| 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 2 | * |
| 3 | * lttng-context-perf-counters.c |
| 4 | * |
| 5 | * LTTng performance monitoring counters (perf-counters) integration module. |
| 6 | * |
| 7 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/perf_event.h> |
| 13 | #include <linux/list.h> |
| 14 | #include <linux/string.h> |
| 15 | #include <linux/cpu.h> |
| 16 | #include <linux/mm.h> |
| 17 | #include <lttng-events.h> |
| 18 | #include <wrapper/ringbuffer/frontend_types.h> |
| 19 | #include <lttng-tracer.h> |
| 20 | |
| 21 | static |
| 22 | size_t perf_counter_get_size(size_t offset) |
| 23 | { |
| 24 | size_t size = 0; |
| 25 | |
| 26 | size += lib_ring_buffer_align(offset, lttng_alignof(uint64_t)); |
| 27 | size += sizeof(uint64_t); |
| 28 | return size; |
| 29 | } |
| 30 | |
| 31 | static |
| 32 | void perf_counter_record(struct lttng_ctx_field *field, |
| 33 | struct lib_ring_buffer_ctx *ctx, |
| 34 | struct lttng_channel *chan) |
| 35 | { |
| 36 | struct perf_event *event; |
| 37 | uint64_t value; |
| 38 | |
| 39 | event = field->u.perf_counter->e[ctx->cpu]; |
| 40 | if (likely(event)) { |
| 41 | if (unlikely(event->state == PERF_EVENT_STATE_ERROR)) { |
| 42 | value = 0; |
| 43 | } else { |
| 44 | event->pmu->read(event); |
| 45 | value = local64_read(&event->count); |
| 46 | } |
| 47 | } else { |
| 48 | /* |
| 49 | * Perf chooses not to be clever and not to support enabling a |
| 50 | * perf counter before the cpu is brought up. Therefore, we need |
| 51 | * to support having events coming (e.g. scheduler events) |
| 52 | * before the counter is setup. Write an arbitrary 0 in this |
| 53 | * case. |
| 54 | */ |
| 55 | value = 0; |
| 56 | } |
| 57 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(value)); |
| 58 | chan->ops->event_write(ctx, &value, sizeof(value)); |
| 59 | } |
| 60 | |
| 61 | static |
| 62 | void overflow_callback(struct perf_event *event, |
| 63 | struct perf_sample_data *data, |
| 64 | struct pt_regs *regs) |
| 65 | { |
| 66 | } |
| 67 | |
| 68 | static |
| 69 | void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field) |
| 70 | { |
| 71 | struct perf_event **events = field->u.perf_counter->e; |
| 72 | |
| 73 | { |
| 74 | int ret; |
| 75 | |
| 76 | ret = cpuhp_state_remove_instance(lttng_hp_online, |
| 77 | &field->u.perf_counter->cpuhp_online.node); |
| 78 | WARN_ON(ret); |
| 79 | ret = cpuhp_state_remove_instance(lttng_hp_prepare, |
| 80 | &field->u.perf_counter->cpuhp_prepare.node); |
| 81 | WARN_ON(ret); |
| 82 | } |
| 83 | kfree(field->event_field.name); |
| 84 | kfree(field->u.perf_counter->attr); |
| 85 | kvfree(events); |
| 86 | kfree(field->u.perf_counter); |
| 87 | } |
| 88 | |
| 89 | int lttng_cpuhp_perf_counter_online(unsigned int cpu, |
| 90 | struct lttng_cpuhp_node *node) |
| 91 | { |
| 92 | struct lttng_perf_counter_field *perf_field = |
| 93 | container_of(node, struct lttng_perf_counter_field, |
| 94 | cpuhp_online); |
| 95 | struct perf_event **events = perf_field->e; |
| 96 | struct perf_event_attr *attr = perf_field->attr; |
| 97 | struct perf_event *pevent; |
| 98 | |
| 99 | pevent = perf_event_create_kernel_counter(attr, |
| 100 | cpu, NULL, overflow_callback, NULL); |
| 101 | if (!pevent || IS_ERR(pevent)) |
| 102 | return -EINVAL; |
| 103 | if (pevent->state == PERF_EVENT_STATE_ERROR) { |
| 104 | perf_event_release_kernel(pevent); |
| 105 | return -EINVAL; |
| 106 | } |
| 107 | barrier(); /* Create perf counter before setting event */ |
| 108 | events[cpu] = pevent; |
| 109 | return 0; |
| 110 | } |
| 111 | |
| 112 | int lttng_cpuhp_perf_counter_dead(unsigned int cpu, |
| 113 | struct lttng_cpuhp_node *node) |
| 114 | { |
| 115 | struct lttng_perf_counter_field *perf_field = |
| 116 | container_of(node, struct lttng_perf_counter_field, |
| 117 | cpuhp_prepare); |
