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SubjectRe: [PATCH v3 03/21] powerpc/8xx: exception InstructionAccess does not exist on MPC8xx

Le 18/09/2014 17:15, Joakim Tjernlund a écrit :
> Christophe Leroy <christophe.leroy@c-s.fr> wrote on 2014/09/17 18:36:57:
>> Exception InstructionAccess does not exist on MPC8xx. No need to branch
> there from somewhere else.
>> Handling can be done directly in InstructionTLBError Exception.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>>
>> ---
>> Changes in v2:
>> - None
>>
>> Changes in v3:
>> - arch/powerpc/mm/fault.c uses the vector number, so make sure it
> understand
>> the new ones.
>>
>> arch/powerpc/kernel/head_8xx.S | 17 +++++++----------
>> arch/powerpc/mm/fault.c | 1 +
>> 2 files changed, 8 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/head_8xx.S
> b/arch/powerpc/kernel/head_8xx.S
>> index 3af6db1..fbe5d10 100644
>> --- a/arch/powerpc/kernel/head_8xx.S
>> +++ b/arch/powerpc/kernel/head_8xx.S
>> @@ -234,15 +234,9 @@ DataAccess:
>> EXC_XFER_LITE(0x300, handle_page_fault)
>>
>> /* Instruction access exception.
>> - * This is "never generated" by the MPC8xx. We jump to it for other
>> - * translation errors.
>> + * This is "never generated" by the MPC8xx.
>> */
>> - . = 0x400
>> -InstructionAccess:
>> - EXCEPTION_PROLOG
>> - mr r4,r12
>> - mr r5,r9
>> - EXC_XFER_LITE(0x400, handle_page_fault)
>> + EXCEPTION(0x400, InstructionAccess, unknown_exception, EXC_XFER_STD)
>>
>> /* External interrupt */
>> EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
>> @@ -382,7 +376,7 @@ InstructionTLBMiss:
>> #endif
>> mfspr r10, SPRN_SPRG_SCRATCH2
>> EXCEPTION_EPILOG_0
>> - b InstructionAccess
>> + b InstructionTLBError
>>
>> . = 0x1200
>> DataStoreTLBMiss:
>> @@ -477,7 +471,10 @@ DataStoreTLBMiss:
>> */
>> . = 0x1300
>> InstructionTLBError:
>> - b InstructionAccess
>> + EXCEPTION_PROLOG
>> + mr r4,r12
>> + mr r5,r9
>> + EXC_XFER_LITE(0x1300, handle_page_fault)
> Still don't like that you change the vector number, every other ppc uses
> the
> standard number.
>
> Can you not just lie here(EXC_XFER_LITE(0x400, handle_page_fault))?
> Move the code to InstructionAccess too and let TLBError branch there.
My issue was that if I do EXC_XFER_LITE(0x400, handle_page_fault), I
can't leave the
EXCEPTION(0x400, InstructionAccess, unknown_exception,
EXC_XFER_STD) at address .400
Otherwise, I get twice the same label.

What about the following patch then ? Would this be acceptable ?

@@ -234,15 +234,13 @@ DataAccess:
EXC_XFER_LITE(0x300, handle_page_fault)

/* Instruction access exception.
- * This is "never generated" by the MPC8xx. We jump to it for other
- * translation errors.
+ * This is "never generated" by the MPC8xx.
*/
. = 0x400
InstructionAccess:
EXCEPTION_PROLOG
- mr r4,r12
- mr r5,r9
- EXC_XFER_LITE(0x400, handle_page_fault)
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ EXC_XFER_STD(0x401, unknown_exception)

/* External interrupt */
EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
@@ -382,7 +380,7 @@ InstructionTLBMiss:
#endif
mfspr r10, SPRN_SPRG_SCRATCH2
EXCEPTION_EPILOG_0
- b InstructionAccess
+ b InstructionTLBError

. = 0x1200
DataStoreTLBMiss:
@@ -477,7 +475,11 @@ DataStoreTLBMiss:
*/
. = 0x1300
InstructionTLBError:
- b InstructionAccess
+ EXCEPTION_PROLOG
+ mr r4,r12
+ mr r5,r9
+ /* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
+ EXC_XFER_LITE(0x400, handle_page_fault)

/* This is the data TLB error on the MPC8xx. This could be due to
* many reasons, including a dirty update to a pte. We can catch that

>
> If not I think you should keep the old/current way?
>
> Same for DataTLB Miss/Error
>
>> /* This is the data TLB error on the MPC8xx. This could be due to
>> * many reasons, including a dirty update to a pte. We can catch that
>> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
>> index 51ab9e7..4d63c96 100644
>> --- a/arch/powerpc/mm/fault.c
>> +++ b/arch/powerpc/mm/fault.c
>> @@ -526,6 +526,7 @@ void bad_page_fault(struct pt_regs *regs, unsigned
> long address, int sig)
>> break;
>> case 0x400:
>> case 0x480:
>> + case 0x1300:
>> printk(KERN_ALERT "Unable to handle kernel paging request for "
>> "instruction fetch\n");
>> break;
>> --
>> 2.1.0
>>

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