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kernel_optimize_test/kernel/trace/trace.c
Steven Rostedt 4a9bd3f134 tracing: Have dynamic size event stack traces 
Currently the stack trace per event in ftace is only 8 frames.
This can be quite limiting and sometimes useless. Especially when
the "ignore frames" is wrong and we also use up stack frames for
the event processing itself.

Change this to be dynamic by adding a percpu buffer that we can
write a large stack frame into and then copy into the ring buffer.

For interrupts and NMIs that come in while another event is being
process, will only get to use the 8 frame stack. That should be enough
as the task that it interrupted will have the full stack frame anyway.

Requested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-07-14 16:36:53 -04:00

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/*
* ring buffer based function tracer
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
* Originally taken from the RT patch by:
* Arnaldo Carvalho de Melo <acme@redhat.com>
*
* Based on code from the latency_tracer, that is:
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
#include <linux/ring_buffer.h>
#include <generated/utsrelease.h>
#include <linux/stacktrace.h>
#include <linux/writeback.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/irqflags.h>
#include <linux/debugfs.h>
#include <linux/pagemap.h>
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/splice.h>
#include <linux/kdebug.h>
#include <linux/string.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include "trace.h"
#include "trace_output.h"
/*
* On boot up, the ring buffer is set to the minimum size, so that
* we do not waste memory on systems that are not using tracing.
*/
int ring_buffer_expanded;
/*
* We need to change this state when a selftest is running.
* A selftest will lurk into the ring-buffer to count the
* entries inserted during the selftest although some concurrent
* insertions into the ring-buffer such as trace_printk could occurred
* at the same time, giving false positive or negative results.
*/
static bool __read_mostly tracing_selftest_running;
/*
* If a tracer is running, we do not want to run SELFTEST.
*/
bool __read_mostly tracing_selftest_disabled;
/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
{ }
};
static struct tracer_flags dummy_tracer_flags = {
.val = 0,
.opts = dummy_tracer_opt
};
static int dummy_set_flag(u32 old_flags, u32 bit, int set)
{
return 0;
}
/*
* Kill all tracing for good (never come back).
* It is initialized to 1 but will turn to zero if the initialization
* of the tracer is successful. But that is the only place that sets
* this back to zero.
*/
static int tracing_disabled = 1;
DEFINE_PER_CPU(int, ftrace_cpu_disabled);
static inline void ftrace_disable_cpu(void)
{
preempt_disable();
__this_cpu_inc(ftrace_cpu_disabled);
}
static inline void ftrace_enable_cpu(void)
{
__this_cpu_dec(ftrace_cpu_disabled);
preempt_enable();
}
cpumask_var_t __read_mostly tracing_buffer_mask;
/*
* ftrace_dump_on_oops - variable to dump ftrace buffer on oops
*
* If there is an oops (or kernel panic) and the ftrace_dump_on_oops
* is set, then ftrace_dump is called. This will output the contents
* of the ftrace buffers to the console. This is very useful for
* capturing traces that lead to crashes and outputing it to a
* serial console.
*
* It is default off, but you can enable it with either specifying
* "ftrace_dump_on_oops" in the kernel command line, or setting
* /proc/sys/kernel/ftrace_dump_on_oops
* Set 1 if you want to dump buffers of all CPUs
* Set 2 if you want to dump the buffer of the CPU that triggered oops
*/
enum ftrace_dump_mode ftrace_dump_on_oops;
static int tracing_set_tracer(const char *buf);
#define MAX_TRACER_SIZE 100
static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;
static int __init set_cmdline_ftrace(char *str)
{
strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
default_bootup_tracer = bootup_tracer_buf;
/* We are using ftrace early, expand it */
ring_buffer_expanded = 1;
return 1;
}
__setup("ftrace=", set_cmdline_ftrace);
static int __init set_ftrace_dump_on_oops(char *str)
{
if (*str++ != '=' || !*str) {
ftrace_dump_on_oops = DUMP_ALL;
return 1;
}
if (!strcmp("orig_cpu", str)) {
ftrace_dump_on_oops = DUMP_ORIG;
return 1;
}
return 0;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
unsigned long long ns2usecs(cycle_t nsec)
{
nsec += 500;
do_div(nsec, 1000);
return nsec;
}
/*
* The global_trace is the descriptor that holds the tracing
* buffers for the live tracing. For each CPU, it contains
* a link list of pages that will store trace entries. The
* page descriptor of the pages in the memory is used to hold
* the link list by linking the lru item in the page descriptor
* to each of the pages in the buffer per CPU.
*
* For each active CPU there is a data field that holds the
* pages for the buffer for that CPU. Each CPU has the same number
* of pages allocated for its buffer.
*/
static struct trace_array global_trace;
static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
int filter_current_check_discard(struct ring_buffer *buffer,
struct ftrace_event_call *call, void *rec,
struct ring_buffer_event *event)
{
return filter_check_discard(call, rec, buffer, event);
}
EXPORT_SYMBOL_GPL(filter_current_check_discard);
cycle_t ftrace_now(int cpu)
{
u64 ts;
/* Early boot up does not have a buffer yet */
if (!global_trace.buffer)
return trace_clock_local();
ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
return ts;
}
/*
* The max_tr is used to snapshot the global_trace when a maximum
* latency is reached. Some tracers will use this to store a maximum
* trace while it continues examining live traces.
*
* The buffers for the max_tr are set up the same as the global_trace.
* When a snapshot is taken, the link list of the max_tr is swapped
* with the link list of the global_trace and the buffers are reset for
* the global_trace so the tracing can continue.
*/
static struct trace_array max_tr;
static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
/* tracer_enabled is used to toggle activation of a tracer */
static int tracer_enabled = 1;
/**
* tracing_is_enabled - return tracer_enabled status
*
* This function is used by other tracers to know the status
* of the tracer_enabled flag. Tracers may use this function
* to know if it should enable their features when starting
* up. See irqsoff tracer for an example (start_irqsoff_tracer).
*/
int tracing_is_enabled(void)
{
return tracer_enabled;
}
/*
* trace_buf_size is the size in bytes that is allocated
* for a buffer. Note, the number of bytes is always rounded
* to page size.
*
* This number is purposely set to a low number of 16384.
* If the dump on oops happens, it will be much appreciated
* to not have to wait for all that output. Anyway this can be
* boot time and run time configurable.
*/
#define TRACE_BUF_SIZE_DEFAULT 1441792UL /* 16384 * 88 (sizeof(entry)) */
static unsigned long trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
/* trace_types holds a link list of available tracers. */
static struct tracer *trace_types __read_mostly;
/* current_trace points to the tracer that is currently active */
static struct tracer *current_trace __read_mostly;
/*
* trace_types_lock is used to protect the trace_types list.
*/
static DEFINE_MUTEX(trace_types_lock);
/*
* serialize the access of the ring buffer
*
* ring buffer serializes readers, but it is low level protection.
* The validity of the events (which returns by ring_buffer_peek() ..etc)
* are not protected by ring buffer.
*
* The content of events may become garbage if we allow other process consumes
* these events concurrently:
* A) the page of the consumed events may become a normal page
* (not reader page) in ring buffer, and this page will be rewrited
* by events producer.
* B) The page of the consumed events may become a page for splice_read,
* and this page will be returned to system.
*
* These primitives allow multi process access to different cpu ring buffer
* concurrently.
*
* These primitives don't distinguish read-only and read-consume access.
* Multi read-only access are also serialized.
*/
#ifdef CONFIG_SMP
static DECLARE_RWSEM(all_cpu_access_lock);
static DEFINE_PER_CPU(struct mutex, cpu_access_lock);
static inline void trace_access_lock(int cpu)
{
if (cpu == TRACE_PIPE_ALL_CPU) {
/* gain it for accessing the whole ring buffer. */
down_write(&all_cpu_access_lock);
} else {
/* gain it for accessing a cpu ring buffer. */
/* Firstly block other trace_access_lock(TRACE_PIPE_ALL_CPU). */
down_read(&all_cpu_access_lock);
/* Secondly block other access to this @cpu ring buffer. */
mutex_lock(&per_cpu(cpu_access_lock, cpu));
}
}
static inline void trace_access_unlock(int cpu)
{
if (cpu == TRACE_PIPE_ALL_CPU) {
up_write(&all_cpu_access_lock);
} else {
mutex_unlock(&per_cpu(cpu_access_lock, cpu));
up_read(&all_cpu_access_lock);
}
}
static inline void trace_access_lock_init(void)
{
int cpu;
for_each_possible_cpu(cpu)
mutex_init(&per_cpu(cpu_access_lock, cpu));
}
#else
static DEFINE_MUTEX(access_lock);
static inline void trace_access_lock(int cpu)
{
(void)cpu;
mutex_lock(&access_lock);
}
static inline void trace_access_unlock(int cpu)
{
(void)cpu;
mutex_unlock(&access_lock);
}
static inline void trace_access_lock_init(void)
{
}
#endif
/* trace_wait is a waitqueue for tasks blocked on trace_poll */
static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
/* trace_flags holds trace_options default values */
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE;
static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);
static void wakeup_work_handler(struct work_struct *work)
{
wake_up(&trace_wait);
}
static DECLARE_DELAYED_WORK(wakeup_work, wakeup_work_handler);
/**
* trace_wake_up - wake up tasks waiting for trace input
*
* Schedules a delayed work to wake up any task that is blocked on the
* trace_wait queue. These is used with trace_poll for tasks polling the
* trace.
