linux-loongson/include/linux/perf/arm_pmu.h
Rob Herring (Arm) 58074a0fce perf: arm_pmuv3: Add support for the Branch Record Buffer Extension (BRBE)
The ARMv9.2 architecture introduces the optional Branch Record Buffer
Extension (BRBE), which records information about branches as they are
executed into set of branch record registers. BRBE is similar to x86's
Last Branch Record (LBR) and PowerPC's Branch History Rolling Buffer
(BHRB).

BRBE supports filtering by exception level and can filter just the
source or target address if excluded to avoid leaking privileged
addresses. The h/w filter would be sufficient except when there are
multiple events with disjoint filtering requirements. In this case, BRBE
is configured with a union of all the events' desired branches, and then
the recorded branches are filtered based on each event's filter. For
example, with one event capturing kernel events and another event
capturing user events, BRBE will be configured to capture both kernel
and user branches. When handling event overflow, the branch records have
to be filtered by software to only include kernel or user branch
addresses for that event. In contrast, x86 simply configures LBR using
the last installed event which seems broken.

It is possible on x86 to configure branch filter such that no branches
are ever recorded (e.g. -j save_type). For BRBE, events with a
configuration that will result in no samples are rejected.

Recording branches in KVM guests is not supported like x86. However,
perf on x86 allows requesting branch recording in guests. The guest
events are recorded, but the resulting branches are all from the host.
For BRBE, events with branch recording and "exclude_host" set are
rejected. Requiring "exclude_guest" to be set did not work. The default
for the perf tool does set "exclude_guest" if no exception level
options are specified. However, specifying kernel or user events
defaults to including both host and guest. In this case, only host
branches are recorded.

BRBE can support some additional exception branch types compared to
x86. On x86, all exceptions other than syscalls are recorded as IRQ.
With BRBE, it is possible to better categorize these exceptions. One
limitation relative to x86 is we cannot distinguish a syscall return
from other exception returns. So all exception returns are recorded as
ERET type. The FIQ branch type is omitted as the only FIQ user is Apple
platforms which don't support BRBE. The debug branch types are omitted
as there is no clear need for them.

BRBE records are invalidated whenever events are reconfigured, a new
task is scheduled in, or after recording is paused (and the records
have been recorded for the event). The architecture allows branch
records to be invalidated by the PE under implementation defined
conditions. It is expected that these conditions are rare.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Co-developed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Co-developed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
tested-by: Adam Young <admiyo@os.amperecomputing.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250611-arm-brbe-v19-v23-4-e7775563036e@kernel.org
[will: Fix sparse warnings about mixed declarations and code.
       Fix C99 comment syntax.]
Signed-off-by: Will Deacon <will@kernel.org>
2025-07-08 17:58:49 +01:00

