Nicholas Piggin <npig...@gmail.com> writes:
> 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.
>
Reviewed-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
> Fixes: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
> Cc: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> Reported-by: Anton Blanchard <an...@samba.org>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> 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)
> --
> 2.20.1
