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perf/x86/intel/pt: Export CPU frequency ratios needed by PT decoders 

Intel PT decoders need access to various bits of timing related
information to be able to correctly decode timing packets from a PT
stream (MTC and CBR packets). This patch exports all the necessary
bits as sysfs attributes for the sake of consistency:

  * max_nonturbo_ratio: ratio between the invariant TSC and base clock;

  * tsc_art_ratio: TSC to core crystal clock ratio (also available as CPUID.15H).

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/87zisdvibe.fsf@ashishki-desk.ger.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Alexander Shishkin 2015-08-19 17:02:10 +03:00 committed by Ingo Molnar
parent ccbebba4c6
commit 65c7e6f1c4
2 changed files with 60 additions and 0 deletions
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54
arch/x86/events/intel/pt.c
View File

@ -127,9 +127,46 @@ static struct attribute_group pt_format_group = {
.attrs = pt_formats_attr,
};
static ssize_t
pt_timing_attr_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);
switch (pmu_attr->id) {
case 0:
return sprintf(page, "%lu\n", pt_pmu.max_nonturbo_ratio);
case 1:
return sprintf(page, "%u:%u\n",
pt_pmu.tsc_art_num,
pt_pmu.tsc_art_den);
default:
break;
}
return -EINVAL;
}
PMU_EVENT_ATTR(max_nonturbo_ratio, timing_attr_max_nonturbo_ratio, 0,
pt_timing_attr_show);
PMU_EVENT_ATTR(tsc_art_ratio, timing_attr_tsc_art_ratio, 1,
pt_timing_attr_show);
static struct attribute *pt_timing_attr[] = {
&timing_attr_max_nonturbo_ratio.attr.attr,
&timing_attr_tsc_art_ratio.attr.attr,
NULL,
};
static struct attribute_group pt_timing_group = {
.attrs = pt_timing_attr,
};
static const struct attribute_group *pt_attr_groups[] = {
&pt_cap_group,
&pt_format_group,
&pt_timing_group,
NULL,
};
@ -142,6 +179,23 @@ static int __init pt_pmu_hw_init(void)
int ret;
long i;
rdmsrl(MSR_PLATFORM_INFO, reg);
pt_pmu.max_nonturbo_ratio = (reg & 0xff00) >> 8;
/*
* if available, read in TSC to core crystal clock ratio,
* otherwise, zero for numerator stands for "not enumerated"
* as per SDM
*/
if (boot_cpu_data.cpuid_level >= CPUID_TSC_LEAF) {
u32 eax, ebx, ecx, edx;
cpuid(CPUID_TSC_LEAF, &eax, &ebx, &ecx, &edx);
pt_pmu.tsc_art_num = ebx;
pt_pmu.tsc_art_den = eax;
}
if (boot_cpu_has(X86_FEATURE_VMX)) {
/*
* Intel SDM, 36.5 "Tracing post-VMXON" says that

6
arch/x86/events/intel/pt.h
View File

@ -82,6 +82,9 @@ struct topa_entry {
#define PT_CPUID_LEAVES 2
#define PT_CPUID_REGS_NUM 4 /* number of regsters (eax, ebx, ecx, edx) */
/* TSC to Core Crystal Clock Ratio */
#define CPUID_TSC_LEAF 0x15
enum pt_capabilities {
PT_CAP_max_subleaf = 0,
PT_CAP_cr3_filtering,
@ -102,6 +105,9 @@ struct pt_pmu {
struct pmu pmu;
u32 caps[PT_CPUID_REGS_NUM * PT_CPUID_LEAVES];
bool vmx;
unsigned long max_nonturbo_ratio;
unsigned int tsc_art_num;
unsigned int tsc_art_den;
};
/**