Re: [PATCH] selftests/x86: Add test_vsyscall

[Ingo Molnar]

* Andy Lutomirski <luto@xxxxxxxxxx> wrote:

> This tests that the vsyscall entries do what they're expected to do.
> It also confirms that attempts to read the vsyscall page behave as
> expected.
> 
> If changes are made to the vsyscall code or its memory map handling,
> running this test in all three of vsyscall=none, vsyscall=emulate,
> and vsyscall=native are helpful.
> 
> (Because it's easy, this also compares the vsyscall results to their
>  vDSO equivalents.)
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> ---
> 
> Note to KAISER backporters: please test this under all three
> vsyscall modes.  Also, in the emulate and native modes, make sure
> that test_vsyscall_64 agrees with the command line or config
> option as to which mode you're in.  It's quite easy to mess up
> the kernel such that native mode accidentally emulates
> or vice versa.
> 
> Greg, etc: please backport this to all your Meltdown-patched
> kernels.  It'll help make sure the patches didn't regress
> vsyscalls.

I've added this to tip:x86/pti, that way it will end up in the linear backport 
range of commits.

Thanks,

	Ingo