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perf/x86/intel/pt: Add a capability and config bit for disabling TNTs 

As of Intel SDM (https://www.intel.com/sdm) version 076, there is a new
Intel PT feature called TNT-Disable which is enabled config bit 55.

TNT-Disable disables Taken-Not-Taken packets to reduce the tracing
overhead, but with the result that exact control flow information is
lost.

Add a capability and config bit for TNT-Disable.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20220126104815.2807416-3-adrian.hunter@intel.com
This commit is contained in:
Alexander Shishkin 2022-01-26 12:48:15 +02:00 committed by Peter Zijlstra
parent 28c24ded64
commit 161a9a3370
3 changed files with 10 additions and 0 deletions
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8
arch/x86/events/intel/pt.c
View File

@ -60,6 +60,7 @@ static struct pt_cap_desc {
PT_CAP(ptwrite, 0, CPUID_EBX, BIT(4)),
PT_CAP(power_event_trace, 0, CPUID_EBX, BIT(5)),
PT_CAP(event_trace, 0, CPUID_EBX, BIT(7)),
PT_CAP(tnt_disable, 0, CPUID_EBX, BIT(8)),
PT_CAP(topa_output, 0, CPUID_ECX, BIT(0)),
PT_CAP(topa_multiple_entries, 0, CPUID_ECX, BIT(1)),
PT_CAP(single_range_output, 0, CPUID_ECX, BIT(2)),
@ -112,6 +113,7 @@ PMU_FORMAT_ATTR(noretcomp, "config:11" );
PMU_FORMAT_ATTR(ptw, "config:12" );
PMU_FORMAT_ATTR(branch, "config:13" );
PMU_FORMAT_ATTR(event, "config:31" );
PMU_FORMAT_ATTR(notnt, "config:55" );
PMU_FORMAT_ATTR(mtc_period, "config:14-17" );
PMU_FORMAT_ATTR(cyc_thresh, "config:19-22" );
PMU_FORMAT_ATTR(psb_period, "config:24-27" );
@ -121,6 +123,7 @@ static struct attribute *pt_formats_attr[] = {
&format_attr_cyc.attr,
&format_attr_pwr_evt.attr,
&format_attr_event.attr,
&format_attr_notnt.attr,
&format_attr_fup_on_ptw.attr,
&format_attr_mtc.attr,
&format_attr_tsc.attr,
@ -302,6 +305,7 @@ fail:
RTIT_CTL_MTC | \
RTIT_CTL_PWR_EVT_EN | \
RTIT_CTL_EVENT_EN | \
RTIT_CTL_NOTNT | \
RTIT_CTL_FUP_ON_PTW | \
RTIT_CTL_PTW_EN)
@ -360,6 +364,10 @@ static bool pt_event_valid(struct perf_event *event)
!intel_pt_validate_hw_cap(PT_CAP_event_trace))
return false;
if (config & RTIT_CTL_NOTNT &&
!intel_pt_validate_hw_cap(PT_CAP_tnt_disable))
return false;
if (config & RTIT_CTL_PTW) {
if (!intel_pt_validate_hw_cap(PT_CAP_ptwrite))
return false;

1
arch/x86/include/asm/intel_pt.h
View File

@ -14,6 +14,7 @@ enum pt_capabilities {
PT_CAP_ptwrite,
PT_CAP_power_event_trace,
PT_CAP_event_trace,
PT_CAP_tnt_disable,
PT_CAP_topa_output,
PT_CAP_topa_multiple_entries,
PT_CAP_single_range_output,

1
arch/x86/include/asm/msr-index.h
View File

@ -206,6 +206,7 @@
#define RTIT_CTL_PTW_EN BIT(12)
#define RTIT_CTL_BRANCH_EN BIT(13)
#define RTIT_CTL_EVENT_EN BIT(31)
#define RTIT_CTL_NOTNT BIT_ULL(55)
#define RTIT_CTL_MTC_RANGE_OFFSET 14
#define RTIT_CTL_MTC_RANGE (0x0full << RTIT_CTL_MTC_RANGE_OFFSET)
#define RTIT_CTL_CYC_THRESH_OFFSET 19