of test could possibly be shared with the x86 > architecture (though UM does not support all features). Can the expected feature detection be performed at runtime? If so I would write the test as x86 kselftest in tools/testing/kselftests/x86/ and then also hook it up for kunit on UML and x86. This gives you the advantages of all worlds. For an example see [0]. That is still based on an old version of the framework, so can't be used as-is. But you should get the idea. > And, a 64 bit build might even want to include a second 32 bit binary. Indeed, for compat binaries we'll probably want some sort of common pattern. Unfortunately it's not as easy as building a second binary when CONFIG_COMPAT=y, as some architectures have more than 2 supported ABIs. MIPS for example or x86_64 when counting x32. Or maybe we can just pretend that those don't matter. Something we can work on when the first series has been merged. > So, I suppose > one would ideally want the test to be in arch/x86/tests, with some way > to pick up it up in arch/x86/um/tests. > > Does this seem sensible in general? It does. > Benjamin [0] https://git.kernel.org/pub/scm/linux/kernel/git/thomas.weissschuh/linux.git/commit/?h=kunit-kselftests-integration&id=14bf93f09eaa328a18e9190f46fa4ee697378617 > > Benjamin Berg (2): > tools/nolibc: add sigaction() > um: add a mcontext FP register handling test > > arch/x86/um/Makefile | 2 + > arch/x86/um/tests/Makefile | 12 +++ > arch/x86/um/tests/registers.c | 22 +++++ > arch/x86/um/tests/test-fp-save-restore.c | 118 +++++++++++++++++++++++ > tools/include/nolibc/nolibc.h | 3 + > tools/include/nolibc/signal.h | 34 +++++++ > 6 files changed, 191 insertions(+) > create mode 100644 arch/x86/um/tests/Makefile > create mode 100644 arch/x86/um/tests/registers.c > create mode 100644 arch/x86/um/tests/test-fp-save-restore.c > > -- > 2.50.0 >
