// 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 "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)
{
if (tp_event->perf_perm) {
int 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)) {
if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
return -EPERM;
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.
*/
if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
return -EPERM;
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;
int pc = preempt_count();
unsigned long flags;
local_save_flags(flags);
tracing_generic_entry_update(entry, type, flags, pc);
}
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 pt_regs *pt_regs)
{
struct ftrace_entry *entry;
struct perf_event *event;
struct hlist_head head;
struct pt_regs regs;
int rctx;
if ((unsigned long)ops->private != smp_processor_id())
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)
return;
entry->ip = ip;
entry->parent_ip = parent_ip;
perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN,
1, ®s, &head, NULL);
#undef ENTRY_SIZE
}
static int perf_ftrace_function_register(struct perf_event *event)
{
struct ftrace_ops *ops = &event->ftrace_ops;
ops->flags = FTRACE_OPS_FL_RCU;
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 */