*/
void trace_wake_up(void)
{
const unsigned long delay = msecs_to_jiffies(2);
if (trace_flags & TRACE_ITER_BLOCK)
return;
schedule_delayed_work(&wakeup_work, delay);
}
static int __init set_buf_size(char *str)
{
unsigned long buf_size;
if (!str)
return 0;
buf_size = memparse(str, &str);
/* nr_entries can not be zero */
if (buf_size == 0)
return 0;
trace_buf_size = buf_size;
return 1;
}
__setup("trace_buf_size=", set_buf_size);
static int __init set_tracing_thresh(char *str)
{
unsigned long threshhold;
int ret;
if (!str)
return 0;
ret = strict_strtoul(str, 0, &threshhold);
if (ret < 0)
return 0;
tracing_thresh = threshhold * 1000;
return 1;
}
__setup("tracing_thresh=", set_tracing_thresh);
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
return nsecs / 1000;
}
/* These must match the bit postions in trace_iterator_flags */
static const char *trace_options[] = {
"print-parent",
"sym-offset",
"sym-addr",
"verbose",
"raw",
"hex",
"bin",
"block",
"stacktrace",
"trace_printk",
"ftrace_preempt",
"branch",
"annotate",
"userstacktrace",
"sym-userobj",
"printk-msg-only",
"context-info",
"latency-format",
"sleep-time",
"graph-time",
"record-cmd",
"overwrite",
"disable_on_free",
NULL
};
static struct {
u64 (*func)(void);
const char *name;
} trace_clocks[] = {
{ trace_clock_local, "local" },
{ trace_clock_global, "global" },
};
int trace_clock_id;
/*
* trace_parser_get_init - gets the buffer for trace parser
*/
int trace_parser_get_init(struct trace_parser *parser, int size)
{
memset(parser, 0, sizeof(*parser));
parser->buffer = kmalloc(size, GFP_KERNEL);
if (!parser->buffer)
return 1;
parser->size = size;
return 0;
}
/*
* trace_parser_put - frees the buffer for trace parser
*/
void trace_parser_put(struct trace_parser *parser)
{
kfree(parser->buffer);
}
/*
* trace_get_user - reads the user input string separated by space
* (matched by isspace(ch))
*
* For each string found the 'struct trace_parser' is updated,
* and the function returns.
*
* Returns number of bytes read.
*
* See kernel/trace/trace.h for 'struct trace_parser' details.
*/
int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char ch;
size_t read = 0;
ssize_t ret;
if (!*ppos)
trace_parser_clear(parser);
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
/*
* The parser is not finished with the last write,
* continue reading the user input without skipping spaces.
*/
if (!parser->cont) {
/* skip white space */
while (cnt && isspace(ch)) {
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
/* only spaces were written */
if (isspace(ch)) {
*ppos += read;
ret = read;
goto out;
}
parser->idx = 0;
}
/* read the non-space input */
while (cnt && !isspace(ch)) {
if (parser->idx < parser->size - 1)
parser->buffer[parser->idx++] = ch;
else {
ret = -EINVAL;
goto out;
}
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
/* We either got finished input or we have to wait for another call. */
if (isspace(ch)) {
parser->buffer[parser->idx] = 0;
parser->cont = false;
} else {
parser->cont = true;
parser->buffer[parser->idx++] = ch;
}
*ppos += read;
ret = read;
out:
return ret;
}
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
int len;
int ret;
if (!cnt)
return 0;
if (s->len <= s->readpos)
return -EBUSY;
len = s->len - s->readpos;
if (cnt > len)
cnt = len;
ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
if (ret == cnt)
return -EFAULT;
cnt -= ret;
s->readpos += cnt;
return cnt;
}
static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
void *ret;
if (s->len <= s->readpos)
return -EBUSY;
len = s->len - s->readpos;
if (cnt > len)
cnt = len;
ret = memcpy(buf, s->buffer + s->readpos, cnt);
if (!ret)
return -EFAULT;
s->readpos += cnt;
return cnt;
}
/*
* ftrace_max_lock is used to protect the swapping of buffers
* when taking a max snapshot. The buffers themselves are
* protected by per_cpu spinlocks. But the action of the swap
* needs its own lock.
*
* This is defined as a arch_spinlock_t in order to help
* with performance when lockdep debugging is enabled.
*
* It is also used in other places outside the update_max_tr
* so it needs to be defined outside of the
* CONFIG_TRACER_MAX_TRACE.
*/
static arch_spinlock_t ftrace_max_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
unsigned long __read_mostly tracing_thresh;
#ifdef CONFIG_TRACER_MAX_TRACE
unsigned long __read_mostly tracing_max_latency;
/*
* Copy the new maximum trace into the separate maximum-trace
* structure. (this way the maximum trace is permanently saved,
* for later retrieval via /sys/kernel/debug/tracing/latency_trace)
*/
static void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct trace_array_cpu *data = tr->data[cpu];
struct trace_array_cpu *max_data;
max_tr.cpu = cpu;
max_tr.time_start = data->preempt_timestamp;
max_data = max_tr.data[cpu];
max_data->saved_latency = tracing_max_latency;
max_data->critical_start = data->critical_start;
max_data->critical_end = data->critical_end;
memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
max_data->pid = tsk->pid;
max_data->uid = task_uid(tsk);
max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
max_data->policy = tsk->policy;
max_data->rt_priority = tsk->rt_priority;
/* record this tasks comm */
tracing_record_cmdline(tsk);
}
/**
* update_max_tr - snapshot all trace buffers from global_trace to max_tr
* @tr: tracer
* @tsk: the task with the latency
* @cpu: The cpu that initiated the trace.
*
* Flip the buffers between the @tr and the max_tr and record information
* about which task was the cause of this latency.
*/
void
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct ring_buffer *buf = tr->buffer;
if (trace_stop_count)
return;
WARN_ON_ONCE(!irqs_disabled());
if (!current_trace->use_max_tr) {
WARN_ON_ONCE(1);
return;
}
arch_spin_lock(&ftrace_max_lock);
tr->buffer = max_tr.buffer;
max_tr.buffer = buf;
__update_max_tr(tr, tsk, cpu);
arch_spin_unlock(&ftrace_max_lock);
}
/**
* update_max_tr_single - only copy one trace over, and reset the rest
* @tr - tracer
* @tsk - task with the latency
* @cpu - the cpu of the buffer to copy.
*
* Flip the trace of a single CPU buffer between the @tr and the max_tr.
*/
void
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
int ret;
if (trace_stop_count)
return;
WARN_ON_ONCE(!irqs_disabled());
if (!current_trace->use_max_tr) {
WARN_ON_ONCE(1);
return;
}
arch_spin_lock(&ftrace_max_lock);
ftrace_disable_cpu();
ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
if (ret == -EBUSY) {
/*
* We failed to swap the buffer due to a commit taking
* place on this CPU. We fail to record, but we reset
* the max trace buffer (no one writes directly to it)
* and flag that it failed.
*/
trace_array_printk(&max_tr, _THIS_IP_,
"Failed to swap buffers due to commit in progress\n");
}
ftrace_enable_cpu();
WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
__update_max_tr(tr, tsk, cpu);
arch_spin_unlock(&ftrace_max_lock);
}
#endif /* CONFIG_TRACER_MAX_TRACE */
/**
* register_tracer - register a tracer with the ftrace system.
* @type - the plugin for the tracer
*
* Register a new plugin tracer.
