Re: powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs
From: Michael Ellerman <hidden>
Date: 2018-03-25 20:52:59
On Fri, 2018-03-23 at 05:53:38 UTC, Nicholas Piggin wrote:
The SLB bad address handler's trap number fixup does not preserve the
low bit that indicates nonvolatile GPRs have not been saved. This
leads save_nvgprs to skip saving them, and subsequent functions and
return from interrupt will think they are saved.
This causes kernel branch-to-garbage debugging to not have correct
registers, can also cause userspace to have its registers clobbered
after a segfault.
Fixes: f0f558b131 ("powerpc/mm: Preserve CFAR value on SLB miss caused by access to bogus address")
Cc: Paul Mackerras <redacted>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>I added: Cc: stable@vger.kernel.org # v4.9+ Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/52396500f97c53860164debc7d4f75 cheers