[RFC PATCH] perf: Provide status of known PMUs
From: Adrian Hunter
Date: Thu Jul 09 2015 - 03:50:45 EST
Known PMUs may not be present for various reasons.
Provide a way for the user to know what the reason
is.
A bus attribute is created for each known PMU beneath
a group "known_pmus". The attribute name is the same
as the PMU name. The value is a string consisting of
one or, optionally, two parts: a canonical part, and
a driver specific part. If there are two parts, they
are separated by " - ". The canonical part is one of:
Supported
Driver error
Driver not loaded
Driver not in kernel config
Not supported by kernel
Not supported by hardware
Wrong vendor
Wrong architecture
Unknown status
Example:
$ cat /sys/bus/event_source/known_pmus/intel_pt
Supported
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
arch/x86/kernel/cpu/perf_event.c | 3 +
arch/x86/kernel/cpu/perf_event_intel_bts.c | 20 +++-
arch/x86/kernel/cpu/perf_event_intel_pt.c | 18 ++-
include/linux/perf_event.h | 23 ++++
kernel/events/core.c | 171 +++++++++++++++++++++++++++++
5 files changed, 226 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 3658de47900f..546163a42a30 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1670,12 +1670,15 @@ static int __init init_hw_perf_events(void)
switch (boot_cpu_data.x86_vendor) {
case X86_VENDOR_INTEL:
+ perf_pmu_vendor("Intel");
err = intel_pmu_init();
break;
case X86_VENDOR_AMD:
+ perf_pmu_vendor("AMD");
err = amd_pmu_init();
break;
default:
+ perf_pmu_vendor("Unknown");
err = -ENOTSUPP;
}
if (err != 0) {
diff --git a/arch/x86/kernel/cpu/perf_event_intel_bts.c b/arch/x86/kernel/cpu/perf_event_intel_bts.c
index 43dd672d788b..6eb1b637668a 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_bts.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_bts.c
@@ -514,8 +514,19 @@ static void bts_event_read(struct perf_event *event)
static __init int bts_init(void)
{
- if (!boot_cpu_has(X86_FEATURE_DTES64) || !x86_pmu.bts)
- return -ENODEV;
+ const char *status_msg = NULL;
+ int ret;
+
+ if (!x86_pmu.bts) {
+ ret = -ENODEV;
+ goto out;
+ }
+
+ if (!boot_cpu_has(X86_FEATURE_DTES64)) {
+ status_msg = "requires 64-bit kernel";
+ ret = -ENOTSUPP;
+ goto out;
+ }
bts_pmu.capabilities = PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_ITRACE;
bts_pmu.task_ctx_nr = perf_sw_context;
@@ -528,6 +539,9 @@ static __init int bts_init(void)
bts_pmu.setup_aux = bts_buffer_setup_aux;
bts_pmu.free_aux = bts_buffer_free_aux;
- return perf_pmu_register(&bts_pmu, "intel_bts", -1);
+ ret = perf_pmu_register(&bts_pmu, "intel_bts", -1);
+out:
+ perf_pmu_error_status("intel_bts", ret, status_msg);
+ return ret;
}
arch_initcall(bts_init);
diff --git a/arch/x86/kernel/cpu/perf_event_intel_pt.c b/arch/x86/kernel/cpu/perf_event_intel_pt.c
index 183de719628d..e2dc697ab1a6 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_pt.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_pt.c
@@ -1059,6 +1059,7 @@ static int pt_event_init(struct perf_event *event)
static __init int pt_init(void)
{
int ret, cpu, prior_warn = 0;
+ const char *status_msg = NULL;
BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE);
get_online_cpus();
@@ -1073,18 +1074,19 @@ static __init int pt_init(void)
if (prior_warn) {
x86_add_exclusive(x86_lbr_exclusive_pt);
- pr_warn("PT is enabled at boot time, doing nothing\n");
-
- return -EBUSY;
