Commit 2e2a441d authored Apr 08, 2021 by Madhavan Srinivasan Committed by Michael Ellerman Apr 14, 2021

powerpc/perf: Infrastructure to support checking of attr.config*



Introduce code to support the checking of attr.config* for
values which are reserved for a given platform.
Performance Monitoring Unit (PMU) configuration registers
have fields that are reserved and some specific values for
bit fields are reserved. For ex., MMCRA[61:62] is
Random Sampling Mode (SM) and value of 0b11 for this field
is reserved.

Writing non-zero or invalid values in these fields will
have unknown behaviours.

Patch adds a generic call-back function "check_attr_config"
in "struct power_pmu", to be called in event_init to
check for attr.config* values for a given platform.

Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210408074504.248211-1-maddy@linux.ibm.com

parent 59fd366b

arch/powerpc/include/asm/perf_event_server.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -67,6 +67,12 @@ struct power_pmu {
		* the pmu supports extended perf regs capability
		*/
		int capabilities;
		/*
		* Function to check event code for values which are
		* reserved. Function takes struct perf_event as input,
		* since event code could be spread in attr.config*
		*/
		int (check_attr_config)(struct perf_event ev);
		};

		/*

arch/powerpc/perf/core-book3s.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -1963,6 +1963,17 @@ static int power_pmu_event_init(struct perf_event *event)
		return -ENOENT;
		}

		/*
		* PMU config registers have fields that are
		* reserved and some specific values for bit fields are reserved.
		* For ex., MMCRA[61:62] is Randome Sampling Mode (SM)
		* and value of 0b11 to this field is reserved.
		* Check for invalid values in attr.config.
		*/
		if (ppmu->check_attr_config &&
		ppmu->check_attr_config(event))
		return -EINVAL;

		event->hw.config_base = ev;
		event->hw.idx = 0;