* [PATCH] powerpc/64s/radix: Fix radix segment exception handling
@ 2019-03-29 7:42 Nicholas Piggin
2019-03-30 5:58 ` Aneesh Kumar K.V
2019-04-10 14:49 ` Michael Ellerman
0 siblings, 2 replies; 6+ messages in thread
From: Nicholas Piggin @ 2019-03-29 7:42 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Aneesh Kumar K . V, Nicholas Piggin, Anton Blanchard
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: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Nicholas Piggin <npiggin@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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] powerpc/64s/radix: Fix radix segment exception handling
2019-03-29 7:42 [PATCH] powerpc/64s/radix: Fix radix segment exception handling Nicholas Piggin
@ 2019-03-30 5:58 ` Aneesh Kumar K.V
2019-04-10 14:49 ` Michael Ellerman
1 sibling, 0 replies; 6+ messages in thread
From: Aneesh Kumar K.V @ 2019-03-30 5:58 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Cc: Aneesh Kumar K . V, Nicholas Piggin, Anton Blanchard
Nicholas Piggin <npiggin@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.kumar@linux.ibm.com>
> Fixes: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Reported-by: Anton Blanchard <anton@samba.org>
> Signed-off-by: Nicholas Piggin <npiggin@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
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: powerpc/64s/radix: Fix radix segment exception handling
2019-03-29 7:42 [PATCH] powerpc/64s/radix: Fix radix segment exception handling Nicholas Piggin
2019-03-30 5:58 ` Aneesh Kumar K.V
@ 2019-04-10 14:49 ` Michael Ellerman
2019-04-12 3:35 ` Nicholas Piggin
1 sibling, 1 reply; 6+ messages in thread
From: Michael Ellerman @ 2019-04-10 14:49 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev
Cc: Aneesh Kumar K . V, Nicholas Piggin, Anton Blanchard
On Fri, 2019-03-29 at 07:42:57 UTC, Nicholas Piggin wrote:
> 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: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> 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>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/7100e8704b61247649c50551b965e71d
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: powerpc/64s/radix: Fix radix segment exception handling
2019-04-10 14:49 ` Michael Ellerman
@ 2019-04-12 3:35 ` Nicholas Piggin
2019-04-13 3:39 ` Michael Ellerman
0 siblings, 1 reply; 6+ messages in thread
From: Nicholas Piggin @ 2019-04-12 3:35 UTC (permalink / raw)
To: linuxppc-dev, Michael Ellerman; +Cc: Aneesh Kumar K . V, Anton Blanchard
Michael Ellerman's on April 11, 2019 12:49 am:
> On Fri, 2019-03-29 at 07:42:57 UTC, Nicholas Piggin wrote:
>> 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: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
>> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>> 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>
>
> Applied to powerpc fixes, thanks.
>
> https://git.kernel.org/powerpc/c/7100e8704b61247649c50551b965e71d
I sent a v2 with a selftests that triggers the crash if you want it.
Code was unchanged to no big deal there.
Thanks,
Nick
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: powerpc/64s/radix: Fix radix segment exception handling
2019-04-12 3:35 ` Nicholas Piggin
@ 2019-04-13 3:39 ` Michael Ellerman
2019-04-13 5:59 ` Nicholas Piggin
0 siblings, 1 reply; 6+ messages in thread
From: Michael Ellerman @ 2019-04-13 3:39 UTC (permalink / raw)
To: Nicholas Piggin, linuxppc-dev, Michael Ellerman
Cc: Aneesh Kumar K . V, Anton Blanchard
Nicholas Piggin <npiggin@gmail.com> writes:
> Michael Ellerman's on April 11, 2019 12:49 am:
>> On Fri, 2019-03-29 at 07:42:57 UTC, Nicholas Piggin wrote:
>>> 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: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
>>> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>>> 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>
>>
>> Applied to powerpc fixes, thanks.
>>
>> https://git.kernel.org/powerpc/c/7100e8704b61247649c50551b965e71d
>
> I sent a v2 with a selftests that triggers the crash if you want it.
> Code was unchanged to no big deal there.
Yeah I checked the kernel part was unchanged so stuck with v1.
I also sent a self test, which is similar but slightly different to
yours, though yours is better in general. I'll try and merge them into
one test.
cheers
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: powerpc/64s/radix: Fix radix segment exception handling
2019-04-13 3:39 ` Michael Ellerman
@ 2019-04-13 5:59 ` Nicholas Piggin
0 siblings, 0 replies; 6+ messages in thread
From: Nicholas Piggin @ 2019-04-13 5:59 UTC (permalink / raw)
To: linuxppc-dev, Michael Ellerman, Michael Ellerman
Cc: Aneesh Kumar K . V, Anton Blanchard
Michael Ellerman's on April 13, 2019 1:39 pm:
> Nicholas Piggin <npiggin@gmail.com> writes:
>> Michael Ellerman's on April 11, 2019 12:49 am:
>>> On Fri, 2019-03-29 at 07:42:57 UTC, Nicholas Piggin wrote:
>>>> 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: 48e7b76957 ("powerpc/64s/hash: Convert SLB miss handlers to C")
>>>> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>>>> 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>
>>>
>>> Applied to powerpc fixes, thanks.
>>>
>>> https://git.kernel.org/powerpc/c/7100e8704b61247649c50551b965e71d
>>
>> I sent a v2 with a selftests that triggers the crash if you want it.
>> Code was unchanged to no big deal there.
>
> Yeah I checked the kernel part was unchanged so stuck with v1.
>
> I also sent a self test, which is similar but slightly different to
> yours, though yours is better in general. I'll try and merge them into
> one test.
If you don't mind that would be good. The siglongjmp handler is
cleaner though, and should make it simpler to test ifetch accesses.
We just need to get the sig info into yours, and an array of
interesting addresses.
Thanks,
Nick
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-04-13 6:01 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-03-29 7:42 [PATCH] powerpc/64s/radix: Fix radix segment exception handling Nicholas Piggin
2019-03-30 5:58 ` Aneesh Kumar K.V
2019-04-10 14:49 ` Michael Ellerman
2019-04-12 3:35 ` Nicholas Piggin
2019-04-13 3:39 ` Michael Ellerman
2019-04-13 5:59 ` Nicholas Piggin
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