From 7100e8704b61247649c50551b965e71d168df30b Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Fri, 29 Mar 2019 17:42:57 +1000 Subject: [PATCH] powerpc/64s/radix: Fix radix segment exception handling Commit 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C") broke the radix-mode segment exception handler. In radix mode, this is exception is not an SLB miss, rather it signals that the EA is outside the range translated by any page table. The commit lost the radix feature alternate code patch, which can cause faults to some EAs to kernel BUG at arch/powerpc/mm/slb.c:639! The original radix code would send faults to slb_miss_large_addr, which would end up faulting due to slb_addr_limit being 0. This patch sends radix directly to do_bad_slb_fault, which is a bit clearer. Fixes: 48e7b7695745 ("powerpc/64s/hash: Convert SLB miss handlers to C") Cc: stable@vger.kernel.org # v4.20+ Reported-by: Anton Blanchard Signed-off-by: Nicholas Piggin Reviewed-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/exceptions-64s.S | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index a5b8fbae56a0..9481a117e242 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -656,11 +656,17 @@ EXC_COMMON_BEGIN(data_access_slb_common) ld r4,PACA_EXSLB+EX_DAR(r13) std r4,_DAR(r1) addi r3,r1,STACK_FRAME_OVERHEAD +BEGIN_MMU_FTR_SECTION + /* HPT case, do SLB fault */ bl do_slb_fault cmpdi r3,0 bne- 1f b fast_exception_return 1: /* Error case */ +MMU_FTR_SECTION_ELSE + /* Radix case, access is outside page table range */ + li r3,-EFAULT +ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX) std r3,RESULT(r1) bl save_nvgprs RECONCILE_IRQ_STATE(r10, r11) @@ -705,11 +711,17 @@ EXC_COMMON_BEGIN(instruction_access_slb_common) EXCEPTION_PROLOG_COMMON(0x480, PACA_EXSLB) ld r4,_NIP(r1) addi r3,r1,STACK_FRAME_OVERHEAD +BEGIN_MMU_FTR_SECTION + /* HPT case, do SLB fault */ bl do_slb_fault cmpdi r3,0 bne- 1f b fast_exception_return 1: /* Error case */ +MMU_FTR_SECTION_ELSE + /* Radix case, access is outside page table range */ + li r3,-EFAULT +ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX) std r3,RESULT(r1) bl save_nvgprs RECONCILE_IRQ_STATE(r10, r11)