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