Commit cc37e520 authored by Stephane Eranian's avatar Stephane Eranian Committed by Peter Zijlstra
Browse files

perf/x86/amd: Make Zen3 branch sampling opt-in 



Add a kernel config option CONFIG_PERF_EVENTS_AMD_BRS
to make the support for AMD Zen3 Branch Sampling (BRS) an opt-in
compile time option.

Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220322221517.2510440-8-eranian@google.com
parent ba2fe750

arch/x86/events/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -44,4 +44,12 @@ config PERF_EVENTS_AMD_UNCORE 


	  To compile this driver as a module, choose M here: the

	  module will be called 'amd-uncore'.



config PERF_EVENTS_AMD_BRS

	depends on PERF_EVENTS && CPU_SUP_AMD

	bool "AMD Zen3 Branch Sampling support"

	help

	  Enable AMD Zen3 branch sampling support (BRS) which samples up to

	  16 consecutive taken branches in registers.



endmenu

arch/x86/events/amd/Makefile

+2 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_CPU_SUP_AMD)		+= core.o brs.o

obj-$(CONFIG_CPU_SUP_AMD)		+= core.o

obj-$(CONFIG_PERF_EVENTS_AMD_BRS)	+= brs.o

obj-$(CONFIG_PERF_EVENTS_AMD_POWER)	+= power.o

obj-$(CONFIG_X86_LOCAL_APIC)		+= ibs.o

obj-$(CONFIG_PERF_EVENTS_AMD_UNCORE)	+= amd-uncore.o

arch/x86/events/perf_event.h

+39 −10
Original line number Diff line number Diff line
@@ -1218,6 +1218,8 @@ static inline bool fixed_counter_disabled(int i, struct pmu *pmu) 
#ifdef CONFIG_CPU_SUP_AMD



int amd_pmu_init(void);



#ifdef CONFIG_PERF_EVENTS_AMD_BRS

int amd_brs_init(void);

void amd_brs_disable(void);

void amd_brs_enable(void);
@@ -1252,25 +1254,52 @@ static inline void amd_pmu_brs_del(struct perf_event *event) 


void amd_pmu_brs_sched_task(struct perf_event_context *ctx, bool sched_in);



/*

 * check if BRS is activated on the CPU

 * active defined as it has non-zero users and DBG_EXT_CFG.BRSEN=1

 */

static inline bool amd_brs_active(void)

static inline s64 amd_brs_adjust_period(s64 period)

{

	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

	if (period > x86_pmu.lbr_nr)

		return period - x86_pmu.lbr_nr;



	return cpuc->brs_active;

	return period;

}

#else

static inline int amd_brs_init(void)

{

	return 0;

}

static inline void amd_brs_disable(void) {}

static inline void amd_brs_enable(void) {}

static inline void amd_brs_drain(void) {}

static inline void amd_brs_lopwr_init(void) {}

static inline void amd_brs_disable_all(void) {}

static inline int amd_brs_setup_filter(struct perf_event *event)

{

	return 0;

}

static inline void amd_brs_reset(void) {}



static inline s64 amd_brs_adjust_period(s64 period)

static inline void amd_pmu_brs_add(struct perf_event *event)

{

	if (period > x86_pmu.lbr_nr)

		return period - x86_pmu.lbr_nr;

}



static inline void amd_pmu_brs_del(struct perf_event *event)

{

}



static inline void amd_pmu_brs_sched_task(struct perf_event_context *ctx, bool sched_in)

{

}



static inline s64 amd_brs_adjust_period(s64 period)

{

	return period;

}



static inline void amd_brs_enable_all(void)

{

}



#endif



#else /* CONFIG_CPU_SUP_AMD */



static inline int amd_pmu_init(void)