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

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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
This commit is contained in:
Madhavan Srinivasan
2021-04-08 13:15:03 +05:30
committed by Michael Ellerman
parent 59fd366b9b
commit 2e2a441d2c
2 changed files with 17 additions and 0 deletions
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11
arch/powerpc/perf/core-book3s.c
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@@ -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;