[PATCH v2 09/10] tools/perf: Add perf tools support for extended register capability in powerpc

[Athira Rajeev]

> On 08-Jul-2020, at 5:34 PM, Michael Ellerman <mpe at ellerman.id.au> wrote:
> 
> Athira Rajeev <atrajeev at linux.vnet.ibm.com <mailto:atrajeev at linux.vnet.ibm.com>> writes:
>> From: Anju T Sudhakar <anju at linux.vnet.ibm.com>
>> 
>> Add extended regs to sample_reg_mask in the tool side to use
>> with `-I?` option. Perf tools side uses extended mask to display
>> the platform supported register names (with -I? option) to the user
>> and also send this mask to the kernel to capture the extended registers
>> in each sample. Hence decide the mask value based on the processor
>> version.
>> 
>> Signed-off-by: Anju T Sudhakar <anju at linux.vnet.ibm.com>
>> [Decide extended mask at run time based on platform]
>> Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
>> Reviewed-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> 
> Will need an ack from perf tools folks, who are not on Cc by the looks.
> 
>> diff --git a/tools/arch/powerpc/include/uapi/asm/perf_regs.h b/tools/arch/powerpc/include/uapi/asm/perf_regs.h
>> index f599064..485b1d5 100644
>> --- a/tools/arch/powerpc/include/uapi/asm/perf_regs.h
>> +++ b/tools/arch/powerpc/include/uapi/asm/perf_regs.h
>> @@ -48,6 +48,18 @@ enum perf_event_powerpc_regs {
>> 	PERF_REG_POWERPC_DSISR,
>> 	PERF_REG_POWERPC_SIER,
>> 	PERF_REG_POWERPC_MMCRA,
>> -	PERF_REG_POWERPC_MAX,
>> +	/* Extended registers */
>> +	PERF_REG_POWERPC_MMCR0,
>> +	PERF_REG_POWERPC_MMCR1,
>> +	PERF_REG_POWERPC_MMCR2,
>> +	/* Max regs without the extended regs */
>> +	PERF_REG_POWERPC_MAX = PERF_REG_POWERPC_MMCRA + 1,
> 
> I don't really understand this idea of a max that's not the max.

Hi Michael

This is the MAX without extended regs. This is mainly used in `arch/powerpc/perf/perf_regs.c` to define pt_regs_offset ( to get index
for other regs ) and also is used to determine whether requested register is an extended reg while capturing data in sample
( in `perf_reg_value` )

