tracing: add event trace infrastructure
This patch creates the event tracing infrastructure of ftrace. It will create the files: /debug/tracing/available_events /debug/tracing/set_event The available_events will list the trace points that have been registered with the event tracer. set_events will allow the user to enable or disable an event hook. example: # echo sched_wakeup > /debug/tracing/set_event Will enable the sched_wakeup event (if it is registered). # echo "!sched_wakeup" >> /debug/tracing/set_event Will disable the sched_wakeup event (and only that event). # echo > /debug/tracing/set_event Will disable all events (notice the '>') # cat /debug/tracing/available_events > /debug/tracing/set_event Will enable all registered event hooks. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
Steven Rostedt
parent
7c37730cd3
commit
b77e38aa24
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@ -61,6 +61,14 @@
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#define BRANCH_PROFILE()
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#endif
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#ifdef CONFIG_EVENT_TRACER
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#define FTRACE_EVENTS() VMLINUX_SYMBOL(__start_ftrace_events) = .; \
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*(_ftrace_events) \
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VMLINUX_SYMBOL(__stop_ftrace_events) = .;
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#else
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#define FTRACE_EVENTS()
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#endif
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/* .data section */
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#define DATA_DATA \
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*(.data) \
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@ -81,7 +89,8 @@
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*(__tracepoints) \
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VMLINUX_SYMBOL(__stop___tracepoints) = .; \
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LIKELY_PROFILE() \
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BRANCH_PROFILE()
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BRANCH_PROFILE() \
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FTRACE_EVENTS()
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#define RO_DATA(align) \
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. = ALIGN((align)); \
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@ -159,6 +159,15 @@ config CONTEXT_SWITCH_TRACER
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This tracer gets called from the context switch and records
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all switching of tasks.
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config EVENT_TRACER
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bool "Trace various events in the kernel"
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depends on DEBUG_KERNEL
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select TRACING
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help
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This tracer hooks to various trace points in the kernel
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allowing the user to pick and choose which trace point they
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want to trace.
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config BOOT_TRACER
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bool "Trace boot initcalls"
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depends on DEBUG_KERNEL
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@ -38,5 +38,6 @@ obj-$(CONFIG_POWER_TRACER) += trace_power.o
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obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
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obj-$(CONFIG_WORKQUEUE_TRACER) += trace_workqueue.o
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obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
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obj-$(CONFIG_EVENT_TRACER) += trace_events.o
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libftrace-y := ftrace.o
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@ -0,0 +1,280 @@
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/*
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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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*/
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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_events.h"
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void event_trace_printk(unsigned long ip, const char *fmt, ...)
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{
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va_list ap;
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va_start(ap, fmt);
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tracing_record_cmdline(current);
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trace_vprintk(ip, task_curr_ret_stack(current), fmt, ap);
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va_end(ap);
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}
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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 int ftrace_set_clr_event(char *buf, int set)
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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 (strcmp(buf, call->name) != 0) {
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call++;
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continue;
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}
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if (set) {
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/* Already set? */
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if (call->enabled)
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return 0;
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call->enabled = 1;
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call->regfunc();
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} else {
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/* Already cleared? */
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if (!call->enabled)
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return 0;
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call->enabled = 0;
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call->unregfunc();
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}
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return 0;
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}
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return -EINVAL;
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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 = 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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if ((unsigned long)call >= (unsigned long)__stop_ftrace_events)
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return NULL;
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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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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 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 __init int event_trace_init(void)
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{
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struct dentry *d_tracer;
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struct dentry *entry;
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d_tracer = tracing_init_dentry();
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if (!d_tracer)
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return 0;
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entry = debugfs_create_file("available_events", 0444, d_tracer,
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(void *)&show_event_seq_ops,
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&ftrace_avail_fops);
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if (!entry)
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pr_warning("Could not create debugfs "
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"'available_events' entry\n");
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entry = debugfs_create_file("set_event", 0644, d_tracer,
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(void *)&show_set_event_seq_ops,
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&ftrace_set_event_fops);
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if (!entry)
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pr_warning("Could not create debugfs "
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"'set_event' entry\n");
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return 0;
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}
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fs_initcall(event_trace_init);
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@ -0,0 +1,52 @@
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#ifndef _LINUX_KERNEL_TRACE_EVENTS_H
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#define _LINUX_KERNEL_TRACE_EVENTS_H
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#include <linux/ftrace.h>
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#include "trace.h"
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struct ftrace_event_call {
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char *name;
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int enabled;
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int (*regfunc)(void);
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void (*unregfunc)(void);
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};
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#undef TPFMT
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#define TPFMT(fmt, args...) fmt "\n", ##args
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#undef DEFINE_TRACE_FMT
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#define DEFINE_TRACE_FMT(call, proto, args, fmt) \
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static void ftrace_event_##call(proto) \
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{ \
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event_trace_printk(_RET_IP_, "(" #call ") " fmt); \
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} \
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\
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static int ftrace_reg_event_##call(void) \
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{ \
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int ret; \
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\
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ret = register_trace_##call(ftrace_event_##call); \
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if (!ret) \
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pr_info("event trace: Could not activate trace point " \
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"probe to " #call); \
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return ret; \
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} \
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\
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static void ftrace_unreg_event_##call(void) \
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{ \
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unregister_trace_##call(ftrace_event_##call); \
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} \
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\
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static struct ftrace_event_call __used \
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__attribute__((section("_ftrace_events"))) event_##call = { \
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.name = #call, \
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.regfunc = ftrace_reg_event_##call, \
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.unregfunc = ftrace_unreg_event_##call, \
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}
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void event_trace_printk(unsigned long ip, const char *fmt, ...);
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extern unsigned long __start_ftrace_events[];
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extern unsigned long __stop_ftrace_events[];
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#endif /* _LINUX_KERNEL_TRACE_EVENTS_H */
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