226 lines
6.3 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* linux/arch/arm/include/asm/pmu.h
*
* Copyright (C) 2009 picoChip Designs Ltd, Jamie Iles
*/
#ifndef __ARM_PMU_H__
#define __ARM_PMU_H__
#include <linux/interrupt.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/sysfs.h>
#include <asm/cputype.h>
#ifdef CONFIG_ARM_PMU
/*
* The Armv7 and Armv8.8 or less CPU PMU supports up to 32 event counters.
* The Armv8.9/9.4 CPU PMU supports up to 33 event counters.
*/
#ifdef CONFIG_ARM
#define ARMPMU_MAX_HWEVENTS 32
#else
#define ARMPMU_MAX_HWEVENTS 33
#endif
/*
* ARM PMU hw_event flags
*/
#define ARMPMU_EVT_64BIT 0x00001 /* Event uses a 64bit counter */
#define ARMPMU_EVT_47BIT 0x00002 /* Event uses a 47bit counter */
#define ARMPMU_EVT_63BIT 0x00004 /* Event uses a 63bit counter */
static_assert((PERF_EVENT_FLAG_ARCH & ARMPMU_EVT_64BIT) == ARMPMU_EVT_64BIT);
static_assert((PERF_EVENT_FLAG_ARCH & ARMPMU_EVT_47BIT) == ARMPMU_EVT_47BIT);
static_assert((PERF_EVENT_FLAG_ARCH & ARMPMU_EVT_63BIT) == ARMPMU_EVT_63BIT);
#define HW_OP_UNSUPPORTED 0xFFFF
#define C(_x) PERF_COUNT_HW_CACHE_##_x
#define CACHE_OP_UNSUPPORTED 0xFFFF
#define PERF_MAP_ALL_UNSUPPORTED \
[0 ... PERF_COUNT_HW_MAX - 1] = HW_OP_UNSUPPORTED
#define PERF_CACHE_MAP_ALL_UNSUPPORTED \
[0 ... C(MAX) - 1] = { \
[0 ... C(OP_MAX) - 1] = { \
[0 ... C(RESULT_MAX) - 1] = CACHE_OP_UNSUPPORTED, \
}, \
}
/* The events for a given PMU register set. */
struct pmu_hw_events {
/*
* The events that are active on the PMU for the given index.
*/
struct perf_event *events[ARMPMU_MAX_HWEVENTS];
/*
* A 1 bit for an index indicates that the counter is being used for
* an event. A 0 means that the counter can be used.
*/
DECLARE_BITMAP(used_mask, ARMPMU_MAX_HWEVENTS);
/*
* When using percpu IRQs, we need a percpu dev_id. Place it here as we
* already have to allocate this struct per cpu.
*/
struct arm_pmu *percpu_pmu;
int irq;
struct perf_branch_stack *branch_stack;
/* Active events requesting branch records */
unsigned int branch_users;
};
enum armpmu_attr_groups {
ARMPMU_ATTR_GROUP_COMMON,
ARMPMU_ATTR_GROUP_EVENTS,
ARMPMU_ATTR_GROUP_FORMATS,
ARMPMU_ATTR_GROUP_CAPS,
ARMPMU_NR_ATTR_GROUPS
};
struct arm_pmu {
struct pmu pmu;
cpumask_t supported_cpus;
char *name;
irqreturn_t (*handle_irq)(struct arm_pmu *pmu);
void (*enable)(struct perf_event *event);
void (*disable)(struct perf_event *event);
int (*get_event_idx)(struct pmu_hw_events *hw_events,
struct perf_event *event);
void (*clear_event_idx)(struct pmu_hw_events *hw_events,
struct perf_event *event);
int (*set_event_filter)(struct hw_perf_event *evt,
struct perf_event_attr *attr);
u64 (*read_counter)(struct perf_event *event);
void (*write_counter)(struct perf_event *event, u64 val);
void (*start)(struct arm_pmu *);
void (*stop)(struct arm_pmu *);
void (*reset)(void *);
int (*map_event)(struct perf_event *event);
/*
* Called by KVM to map the PMUv3 event space onto non-PMUv3 hardware.
*/
int (*map_pmuv3_event)(unsigned int eventsel);
DECLARE_BITMAP(cntr_mask, ARMPMU_MAX_HWEVENTS);
bool secure_access; /* 32-bit ARM only */
struct platform_device *plat_device;
struct pmu_hw_events __percpu *hw_events;
struct hlist_node node;
struct notifier_block cpu_pm_nb;
/* the attr_groups array must be NULL-terminated */
const struct attribute_group *attr_groups[ARMPMU_NR_ATTR_GROUPS + 1];
/* PMUv3 only */
int pmuver;
u64 reg_pmmir;
u64 reg_brbidr;
#define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS);
#define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000
DECLARE_BITMAP(pmceid_ext_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS);
/* Only to be used by ACPI probing code */
unsigned long acpi_cpuid;
};
#define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu))
DECLARE_PER_CPU(struct arm_pmu *, cpu_armpmu);
u64 armpmu_event_update(struct perf_event *event);
int armpmu_event_set_period(struct perf_event *event);
int armpmu_map_event(struct perf_event *event,
const unsigned (*event_map)[PERF_COUNT_HW_MAX],
const unsigned (*cache_map)[PERF_COUNT_HW_CACHE_MAX]
[PERF_COUNT_HW_CACHE_OP_MAX]
[PERF_COUNT_HW_CACHE_RESULT_MAX],
u32 raw_event_mask);
typedef int (*armpmu_init_fn)(struct arm_pmu *);
struct pmu_probe_info {
unsigned int cpuid;
unsigned int mask;
armpmu_init_fn init;
};
#define PMU_PROBE(_cpuid, _mask, _fn) \
{ \
.cpuid = (_cpuid), \
.mask = (_mask), \
.init = (_fn), \
}
#define ARM_PMU_PROBE(_cpuid, _fn) \
PMU_PROBE(_cpuid, ARM_CPU_PART_MASK, _fn)
#define ARM_PMU_XSCALE_MASK ((0xff << 24) | ARM_CPU_XSCALE_ARCH_MASK)
#define XSCALE_PMU_PROBE(_version, _fn) \
PMU_PROBE(ARM_CPU_IMP_INTEL << 24 | _version, ARM_PMU_XSCALE_MASK, _fn)
int arm_pmu_device_probe(struct platform_device *pdev,
const struct of_device_id *of_table,
const struct pmu_probe_info *probe_table);
#ifdef CONFIG_ACPI
int arm_pmu_acpi_probe(armpmu_init_fn init_fn);
#else
static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 0; }
#endif
#ifdef CONFIG_KVM
void kvm_host_pmu_init(struct arm_pmu *pmu);
#else
#define kvm_host_pmu_init(x) do { } while(0)
#endif
bool arm_pmu_irq_is_nmi(void);
/* Internal functions only for core arm_pmu code */
struct arm_pmu *armpmu_alloc(void);
void armpmu_free(struct arm_pmu *pmu);
int armpmu_register(struct arm_pmu *pmu);
int armpmu_request_irq(int irq, int cpu);
void armpmu_free_irq(int irq, int cpu);
#define ARMV8_PMU_PDEV_NAME "armv8-pmu"
#endif /* CONFIG_ARM_PMU */
#define ARMV8_SPE_PDEV_NAME "arm,spe-v1"
#define ARMV8_TRBE_PDEV_NAME "arm,trbe"
/* Why does everything I do descend into this? */
#define __GEN_PMU_FORMAT_ATTR(cfg, lo, hi) \
(lo) == (hi) ? #cfg ":" #lo "\n" : #cfg ":" #lo "-" #hi
#define _GEN_PMU_FORMAT_ATTR(cfg, lo, hi) \
__GEN_PMU_FORMAT_ATTR(cfg, lo, hi)
#define GEN_PMU_FORMAT_ATTR(name) \
PMU_FORMAT_ATTR(name, \
_GEN_PMU_FORMAT_ATTR(ATTR_CFG_FLD_##name##_CFG, \
ATTR_CFG_FLD_##name##_LO, \
ATTR_CFG_FLD_##name##_HI))
#define _ATTR_CFG_GET_FLD(attr, cfg, lo, hi) \
((((attr)->cfg) >> lo) & GENMASK_ULL(hi - lo, 0))
#define ATTR_CFG_GET_FLD(attr, name) \
_ATTR_CFG_GET_FLD(attr, \
ATTR_CFG_FLD_##name##_CFG, \
ATTR_CFG_FLD_##name##_LO, \
ATTR_CFG_FLD_##name##_HI)
#endif /* __ARM_PMU_H__ */