This is a note to let you know that I've just added the patch titled

powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: powerpc-64s-fix-i-side-slb-miss-bad-address-handler-saving-nonvolatile-gprs.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 52396500f97c53860164debc7d4f759077853423 Mon Sep 17 00:00:00 2001

From: Nicholas Piggin npiggin@gmail.com Date: Fri, 23 Mar 2018 15:53:38 +1000 Subject: powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs

From: Nicholas Piggin npiggin@gmail.com

commit 52396500f97c53860164debc7d4f759077853423 upstream.

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: f0f558b131db ("powerpc/mm: Preserve CFAR value on SLB miss caused by access to bogus address") Cc: stable@vger.kernel.org # v4.9+ Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/powerpc/kernel/exceptions-64s.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -706,7 +706,7 @@ EXC_COMMON_BEGIN(bad_addr_slb) ld r3, PACA_EXSLB+EX_DAR(r13) std r3, _DAR(r1) beq cr6, 2f - li r10, 0x480 /* fix trap number for I-SLB miss */ + li r10, 0x481 /* fix trap number for I-SLB miss */ std r10, _TRAP(r1) 2: bl save_nvgprs addi r3, r1, STACK_FRAME_OVERHEAD

Patches currently in stable-queue which might be from npiggin@gmail.com are

queue-4.15/powerpc-64s-fix-lost-pending-interrupt-due-to-race-causing-lost-update-to-irq_happened.patch queue-4.15/powerpc-64s-fix-i-side-slb-miss-bad-address-handler-saving-nonvolatile-gprs.patch