![Peter Zijlstra](/assets/img/avatar_default.png)
Impact: new tracing infrastructure feature Provide infrastructure to generate software perf counter events from tracepoints. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <20090319194233.557364871@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
636 lines
12 KiB
C
636 lines
12 KiB
C
/*
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* event tracer
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*
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* Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
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*
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* - Added format output of fields of the trace point.
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* This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
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*
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*/
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/ctype.h>
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#include "trace_output.h"
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#define TRACE_SYSTEM "TRACE_SYSTEM"
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static DEFINE_MUTEX(event_mutex);
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static void ftrace_clear_events(void)
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{
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struct ftrace_event_call *call = (void *)__start_ftrace_events;
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while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {
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if (call->enabled) {
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call->enabled = 0;
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call->unregfunc();
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}
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call++;
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}
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}
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static void ftrace_event_enable_disable(struct ftrace_event_call *call,
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int enable)
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{
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switch (enable) {
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case 0:
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if (call->enabled) {
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call->enabled = 0;
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call->unregfunc();
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}
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break;
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case 1:
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if (!call->enabled) {
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call->enabled = 1;
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call->regfunc();
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}
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break;
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}
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}
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static int ftrace_set_clr_event(char *buf, int set)
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{
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struct ftrace_event_call *call = __start_ftrace_events;
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char *event = NULL, *sub = NULL, *match;
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int ret = -EINVAL;
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/*
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* The buf format can be <subsystem>:<event-name>
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* *:<event-name> means any event by that name.
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* :<event-name> is the same.
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*
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* <subsystem>:* means all events in that subsystem
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* <subsystem>: means the same.
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*
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* <name> (no ':') means all events in a subsystem with
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* the name <name> or any event that matches <name>
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*/
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match = strsep(&buf, ":");
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if (buf) {
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sub = match;
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event = buf;
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match = NULL;
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if (!strlen(sub) || strcmp(sub, "*") == 0)
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sub = NULL;
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if (!strlen(event) || strcmp(event, "*") == 0)
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event = NULL;
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}
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mutex_lock(&event_mutex);
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for_each_event(call) {
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if (!call->name || !call->regfunc)
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continue;
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if (match &&
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strcmp(match, call->name) != 0 &&
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strcmp(match, call->system) != 0)
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continue;
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if (sub && strcmp(sub, call->system) != 0)
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continue;
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if (event && strcmp(event, call->name) != 0)
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continue;
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ftrace_event_enable_disable(call, set);
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ret = 0;
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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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/* 128 should be much more than enough */
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#define EVENT_BUF_SIZE 127
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static ssize_t
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ftrace_event_write(struct file *file, const char __user *ubuf,
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size_t cnt, loff_t *ppos)
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{
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size_t read = 0;
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int i, set = 1;
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ssize_t ret;
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char *buf;
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char ch;
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if (!cnt || cnt < 0)
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return 0;
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ret = tracing_update_buffers();
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if (ret < 0)
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return ret;
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ret = get_user(ch, ubuf++);
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if (ret)
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return ret;
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read++;
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cnt--;
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/* skip white space */
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while (cnt && isspace(ch)) {
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ret = get_user(ch, ubuf++);
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if (ret)
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return ret;
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read++;
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cnt--;
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}
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/* Only white space found? */
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if (isspace(ch)) {
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file->f_pos += read;
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ret = read;
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return ret;
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}
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buf = kmalloc(EVENT_BUF_SIZE+1, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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if (cnt > EVENT_BUF_SIZE)
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cnt = EVENT_BUF_SIZE;
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i = 0;
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while (cnt && !isspace(ch)) {
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if (!i && ch == '!')
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set = 0;
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else
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buf[i++] = ch;
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ret = get_user(ch, ubuf++);
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if (ret)
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goto out_free;
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read++;
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cnt--;
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}
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buf[i] = 0;
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file->f_pos += read;
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ret = ftrace_set_clr_event(buf, set);
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if (ret)
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goto out_free;
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ret = read;
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out_free:
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kfree(buf);
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return ret;
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}
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static void *
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t_next(struct seq_file *m, void *v, loff_t *pos)
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{
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struct ftrace_event_call *call = m->private;
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struct ftrace_event_call *next = call;
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(*pos)++;
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for (;;) {
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if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
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return NULL;
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/*
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* The ftrace subsystem is for showing formats only.
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* They can not be enabled or disabled via the event files.
