diff options
Diffstat (limited to 'kernel/trace/trace_event_perf.c')
| -rw-r--r-- | kernel/trace/trace_event_perf.c | 529 |
1 files changed, 529 insertions, 0 deletions
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c new file mode 100644 index 000000000..61e3a2620 --- /dev/null +++ b/kernel/trace/trace_event_perf.c @@ -0,0 +1,529 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * trace event based perf event profiling/tracing + * + * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra + * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com> + */ + +#include <linux/module.h> +#include <linux/kprobes.h> +#include <linux/security.h> +#include "trace.h" +#include "trace_probe.h" + +static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS]; + +/* + * Force it to be aligned to unsigned long to avoid misaligned accesses + * surprises + */ +typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)]) + perf_trace_t; + +/* Count the events in use (per event id, not per instance) */ +static int total_ref_count; + +static int perf_trace_event_perm(struct trace_event_call *tp_event, + struct perf_event *p_event) +{ + int ret; + + if (tp_event->perf_perm) { + ret = tp_event->perf_perm(tp_event, p_event); + if (ret) + return ret; + } + + /* + * We checked and allowed to create parent, + * allow children without checking. + */ + if (p_event->parent) + return 0; + + /* + * It's ok to check current process (owner) permissions in here, + * because code below is called only via perf_event_open syscall. + */ + + /* The ftrace function trace is allowed only for root. */ + if (ftrace_event_is_function(tp_event)) { + ret = perf_allow_tracepoint(&p_event->attr); + if (ret) + return ret; + + if (!is_sampling_event(p_event)) + return 0; + + /* + * We don't allow user space callchains for function trace + * event, due to issues with page faults while tracing page + * fault handler and its overall trickiness nature. + */ + if (!p_event->attr.exclude_callchain_user) + return -EINVAL; + + /* + * Same reason to disable user stack dump as for user space + * callchains above. + */ + if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER) + return -EINVAL; + } + + /* No tracing, just counting, so no obvious leak */ + if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW)) + return 0; + + /* Some events are ok to be traced by non-root users... */ + if (p_event->attach_state == PERF_ATTACH_TASK) { + if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY) + return 0; + } + + /* + * ...otherwise raw tracepoint data can be a severe data leak, + * only allow root to have these. + */ + ret = perf_allow_tracepoint(&p_event->attr); + if (ret) + return ret; + + return 0; +} + +static int perf_trace_event_reg(struct trace_event_call *tp_event, + struct perf_event *p_event) +{ + struct hlist_head __percpu *list; + int ret = -ENOMEM; + int cpu; + + p_event->tp_event = tp_event; + if (tp_event->perf_refcount++ > 0) + return 0; + + list = alloc_percpu(struct hlist_head); + if (!list) + goto fail; + + for_each_possible_cpu(cpu) + INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); + + tp_event->perf_events = list; + + if (!total_ref_count) { + char __percpu *buf; + int i; + + for (i = 0; i < PERF_NR_CONTEXTS; i++) { + buf = (char __percpu *)alloc_percpu(perf_trace_t); + if (!buf) + goto fail; + + perf_trace_buf[i] = buf; + } + } + + ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL); + if (ret) + goto fail; + + total_ref_count++; + return 0; + +fail: + if (!total_ref_count) { + int i; + + for (i = 0; i < PERF_NR_CONTEXTS; i++) { + free_percpu(perf_trace_buf[i]); + perf_trace_buf[i] = NULL; + } + } + + if (!--tp_event->perf_refcount) { + free_percpu(tp_event->perf_events); + tp_event->perf_events = NULL; + } + + return ret; +} + +static void perf_trace_event_unreg(struct perf_event *p_event) +{ + struct trace_event_call *tp_event = p_event->tp_event; + int i; + + if (--tp_event->perf_refcount > 0) + return; + + tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); + + /* + * Ensure our callback won't be called anymore. The buffers + * will be freed after that. + */ + tracepoint_synchronize_unregister(); + + free_percpu(tp_event->perf_events); + tp_event->perf_events = NULL; + + if (!