+ status_msg = "PT is enabled at boot time, doing nothing";
+ ret = -EBUSY;
+ goto out;
}
ret = pt_pmu_hw_init();
if (ret)
- return ret;
+ goto out;
if (!pt_cap_get(PT_CAP_topa_output)) {
- pr_warn("ToPA output is not supported on this CPU\n");
- return -ENODEV;
+ status_msg = "ToPA output is not supported on this CPU";
+ ret = -ENODEV;
+ goto out;
}
if (!pt_cap_get(PT_CAP_topa_multiple_entries))
@@ -1103,6 +1105,10 @@ static __init int pt_init(void)
pt_pmu.pmu.setup_aux = pt_buffer_setup_aux;
pt_pmu.pmu.free_aux = pt_buffer_free_aux;
ret = perf_pmu_register(&pt_pmu.pmu, "intel_pt", -1);
+out:
+ if (status_msg)
+ pr_warn("%s\n", status_msg);
+ perf_pmu_error_status("intel_pt", ret, status_msg);
return ret;
}
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 2027809433b3..e1eb95ec3e23 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -179,6 +179,22 @@ struct perf_event;
#define PERF_PMU_CAP_ITRACE 0x20
/**
+ * enum perf_pmu_status - the status of known PMUs
+ */
+enum perf_pmu_status {
+ PERF_PMU_STATUS_SUPPORTED,
+ PERF_PMU_STATUS_ERROR,
+ PERF_PMU_STATUS_NOT_LOADED,
+ PERF_PMU_STATUS_NOT_CONFIG,
+ PERF_PMU_STATUS_NOT_SUPPORTED,
+ PERF_PMU_STATUS_WRONG_HW,
+ PERF_PMU_STATUS_WRONG_VENDOR,
+ PERF_PMU_STATUS_WRONG_ARCH,
+ PERF_PMU_STATUS_UNKNOWN,
+ PERF_PMU_STATUS_MAX,
+};
+
+/**
* struct pmu - generic performance monitoring unit
*/
struct pmu {
@@ -631,6 +647,13 @@ extern void *perf_get_aux(struct perf_output_handle *handle);
extern int perf_pmu_register(struct pmu *pmu, const char *name, int type);
extern void perf_pmu_unregister(struct pmu *pmu);
+extern void perf_pmu_update_status(const char *name,
+ enum perf_pmu_status status,
+ const char *status_msg);
+extern void perf_pmu_error_status(const char *name, int err,
+ const char *status_msg);
+extern void perf_pmu_vendor(const char *vendor);
+
extern int perf_num_counters(void);
extern const char *perf_pmu_name(void);
extern void __perf_event_task_sched_in(struct task_struct *prev,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d3dae3419b99..ad3e9ec1f32b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7154,6 +7154,176 @@ out:
}
static struct idr pmu_idr;
+struct known_pmu {
+ const char *name;
+ const char *vendor;
+ const char *status_msg;
+ int status;
+};
+
+#define KNOWN_PMU(_name, _vendor, _status) { \
+ .name = _name, \
+ .vendor = _vendor, \
+ .status = _status, \
+}
+
+#if defined(CONFIG_X86)
+#define PERF_PMU_STATUS_ARCH_X86 PERF_PMU_STATUS_UNKNOWN
+#else
+#define PERF_PMU_STATUS_ARCH_X86 PERF_PMU_STATUS_WRONG_ARCH
+#endif
+
+static struct known_pmu known_pmus[] = {
+ KNOWN_PMU("intel_pt", "Intel", PERF_PMU_STATUS_ARCH_X86),
+ KNOWN_PMU("intel_bts", "Intel", PERF_PMU_STATUS_ARCH_X86),
+ KNOWN_PMU(NULL, NULL, 0),
+};
+
+static DEFINE_MUTEX(known_pmus_lock);
+
+static struct known_pmu *known_pmu_find(const char *name)
+{
+ struct known_pmu *known_pmu;
+
+ if (!name)
+ return NULL;
+
+ for (known_pmu = known_pmus; known_pmu->name; known_pmu++) {
+ if (!strcmp(known_pmu->name, name))
+ return known_pmu;
+ }
+ return NULL;
+}
+
+static const char *pmu_status_msg[] = {
+ [PERF_PMU_STATUS_SUPPORTED] = "Supported",
+ [PERF_PMU_STATUS_ERROR] = "Driver error",
+ [PERF_PMU_STATUS_NOT_LOADED] = "Driver not loaded",
+ [PERF_PMU_STATUS_NOT_CONFIG] = "Driver not in kernel config",
+ [PERF_PMU_STATUS_NOT_SUPPORTED] = "Not supported by kernel",
