| // 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 |
| * suprises |
| */ |
| 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) |
| goto out; |
| |
| 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; |
| } |
| } |
| out: |
| module_put(tp_event->mod); |
| } |
| |
| 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 && |
| try_module_get(tp_event->mod)) { |
| ret = perf_trace_event_init(tp_event, p_event); |
| if (ret) |
| module_put(tp_event->mod); |
| 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); |
| 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); |
| 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); |
| 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")) |
| 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; |
| |
| if ((unsigned long)ops->private != smp_processor_id()) |
| return; |
| |
| bit = ftrace_test_recursion_trylock(ip, parent_ip); |
| if (bit < 0) |
| return; |
| |
| 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 */ |