From: Nicholas Piggin npiggin@gmail.com
commit 7100e8704b61247649c50551b965e71d168df30b upstream.
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 anton@samba.org Signed-off-by: Nicholas Piggin npiggin@gmail.com Reviewed-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.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 | 12 ++++++++++++ 1 file changed, 12 insertions(+)
--- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -612,11 +612,17 @@ 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) @@ -661,11 +667,17 @@ EXC_COMMON_BEGIN(instruction_access_slb_ 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)