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FROMLIST: arm64: perf: Make exporting of pmu events configurable

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The PMU export bit (PMCR_EL0.X) is getting reset during pmu reset,
Make is configurable using sysctls to enable/disable at runtime.
It can also be enabled at early bootup with kernel arguments.

Bug: 230559577
Change-Id: I35dcfeed23e64ec9493f9a15dbb43e9966108664
Link: https://lore.kernel.org/lkml/1653306574-20946-1-git-send-email-quic_c_spathi@quicinc.com/
Signed-off-by: Srinivasarao Pathipati <quic_spathi@quicinc.com>
This commit is contained in:
Srinivasarao Pathipati
2022-05-31 17:07:24 +05:30
committed by Carlos Llamas
parent bb964d6864
commit 031e91e83d
3 changed files with 39 additions and 0 deletions
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4
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -1400,6 +1400,10 @@
Format: { "fix" }
Permit 'security.evm' to be updated regardless of
current integrity status.
export_pmu_events
[KNL,ARM64] Sets the PMU export bit (PMCR_EL0.X), which enables
the exporting of events over an IMPLEMENTATION DEFINED PMU event
export bus to another device.
failslab=
fail_usercopy=

11
Documentation/admin-guide/sysctl/kernel.rst
View File

@@ -267,6 +267,17 @@ domain names are in general different. For a detailed discussion
see the ``hostname(1)`` man page.
export_pmu_events (arm64 only)
==============================
Controls the PMU export bit (PMCR_EL0.X), which enables the exporting of
events over an IMPLEMENTATION DEFINED PMU event export bus to another device.
0: disables exporting of events (default).
1: enables exporting of events.
firmware_config
===============

24
arch/arm64/kernel/perf_event.c
View File

@@ -287,6 +287,7 @@ PMU_FORMAT_ATTR(event, "config:0-15");
PMU_FORMAT_ATTR(long, "config1:0");
static int sysctl_perf_user_access __read_mostly;
static int sysctl_export_pmu_events __read_mostly;
static inline bool armv8pmu_event_is_64bit(struct perf_event *event)
{
@@ -955,6 +956,17 @@ static int armv8pmu_filter_match(struct perf_event *event)
return evtype != ARMV8_PMUV3_PERFCTR_CHAIN;
}
static int __init export_pmu_events(char *str)
{
/* Enable exporting of pmu events at early bootup with kernel
* arguments.
*/
sysctl_export_pmu_events = 1;
return 0;
}
early_param("export_pmu_events", export_pmu_events);
static void armv8pmu_reset(void *info)
{
struct arm_pmu *cpu_pmu = (struct arm_pmu *)info;
@@ -977,6 +989,9 @@ static void armv8pmu_reset(void *info)
if (armv8pmu_has_long_event(cpu_pmu))
pmcr |= ARMV8_PMU_PMCR_LP;
if (sysctl_export_pmu_events)
pmcr |= ARMV8_PMU_PMCR_X;
armv8pmu_pmcr_write(pmcr);
}
@@ -1116,6 +1131,15 @@ static struct ctl_table armv8_pmu_sysctl_table[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{
.procname = "export_pmu_events",
.data = &sysctl_export_pmu_events,
.maxlen = sizeof(unsigned int),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
{ }
};