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SubjectRe: [PATCH v2 36/43] powerpc/32: Set current->thread.regs in C interrupt entry
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Le 10/03/2021 à 02:33, Nicholas Piggin a écrit :
> Excerpts from Christophe Leroy's message of March 9, 2021 10:10 pm:
>> No need to do that is assembly, do it in C.
>
> Hmm. No issues with the patch as such, but why does ppc32 need this but
> not 64? AFAIKS 64 sets this when a thread is created.

Looks like ppc64 was doing the same in function save_remaining_regs() in arch/ppc64/kernel/head.S
until commit https://github.com/mpe/linux-fullhistory/commit/e5bb080d

But I can't find what happend to it in that commit.

Where is it done now ? Maybe that's also already done for ppc32.

Thanks
Christophe


>
> Thanks,
> Nick
>
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>> arch/powerpc/include/asm/interrupt.h | 4 +++-
>> arch/powerpc/kernel/entry_32.S | 3 +--
>> 2 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
>> index 861e6eadc98c..e6d71c2e3aa2 100644
>> --- a/arch/powerpc/include/asm/interrupt.h
>> +++ b/arch/powerpc/include/asm/interrupt.h
>> @@ -33,8 +33,10 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
>> if (!arch_irq_disabled_regs(regs))
>> trace_hardirqs_off();
>>
>> - if (user_mode(regs))
>> + if (user_mode(regs)) {
>> + current->thread.regs = regs;
>> account_cpu_user_entry();
>> + }
>> #endif
>> /*
>> * Book3E reconciles irq soft mask in asm
>> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
>> index 8fe1c3fdfa6e..815a4ff1ba76 100644
>> --- a/arch/powerpc/kernel/entry_32.S
>> +++ b/arch/powerpc/kernel/entry_32.S
>> @@ -52,8 +52,7 @@
>> prepare_transfer_to_handler:
>> andi. r0,r9,MSR_PR
>> addi r12, r2, THREAD
>> - beq 2f /* if from user, fix up THREAD.regs */
>> - stw r3,PT_REGS(r12)
>> + beq 2f
>> #ifdef CONFIG_PPC_BOOK3S_32
>> kuep_lock r11, r12
>> #endif
>> --
>> 2.25.0
>>
>>

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