From 1dffed71ef3650c8ff7d30a7058047bfaef1e5e6 Mon Sep 17 00:00:00 2001
From: Like Xu <like.xu@linux.intel.com>
Date: Tue, 27 Sep 2022 14:56:47 +0800
Subject: [PATCH] perf/core: Provide a kernel-internal interface to recalibrate
event period
mainline inclusion
from mainline-v5.4
commit 3ca270fc9edb258d5bfa271bcf851614e9e6e7d4
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5SDUS
CVE: NA
-------------
Currently, perf_event_period() is used by user tools via ioctl. Based on
naming convention, exporting perf_event_period() for kernel users (such
as KVM) who may recalibrate the event period for their assigned counter
according to their requirements.
The perf_event_period() is an external accessor, just like the
perf_event_{en,dis}able() and should thus use perf_event_ctx_lock().
Suggested-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
---
include/linux/perf_event.h | 5 +++++
kernel/events/core.c | 28 +++++++++++++++++++++-------
2 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 41bc1d3b311f..514962a49c62 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1336,6 +1336,7 @@ extern void perf_event_disable_local(struct perf_event *event);
extern void perf_event_disable_inatomic(struct perf_event *event);
extern void perf_event_task_tick(void);
extern int perf_event_account_interrupt(struct perf_event *event);
+extern int perf_event_period(struct perf_event *event, u64 value);
#else /* !CONFIG_PERF_EVENTS: */
static inline void *
perf_aux_output_begin(struct perf_output_handle *handle,
@@ -1408,6 +1409,10 @@ static inline void perf_event_disable(struct perf_event *event) { }
static inline int __perf_event_disable(void *info) { return -1; }
static inline void perf_event_task_tick(void) { }
static inline int perf_event_release_kernel(struct perf_event *event) { return 0; }
+static inline int perf_event_period(struct perf_event *event, u64 value)
+{
+ return -EINVAL;
+}
#endif
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 616cccf9c835..b1e4beb6931c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5034,16 +5034,11 @@ static int perf_event_check_period(struct perf_event *event, u64 value)
return event->pmu->check_period(event, value);
}
-static int perf_event_period(struct perf_event *event, u64 __user *arg)
+static int _perf_event_period(struct perf_event *event, u64 value)
{
- u64 value;
-
if (!is_sampling_event(event))
return -EINVAL;
- if (copy_from_user(&value, arg, sizeof(value)))
- return -EFAULT;
-
if (!value)
return -EINVAL;
@@ -5058,6 +5053,19 @@ static int perf_event_period(struct perf_event *event, u64 __user *arg)
return 0;
}
+int perf_event_period(struct perf_event *event, u64 value)
+{
+ struct perf_event_context *ctx;
+ int ret;
+
+ ctx = perf_event_ctx_lock(event);
+ ret = _perf_event_period(event, value);
+ perf_event_ctx_unlock(event, ctx);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(perf_event_period);
+
static const struct file_operations perf_fops;
static inline int perf_fget_light(int fd, struct fd *p)
@@ -5101,8 +5109,14 @@ static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned lon
return _perf_event_refresh(event, arg);
case PERF_EVENT_IOC_PERIOD:
- return perf_event_period(event, (u64 __user *)arg);
+ {
+ u64 value;
+
+ if (copy_from_user(&value, (u64 __user *)arg, sizeof(value)))
+ return -EFAULT;
+ return _perf_event_period(event, value);
+ }
case PERF_EVENT_IOC_ID:
{
u64 id = primary_event_id(event);
--
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