Re: [PATCH v2 10/10] powerpc/perf: Add extended regs support for power10 platform

[Athira Rajeev <atrajeev@linux.vnet.ibm.com>]

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> On 08-Jul-2020, at 5:34 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> 
> Athira Rajeev <atrajeev@linux.vnet.ibm.com <mailto:atrajeev@linux.vnet.ibm.com>> writes:
>> Include capability flag `PERF_PMU_CAP_EXTENDED_REGS` for power10
>> and expose MMCR3, SIER2, SIER3 registers as part of extended regs.
>> Also introduce `PERF_REG_PMU_MASK_31` to define extended mask
>> value at runtime for power10
>> 
>> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
>> ---
>> arch/powerpc/include/uapi/asm/perf_regs.h       |  6 ++++++
>> arch/powerpc/perf/perf_regs.c                   | 10 +++++++++-
>> arch/powerpc/perf/power10-pmu.c                 |  6 ++++++
>> tools/arch/powerpc/include/uapi/asm/perf_regs.h |  6 ++++++
>> tools/perf/arch/powerpc/include/perf_regs.h     |  3 +++
>> tools/perf/arch/powerpc/util/perf_regs.c        |  6 ++++++
> 
> Please split into a kernel patch and a tools patch. And cc the tools people.

Ok sure
> 
>> 6 files changed, 36 insertions(+), 1 deletion(-)
>> 
>> diff --git a/arch/powerpc/include/uapi/asm/perf_regs.h b/arch/powerpc/include/uapi/asm/perf_regs.h
>> index 485b1d5..020b51c 100644
>> --- a/arch/powerpc/include/uapi/asm/perf_regs.h
>> +++ b/arch/powerpc/include/uapi/asm/perf_regs.h
>> @@ -52,6 +52,9 @@ enum perf_event_powerpc_regs {
>> 	PERF_REG_POWERPC_MMCR0,
>> 	PERF_REG_POWERPC_MMCR1,
>> 	PERF_REG_POWERPC_MMCR2,
>> +	PERF_REG_POWERPC_MMCR3,
>> +	PERF_REG_POWERPC_SIER2,
>> +	PERF_REG_POWERPC_SIER3,
>> 	/* Max regs without the extended regs */
>> 	PERF_REG_POWERPC_MAX = PERF_REG_POWERPC_MMCRA + 1,
>> };
>> @@ -62,4 +65,7 @@ enum perf_event_powerpc_regs {
>> #define PERF_REG_PMU_MASK_300   (((1ULL << (PERF_REG_POWERPC_MMCR2 + 1)) - 1) \
>> 				- PERF_REG_PMU_MASK)
>> 
>> +/* PERF_REG_EXTENDED_MASK value for CPU_FTR_ARCH_31 */
>> +#define PERF_REG_PMU_MASK_31	(((1ULL << (PERF_REG_POWERPC_SIER3 + 1)) - 1) \
>> +				- PERF_REG_PMU_MASK)
> 
> Wrapping that provides no benefit, just let it be long.
> 

Ok,

>> #endif /* _UAPI_ASM_POWERPC_PERF_REGS_H */
>> diff --git a/arch/powerpc/perf/perf_regs.c b/arch/powerpc/perf/perf_regs.c
>> index c8a7e8c..c969935 100644
>> --- a/arch/powerpc/perf/perf_regs.c
>> +++ b/arch/powerpc/perf/perf_regs.c
>> @@ -81,6 +81,12 @@ static u64 get_ext_regs_value(int idx)
>> 		return mfspr(SPRN_MMCR1);
>> 	case PERF_REG_POWERPC_MMCR2:
>> 		return mfspr(SPRN_MMCR2);
>> +	case PERF_REG_POWERPC_MMCR3:
>> +			return mfspr(SPRN_MMCR3);
>> +	case PERF_REG_POWERPC_SIER2:
>> +			return mfspr(SPRN_SIER2);
>> +	case PERF_REG_POWERPC_SIER3:
>> +			return mfspr(SPRN_SIER3);
> 
> Indentation is wrong.
> 
>> 	default: return 0;
>> 	}
>> }
>> @@ -89,7 +95,9 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
>> {
>> 	u64 PERF_REG_EXTENDED_MAX;
>> 
>> -	if (cpu_has_feature(CPU_FTR_ARCH_300))
>> +	if (cpu_has_feature(CPU_FTR_ARCH_31))
>> +		PERF_REG_EXTENDED_MAX = PERF_REG_POWERPC_SIER3 + 1;
> 
> There's no way to know if that's correct other than going back to the
> header to look at the list of values.
> 
> So instead you should define it in the header, next to the other values,
> with a meaningful name, like PERF_REG_MAX_ISA_31 or something.
> 
>> +	else if (cpu_has_feature(CPU_FTR_ARCH_300))
>> 		PERF_REG_EXTENDED_MAX = PERF_REG_POWERPC_MMCR2 + 1;
> 
> Same.
> 

Ok, will make this change

>> 	if (idx == PERF_REG_POWERPC_SIER &&
>> diff --git a/arch/powerpc/perf/power10-pmu.c b/arch/powerpc/perf/power10-pmu.c
>> index 07fb919..51082d6 100644
>> --- a/arch/powerpc/perf/power10-pmu.c
>> +++ b/arch/powerpc/perf/power10-pmu.c
>> @@ -86,6 +86,8 @@
>> #define POWER10_MMCRA_IFM3		0x00000000C0000000UL
>> #define POWER10_MMCRA_BHRB_MASK		0x00000000C0000000UL
>> 
>> +extern u64 mask_var;
> 
> Why is it extern? Also not a good name for a global.
> 
> Hang on, it's not even used? Is there some macro magic somewhere?

This is defined in patch 8 "powerpc/perf: Add support for outputting extended regs in perf intr_regs”, 
which adds the base support for extended regs in powerpc. Current patch covers changes to support
It for power10. 

`mask_var` is used to define `PERF_REG_EXTENDED_MASK` at run time. 
`PERF_REG_EXTENDED_MASK` basically contains mask value of supported extended registers.
And since supported registers may differ between processor versions, we are defining this mask at runtime.

The #define is done in arch/powerpc/include/asm/perf_event_server.h ( in patch 8 ).
In the PMU driver init, we will set the respective mask value ( in the below code ). Hence it is extern

Sorry for the confusion here. 

Thanks
Athira

> 
>> /* Table of alternatives, sorted by column 0 */
>> static const unsigned int power10_event_alternatives[][MAX_ALT] = {
>> 	{ PM_RUN_CYC_ALT,		PM_RUN_CYC },
>> @@ -397,6 +399,7 @@ static void power10_config_bhrb(u64 pmu_bhrb_filter)
>> 	.cache_events		= &power10_cache_events,
>> 	.attr_groups		= power10_pmu_attr_groups,
>> 	.bhrb_nr		= 32,
>> +	.capabilities           = PERF_PMU_CAP_EXTENDED_REGS,
>> };
>> 
>> int init_power10_pmu(void)
>> @@ -408,6 +411,9 @@ int init_power10_pmu(void)
>> 	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power10"))
>> 		return -ENODEV;
>> 
>> +	/* Set the PERF_REG_EXTENDED_MASK here */
>> +	mask_var = PERF_REG_PMU_MASK_31;
>> +
>> 	rc = register_power_pmu(&power10_pmu);
>> 	if (rc)
>> 		return rc;
> 
> 
> cheers


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