| 118 | struct perf_event **events = perf_field->e; |
| 119 | struct perf_event *pevent; |
| 120 | |
| 121 | pevent = events[cpu]; |
| 122 | events[cpu] = NULL; |
| 123 | barrier(); /* NULLify event before perf counter teardown */ |
| 124 | perf_event_release_kernel(pevent); |
| 125 | return 0; |
| 126 | } |
| 127 | |
| 128 | int lttng_add_perf_counter_to_ctx(uint32_t type, |
| 129 | uint64_t config, |
| 130 | const char *name, |
| 131 | struct lttng_ctx **ctx) |
| 132 | { |
| 133 | struct lttng_ctx_field *field; |
| 134 | struct lttng_perf_counter_field *perf_field; |
| 135 | struct perf_event **events; |
| 136 | struct perf_event_attr *attr; |
| 137 | int ret; |
| 138 | char *name_alloc; |
| 139 | |
| 140 | events = kvzalloc(num_possible_cpus() * sizeof(*events), GFP_KERNEL); |
| 141 | if (!events) |
| 142 | return -ENOMEM; |
| 143 | |
| 144 | attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL); |
| 145 | if (!attr) { |
| 146 | ret = -ENOMEM; |
| 147 | goto error_attr; |
| 148 | } |
| 149 | |
| 150 | attr->type = type; |
| 151 | attr->config = config; |
| 152 | attr->size = sizeof(struct perf_event_attr); |
| 153 | attr->pinned = 1; |
| 154 | attr->disabled = 0; |
| 155 | |
| 156 | perf_field = kzalloc(sizeof(struct lttng_perf_counter_field), GFP_KERNEL); |
| 157 | if (!perf_field) { |
| 158 | ret = -ENOMEM; |
| 159 | goto error_alloc_perf_field; |
| 160 | } |
| 161 | perf_field->e = events; |
| 162 | perf_field->attr = attr; |
| 163 | |
| 164 | name_alloc = kstrdup(name, GFP_KERNEL); |
| 165 | if (!name_alloc) { |
| 166 | ret = -ENOMEM; |
| 167 | goto name_alloc_error; |
| 168 | } |
| 169 | |
| 170 | field = lttng_append_context(ctx); |
| 171 | if (!field) { |
| 172 | ret = -ENOMEM; |
| 173 | goto append_context_error; |
| 174 | } |
| 175 | if (lttng_find_context(*ctx, name_alloc)) { |
| 176 | ret = -EEXIST; |
| 177 | goto find_error; |
| 178 | } |
| 179 | |
| 180 | perf_field->cpuhp_prepare.component = LTTNG_CONTEXT_PERF_COUNTERS; |
| 181 | ret = cpuhp_state_add_instance(lttng_hp_prepare, |
| 182 | &perf_field->cpuhp_prepare.node); |
| 183 | if (ret) |
| 184 | goto cpuhp_prepare_error; |
| 185 | |
| 186 | perf_field->cpuhp_online.component = LTTNG_CONTEXT_PERF_COUNTERS; |
| 187 | ret = cpuhp_state_add_instance(lttng_hp_online, |
| 188 | &perf_field->cpuhp_online.node); |
| 189 | if (ret) |
| 190 | goto cpuhp_online_error; |
| 191 | |
| 192 | field->destroy = lttng_destroy_perf_counter_field; |
| 193 | |
| 194 | field->event_field.name = name_alloc; |
| 195 | field->event_field.type.atype = atype_integer; |
| 196 | field->event_field.type.u.integer.size = sizeof(uint64_t) * CHAR_BIT; |
| 197 | field->event_field.type.u.integer.alignment = lttng_alignof(uint64_t) * CHAR_BIT; |
| 198 | field->event_field.type.u.integer.signedness = lttng_is_signed_type(uint64_t); |
| 199 | field->event_field.type.u.integer.reverse_byte_order = 0; |
| 200 | field->event_field.type.u.integer.base = 10; |
| 201 | field->event_field.type.u.integer.encoding = lttng_encode_none; |
| 202 | field->get_size = perf_counter_get_size; |
| 203 | field->record = perf_counter_record; |
| 204 | field->u.perf_counter = perf_field; |
| 205 | lttng_context_update(*ctx); |
| 206 | |
| 207 | return 0; |
| 208 | |
| 209 | cpuhp_online_error: |
| 210 | { |
| 211 | int remove_ret; |
| 212 | |
| 213 | remove_ret = cpuhp_state_remove_instance(lttng_hp_prepare, |
| 214 | &perf_field->cpuhp_prepare.node); |
| 215 | WARN_ON(remove_ret); |
| 216 | } |
| 217 | cpuhp_prepare_error: |
| 218 | find_error: |
| 219 | lttng_remove_context_field(ctx, field); |
| 220 | append_context_error: |
| 221 | kfree(name_alloc); |
| 222 | name_alloc_error: |
| 223 | kfree(perf_field); |
| 224 | error_alloc_perf_field: |
| 225 | kfree(attr); |
| 226 | error_attr: |
| 227 | kvfree(events); |
| 228 | return ret; |
| 229 | } |