Patch "powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs" has been added to the 4.15-stable tree

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;a=summary

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 <[email protected]> know about it.

From: Nicholas Piggin <[email protected]>
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 <[email protected]>

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.

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

@@ -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 [email protected] 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