The existing mechanism to assign Trace ID values to sources is limited and does not scale for larger multicore / multi trace source systems.
The API introduces functions that reserve IDs based on availabilty represented by a coresight_trace_id_map structure. This records the used and free IDs in a bitmap.
CPU bound sources such as ETMs use the coresight_trace_id_get_cpu_id / coresight_trace_id_put_cpu_id pair of functions. The API will record the ID associated with the CPU. This ensures that the same ID will be re-used while perf events are active on the CPU. The put_cpu_id function will pend release of the ID until all perf cs_etm sessions are complete.
Non-cpu sources, such as the STM can use coresight_trace_id_get_system_id / coresight_trace_id_put_system_id.
Signed-off-by: Mike Leach mike.leach@linaro.org --- drivers/hwtracing/coresight/Makefile | 2 +- .../hwtracing/coresight/coresight-trace-id.c | 222 ++++++++++++++++++ .../hwtracing/coresight/coresight-trace-id.h | 69 ++++++ 3 files changed, 292 insertions(+), 1 deletion(-) create mode 100644 drivers/hwtracing/coresight/coresight-trace-id.c create mode 100644 drivers/hwtracing/coresight/coresight-trace-id.h
diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile index b6c4a48140ec..329a0c704b87 100644 --- a/drivers/hwtracing/coresight/Makefile +++ b/drivers/hwtracing/coresight/Makefile @@ -6,7 +6,7 @@ obj-$(CONFIG_CORESIGHT) += coresight.o coresight-y := coresight-core.o coresight-etm-perf.o coresight-platform.o \ coresight-sysfs.o coresight-syscfg.o coresight-config.o \ coresight-cfg-preload.o coresight-cfg-afdo.o \ - coresight-syscfg-configfs.o + coresight-syscfg-configfs.o coresight-trace-id.o obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o coresight-tmc-y := coresight-tmc-core.o coresight-tmc-etf.o \ coresight-tmc-etr.o diff --git a/drivers/hwtracing/coresight/coresight-trace-id.c b/drivers/hwtracing/coresight/coresight-trace-id.c new file mode 100644 index 000000000000..ce6c7d7b55d6 --- /dev/null +++ b/drivers/hwtracing/coresight/coresight-trace-id.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2022, Linaro Limited, All rights reserved. + * Author: Mike Leach mike.leach@linaro.org + */ +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/spinlock.h> + +#include "coresight-trace-id.h" + +/* need to keep data on ids & association with cpus. */ +struct cpu_id_info { + int id; + bool pend_rel; +}; + +/* maintain a record of the current mapping of cpu IDs */ +static DEFINE_PER_CPU(struct cpu_id_info, cpu_ids); + +/* a list of currently used id_maps */ +static LIST_HEAD(id_map_list); + +/* perf session active flag */ +static int perf_cs_etm_session_active; + +/* lock to protect id_map list and cpu data */ +static DEFINE_SPINLOCK(id_map_lock); + +/* ID 0 is reserved */ +#define CORESIGHT_TRACE_ID_RES_0 0 + +/* ID 0x70 onwards are reserved */ +#define CORESIGHT_TRACE_ID_RES_RANGE_LO 0x70 +#define CORESIGHT_TRACE_ID_RES_RANGE_HI 0x7F + +#define IS_VALID_ID(id) \ + ((id > CORESIGHT_TRACE_ID_RES_0) && (id < CORESIGHT_TRACE_ID_RES_RANGE_LO)) + +static void coresight_trace_id_set_inuse(int id, struct coresight_trace_id_map *id_map) +{ + if (IS_VALID_ID(id)) + set_bit(id, id_map->avail_ids); +} + +static void coresight_trace_id_clear_inuse(int id, struct coresight_trace_id_map *id_map) +{ + if (IS_VALID_ID(id)) + clear_bit(id, id_map->avail_ids); +} + +static void coresight_trace_id_set_pend_rel(int id, struct coresight_trace_id_map *id_map) +{ + if (IS_VALID_ID(id)) + set_bit(id, id_map->pend_rel_ids); +} + +static void coresight_trace_id_clear_pend_rel(int