*/
int register_tracer(struct tracer *type)
__releases(kernel_lock)
__acquires(kernel_lock)
{
struct tracer *t;
int ret = 0;
if (!type->name) {
pr_info("Tracer must have a name\n");
return -1;
}
if (strlen(type->name) >= MAX_TRACER_SIZE) {
pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
return -1;
}
mutex_lock(&trace_types_lock);
tracing_selftest_running = true;
for (t = trace_types; t; t = t->next) {
if (strcmp(type->name, t->name) == 0) {
/* already found */
pr_info("Tracer %s already registered\n",
type->name);
ret = -1;
goto out;
}
}
if (!type->set_flag)
type->set_flag = &dummy_set_flag;
if (!type->flags)
type->flags = &dummy_tracer_flags;
else
if (!type->flags->opts)
type->flags->opts = dummy_tracer_opt;
if (!type->wait_pipe)
type->wait_pipe = default_wait_pipe;
#ifdef CONFIG_FTRACE_STARTUP_TEST
if (type->selftest && !tracing_selftest_disabled) {
struct tracer *saved_tracer = current_trace;
struct trace_array *tr = &global_trace;
/*
* Run a selftest on this tracer.
* Here we reset the trace buffer, and set the current
* tracer to be this tracer. The tracer can then run some
* internal tracing to verify that everything is in order.
* If we fail, we do not register this tracer.
*/
tracing_reset_online_cpus(tr);
current_trace = type;
/* If we expanded the buffers, make sure the max is expanded too */
if (ring_buffer_expanded && type->use_max_tr)
ring_buffer_resize(max_tr.buffer, trace_buf_size);
/* the test is responsible for initializing and enabling */
pr_info("Testing tracer %s: ", type->name);
ret = type->selftest(type, tr);
/* the test is responsible for resetting too */
current_trace = saved_tracer;
if (ret) {
printk(KERN_CONT "FAILED!\n");
goto out;
}
/* Only reset on passing, to avoid touching corrupted buffers */
tracing_reset_online_cpus(tr);
/* Shrink the max buffer again */
if (ring_buffer_expanded && type->use_max_tr)
ring_buffer_resize(max_tr.buffer, 1);
printk(KERN_CONT "PASSED\n");
}
#endif
type->next = trace_types;
trace_types = type;
out:
tracing_selftest_running = false;
mutex_unlock(&trace_types_lock);
if (ret || !default_bootup_tracer)
goto out_unlock;
if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
goto out_unlock;
printk(KERN_INFO "Starting tracer '%s'\n", type->name);
/* Do we want this tracer to start on bootup? */
tracing_set_tracer(type->name);
default_bootup_tracer = NULL;
/* disable other selftests, since this will break it. */
tracing_selftest_disabled = 1;
#ifdef CONFIG_FTRACE_STARTUP_TEST
printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
type->name);
#endif
out_unlock:
return ret;
}
void unregister_tracer(struct tracer *type)
{
struct tracer **t;
mutex_lock(&trace_types_lock);
for (t = &trace_types; *t; t = &(*t)->next) {
if (*t == type)
goto found;
}
pr_info("Tracer %s not registered\n", type->name);
goto out;
found:
*t = (*t)->next;
if (type == current_trace && tracer_enabled) {
tracer_enabled = 0;
tracing_stop();
if (current_trace->stop)
current_trace->stop(&global_trace);
current_trace = &nop_trace;
}
out:
mutex_unlock(&trace_types_lock);
}
static void __tracing_reset(struct ring_buffer *buffer, int cpu)
{
ftrace_disable_cpu();
ring_buffer_reset_cpu(buffer, cpu);
ftrace_enable_cpu();
}
void tracing_reset(struct trace_array *tr, int cpu)
{
struct ring_buffer *buffer = tr->buffer;
ring_buffer_record_disable(buffer);
/* Make sure all commits have finished */
synchronize_sched();
__tracing_reset(buffer, cpu);
ring_buffer_record_enable(buffer);
}
void tracing_reset_online_cpus(struct trace_array *tr)
{
struct ring_buffer *buffer = tr->buffer;
int cpu;
ring_buffer_record_disable(buffer);
/* Make sure all commits have finished */
synchronize_sched();
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
__tracing_reset(buffer, cpu);
ring_buffer_record_enable(buffer);
}
void tracing_reset_current(int cpu)
{
tracing_reset(&global_trace, cpu);
}
void tracing_reset_current_online_cpus(void)
{
tracing_reset_online_cpus(&global_trace);
}
#define SAVED_CMDLINES 128
#define NO_CMDLINE_MAP UINT_MAX
static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
static int cmdline_idx;
static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
/* temporary disable recording */
static atomic_t trace_record_cmdline_disabled __read_mostly;
static void trace_init_cmdlines(void)
{
memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
cmdline_idx = 0;
}
int is_tracing_stopped(void)
{
return trace_stop_count;
}
/**
* ftrace_off_permanent - disable all ftrace code permanently
*
* This should only be called when a serious anomally has
* been detected. This will turn off the function tracing,
* ring buffers, and other tracing utilites. It takes no
* locks and can be called from any context.
*/
void ftrace_off_permanent(void)
{
tracing_disabled = 1;
ftrace_stop();
tracing_off_permanent();
}
/**
* tracing_start - quick start of the tracer
*
* If tracing is enabled but was stopped by tracing_stop,
* this will start the tracer back up.
*/
void tracing_start(void)
{
struct ring_buffer *buffer;
unsigned long flags;
if (tracing_disabled)
return;
spin_lock_irqsave(&tracing_start_lock, flags);
if (--trace_stop_count) {
if (trace_stop_count < 0) {
/* Someone screwed up their debugging */
WARN_ON_ONCE(1);
trace_stop_count = 0;
}
goto out;
}
/* Prevent the buffers from switching */
arch_spin_lock(&ftrace_max_lock);
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
arch_spin_unlock(&ftrace_max_lock);
ftrace_start();
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
/**
* tracing_stop - quick stop of the tracer
*
* Light weight way to stop tracing. Use in conjunction with
* tracing_start.
*/
void tracing_stop(void)
{
struct ring_buffer *buffer;
unsigned long flags;
ftrace_stop();
spin_lock_irqsave(&tracing_start_lock, flags);
if (trace_stop_count++)
goto out;
/* Prevent the buffers from switching */
arch_spin_lock(&ftrace_max_lock);
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
arch_spin_unlock(&ftrace_max_lock);
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
void trace_stop_cmdline_recording(void);
static void trace_save_cmdline(struct task_struct *tsk)
{
unsigned pid, idx;
if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
return;
/*
* It's not the end of the world if we don't get
* the lock, but we also don't want to spin
* nor do we want to disable interrupts,
* so if we miss here, then better luck next time.
*/
if (!arch_spin_trylock(&trace_cmdline_lock))
return;
idx = map_pid_to_cmdline[tsk->pid];
if (idx == NO_CMDLINE_MAP) {
idx = (cmdline_idx + 1) % SAVED_CMDLINES;
/*
* Check whether the cmdline buffer at idx has a pid
* mapped. We are going to overwrite that entry so we
* need to clear the map_pid_to_cmdline. Otherwise we
* would read the new comm for the old pid.
