Re: [PATCH v5 17/21] powerpc/64: entry cpu time accounting in C

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Christophe Leroy's message of January 14, 2021 1:05 am:
> 
> 
> Le 13/01/2021 à 08:32, Nicholas Piggin a écrit :
>> There is no need for this to be in asm, use the new intrrupt entry wrapper.
>> 
>> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>> ---
>>   arch/powerpc/include/asm/interrupt.h |  7 +++++++
>>   arch/powerpc/include/asm/ppc_asm.h   | 24 ------------------------
>>   arch/powerpc/kernel/exceptions-64e.S |  1 -
>>   arch/powerpc/kernel/exceptions-64s.S |  5 -----
>>   4 files changed, 7 insertions(+), 30 deletions(-)
>> 
>> diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
>> index 6eba7c489753..e278dffe7657 100644
>> --- a/arch/powerpc/include/asm/interrupt.h
>> +++ b/arch/powerpc/include/asm/interrupt.h
>> @@ -4,6 +4,7 @@
>>   
>>   #include <linux/context_tracking.h>
>>   #include <linux/hardirq.h>
>> +#include <asm/cputime.h>
>>   #include <asm/ftrace.h>
>>   
>>   struct interrupt_state {
>> @@ -25,6 +26,9 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
>>   	if (user_mode(regs)) {
>>   		CT_WARN_ON(ct_state() != CONTEXT_USER);
>>   		user_exit_irqoff();
>> +
>> +		account_cpu_user_entry();
> 
> Are interrupts still disabled here ? Otherwise you risk getting IRQ time accounted on user.

Yes. Only the handlers themselves will enable interrupts, with
interrupt_cond_local_irq_enable.

> 
>> +		account_stolen_time();
>>   	} else {
>>   		/*
>>   		 * CT_WARN_ON comes here via program_check_exception,
>> @@ -38,6 +42,9 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
>>   #ifdef CONFIG_PPC_BOOK3E_64
>>   	state->ctx_state = exception_enter();
>>   #endif
>> +
>> +	if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) && user_mode(regs))
>> +		account_cpu_user_entry();
> 
> Isn't this interrupt_enter_prepare() function called also on PPC32 ?
> Have you removed the ACCOUNT_CPU_USER_ENTRY() from entry_32.S ?

Yes and no, I was thinking of 64 only :( I can make that for 64E. 32-bit
could be another patch if you want it.

Thanks,
Nick