From 52396500f97c53860164debc7d4f759077853423 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Fri, 23 Mar 2018 15:53:38 +1000 Subject: [PATCH] powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs 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 Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/exceptions-64s.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 3ac87e5..1ecfd8f 100644 --- 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 -- 2.7.4