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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
Bug: 427401803
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 Treehugger Robot
parent 22d634eb24
commit 273b788415
3 changed files with 39 additions and 0 deletions
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4
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -1541,6 +1541,10 @@
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.
early_page_ext [KNL,EARLY] Enforces page_ext initialization to earlier
stages so cover more early boot allocations.

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

@@ -286,6 +286,17 @@ 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
drivers/perf/arm_pmuv3.c
View File

@@ -325,6 +325,7 @@ GEN_PMU_FORMAT_ATTR(threshold_compare);
GEN_PMU_FORMAT_ATTR(threshold);
static int sysctl_perf_user_access __read_mostly;
static int sysctl_export_pmu_events __read_mostly;
static bool armv8pmu_event_is_64bit(struct perf_event *event)
{
@@ -1053,6 +1054,17 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
return 0;
}
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;
@@ -1077,6 +1089,9 @@ 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);
}
@@ -1280,6 +1295,15 @@ 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,
},
};
static void armv8_pmu_register_sysctl_table(void)