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*/
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if (call->regfunc)
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break;
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call++;
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next = call;
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}
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m->private = ++next;
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return call;
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}
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static void *t_start(struct seq_file *m, loff_t *pos)
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{
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return t_next(m, NULL, pos);
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}
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static void *
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s_next(struct seq_file *m, void *v, loff_t *pos)
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{
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struct ftrace_event_call *call = m->private;
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struct ftrace_event_call *next;
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(*pos)++;
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retry:
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if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
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return NULL;
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if (!call->enabled) {
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call++;
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goto retry;
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}
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next = call;
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m->private = ++next;
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return call;
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}
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static void *s_start(struct seq_file *m, loff_t *pos)
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{
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return s_next(m, NULL, pos);
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}
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static int t_show(struct seq_file *m, void *v)
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{
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struct ftrace_event_call *call = v;
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if (strcmp(call->system, TRACE_SYSTEM) != 0)
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seq_printf(m, "%s:", call->system);
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seq_printf(m, "%s\n", call->name);
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return 0;
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}
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static void t_stop(struct seq_file *m, void *p)
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{
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}
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static int
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ftrace_event_seq_open(struct inode *inode, struct file *file)
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{
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int ret;
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const struct seq_operations *seq_ops;
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if ((file->f_mode & FMODE_WRITE) &&
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!(file->f_flags & O_APPEND))
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ftrace_clear_events();
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seq_ops = inode->i_private;
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ret = seq_open(file, seq_ops);
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if (!ret) {
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struct seq_file *m = file->private_data;
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m->private = __start_ftrace_events;
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}
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return ret;
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}
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static ssize_t
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event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
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loff_t *ppos)
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{
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struct ftrace_event_call *call = filp->private_data;
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char *buf;
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if (call->enabled)
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buf = "1\n";
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else
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buf = "0\n";
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return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
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}
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static ssize_t
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event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
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loff_t *ppos)
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{
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struct ftrace_event_call *call = filp->private_data;
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char buf[64];
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unsigned long val;
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int ret;
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if (cnt >= sizeof(buf))
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return -EINVAL;
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if (copy_from_user(&buf, ubuf, cnt))
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return -EFAULT;
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buf[cnt] = 0;
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ret = strict_strtoul(buf, 10, &val);
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if (ret < 0)
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return ret;
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ret = tracing_update_buffers();
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if (ret < 0)
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return ret;
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switch (val) {
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case 0:
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case 1:
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mutex_lock(&event_mutex);
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ftrace_event_enable_disable(call, val);
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mutex_unlock(&event_mutex);
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break;
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default:
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return -EINVAL;
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}
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*ppos += cnt;
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return cnt;
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}
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#undef FIELD
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#define FIELD(type, name) \
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#type, #name, offsetof(typeof(field), name), sizeof(field.name)
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static int trace_write_header(struct trace_seq *s)
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{
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struct trace_entry field;
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/* struct trace_entry */
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return trace_seq_printf(s,
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"\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
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"\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
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"\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
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"\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
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"\tfield:%s %s;\toffset:%zu;\tsize:%zu;\n"
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"\n",
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FIELD(unsigned char, type),
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FIELD(unsigned char, flags),
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FIELD(unsigned char, preempt_count),
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FIELD(int, pid),
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FIELD(int, tgid));
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}
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static ssize_t
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event_format_read(struct file *filp, char __user *ubuf, size_t cnt,
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loff_t *ppos)
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{
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struct ftrace_event_call *call = filp->private_data;
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struct trace_seq *s;
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char *buf;
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int r;
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if (*ppos)
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return 0;
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s = kmalloc(sizeof(*s), GFP_KERNEL);
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if (!s)
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return -ENOMEM;
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trace_seq_init(s);
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/* If any of the first writes fail, so will the show_format. */
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trace_seq_printf(s, "name: %s\n", call->name);
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trace_seq_printf(s, "ID: %d\n", call->id);
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trace_seq_printf(s, "format:\n");
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trace_write_header(s);
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r = call->show_format(s);
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if (!r) {
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/*
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* ug! The format output is bigger than a PAGE!!