*/
pid = map_cmdline_to_pid[idx];
if (pid != NO_CMDLINE_MAP)
map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
map_cmdline_to_pid[idx] = tsk->pid;
map_pid_to_cmdline[tsk->pid] = idx;
cmdline_idx = idx;
}
memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
arch_spin_unlock(&trace_cmdline_lock);
}
void trace_find_cmdline(int pid, char comm[])
{
unsigned map;
if (!pid) {
strcpy(comm, "<idle>");
return;
}
if (WARN_ON_ONCE(pid < 0)) {
strcpy(comm, "<XXX>");
return;
}
if (pid > PID_MAX_DEFAULT) {
strcpy(comm, "<...>");
return;
}
preempt_disable();
arch_spin_lock(&trace_cmdline_lock);
map = map_pid_to_cmdline[pid];
if (map != NO_CMDLINE_MAP)
strcpy(comm, saved_cmdlines[map]);
else
strcpy(comm, "<...>");
arch_spin_unlock(&trace_cmdline_lock);
preempt_enable();
}
void tracing_record_cmdline(struct task_struct *tsk)
{
if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
!tracing_is_on())
return;
trace_save_cmdline(tsk);
}
void
tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
int pc)
{
struct task_struct *tsk = current;
entry->preempt_count = pc & 0xff;
entry->pid = (tsk) ? tsk->pid : 0;
entry->padding = 0;
entry->flags =
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
#else
TRACE_FLAG_IRQS_NOSUPPORT |
#endif
((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
}
EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
struct ring_buffer_event *
trace_buffer_lock_reserve(struct ring_buffer *buffer,
int type,
unsigned long len,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
event = ring_buffer_lock_reserve(buffer, len);
if (event != NULL) {
struct trace_entry *ent = ring_buffer_event_data(event);
tracing_generic_entry_update(ent, flags, pc);
ent->type = type;
}
return event;
}
static inline void
__trace_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc,
int wake)
{
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);
ftrace_trace_userstack(buffer, flags, pc);
if (wake)
trace_wake_up();
}
void trace_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
}
struct ring_buffer_event *
trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
int type, unsigned long len,
unsigned long flags, int pc)
{
*current_rb = global_trace.buffer;
return trace_buffer_lock_reserve(*current_rb,
type, len, flags, pc);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(buffer, event, flags, pc, 0);
}
EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc,
struct pt_regs *regs)
{
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
ftrace_trace_userstack(buffer, flags, pc);
}
EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit_regs);
void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event)
{
ring_buffer_discard_commit(buffer, event);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);
void
trace_function(struct trace_array *tr,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
struct ftrace_event_call *call = &event_function;
struct ring_buffer *buffer = tr->buffer;
struct ring_buffer_event *event;
struct ftrace_entry *entry;
/* If we are reading the ring buffer, don't trace */
if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
return;
event = trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->ip = ip;
entry->parent_ip = parent_ip;
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);
}
void
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
if (likely(!atomic_read(&data->disabled)))
trace_function(tr, ip, parent_ip, flags, pc);
}
#ifdef CONFIG_STACKTRACE
#define FTRACE_STACK_MAX_ENTRIES (PAGE_SIZE / sizeof(unsigned long))
struct ftrace_stack {
unsigned long calls[FTRACE_STACK_MAX_ENTRIES];
};
static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack);
static DEFINE_PER_CPU(int, ftrace_stack_reserve);
static void __ftrace_trace_stack(struct ring_buffer *buffer,
unsigned long flags,
int skip, int pc, struct pt_regs *regs)
{
struct ftrace_event_call *call = &event_kernel_stack;
struct ring_buffer_event *event;
struct stack_entry *entry;
struct stack_trace trace;
int use_stack;
int size = FTRACE_STACK_ENTRIES;
trace.nr_entries = 0;
trace.skip = skip;
/*
* Since events can happen in NMIs there's no safe way to
* use the per cpu ftrace_stacks. We reserve it and if an interrupt
* or NMI comes in, it will just have to use the default
* FTRACE_STACK_SIZE.
*/
preempt_disable_notrace();
use_stack = ++__get_cpu_var(ftrace_stack_reserve);
/*
* We don't need any atomic variables, just a barrier.
* If an interrupt comes in, we don't care, because it would
* have exited and put the counter back to what we want.
* We just need a barrier to keep gcc from moving things
* around.
*/
barrier();
if (use_stack == 1) {
trace.entries = &__get_cpu_var(ftrace_stack).calls[0];
trace.max_entries = FTRACE_STACK_MAX_ENTRIES;
if (regs)
save_stack_trace_regs(regs, &trace);
else
save_stack_trace(&trace);
if (trace.nr_entries > size)
size = trace.nr_entries;
} else
/* From now on, use_stack is a boolean */
use_stack = 0;
size *= sizeof(unsigned long);
event = trace_buffer_lock_reserve(buffer, TRACE_STACK,
sizeof(*entry) + size, flags, pc);
if (!event)
goto out;
entry = ring_buffer_event_data(event);
memset(&entry->caller, 0, size);
if (use_stack)
memcpy(&entry->caller, trace.entries,
trace.nr_entries * sizeof(unsigned long));
else {
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.entries = entry->caller;
if (regs)
save_stack_trace_regs(regs, &trace);
else
save_stack_trace(&trace);
}
entry->size = trace.nr_entries;
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);
out:
/* Again, don't let gcc optimize things here */
barrier();
__get_cpu_var(ftrace_stack_reserve)--;
preempt_enable_notrace();
}
void ftrace_trace_stack_regs(struct ring_buffer *buffer, unsigned long flags,
int skip, int pc, struct pt_regs *regs)
{
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
__ftrace_trace_stack(buffer, flags, skip, pc, regs);
}
void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
int skip, int pc)
{
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
}
void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
int pc)
{
__ftrace_trace_stack(tr->buffer, flags, skip, pc, NULL);
}
/**
* trace_dump_stack - record a stack back trace in the trace buffer
*/
void trace_dump_stack(void)
{
unsigned long flags;
if (tracing_disabled || tracing_selftest_running)
return;
local_save_flags(flags);
/* skipping 3 traces, seems to get us at the caller of this function */
__ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count(), NULL);
}
static DEFINE_PER_CPU(int, user_stack_count);
void
ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
{
struct ftrace_event_call *call = &event_user_stack;
struct ring_buffer_event *event;
struct userstack_entry *entry;
struct stack_trace trace;
if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
return;
/*
* NMIs can not handle page faults, even with fix ups.
* The save user stack can (and often does) fault.
*/
if (unlikely(in_nmi()))
return;
/*
* prevent recursion, since the user stack tracing may
* trigger other kernel events.
*/
preempt_disable();
if (__this_cpu_read(user_stack_count))
goto out;
__this_cpu_inc(user_stack_count);
event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
sizeof(*entry), flags, pc);
if (!event)
goto out_drop_count;
entry = ring_buffer_event_data(event);
entry->tgid = current->tgid;
memset(&entry->caller, 0, sizeof(entry->caller));
trace.nr_entries = 0;
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.skip = 0;
trace.entries = entry->caller;
save_stack_trace_user(&trace);
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);
out_drop_count:
__this_cpu_dec(user_stack_count);
out:
preempt_enable();
}
#ifdef UNUSED
static void __trace_userstack(struct trace_array *tr, unsigned long flags)
{
ftrace_trace_userstack(tr, flags, preempt_count());
}
#endif /* UNUSED */
#endif /* CONFIG_STACKTRACE */
/**
* trace_vbprintk - write binary msg to tracing buffer
*
*/
int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
{
static arch_spinlock_t trace_buf_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
static u32 trace_buf[TRACE_BUF_SIZE];
struct ftrace_event_call *call = &event_bprint;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
struct bprint_entry *entry;
unsigned long flags;
int disable;
int cpu, len = 0, size, pc;
if (unlikely(tracing_selftest_running || tracing_disabled))
return 0;
/* Don't pollute graph traces with trace_vprintk internals */
pause_graph_tracing();
pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disable = atomic_inc_return(&data->disabled);
if (unlikely(disable != 1))
goto out;
/* Lockdep uses trace_printk for lock tracing */
local_irq_save(flags);
arch_spin_lock(&trace_buf_lock);
len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);
if (len > TRACE_BUF_SIZE || len < 0)
goto out_unlock;
size = sizeof(*entry) + sizeof(u32) * len;
buffer = tr->buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
flags, pc);
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
entry->ip = ip;
entry->fmt = fmt;
memcpy(entry->buf, trace_buf, sizeof(u32) * len);
if (!filter_check_discard(call, entry, buffer, event)) {
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);
}
out_unlock:
arch_spin_unlock(&trace_buf_lock);
local_irq_restore(flags);
out:
atomic_dec_return(&data->disabled);
preempt_enable_notrace();
unpause_graph_tracing();
return len;
}
EXPORT_SYMBOL_GPL(trace_vbprintk);
int trace_array_printk(struct trace_array *tr,
unsigned long ip, const char *fmt, ...)