+ [PERF_PMU_STATUS_WRONG_HW] = "Not supported by hardware",
+ [PERF_PMU_STATUS_WRONG_VENDOR] = "Wrong vendor",
+ [PERF_PMU_STATUS_WRONG_ARCH] = "Wrong architecture",
+ [PERF_PMU_STATUS_UNKNOWN] = "Unknown status",
+};
+
+static ssize_t __known_pmu_show(struct known_pmu *known_pmu, char *buf)
+{
+ const char *msg, *vendor;
+ int status;
+
+ status = known_pmu->status;
+ msg = known_pmu->status_msg;
+ vendor = known_pmu->vendor;
+
+ if (status < 0 || status >= PERF_PMU_STATUS_MAX)
+ status = PERF_PMU_STATUS_UNKNOWN;
+
+ if (!msg && status == PERF_PMU_STATUS_WRONG_VENDOR && vendor)
+ return sprintf(buf, "%s - requires %s CPU\n",
+ pmu_status_msg[status], vendor);
+
+ if (!msg)
+ return sprintf(buf, "%s\n", pmu_status_msg[status]);
+
+ return sprintf(buf, "%s - %s\n", pmu_status_msg[status], msg);
+}
+
+static ssize_t known_pmu_show(const char *name, char *buf)
+{
+ struct known_pmu *known_pmu = known_pmu_find(name);
+ ssize_t ret;
+
+ if (!known_pmu)
+ return sprintf(buf, "Unknown PMU\n");
+
+ mutex_lock(&known_pmus_lock);
+ ret = __known_pmu_show(known_pmu, buf);
+ mutex_unlock(&known_pmus_lock);
+
+ return ret;
+}
+
+void perf_pmu_update_status(const char *name, enum perf_pmu_status status,
+ const char *status_msg)
+{
+ struct known_pmu *known_pmu = known_pmu_find(name);
+
+ if (known_pmu) {
+ mutex_lock(&known_pmus_lock);
+ known_pmu->status = status;
+ kfree_const(known_pmus->status_msg);
+ known_pmus->status_msg = kstrdup_const(status_msg, GFP_KERNEL);
+ mutex_unlock(&known_pmus_lock);
+ }
+}
+
+void perf_pmu_error_status(const char *name, int err, const char *status_msg)
+{
+ enum perf_pmu_status status;
+
+ switch (err) {
+ case 0:
+ status = PERF_PMU_STATUS_SUPPORTED;
+ break;
+ case -ENODEV:
+ status = PERF_PMU_STATUS_WRONG_HW;
+ break;
+ case -ENOTSUPP:
+ status = PERF_PMU_STATUS_NOT_SUPPORTED;
+ break;
+ default:
+ status = PERF_PMU_STATUS_ERROR;
+ }
+
+ perf_pmu_update_status(name, status, status_msg);
+}
+
+void perf_pmu_vendor(const char *vendor)
+{
+ struct known_pmu *known_pmu;
+
+ if (!vendor)
+ return;
+
+ mutex_lock(&known_pmus_lock);
+ for (known_pmu = known_pmus; known_pmu->name; known_pmu++) {
+ if (known_pmu->status == PERF_PMU_STATUS_UNKNOWN &&
+ known_pmu->vendor && strcmp(known_pmu->vendor, vendor)) {
+ known_pmu->status = PERF_PMU_STATUS_WRONG_VENDOR;
+ kfree_const(known_pmus->status_msg);
+ known_pmu->status_msg = NULL;
+ }
+ }
+ mutex_unlock(&known_pmus_lock);
+}
+
+#define KNOWN_PMU_ATTR(_name) \
+static ssize_t _name##_show(struct bus_type *bus, char *buf) \
+{ \
+ return known_pmu_show(__stringify(_name), buf); \
+} \
+static BUS_ATTR_RO(_name);
+
+KNOWN_PMU_ATTR(intel_pt);
+KNOWN_PMU_ATTR(intel_bts);
+
+static struct attribute *known_pmus_attrs[] = {
+ &bus_attr_intel_pt.attr,
+ &bus_attr_intel_bts.attr,
+ NULL,
+};
+
+static const struct attribute_group pmu_bus_known_pmus_group = {
+ .name = "known_pmus",
+ .attrs = known_pmus_attrs,
+};
+
+static const struct attribute_group *pmu_bus_groups[] = {
+ &pmu_bus_known_pmus_group,
+ NULL,
+};
+
static ssize_t
type_show(struct device *dev, struct device_attribute *attr, char *page)
{
@@ -7224,6 +7394,7 @@ ATTRIBUTE_GROUPS(pmu_dev);
static int pmu_bus_running;
static struct bus_type pmu_bus = {
.name = "event_source",
+ .bus_groups = pmu_bus_groups,
.dev_groups = pmu_dev_groups,
};
--
1.9.1
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