Re: powerpc/64s: Fix hypercall entry clobbering r12 input
From: Michael Ellerman <hidden>
Date: 2017-07-21 11:13:06
On Tue, 2017-07-18 at 05:32:44 UTC, Nicholas Piggin wrote:
A previous optimisation incorrectly assumed the PAPR hcall does
not use r12, and clobbers it upon entry. In fact it is used as
an input. This can result in KVM guests crashing (observed with
PR KVM).
Instead of using r12 to save r13, tihs patch saves r13 in ctr.
This is more costly, but not as slow as using the SPRG.
Fixes: acd7d8cef0153 ("powerpc/64s: Optimize hypercall/syscall entry")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/76fc0cfcc5b0f520062ca6d7225b22 cheers