Thanks
Athira

> 
>> };
>> +
>> +#define PERF_REG_PMU_MASK	((1ULL << PERF_REG_POWERPC_MAX) - 1)
>> +
>> +/* PERF_REG_EXTENDED_MASK value for CPU_FTR_ARCH_300 */
>> +#define PERF_REG_PMU_MASK_300   (((1ULL << (PERF_REG_POWERPC_MMCR2 + 1)) - 1) \
>> +				- PERF_REG_PMU_MASK)
>> +
>> #endif /* _UAPI_ASM_POWERPC_PERF_REGS_H */
>> diff --git a/tools/perf/arch/powerpc/include/perf_regs.h b/tools/perf/arch/powerpc/include/perf_regs.h
>> index e18a355..46ed00d 100644
>> --- a/tools/perf/arch/powerpc/include/perf_regs.h
>> +++ b/tools/perf/arch/powerpc/include/perf_regs.h
>> @@ -64,7 +64,10 @@
>> 	[PERF_REG_POWERPC_DAR] = "dar",
>> 	[PERF_REG_POWERPC_DSISR] = "dsisr",
>> 	[PERF_REG_POWERPC_SIER] = "sier",
>> -	[PERF_REG_POWERPC_MMCRA] = "mmcra"
>> +	[PERF_REG_POWERPC_MMCRA] = "mmcra",
>> +	[PERF_REG_POWERPC_MMCR0] = "mmcr0",
>> +	[PERF_REG_POWERPC_MMCR1] = "mmcr1",
>> +	[PERF_REG_POWERPC_MMCR2] = "mmcr2",
>> };
>> 
>> static inline const char *perf_reg_name(int id)
>> diff --git a/tools/perf/arch/powerpc/util/perf_regs.c b/tools/perf/arch/powerpc/util/perf_regs.c
>> index 0a52429..9179230 100644
>> --- a/tools/perf/arch/powerpc/util/perf_regs.c
>> +++ b/tools/perf/arch/powerpc/util/perf_regs.c
>> @@ -6,9 +6,14 @@
>> 
>> #include "../../../util/perf_regs.h"
>> #include "../../../util/debug.h"
>> +#include "../../../util/event.h"
>> +#include "../../../util/header.h"
>> +#include "../../../perf-sys.h"
>> 
>> #include <linux/kernel.h>
>> 
>> +#define PVR_POWER9		0x004E
>> +
>> const struct sample_reg sample_reg_masks[] = {
>> 	SMPL_REG(r0, PERF_REG_POWERPC_R0),
>> 	SMPL_REG(r1, PERF_REG_POWERPC_R1),
>> @@ -55,6 +60,9 @@
>> 	SMPL_REG(dsisr, PERF_REG_POWERPC_DSISR),
>> 	SMPL_REG(sier, PERF_REG_POWERPC_SIER),
>> 	SMPL_REG(mmcra, PERF_REG_POWERPC_MMCRA),
>> +	SMPL_REG(mmcr0, PERF_REG_POWERPC_MMCR0),
>> +	SMPL_REG(mmcr1, PERF_REG_POWERPC_MMCR1),
>> +	SMPL_REG(mmcr2, PERF_REG_POWERPC_MMCR2),
>> 	SMPL_REG_END
>> };
>> 
>> @@ -163,3 +171,50 @@ int arch_sdt_arg_parse_op(char *old_op, char **new_op)
>> 
>> 	return SDT_ARG_VALID;
>> }
>> +
>> +uint64_t arch__intr_reg_mask(void)
>> +{
>> +	struct perf_event_attr attr = {
>> +		.type                   = PERF_TYPE_HARDWARE,
>> +		.config                 = PERF_COUNT_HW_CPU_CYCLES,
>> +		.sample_type            = PERF_SAMPLE_REGS_INTR,
>> +		.precise_ip             = 1,
>> +		.disabled               = 1,
>> +		.exclude_kernel         = 1,
>> +	};
>> +	int fd, ret;
>> +	char buffer[64];
>> +	u32 version;
>> +	u64 extended_mask = 0;
>> +
>> +	/* Get the PVR value to set the extended
>> +	 * mask specific to platform
> 
> Comment format is wrong, and punctuation please.
> 
>> +	 */
>> +	get_cpuid(buffer, sizeof(buffer));
>> +	ret = sscanf(buffer, "%u,", &version);
> 
> This is powerpc specific code, why not just use mfspr(SPRN_PVR), rather
> than redirecting via printf/sscanf.
> 
>> +
>> +	if (ret != 1) {
>> +		pr_debug("Failed to get the processor version, unable to output extended registers\n");
>> +		return PERF_REGS_MASK;
>> +	}
>> +
>> +	if (version == PVR_POWER9)
>> +		extended_mask = PERF_REG_PMU_MASK_300;
>> +	else
>> +		return PERF_REGS_MASK;
>> +
>> +	attr.sample_regs_intr = extended_mask;
>> +	attr.sample_period = 1;
>> +	event_attr_init(&attr);
>> +
>> +	/*
>> +	 * check if the pmu supports perf extended regs, before
>> +	 * returning the register mask to sample.
>> +	 */
>> +	fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
>> +	if (fd != -1) {
>> +		close(fd);
>> +		return (extended_mask | PERF_REGS_MASK);
>> +	}
>> +	return PERF_REGS_MASK;
> 
> I think this would read a bit better like:
> 
> 	mask = PERF_REGS_MASK;
> 
> 	if (version == PVR_POWER9)
> 		extended_mask = PERF_REG_PMU_MASK_300;
>        else
>        	return mask;
> 
>        attr.sample_regs_intr = extended_mask;
>        attr.sample_period = 1;
>        event_attr_init(&attr);
> 
>        /*
>          * check if the pmu supports perf extended regs, before
>          * returning the register mask to sample.
>          */
>        fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
>        if (fd != -1) {
>                close(fd);
>                mask |= extended_mask;
>        }
> 
> 	return mask;
> 
> 
> cheers

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