{
int ret;
va_list ap;
if (!(trace_flags & TRACE_ITER_PRINTK))
return 0;
va_start(ap, fmt);
ret = trace_array_vprintk(tr, ip, fmt, ap);
va_end(ap);
return ret;
}
int trace_array_vprintk(struct trace_array *tr,
unsigned long ip, const char *fmt, va_list args)
{
static arch_spinlock_t trace_buf_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static char trace_buf[TRACE_BUF_SIZE];
struct ftrace_event_call *call = &event_print;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct trace_array_cpu *data;
int cpu, len = 0, size, pc;
struct print_entry *entry;
unsigned long irq_flags;
int disable;
if (tracing_disabled || tracing_selftest_running)
return 0;
pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disable = atomic_inc_return(&data->disabled);
if (unlikely(disable != 1))
goto out;
pause_graph_tracing();
raw_local_irq_save(irq_flags);
arch_spin_lock(&trace_buf_lock);
len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
size = sizeof(*entry) + len + 1;
buffer = tr->buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
irq_flags, pc);
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
entry->ip = ip;
memcpy(&entry->buf, trace_buf, len);
entry->buf[len] = '\0';
if (!filter_check_discard(call, entry, buffer, event)) {
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, irq_flags, 6, pc);
}
out_unlock:
arch_spin_unlock(&trace_buf_lock);
raw_local_irq_restore(irq_flags);
unpause_graph_tracing();
out:
atomic_dec_return(&data->disabled);
preempt_enable_notrace();
return len;
}
int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
{
return trace_array_vprintk(&global_trace, ip, fmt, args);
}
EXPORT_SYMBOL_GPL(trace_vprintk);
static void trace_iterator_increment(struct trace_iterator *iter)
{
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
iter->idx++;
if (iter->buffer_iter[iter->cpu])
ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
ftrace_enable_cpu();
}
static struct trace_entry *
peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
unsigned long *lost_events)
{
struct ring_buffer_event *event;
struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
if (buf_iter)
event = ring_buffer_iter_peek(buf_iter, ts);
else
event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
lost_events);
ftrace_enable_cpu();
if (event) {
iter->ent_size = ring_buffer_event_length(event);
return ring_buffer_event_data(event);
}
iter->ent_size = 0;
return NULL;
}
static struct trace_entry *
__find_next_entry(struct trace_iterator *iter, int *ent_cpu,
unsigned long *missing_events, u64 *ent_ts)
{
struct ring_buffer *buffer = iter->tr->buffer;
struct trace_entry *ent, *next = NULL;
unsigned long lost_events = 0, next_lost = 0;
int cpu_file = iter->cpu_file;
u64 next_ts = 0, ts;
int next_cpu = -1;
int cpu;
/*
* If we are in a per_cpu trace file, don't bother by iterating over
* all cpu and peek directly.
*/
if (cpu_file > TRACE_PIPE_ALL_CPU) {
if (ring_buffer_empty_cpu(buffer, cpu_file))
return NULL;
ent = peek_next_entry(iter, cpu_file, ent_ts, missing_events);
if (ent_cpu)
*ent_cpu = cpu_file;
return ent;
}
for_each_tracing_cpu(cpu) {
if (ring_buffer_empty_cpu(buffer, cpu))
continue;
ent = peek_next_entry(iter, cpu, &ts, &lost_events);
/*
* Pick the entry with the smallest timestamp:
*/
if (ent && (!next || ts < next_ts)) {
next = ent;
next_cpu = cpu;
next_ts = ts;
next_lost = lost_events;
}
}
if (ent_cpu)
*ent_cpu = next_cpu;
if (ent_ts)
*ent_ts = next_ts;
if (missing_events)
*missing_events = next_lost;
return next;
}
/* Find the next real entry, without updating the iterator itself */
struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
int *ent_cpu, u64 *ent_ts)
{
return __find_next_entry(iter, ent_cpu, NULL, ent_ts);
}
/* Find the next real entry, and increment the iterator to the next entry */
void *trace_find_next_entry_inc(struct trace_iterator *iter)
{
iter->ent = __find_next_entry(iter, &iter->cpu,
&iter->lost_events, &iter->ts);
if (iter->ent)
trace_iterator_increment(iter);
return iter->ent ? iter : NULL;
}
static void trace_consume(struct trace_iterator *iter)
{
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
&iter->lost_events);
ftrace_enable_cpu();
}
static void *s_next(struct seq_file *m, void *v, loff_t *pos)
{
struct trace_iterator *iter = m->private;
int i = (int)*pos;
void *ent;
WARN_ON_ONCE(iter->leftover);
(*pos)++;
/* can't go backwards */
if (iter->idx > i)
return NULL;
if (iter->idx < 0)
ent = trace_find_next_entry_inc(iter);
else
ent = iter;
while (ent && iter->idx < i)
ent = trace_find_next_entry_inc(iter);
iter->pos = *pos;
return ent;
}
void tracing_iter_reset(struct trace_iterator *iter, int cpu)
{
struct trace_array *tr = iter->tr;
struct ring_buffer_event *event;
struct ring_buffer_iter *buf_iter;
unsigned long entries = 0;
u64 ts;
tr->data[cpu]->skipped_entries = 0;
if (!iter->buffer_iter[cpu])
return;
buf_iter = iter->buffer_iter[cpu];
ring_buffer_iter_reset(buf_iter);
/*
* We could have the case with the max latency tracers
* that a reset never took place on a cpu. This is evident
* by the timestamp being before the start of the buffer.
*/
while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
if (ts >= iter->tr->time_start)
break;
entries++;
ring_buffer_read(buf_iter, NULL);
}
tr->data[cpu]->skipped_entries = entries;
}
/*
* The current tracer is copied to avoid a global locking
* all around.
*/
static void *s_start(struct seq_file *m, loff_t *pos)
{
struct trace_iterator *iter = m->private;
static struct tracer *old_tracer;
int cpu_file = iter->cpu_file;
void *p = NULL;
loff_t l = 0;
int cpu;
/* copy the tracer to avoid using a global lock all around */
mutex_lock(&trace_types_lock);
if (unlikely(old_tracer != current_trace && current_trace)) {
old_tracer = current_trace;
*iter->trace = *current_trace;
}
mutex_unlock(&trace_types_lock);
atomic_inc(&trace_record_cmdline_disabled);
if (*pos != iter->pos) {
iter->ent = NULL;
iter->cpu = 0;
iter->idx = -1;
ftrace_disable_cpu();
if (cpu_file == TRACE_PIPE_ALL_CPU) {
for_each_tracing_cpu(cpu)
tracing_iter_reset(iter, cpu);
} else
tracing_iter_reset(iter, cpu_file);
ftrace_enable_cpu();
iter->leftover = 0;
for (p = iter; p && l < *pos; p = s_next(m, p, &l))
;
} else {
/*
* If we overflowed the seq_file before, then we want
* to just reuse the trace_seq buffer again.
*/
if (iter->leftover)
p = iter;
else {
l = *pos - 1;
p = s_next(m, p, &l);
}
}
trace_event_read_lock();
trace_access_lock(cpu_file);
return p;
}
static void s_stop(struct seq_file *m, void *p)
{
struct trace_iterator *iter = m->private;
atomic_dec(&trace_record_cmdline_disabled);
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
}
static void print_lat_help_header(struct seq_file *m)
{
seq_puts(m, "# _------=> CPU# \n");
seq_puts(m, "# / _-----=> irqs-off \n");
seq_puts(m, "# | / _----=> need-resched \n");
seq_puts(m, "# || / _---=> hardirq/softirq \n");
seq_puts(m, "# ||| / _--=> preempt-depth \n");
seq_puts(m, "# |||| / delay \n");
seq_puts(m, "# cmd pid ||||| time | caller \n");
seq_puts(m, "# \\ / ||||| \\ | / \n");
}
static void print_func_help_header(struct seq_file *m)
{
seq_puts(m, "# TASK-PID CPU# TIMESTAMP FUNCTION\n");
seq_puts(m, "# | | | | |\n");
}
void
print_trace_header(struct seq_file *m, struct trace_iterator *iter)
{
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_array *tr = iter->tr;
struct trace_array_cpu *data = tr->data[tr->cpu];
struct tracer *type = current_trace;
unsigned long entries = 0;
unsigned long total = 0;
unsigned long count;
const char *name = "preemption";
int cpu;
if (type)
name = type->name;
for_each_tracing_cpu(cpu) {
count = ring_buffer_entries_cpu(tr->buffer, cpu);
/*
* If this buffer has skipped entries, then we hold all
* entries for the trace and we need to ignore the
* ones before the time stamp.
