Excerpts from Christophe Leroy's message of September 7, 2020 9:34 pm:
> On Mon, 2020-09-07 at 11:20 +0200, Christophe Leroy wrote:
>>
>> Le 05/09/2020 à 19:43, Nicholas Piggin a écrit :
>> > Make interrupt handlers all just take the pt_regs * argument and load
>> > DAR/DSISR etc from that. Make those that return a value return long.
>>
>> I like this, it will likely simplify a bit the VMAP_STACK mess.
>>
>> Not sure it is that easy. My board is stuck after the start of init.
>>
>>
>> On the 8xx, on Instruction TLB Error exception, we do
>>
>> andis. r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
>>
>> On book3s/32, on ISI exception we do:
>> andis. r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
>>
>> On 40x and bookE, on ISI exception we do:
>> li r5,0 /* Pass zero as arg3 */
>>
>>
>> And regs->dsisr will just contain nothing
>>
>> So it means we should at least write back r5 into regs->dsisr from there
>> ? The performance impact should be minimal as we already write _DAR so
>> the cache line should already be in the cache.
>>
>> A hacky 'stw r5, _DSISR(r1)' in handle_page_fault() does the trick,
>> allthough we don't want to do it for both ISI and DSI at the end, so
>> you'll have to do it in every head_xxx.S
>
> To get you series build and work, I did the following hacks:
Great, thanks for this.
> diff --git a/arch/powerpc/include/asm/interrupt.h
> b/arch/powerpc/include/asm/interrupt.h
> index acfcc7d5779b..c11045d3113a 100644
> --- a/arch/powerpc/include/asm/interrupt.h
> +++ b/arch/powerpc/include/asm/interrupt.h
> @@ -93,7 +93,9 @@ static inline void interrupt_nmi_exit_prepare(struct
> pt_regs *regs, struct inter
> {
> nmi_exit();
>
> +#ifdef CONFIG_PPC64
> this_cpu_set_ftrace_enabled(state->ftrace_enabled);
> +#endif
This seems okay, not a hack.
> #ifdef CONFIG_PPC_BOOK3S_64
> /* Check we didn't change the pending interrupt mask. */
> diff --git a/arch/powerpc/kernel/entry_32.S
> b/arch/powerpc/kernel/entry_32.S
> index f4d0af8e1136..66f7adbe1076 100644
> --- a/arch/powerpc/kernel/entry_32.S
> +++ b/arch/powerpc/kernel/entry_32.S
> @@ -663,6 +663,7 @@ ppc_swapcontext:
> */
> .globl handle_page_fault
> handle_page_fault:
> + stw r5,_DSISR(r1)
> addi r3,r1,STACK_FRAME_OVERHEAD
> #ifdef CONFIG_PPC_BOOK3S_32
> andis. r0,r5,DSISR_DABRMATCH@h
Is this what you want to do for 32, or do you want to seperate
ISI and DSI sides?
Thanks,
Nick