--total_ref_count) { + for (i = 0; i < PERF_NR_CONTEXTS; i++) { + free_percpu(perf_trace_buf[i]); + perf_trace_buf[i] = NULL; + } + } +} + +static int perf_trace_event_open(struct perf_event *p_event) +{ + struct trace_event_call *tp_event = p_event->tp_event; + return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event); +} + +static void perf_trace_event_close(struct perf_event *p_event) +{ + struct trace_event_call *tp_event = p_event->tp_event; + tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event); +} + +static int perf_trace_event_init(struct trace_event_call *tp_event, + struct perf_event *p_event) +{ + int ret; + + ret = perf_trace_event_perm(tp_event, p_event); + if (ret) + return ret; + + ret = perf_trace_event_reg(tp_event, p_event); + if (ret) + return ret; + + ret = perf_trace_event_open(p_event); + if (ret) { + perf_trace_event_unreg(p_event); + return ret; + } + + return 0; +} + +int perf_trace_init(struct perf_event *p_event) +{ + struct trace_event_call *tp_event; + u64 event_id = p_event->attr.config; + int ret = -EINVAL; + + mutex_lock(&event_mutex); + list_for_each_entry(tp_event, &ftrace_events, list) { + if (tp_event->event.type == event_id && + tp_event->class && tp_event->class->reg && + trace_event_try_get_ref(tp_event)) { + ret = perf_trace_event_init(tp_event, p_event); + if (ret) + trace_event_put_ref(tp_event); + break; + } + } + mutex_unlock(&event_mutex); + + return ret; +} + +void perf_trace_destroy(struct perf_event *p_event) +{ + mutex_lock(&event_mutex); + perf_trace_event_close(p_event); + perf_trace_event_unreg(p_event); + trace_event_put_ref(p_event->tp_event); + mutex_unlock(&event_mutex); +} + +#ifdef CONFIG_KPROBE_EVENTS +int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe) +{ + int ret; + char *func = NULL; + struct trace_event_call *tp_event; + + if (p_event->attr.kprobe_func) { + func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL); + if (!func) + return -ENOMEM; + ret = strncpy_from_user( + func, u64_to_user_ptr(p_event->attr.kprobe_func), + KSYM_NAME_LEN); + if (ret == KSYM_NAME_LEN) + ret = -E2BIG; + if (ret < 0) + goto out; + + if (func[0] == '\0') { + kfree(func); + func = NULL; + } + } + + tp_event = create_local_trace_kprobe( + func, (void *)(unsigned long)(p_event->attr.kprobe_addr), + p_event->attr.probe_offset, is_retprobe); + if (IS_ERR(tp_event)) { + ret = PTR_ERR(tp_event); + goto out; + } + + mutex_lock(&event_mutex); + ret = perf_trace_event_init(tp_event, p_event); + if (ret) + destroy_local_trace_kprobe(tp_event); + mutex_unlock(&event_mutex); +out: + kfree(func); + return ret; +} + +void perf_kprobe_destroy(struct perf_event *p_event) +{ + mutex_lock(&event_mutex); + perf_trace_event_close(p_event); + perf_trace_event_unreg(p_event); + trace_event_put_ref(p_event->tp_event); + mutex_unlock(&event_mutex); + + destroy_local_trace_kprobe(p_event->tp_event); +} +#endif /* CONFIG_KPROBE_EVENTS */ + +#ifdef CONFIG_UPROBE_EVENTS +int perf_uprobe_init(struct perf_event *p_event, + unsigned long ref_ctr_offset, bool is_retprobe) +{ + int ret; + char *path = NULL; + struct trace_event_call *tp_event; + + if (!p_event->attr.uprobe_path) + return -EINVAL; + + path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path), + PATH_MAX); + if (IS_ERR(path)) { + ret = PTR_ERR(path); + return (ret == -EINVAL) ? -E2BIG : ret; + } + if (path[0] == '\0') { + ret = -EINVAL; + goto out; + } + + tp_event = create_local_trace_uprobe(path, p_event->attr.probe_offset, + ref_ctr_offset, is_retprobe); + if (IS_ERR(tp_event)) { + ret = PTR_ERR(tp_event); + goto out; + } + + /* + * local trace_uprobe need to hold event_mutex to call + * uprobe_buffer_enable() and uprobe_buffer_disable(). + * event_mutex is not required for local trace_kprobes. + */ + mutex_lock(&event_mutex); + ret = perf_trace_event_init(tp_event, p_event); + if (ret) + destroy_local_trace_uprobe(tp_event); + mutex_unlock(&event_mutex); +out: + kfree(path); + return ret; +} + +void perf_uprobe_destroy(struct perf_event *p_event) +{ + mutex_lock(&event_mutex); + perf_trace_event_close(p_event); + perf_trace_event_unreg(p_event); + trace_event_put_ref(p_event->tp_event); + mutex_unlock(&event_mutex); + destroy_local_trace_uprobe(p_event->tp_event); +} +#endif /* CONFIG_UPROBE_EVENTS */ + +int perf_trace_add(struct perf_event *p_event, int flags) +{ + struct trace_event_call *tp_event = p_event->tp_event; + + if (!