*/
if (tr->data[cpu]->skipped_entries) {
count -= tr->data[cpu]->skipped_entries;
/* total is the same as the entries */
total += count;
} else
total += count +
ring_buffer_overrun_cpu(tr->buffer, cpu);
entries += count;
}
seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
name, UTS_RELEASE);
seq_puts(m, "# -----------------------------------"
"---------------------------------\n");
seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
" (M:%s VP:%d, KP:%d, SP:%d HP:%d",
nsecs_to_usecs(data->saved_latency),
entries,
total,
tr->cpu,
#if defined(CONFIG_PREEMPT_NONE)
"server",
#elif defined(CONFIG_PREEMPT_VOLUNTARY)
"desktop",
#elif defined(CONFIG_PREEMPT)
"preempt",
#else
"unknown",
#endif
/* These are reserved for later use */
0, 0, 0, 0);
#ifdef CONFIG_SMP
seq_printf(m, " #P:%d)\n", num_online_cpus());
#else
seq_puts(m, ")\n");
#endif
seq_puts(m, "# -----------------\n");
seq_printf(m, "# | task: %.16s-%d "
"(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
data->comm, data->pid, data->uid, data->nice,
data->policy, data->rt_priority);
seq_puts(m, "# -----------------\n");
if (data->critical_start) {
seq_puts(m, "# => started at: ");
seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
trace_print_seq(m, &iter->seq);
seq_puts(m, "\n# => ended at: ");
seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
trace_print_seq(m, &iter->seq);
seq_puts(m, "\n#\n");
}
seq_puts(m, "#\n");
}
static void test_cpu_buff_start(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
if (!(trace_flags & TRACE_ITER_ANNOTATE))
return;
if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
return;
if (cpumask_test_cpu(iter->cpu, iter->started))
return;
if (iter->tr->data[iter->cpu]->skipped_entries)
return;
cpumask_set_cpu(iter->cpu, iter->started);
/* Don't print started cpu buffer for the first entry of the trace */
if (iter->idx > 1)
trace_seq_printf(s, "##### CPU %u buffer started ####\n",
iter->cpu);
}
static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
test_cpu_buff_start(iter);
event = ftrace_find_event(entry->type);
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
if (!trace_print_lat_context(iter))
goto partial;
} else {
if (!trace_print_context(iter))
goto partial;
}
}
if (event)
return event->funcs->trace(iter, sym_flags, event);
if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
goto partial;
return TRACE_TYPE_HANDLED;
partial:
return TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
if (!trace_seq_printf(s, "%d %d %llu ",
entry->pid, iter->cpu, iter->ts))
goto partial;
}
event = ftrace_find_event(entry->type);
if (event)
return event->funcs->raw(iter, 0, event);
if (!trace_seq_printf(s, "%d ?\n", entry->type))
goto partial;
return TRACE_TYPE_HANDLED;
partial:
return TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
unsigned char newline = '\n';
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
}
event = ftrace_find_event(entry->type);
if (event) {
enum print_line_t ret = event->funcs->hex(iter, 0, event);
if (ret != TRACE_TYPE_HANDLED)
return ret;
}
SEQ_PUT_FIELD_RET(s, newline);
return TRACE_TYPE_HANDLED;
}
static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
SEQ_PUT_FIELD_RET(s, entry->pid);
SEQ_PUT_FIELD_RET(s, iter->cpu);
SEQ_PUT_FIELD_RET(s, iter->ts);
}
event = ftrace_find_event(entry->type);
return event ? event->funcs->binary(iter, 0, event) :
TRACE_TYPE_HANDLED;
}
int trace_empty(struct trace_iterator *iter)
{
int cpu;
/* If we are looking at one CPU buffer, only check that one */
if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
cpu = iter->cpu_file;
if (iter->buffer_iter[cpu]) {
if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
return 0;
} else {
if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
return 0;
}
return 1;
}
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu]) {
if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
return 0;
} else {
if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
return 0;
}
}
return 1;
}
/* Called with trace_event_read_lock() held. */
enum print_line_t print_trace_line(struct trace_iterator *iter)
{
enum print_line_t ret;
if (iter->lost_events &&
!trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
iter->cpu, iter->lost_events))
return TRACE_TYPE_PARTIAL_LINE;
if (iter->trace && iter->trace->print_line) {
ret = iter->trace->print_line(iter);
if (ret != TRACE_TYPE_UNHANDLED)
return ret;
}
if (iter->ent->type == TRACE_BPRINT &&
trace_flags & TRACE_ITER_PRINTK &&
trace_flags & TRACE_ITER_PRINTK_MSGONLY)
return trace_print_bprintk_msg_only(iter);
if (iter->ent->type == TRACE_PRINT &&
trace_flags & TRACE_ITER_PRINTK &&
trace_flags & TRACE_ITER_PRINTK_MSGONLY)
return trace_print_printk_msg_only(iter);
if (trace_flags & TRACE_ITER_BIN)
return print_bin_fmt(iter);
if (trace_flags & TRACE_ITER_HEX)
return print_hex_fmt(iter);
if (trace_flags & TRACE_ITER_RAW)
return print_raw_fmt(iter);
return print_trace_fmt(iter);
}
void trace_default_header(struct seq_file *m)
{
struct trace_iterator *iter = m->private;
if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
return;
if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
/* print nothing if the buffers are empty */
if (trace_empty(iter))
return;
print_trace_header(m, iter);
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_lat_help_header(m);
} else {
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_func_help_header(m);
}
}
static int s_show(struct seq_file *m, void *v)
{
struct trace_iterator *iter = v;
int ret;
if (iter->ent == NULL) {
if (iter->tr) {
seq_printf(m, "# tracer: %s\n", iter->trace->name);
seq_puts(m, "#\n");
}
if (iter->trace && iter->trace->print_header)
iter->trace->print_header(m);
else
trace_default_header(m);
} else if (iter->leftover) {
/*
* If we filled the seq_file buffer earlier, we
* want to just show it now.
*/
ret = trace_print_seq(m, &iter->seq);
/* ret should this time be zero, but you never know */
iter->leftover = ret;
} else {
print_trace_line(iter);
ret = trace_print_seq(m, &iter->seq);
/*
* If we overflow the seq_file buffer, then it will
* ask us for this data again at start up.
* Use that instead.
* ret is 0 if seq_file write succeeded.
* -1 otherwise.
*/
iter->leftover = ret;
}
return 0;
}
static const struct seq_operations tracer_seq_ops = {
.start = s_start,
.next = s_next,
.stop = s_stop,
.show = s_show,
};
static struct trace_iterator *
__tracing_open(struct inode *inode, struct file *file)
{
long cpu_file = (long) inode->i_private;
void *fail_ret = ERR_PTR(-ENOMEM);
struct trace_iterator *iter;
struct seq_file *m;
int cpu, ret;
if (tracing_disabled)
return ERR_PTR(-ENODEV);
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return ERR_PTR(-ENOMEM);
/*
* We make a copy of the current tracer to avoid concurrent
* changes on it while we are reading.