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*/
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buf = "FORMAT TOO BIG\n";
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r = simple_read_from_buffer(ubuf, cnt, ppos,
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buf, strlen(buf));
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goto out;
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}
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r = simple_read_from_buffer(ubuf, cnt, ppos,
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s->buffer, s->len);
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out:
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kfree(s);
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return r;
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}
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static ssize_t
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event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
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{
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struct ftrace_event_call *call = filp->private_data;
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struct trace_seq *s;
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int r;
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if (*ppos)
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return 0;
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s = kmalloc(sizeof(*s), GFP_KERNEL);
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if (!s)
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return -ENOMEM;
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trace_seq_init(s);
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trace_seq_printf(s, "%d\n", call->id);
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r = simple_read_from_buffer(ubuf, cnt, ppos,
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s->buffer, s->len);
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kfree(s);
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return r;
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}
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static const struct seq_operations show_event_seq_ops = {
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.start = t_start,
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.next = t_next,
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.show = t_show,
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.stop = t_stop,
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};
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static const struct seq_operations show_set_event_seq_ops = {
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.start = s_start,
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.next = s_next,
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.show = t_show,
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.stop = t_stop,
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};
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static const struct file_operations ftrace_avail_fops = {
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.open = ftrace_event_seq_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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static const struct file_operations ftrace_set_event_fops = {
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.open = ftrace_event_seq_open,
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.read = seq_read,
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.write = ftrace_event_write,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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static const struct file_operations ftrace_enable_fops = {
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.open = tracing_open_generic,
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.read = event_enable_read,
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.write = event_enable_write,
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};
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static const struct file_operations ftrace_event_format_fops = {
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.open = tracing_open_generic,
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.read = event_format_read,
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};
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static const struct file_operations ftrace_event_id_fops = {
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.open = tracing_open_generic,
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.read = event_id_read,
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};
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static struct dentry *event_trace_events_dir(void)
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{
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static struct dentry *d_tracer;
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static struct dentry *d_events;
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if (d_events)
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return d_events;
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d_tracer = tracing_init_dentry();
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if (!d_tracer)
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return NULL;
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d_events = debugfs_create_dir("events", d_tracer);
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if (!d_events)
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pr_warning("Could not create debugfs "
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"'events' directory\n");
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return d_events;
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}
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struct event_subsystem {
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struct list_head list;
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const char *name;
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struct dentry *entry;
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};
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static LIST_HEAD(event_subsystems);
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static struct dentry *
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event_subsystem_dir(const char *name, struct dentry *d_events)
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{
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struct event_subsystem *system;
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/* First see if we did not already create this dir */
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list_for_each_entry(system, &event_subsystems, list) {
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if (strcmp(system->name, name) == 0)
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return system->entry;
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}
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/* need to create new entry */
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system = kmalloc(sizeof(*system), GFP_KERNEL);
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if (!system) {
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pr_warning("No memory to create event subsystem %s\n",
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name);
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return d_events;
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}
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system->entry = debugfs_create_dir(name, d_events);
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if (!system->entry) {
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pr_warning("Could not create event subsystem %s\n",
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name);
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kfree(system);
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return d_events;
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}
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system->name = name;
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list_add(&system->list, &event_subsystems);
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return system->entry;
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}
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static int
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event_create_dir(struct ftrace_event_call *call, struct dentry *d_events)
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{
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struct dentry *entry;
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int ret;
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/*
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* If the trace point header did not define TRACE_SYSTEM
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* then the system would be called "TRACE_SYSTEM".
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*/
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if (strcmp(call->system, "TRACE_SYSTEM") != 0)
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d_events = event_subsystem_dir(call->system, d_events);
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if (call->raw_init) {
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ret = call->raw_init();
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if (ret < 0) {
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pr_warning("Could not initialize trace point"
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" events/%s\n", call->name);
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return ret;
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}
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}
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call->dir = debugfs_create_dir(call->name, d_events);
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if (!call->dir) {
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pr_warning("Could not create debugfs "
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"'%s' directory\n", call->name);
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return -1;
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}
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if (call->regfunc) {
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entry = debugfs_create_file("enable", 0644, call->dir, call,
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&ftrace_enable_fops);
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if (!entry)
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pr_warning("Could not create debugfs "
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"'%s/enable' entry\n", call->name);
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}
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if (call->id) {
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entry = debugfs_create_file("id", 0444, call->dir, call,
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&ftrace_event_id_fops);
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if (!entry)
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pr_warning("Could not create debugfs '%s/id' entry\n",
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call->name);
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}
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/* A trace may not want to export its format */
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if (!call->show_format)
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return 0;
|
|
|
|
entry = debugfs_create_file("format", 0444, call->dir, call,
|
|
&ftrace_event_format_fops);
|
|
if (!entry)
|
|
pr_warning("Could not create debugfs "
|
|
"'%s/format' entry\n", call->name);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static __init int event_trace_init(void)
|
|
{
|
|
struct ftrace_event_call *call = __start_ftrace_events;
|
|
struct dentry *d_tracer;
|
|
struct dentry *entry;
|
|
struct dentry *d_events;
|
|
|
|
d_tracer = tracing_init_dentry();
|
|
if (!d_tracer)
|
|
return 0;
|
|
|
|
entry = debugfs_create_file("available_events", 0444, d_tracer,
|
|
(void *)&show_event_seq_ops,
|
|
&ftrace_avail_fops);
|
|
if (!entry)
|
|
pr_warning("Could not create debugfs "
|
|
"'available_events' entry\n");
|
|
|
|
entry = debugfs_create_file("set_event", 0644, d_tracer,
|
|
(void *)&show_set_event_seq_ops,
|
|
&ftrace_set_event_fops);
|
|
if (!entry)
|
|
pr_warning("Could not create debugfs "
|
|
"'set_event' entry\n");
|
|
|
|
d_events = event_trace_events_dir();
|
|
if (!d_events)
|
|
return 0;
|
|
|
|
for_each_event(call) {
|
|
/* The linker may leave blanks */
|
|
if (!call->name)
|
|
continue;
|
|
event_create_dir(call, d_events);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
fs_initcall(event_trace_init);
|