(flags & PERF_EF_START)) + p_event->hw.state = PERF_HES_STOPPED; + + /* + * If TRACE_REG_PERF_ADD returns false; no custom action was performed + * and we need to take the default action of enqueueing our event on + * the right per-cpu hlist. + */ + if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event)) { + struct hlist_head __percpu *pcpu_list; + struct hlist_head *list; + + pcpu_list = tp_event->perf_events; + if (WARN_ON_ONCE(!pcpu_list)) + return -EINVAL; + + list = this_cpu_ptr(pcpu_list); + hlist_add_head_rcu(&p_event->hlist_entry, list); + } + + return 0; +} + +void perf_trace_del(struct perf_event *p_event, int flags) +{ + struct trace_event_call *tp_event = p_event->tp_event; + + /* + * If TRACE_REG_PERF_DEL returns false; no custom action was performed + * and we need to take the default action of dequeueing our event from + * the right per-cpu hlist. + */ + if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event)) + hlist_del_rcu(&p_event->hlist_entry); +} + +void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp) +{ + char *raw_data; + int rctx; + + BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); + + if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, + "perf buffer not large enough, wanted %d, have %d", + size, PERF_MAX_TRACE_SIZE)) + return NULL; + + *rctxp = rctx = perf_swevent_get_recursion_context(); + if (rctx < 0) + return NULL; + + if (regs) + *regs = this_cpu_ptr(&__perf_regs[rctx]); + raw_data = this_cpu_ptr(perf_trace_buf[rctx]); + + /* zero the dead bytes from align to not leak stack to user */ + memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); + return raw_data; +} +EXPORT_SYMBOL_GPL(perf_trace_buf_alloc); +NOKPROBE_SYMBOL(perf_trace_buf_alloc); + +void perf_trace_buf_update(void *record, u16 type) +{ + struct trace_entry *entry = record; + + tracing_generic_entry_update(entry, type, tracing_gen_ctx()); +} +NOKPROBE_SYMBOL(perf_trace_buf_update); + +#ifdef CONFIG_FUNCTION_TRACER +static void +perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct ftrace_regs *fregs) +{ + struct ftrace_entry *entry; + struct perf_event *event; + struct hlist_head head; + struct pt_regs regs; + int rctx; + int bit; + + if (!rcu_is_watching()) + return; + + bit = ftrace_test_recursion_trylock(ip, parent_ip); + if (bit < 0) + return; + + if ((unsigned long)ops->private != smp_processor_id()) + goto out; + + event = container_of(ops, struct perf_event, ftrace_ops); + + /* + * @event->hlist entry is NULL (per INIT_HLIST_NODE), and all + * the perf code does is hlist_for_each_entry_rcu(), so we can + * get away with simply setting the @head.first pointer in order + * to create a singular list. + */ + head.first = &event->hlist_entry; + +#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ + sizeof(u64)) - sizeof(u32)) + + BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); + + memset(®s, 0, sizeof(regs)); + perf_fetch_caller_regs(®s); + + entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx); + if (!entry) + goto out; + + entry->ip = ip; + entry->parent_ip = parent_ip; + perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN, + 1, ®s, &head, NULL); + +out: + ftrace_test_recursion_unlock(bit); +#undef ENTRY_SIZE +} + +static int perf_ftrace_function_register(struct perf_event *event) +{ + struct ftrace_ops *ops = &event->ftrace_ops; + + ops->func = perf_ftrace_function_call; + ops->private = (void *)(unsigned long)nr_cpu_ids; + + return register_ftrace_function(ops); +} + +static int perf_ftrace_function_unregister(struct perf_event *event) +{ + struct ftrace_ops *ops = &event->ftrace_ops; + int ret = unregister_ftrace_function(ops); + ftrace_free_filter(ops); + return ret; +} + +int perf_ftrace_event_register(struct trace_event_call *call, + enum trace_reg type, void *data) +{ + struct perf_event *event = data; + + switch (type) { + case TRACE_REG_REGISTER: + case TRACE_REG_UNREGISTER: + break; + case TRACE_REG_PERF_REGISTER: + case TRACE_REG_PERF_UNREGISTER: + return 0; + case TRACE_REG_PERF_OPEN: + return perf_ftrace_function_register(data); + case TRACE_REG_PERF_CLOSE: + return perf_ftrace_function_unregister(data); + case TRACE_REG_PERF_ADD: + event->ftrace_ops.private = (void *)(unsigned long)smp_processor_id(); + return 1; + case TRACE_REG_PERF_DEL: + event->ftrace_ops.private = (void *)(unsigned long)nr_cpu_ids; + return 1; + } + + return -EINVAL; +} +#endif /* CONFIG_FUNCTION_TRACER */ |