*/
mutex_lock(&trace_types_lock);
iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
if (!iter->trace)
goto fail;
if (current_trace)
*iter->trace = *current_trace;
if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
goto fail;
if (current_trace && current_trace->print_max)
iter->tr = &max_tr;
else
iter->tr = &global_trace;
iter->pos = -1;
mutex_init(&iter->mutex);
iter->cpu_file = cpu_file;
/* Notify the tracer early; before we stop tracing. */
if (iter->trace && iter->trace->open)
iter->trace->open(iter);
/* Annotate start of buffers if we had overruns */
if (ring_buffer_overruns(iter->tr->buffer))
iter->iter_flags |= TRACE_FILE_ANNOTATE;
/* stop the trace while dumping */
tracing_stop();
if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
for_each_tracing_cpu(cpu) {
iter->buffer_iter[cpu] =
ring_buffer_read_prepare(iter->tr->buffer, cpu);
}
ring_buffer_read_prepare_sync();
for_each_tracing_cpu(cpu) {
ring_buffer_read_start(iter->buffer_iter[cpu]);
tracing_iter_reset(iter, cpu);
}
} else {
cpu = iter->cpu_file;
iter->buffer_iter[cpu] =
ring_buffer_read_prepare(iter->tr->buffer, cpu);
ring_buffer_read_prepare_sync();
ring_buffer_read_start(iter->buffer_iter[cpu]);
tracing_iter_reset(iter, cpu);
}
ret = seq_open(file, &tracer_seq_ops);
if (ret < 0) {
fail_ret = ERR_PTR(ret);
goto fail_buffer;
}
m = file->private_data;
m->private = iter;
mutex_unlock(&trace_types_lock);
return iter;
fail_buffer:
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
free_cpumask_var(iter->started);
tracing_start();
fail:
mutex_unlock(&trace_types_lock);
kfree(iter->trace);
kfree(iter);
return fail_ret;
}
int tracing_open_generic(struct inode *inode, struct file *filp)
{
if (tracing_disabled)
return -ENODEV;
filp->private_data = inode->i_private;
return 0;
}
static int tracing_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
struct trace_iterator *iter;
int cpu;
if (!(file->f_mode & FMODE_READ))
return 0;
iter = m->private;
mutex_lock(&trace_types_lock);
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
if (iter->trace && iter->trace->close)
iter->trace->close(iter);
/* reenable tracing if it was previously enabled */
tracing_start();
mutex_unlock(&trace_types_lock);
seq_release(inode, file);
mutex_destroy(&iter->mutex);
free_cpumask_var(iter->started);
kfree(iter->trace);
kfree(iter);
return 0;
}
static int tracing_open(struct inode *inode, struct file *file)
{
struct trace_iterator *iter;
int ret = 0;
/* If this file was open for write, then erase contents */
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC)) {
long cpu = (long) inode->i_private;
if (cpu == TRACE_PIPE_ALL_CPU)
tracing_reset_online_cpus(&global_trace);
else
tracing_reset(&global_trace, cpu);
}
if (file->f_mode & FMODE_READ) {
iter = __tracing_open(inode, file);
if (IS_ERR(iter))
ret = PTR_ERR(iter);
else if (trace_flags & TRACE_ITER_LATENCY_FMT)
iter->iter_flags |= TRACE_FILE_LAT_FMT;
}
return ret;
}
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct tracer *t = v;
(*pos)++;
if (t)
t = t->next;
return t;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct tracer *t;
loff_t l = 0;
mutex_lock(&trace_types_lock);
for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
;
return t;
}
static void t_stop(struct seq_file *m, void *p)
{
mutex_unlock(&trace_types_lock);
}
static int t_show(struct seq_file *m, void *v)
{
struct tracer *t = v;
if (!t)
return 0;
seq_printf(m, "%s", t->name);
if (t->next)
seq_putc(m, ' ');
else
seq_putc(m, '\n');
return 0;
}
static const struct seq_operations show_traces_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int show_traces_open(struct inode *inode, struct file *file)
{
if (tracing_disabled)
return -ENODEV;
return seq_open(file, &show_traces_seq_ops);
}
static ssize_t
tracing_write_stub(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
return count;
}
static loff_t tracing_seek(struct file *file, loff_t offset, int origin)
{
if (file->f_mode & FMODE_READ)
return seq_lseek(file, offset, origin);
else
return 0;
}
static const struct file_operations tracing_fops = {
.open = tracing_open,
.read = seq_read,
.write = tracing_write_stub,
.llseek = tracing_seek,
.release = tracing_release,
};
static const struct file_operations show_traces_fops = {
.open = show_traces_open,
.read = seq_read,
.release = seq_release,
.llseek = seq_lseek,
};
/*
* Only trace on a CPU if the bitmask is set:
*/
static cpumask_var_t tracing_cpumask;
/*
* The tracer itself will not take this lock, but still we want
* to provide a consistent cpumask to user-space:
*/
static DEFINE_MUTEX(tracing_cpumask_update_lock);
/*
* Temporary storage for the character representation of the
* CPU bitmask (and one more byte for the newline):
*/
static char mask_str[NR_CPUS + 1];
static ssize_t
tracing_cpumask_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
int len;
mutex_lock(&tracing_cpumask_update_lock);
len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
if (count - len < 2) {
count = -EINVAL;
goto out_err;
}
len += sprintf(mask_str + len, "\n");
count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
out_err:
mutex_unlock(&tracing_cpumask_update_lock);
return count;
}
static ssize_t
tracing_cpumask_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
int err, cpu;
cpumask_var_t tracing_cpumask_new;
if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
return -ENOMEM;
err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
if (err)
goto err_unlock;
mutex_lock(&tracing_cpumask_update_lock);
local_irq_disable();
arch_spin_lock(&ftrace_max_lock);
for_each_tracing_cpu(cpu) {
/*
* Increase/decrease the disabled counter if we are
* about to flip a bit in the cpumask:
*/
if (cpumask_test_cpu(cpu, tracing_cpumask) &&
!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
atomic_inc(&global_trace.data[cpu]->disabled);
}
if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
cpumask_test_cpu(cpu, tracing_cpumask_new)) {
atomic_dec(&global_trace.data[cpu]->disabled);
}
}
arch_spin_unlock(&ftrace_max_lock);
local_irq_enable();
cpumask_copy(tracing_cpumask, tracing_cpumask_new);
mutex_unlock(&tracing_cpumask_update_lock);
free_cpumask_var(tracing_cpumask_new);
return count;
err_unlock:
free_cpumask_var(tracing_cpumask_new);
return err;
}
static const struct file_operations tracing_cpumask_fops = {
.open = tracing_open_generic,
.read = tracing_cpumask_read,
.write = tracing_cpumask_write,
.llseek = generic_file_llseek,
};
static int tracing_trace_options_show(struct seq_file *m, void *v)
{
struct tracer_opt *trace_opts;
u32 tracer_flags;
int i;
mutex_lock(&trace_types_lock);
tracer_flags = current_trace->flags->val;
trace_opts = current_trace->flags->opts;
for (i = 0; trace_options[i]; i++) {
if (trace_flags & (1 << i))
seq_printf(m, "%s\n", trace_options[i]);
else
seq_printf(m, "no%s\n", trace_options[i]);
}
for (i = 0; trace_opts[i].name; i++) {
if (tracer_flags & trace_opts[i].bit)
seq_printf(m, "%s\n", trace_opts[i].name);
else
seq_printf(m, "no%s\n", trace_opts[i].name);
}
mutex_unlock(&trace_types_lock);
return 0;
}
static int __set_tracer_option(struct tracer *trace,
struct tracer_flags *tracer_flags,
struct tracer_opt *opts, int neg)
{
int ret;
ret = trace->set_flag(tracer_flags->val, opts->bit, !neg);
if (ret)
return ret;
if (neg)
tracer_flags->val &= ~opts->bit;
else
tracer_flags->val |= opts->bit;
return 0;
}
/* Try to assign a tracer specific option */
static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
{
struct tracer_flags *tracer_flags = trace->flags;
struct tracer_opt *opts = NULL;
int i;
for (i = 0; tracer_flags->opts[i].name; i++) {
opts = &tracer_flags->opts[i];
if (strcmp(cmp, opts->name) == 0)
return __set_tracer_option(trace, trace->flags,
opts, neg);
}
return -EINVAL;
}
static void set_tracer_flags(unsigned int mask, int enabled)
{
/* do nothing if flag is already set */
if (!!(trace_flags & mask) == !!enabled)
return;
if (enabled)
trace_flags |= mask;
else
trace_flags &= ~mask;
if (mask == TRACE_ITER_RECORD_CMD)
trace_event_enable_cmd_record(enabled);
if (mask == TRACE_ITER_OVERWRITE)
ring_buffer_change_overwrite(global_trace.buffer, enabled);
}
static ssize_t
tracing_trace_options_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
char *cmp;
int neg = 0;
int ret;
int i;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
cmp = strstrip(buf);
if (strncmp(cmp, "no", 2) == 0) {
neg = 1;
cmp += 2;
}
for (i = 0; trace_options[i]; i++) {
if (strcmp(cmp, trace_options[i]) == 0) {
set_tracer_flags(1 << i, !neg);
break;
}
}
/* If no option could be set, test the specific tracer options */
if (!trace_options[i]) {
mutex_lock(&trace_types_lock);
ret = set_tracer_option(current_trace, cmp, neg);
mutex_unlock(&trace_types_lock);
if (ret)
return ret;
}
*ppos += cnt;
return cnt;
}
static int tracing_trace_options_open(struct inode *inode, struct file *file)
{
if (tracing_disabled)
return -ENODEV;
return single_open(file, tracing_trace_options_show, NULL);
}
static const struct file_operations tracing_iter_fops = {