id, struct coresight_trace_id_map *id_map) +{ + if (IS_VALID_ID(id)) + clear_bit(id, id_map->pend_rel_ids); +} + +static int coresight_trace_id_find_new_id(struct coresight_trace_id_map *id_map) +{ + int id; + + id = find_first_zero_bit(id_map->avail_ids, CORESIGHT_TRACE_IDS_MAX); + if (id >= CORESIGHT_TRACE_IDS_MAX) + id = -EINVAL; + return id; +} + +/* release all pending IDs for all current maps & clear CPU associations */ +static void coresight_trace_id_release_all_pending(void) +{ + struct coresight_trace_id_map *id_map; + int cpu, bit; + + list_for_each_entry(id_map, &id_map_list, node) { + for_each_set_bit(bit, id_map->pend_rel_ids, CORESIGHT_TRACE_IDS_MAX) { + clear_bit(bit, id_map->avail_ids); + clear_bit(bit, id_map->pend_rel_ids); + } + } + + for_each_possible_cpu(cpu) { + if (per_cpu(cpu_ids, cpu).pend_rel) { + per_cpu(cpu_ids, cpu).pend_rel = false; + per_cpu(cpu_ids, cpu).id = 0; + } + } +} + +int coresight_trace_id_get_cpu_id(int cpu, struct coresight_trace_id_map *id_map) +{ + unsigned long flags; + int id; + + spin_lock_irqsave(&id_map_lock, flags); + id = per_cpu(cpu_ids, cpu).id; + if (!id) { + id = coresight_trace_id_find_new_id(id_map); + if (id < 0) + goto get_cpu_id_out; + } + + per_cpu(cpu_ids, cpu).id = id; + per_cpu(cpu_ids, cpu).pend_rel = false; + coresight_trace_id_set_inuse(id, id_map); + coresight_trace_id_clear_pend_rel(id, id_map); + +get_cpu_id_out: + spin_unlock_irqrestore(&id_map_lock, flags); + return id; +} +EXPORT_SYMBOL_GPL(coresight_trace_id_get_cpu_id); + +void coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_id_map *id_map) +{ + unsigned long flags; + int id; + + spin_lock_irqsave(&id_map_lock, flags); + id = per_cpu(cpu_ids, cpu).id; + if (!id) + goto put_cpu_id_out; + + if (perf_cs_etm_session_active) { + /* set release at pending if perf still active */ + coresight_trace_id_set_pend_rel(id, id_map); + per_cpu(cpu_ids, cpu).pend_rel = true; + } else { + /* otherwise clear id */ + coresight_trace_id_clear_inuse(id, id_map); + per_cpu(cpu_ids, cpu).id = 0; + } + + put_cpu_id_out: + spin_unlock_irqrestore(&id_map_lock, flags); +} +EXPORT_SYMBOL_GPL(coresight_trace_id_put_cpu_id); + +int coresight_trace_id_get_system_id(struct coresight_trace_id_map *id_map) +{ + unsigned long flags; + int id; + + spin_lock_irqsave(&id_map_lock, flags); + id = coresight_trace_id_find_new_id(id_map); + if (id > 0) + coresight_trace_id_set_inuse(id, id_map); + spin_unlock_irqrestore(&id_map_lock, flags); + + return id; +} +EXPORT_SYMBOL_GPL(coresight_trace_id_get_system_id); + +void coresight_trace_id_put_system_id(struct coresight_trace_id_map *id_map, int id) +{ + unsigned long flags; + + spin_lock_irqsave(&id_map_lock, flags); + coresight_trace_id_clear_inuse(id, id_map); + spin_unlock_irqrestore(&id_map_lock, flags); +} +EXPORT_SYMBOL_GPL(coresight_trace_id_put_system_id); + +void coresight_trace_id_perf_start(void) +{ + unsigned long flags; + + spin_lock_irqsave(&id_map_lock, flags); + perf_cs_etm_session_active++; + spin_unlock_irqrestore(&id_map_lock, flags); +} +EXPORT_SYMBOL_GPL(coresight_trace_id_perf_start); + +void coresight_trace_id_perf_stop(void) +{ + unsigned long flags; + + spin_lock_irqsave(&id_map_lock, flags); + perf_cs_etm_session_active--; + if (!perf_cs_etm_session_active) + coresight_trace_id_release_all_pending(); + spin_unlock_irqrestore(&id_map_lock, flags); +} +EXPORT_SYMBOL_GPL(coresight_trace_id_perf_stop); + +void coresight_trace_id_init_id_map(struct coresight_trace_id_map *id_map) +{ + unsigned long flags; + int bit; + + /* set all reserved bits as in-use */ + set_bit(CORESIGHT_TRACE_ID_RES_0, id_map->avail_ids); + for (bit = CORESIGHT_TRACE_ID_RES_RANGE_LO; + bit <= CORESIGHT_TRACE_ID_RES_RANGE_HI; bit++) + set_bit(bit, id_map->avail_ids); + + spin_lock_irqsave(&id_map_lock, flags); + + /* add id_map to the list */ + list_add(&id_map->node, &id_map_list); + + spin_unlock_irqrestore(&id_map_lock, flags); +} +EXPORT_SYMBOL_GPL(coresight_trace_id_init_id_map); + +void coresight_trace_id_release_id_map(struct coresight_trace_id_map *id_map) +{ + unsigned long flags; + + spin_lock_irqsave(&id_map_lock, flags); + + /* remove id_map from list */ + list_del(&id_map->node); + + spin_unlock_irqrestore(&id_map_lock, flags); +} +EXPORT_SYMBOL_GPL(coresight_trace_id_release_id_map); diff --git a/drivers/hwtracing/coresight/coresight-trace-id.h b/drivers/hwtracing/coresight/coresight-trace-id.h new file mode 100644 index 000000000000..01db2441cee6 --- /dev/null +++ b/drivers/hwtracing/coresight/coresight-trace-id.h @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright(C) 2022 Linaro Limited. All rights reserved. + * Author: Mike Leach mike.leach@linaro.org + */ + +#ifndef _CORESIGHT_TRACE_ID_H +#define _CORESIGHT_TRACE_ID_H + +/* + * Coresight trace ID allocation API + * + * With multi cpu systems, and more additional trace sources a scalable + * trace ID reservation system is required. + * + * The system will allocate Ids on a demand basis, and allow them to be + * released when done. + * + * In order to ensure that a consistent cpu / ID matching is maintained + * throughout a perf cs_etm event session - a session in progress flag will + * be maintained, and released IDs not cleared until the perf session is + * complete. This allows the same CPU to be re-allocated its prior ID. + * + * + * Trace ID maps will be created and initialised to prevent architecturally + * reserved IDs from being allocated. + * + * API permits multiple maps to be maintained - for large systems where + * different sets of cpus trace into different independent sinks. + */ + +#include <linux/bitops.h> +#include <linux/types.h> + + +/* architecturally we have 128 IDs some of which are reserved */ +#define CORESIGHT_TRACE_IDS_MAX 128 + +/** + * Trace ID map. + * + * @avail_ids: Bitmap to register available (bit = 0) and in use (bit = 1) IDs. + * Initialised so that the reserved IDs are permanently marked as in use. + * @pend_rel_ids: CPU IDs that have been released by the trace source but not yet marked + * as available, to allow re-allocation to the same CPU during a perf session. + * @node: List entry to add to list of managed trace id maps. + */ +struct coresight_trace_id_map { + DECLARE_BITMAP(avail_ids, CORESIGHT_TRACE_IDS_MAX); + DECLARE_BITMAP(pend_rel_ids, CORESIGHT_TRACE_IDS_MAX); + struct list_head node; +}; + +/* Allocate and release IDs */ +int coresight_trace_id_get_cpu_id(int cpu, struct coresight_trace_id_map *id_map); +int coresight_trace_id_get_system_id(struct coresight_trace_id_map *id_map); +void coresight_trace_id_put_cpu_id(int cpu, struct coresight_trace_id_map *id_map); +void coresight_trace_id_put_system_id(struct coresight_trace_id_map *id_map, int id); + +/* initialise ID map - block reserved IDs, add to list of ID maps */ +void coresight_trace_id_init_id_map(struct coresight_trace_id_map *id_map); +/* remove ID maps from list of maps */ +void coresight_trace_id_release_id_map(struct coresight_trace_id_map *id_map); + +/* notifiers for perf session start and stop */ +void coresight_trace_id_perf_start(void); +void coresight_trace_id_perf_stop(void); + +#endif /* _CORESIGHT_TRACE_ID_H */