x86, selftests: Add a test for the "sysret_ss_attrs" bug

On AMD CPUs, SYSRET can return with a valid SS descriptor with
with the hidden attributes set to an unusable state.  Make sure
the kernel doesn't let this happen.  This detects an
as-yet-unfixed regression.

Note that the 64-bit version of this test fails on AMD CPUs on
all kernel versions, although the issue in the 64-bit case is
much less severe than in the 32-bit case.

Reported-by: Brian Gerst <[email protected]>
Tested-by: Denys Vlasenko <[email protected]>
Signed-off-by: Andy Lutomirski <[email protected]>
Tests: e7d6eefaaa44 ("x86/vdso32/syscall.S: Do not load __USER32_DS to %ss")
Cc: Alexei Starovoitov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Drewry <[email protected]>
Link: http://lkml.kernel.org/r/resend_4d740841bac383742949e2fefb03982736595087.git.luto@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions