Messages in this thread | | | Date | Tue, 2 Jun 2020 12:56:49 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] arch/x86: reset MXCSR to default in kernel_fpu_begin() |
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Hi,
On Tue, Jun 02, 2020 at 01:29:51PM +0300, Petteri Aimonen wrote: > The kernel module is not actually x86-specific, even though it is > currently only enabled for x86. amdgpu driver already does kernel mode > floating point operations on PPC64 also, and the same module could be > used to test the same thing there.
Then make it generic please and put the user portion in, say, tools/testing/selftests/fpu/ and we can ask ppc people to test it too. People might wanna add more stuff to it in the future, which would be good.
> To deterministically trigger the bug, the syscall has to come from the > same thread that has modified MXCSR. Going through /usr/sbin/modprobe > won't work, and manually doing the necessary syscalls for module loading > seems too complicated.
Ok, fair enough. But put that file in debugfs pls.
> The fesetround() and feenableexcept() are the portable ways to modify > MXCSR. The test module does cause Precision Exception and Denormal > Exception if those exceptions are unmasked.
Ok.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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