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Commit 433678bd authored by Stephane Eranian's avatar Stephane Eranian Committed by Ingo Molnar
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perf/rapl: Fix sysfs_show() initialization for RAPL PMU 



This patch fixes a problem with the initialization of the
sysfs_show() routine for the RAPL PMU.

The current code was wrongly relying on the EVENT_ATTR_STR()
macro which uses the events_sysfs_show() function in the x86
PMU code. That function itself was relying on the x86_pmu data
structure. Yet RAPL and the core PMU (x86_pmu) have nothing to
do with each other. They should therefore not interact with
each other.

The x86_pmu structure is initialized at boot time based on
the host CPU model. When the host CPU is not supported, the
x86_pmu remains uninitialized and some of the callbacks it
contains are NULL.

The false dependency with x86_pmu could potentially cause crashes
in case the x86_pmu is not initialized while the RAPL PMU is. This
may, for instance, be the case in virtualized environments.

This patch fixes the problem by using a private sysfs_show()
routine for exporting the RAPL PMU events.

Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150113225953.GA21525@thinkpad


Cc: vincent.weaver@maine.edu
Cc: jolsa@redhat.com
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f800c25b

arch/x86/kernel/cpu/perf_event_intel_rapl.c

+32 −12
Original line number Diff line number Diff line
@@ -103,6 +103,13 @@ static struct kobj_attribute format_attr_##_var = \ 


#define RAPL_CNTR_WIDTH 32 /* 32-bit rapl counters */



#define RAPL_EVENT_ATTR_STR(_name, v, str)				\

static struct perf_pmu_events_attr event_attr_##v = {			\

	.attr		= __ATTR(_name, 0444, rapl_sysfs_show, NULL),	\

	.id		= 0,						\

	.event_str	= str,						\

};



struct rapl_pmu {

	spinlock_t	 lock;

	int		 hw_unit;  /* 1/2^hw_unit Joule */
@@ -379,23 +386,36 @@ static struct attribute_group rapl_pmu_attr_group = { 
	.attrs = rapl_pmu_attrs,

};



EVENT_ATTR_STR(energy-cores, rapl_cores, "event=0x01");

EVENT_ATTR_STR(energy-pkg  ,   rapl_pkg, "event=0x02");

EVENT_ATTR_STR(energy-ram  ,   rapl_ram, "event=0x03");

EVENT_ATTR_STR(energy-gpu  ,   rapl_gpu, "event=0x04");

static ssize_t rapl_sysfs_show(struct device *dev,

			       struct device_attribute *attr,

			       char *page)

{

	struct perf_pmu_events_attr *pmu_attr = \

		container_of(attr, struct perf_pmu_events_attr, attr);



	if (pmu_attr->event_str)

		return sprintf(page, "%s", pmu_attr->event_str);



	return 0;

}



RAPL_EVENT_ATTR_STR(energy-cores, rapl_cores, "event=0x01");

RAPL_EVENT_ATTR_STR(energy-pkg  ,   rapl_pkg, "event=0x02");

RAPL_EVENT_ATTR_STR(energy-ram  ,   rapl_ram, "event=0x03");

RAPL_EVENT_ATTR_STR(energy-gpu  ,   rapl_gpu, "event=0x04");



EVENT_ATTR_STR(energy-cores.unit, rapl_cores_unit, "Joules");

EVENT_ATTR_STR(energy-pkg.unit  ,   rapl_pkg_unit, "Joules");

EVENT_ATTR_STR(energy-ram.unit  ,   rapl_ram_unit, "Joules");

EVENT_ATTR_STR(energy-gpu.unit  ,   rapl_gpu_unit, "Joules");

RAPL_EVENT_ATTR_STR(energy-cores.unit, rapl_cores_unit, "Joules");

RAPL_EVENT_ATTR_STR(energy-pkg.unit  ,   rapl_pkg_unit, "Joules");

RAPL_EVENT_ATTR_STR(energy-ram.unit  ,   rapl_ram_unit, "Joules");

RAPL_EVENT_ATTR_STR(energy-gpu.unit  ,   rapl_gpu_unit, "Joules");



/*

 * we compute in 0.23 nJ increments regardless of MSR

 */

EVENT_ATTR_STR(energy-cores.scale, rapl_cores_scale, "2.3283064365386962890625e-10");

EVENT_ATTR_STR(energy-pkg.scale,     rapl_pkg_scale, "2.3283064365386962890625e-10");

EVENT_ATTR_STR(energy-ram.scale,     rapl_ram_scale, "2.3283064365386962890625e-10");

EVENT_ATTR_STR(energy-gpu.scale,     rapl_gpu_scale, "2.3283064365386962890625e-10");

RAPL_EVENT_ATTR_STR(energy-cores.scale, rapl_cores_scale, "2.3283064365386962890625e-10");

RAPL_EVENT_ATTR_STR(energy-pkg.scale,     rapl_pkg_scale, "2.3283064365386962890625e-10");

RAPL_EVENT_ATTR_STR(energy-ram.scale,     rapl_ram_scale, "2.3283064365386962890625e-10");

RAPL_EVENT_ATTR_STR(energy-gpu.scale,     rapl_gpu_scale, "2.3283064365386962890625e-10");



static struct attribute *rapl_events_srv_attr[] = {

	EVENT_PTR(rapl_cores),