.open = tracing_trace_options_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.write = tracing_trace_options_write,
};
static const char readme_msg[] =
"tracing mini-HOWTO:\n\n"
"# mount -t debugfs nodev /sys/kernel/debug\n\n"
"# cat /sys/kernel/debug/tracing/available_tracers\n"
"wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
"# cat /sys/kernel/debug/tracing/current_tracer\n"
"nop\n"
"# echo sched_switch > /sys/kernel/debug/tracing/current_tracer\n"
"# cat /sys/kernel/debug/tracing/current_tracer\n"
"sched_switch\n"
"# cat /sys/kernel/debug/tracing/trace_options\n"
"noprint-parent nosym-offset nosym-addr noverbose\n"
"# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
"# echo 1 > /sys/kernel/debug/tracing/tracing_enabled\n"
"# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
"# echo 0 > /sys/kernel/debug/tracing/tracing_enabled\n"
;
static ssize_t
tracing_readme_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return simple_read_from_buffer(ubuf, cnt, ppos,
readme_msg, strlen(readme_msg));
}
static const struct file_operations tracing_readme_fops = {
.open = tracing_open_generic,
.read = tracing_readme_read,
.llseek = generic_file_llseek,
};
static ssize_t
tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char *buf_comm;
char *file_buf;
char *buf;
int len = 0;
int pid;
int i;
file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
if (!file_buf)
return -ENOMEM;
buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
if (!buf_comm) {
kfree(file_buf);
return -ENOMEM;
}
buf = file_buf;
for (i = 0; i < SAVED_CMDLINES; i++) {
int r;
pid = map_cmdline_to_pid[i];
if (pid == -1 || pid == NO_CMDLINE_MAP)
continue;
trace_find_cmdline(pid, buf_comm);
r = sprintf(buf, "%d %s\n", pid, buf_comm);
buf += r;
len += r;
}
len = simple_read_from_buffer(ubuf, cnt, ppos,
file_buf, len);
kfree(file_buf);
kfree(buf_comm);
return len;
}
static const struct file_operations tracing_saved_cmdlines_fops = {
.open = tracing_open_generic,
.read = tracing_saved_cmdlines_read,
.llseek = generic_file_llseek,
};
static ssize_t
tracing_ctrl_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
int r;
r = sprintf(buf, "%u\n", tracer_enabled);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_ctrl_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
unsigned long val;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
val = !!val;
mutex_lock(&trace_types_lock);
if (tracer_enabled ^ val) {
/* Only need to warn if this is used to change the state */
WARN_ONCE(1, "tracing_enabled is deprecated. Use tracing_on");
if (val) {
tracer_enabled = 1;
if (current_trace->start)
current_trace->start(tr);
tracing_start();
} else {
tracer_enabled = 0;
tracing_stop();
if (current_trace->stop)
current_trace->stop(tr);
}
}
mutex_unlock(&trace_types_lock);
*ppos += cnt;
return cnt;
}
static ssize_t
tracing_set_trace_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[MAX_TRACER_SIZE+2];
int r;
mutex_lock(&trace_types_lock);
if (current_trace)
r = sprintf(buf, "%s\n", current_trace->name);
else
r = sprintf(buf, "\n");
mutex_unlock(&trace_types_lock);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
int tracer_init(struct tracer *t, struct trace_array *tr)
{
tracing_reset_online_cpus(tr);
return t->init(tr);
}
static int __tracing_resize_ring_buffer(unsigned long size)
{
int ret;
/*
* If kernel or user changes the size of the ring buffer
* we use the size that was given, and we can forget about
* expanding it later.
*/
ring_buffer_expanded = 1;
ret = ring_buffer_resize(global_trace.buffer, size);
if (ret < 0)
return ret;
if (!current_trace->use_max_tr)
goto out;
ret = ring_buffer_resize(max_tr.buffer, size);
if (ret < 0) {
int r;
r = ring_buffer_resize(global_trace.buffer,
global_trace.entries);
if (r < 0) {
/*
* AARGH! We are left with different
* size max buffer!!!!
* The max buffer is our "snapshot" buffer.
* When a tracer needs a snapshot (one of the
* latency tracers), it swaps the max buffer
* with the saved snap shot. We succeeded to
* update the size of the main buffer, but failed to
* update the size of the max buffer. But when we tried
* to reset the main buffer to the original size, we
* failed there too. This is very unlikely to
* happen, but if it does, warn and kill all
* tracing.
*/
WARN_ON(1);
tracing_disabled = 1;
}
return ret;
}
max_tr.entries = size;
out:
global_trace.entries = size;
return ret;
}
static ssize_t tracing_resize_ring_buffer(unsigned long size)
{
int cpu, ret = size;
mutex_lock(&trace_types_lock);
tracing_stop();
/* disable all cpu buffers */
for_each_tracing_cpu(cpu) {
if (global_trace.data[cpu])
atomic_inc(&global_trace.data[cpu]->disabled);
if (max_tr.data[cpu])
atomic_inc(&max_tr.data[cpu]->disabled);
}
if (size != global_trace.entries)
ret = __tracing_resize_ring_buffer(size);
if (ret < 0)
ret = -ENOMEM;
for_each_tracing_cpu(cpu) {
if (global_trace.data[cpu])
atomic_dec(&global_trace.data[cpu]->disabled);
if (max_tr.data[cpu])
atomic_dec(&max_tr.data[cpu]->disabled);
}
tracing_start();
mutex_unlock(&trace_types_lock);
return ret;
}
/**
* tracing_update_buffers - used by tracing facility to expand ring buffers
*
* To save on memory when the tracing is never used on a system with it
* configured in. The ring buffers are set to a minimum size. But once
* a user starts to use the tracing facility, then they need to grow
* to their default size.
*
* This function is to be called when a tracer is about to be used.
*/
int tracing_update_buffers(void)
{
int ret = 0;
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded)
ret = __tracing_resize_ring_buffer(trace_buf_size);
mutex_unlock(&trace_types_lock);
return ret;
}
struct trace_option_dentry;
static struct trace_option_dentry *
create_trace_option_files(struct tracer *tracer);
static void
destroy_trace_option_files(struct trace_option_dentry *topts);
static int tracing_set_tracer(const char *buf)
{
static struct trace_option_dentry *topts;
struct trace_array *tr = &global_trace;
struct tracer *t;
int ret = 0;
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded) {
ret = __tracing_resize_ring_buffer(trace_buf_size);
if (ret < 0)
goto out;
ret = 0;
}
for (t = trace_types; t; t = t->next) {
if (strcmp(t->name, buf) == 0)
break;
}
if (!t) {
ret = -EINVAL;
goto out;
}
if (t == current_trace)
goto out;
trace_branch_disable();
if (current_trace && current_trace->reset)
current_trace->reset(tr);
if (current_trace && current_trace->use_max_tr) {
/*
* We don't free the ring buffer. instead, resize it because
* The max_tr ring buffer has some state (e.g. ring->clock) and
* we want preserve it.
*/
ring_buffer_resize(max_tr.buffer, 1);
max_tr.entries = 1;
}
destroy_trace_option_files(topts);
current_trace = t;
topts = create_trace_option_files(current_trace);
if (current_trace->use_max_tr) {
ret = ring_buffer_resize(max_tr.buffer, global_trace.entries);
if (ret < 0)
goto out;
max_tr.entries = global_trace.entries;
}
if (t->init) {
ret = tracer_init(t, tr);
if (ret)
goto out;
}
trace_branch_enable(tr);
out:
mutex_unlock(&trace_types_lock);
return ret;
}
static ssize_t
tracing_set_trace_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[MAX_TRACER_SIZE+1];
int i;
size_t ret;
int err;
ret = cnt;
if (cnt > MAX_TRACER_SIZE)
cnt = MAX_TRACER_SIZE;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
/* strip ending whitespace. */
for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
buf[i] = 0;
err = tracing_set_tracer(buf);
if (err)
return err;
*ppos += ret;
return ret;
}
static ssize_t
tracing_max_lat_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long *ptr = filp->private_data;
char buf[64];
int r;
r = snprintf(buf, sizeof(buf), "%ld\n",
*ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
if (r > sizeof(buf))
r = sizeof(buf);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_max_lat_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long *ptr = filp->private_data;
unsigned long val;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
*ptr = val * 1000;
return cnt;
}
static int tracing_open_pipe(struct inode *inode, struct file *filp)
{
long cpu_file = (long) inode->i_private;
struct trace_iterator *iter;
int ret = 0;
if (tracing_disabled)
return -ENODEV;
mutex_lock(&trace_types_lock);
/* create a buffer to store the information to pass to userspace */
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter) {
ret = -ENOMEM;
goto out;
}
/*
* We make a copy of the current tracer to avoid concurrent
* changes on it while we are reading.
*/
iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
if (!iter->trace) {
ret = -ENOMEM;
goto fail;
}
if (current_trace)
*iter->trace = *current_trace;
if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
ret = -ENOMEM;
goto fail;
}
/* trace pipe does not show start of buffer */
cpumask_setall(iter->started);
if (trace_flags & TRACE_ITER_LATENCY_FMT)
iter->iter_flags |= TRACE_FILE_LAT_FMT;
iter->cpu_file = cpu_file;
iter->tr = &global_trace;
mutex_init(&iter->mutex);
filp->private_data = iter;
if (iter->trace->pipe_open)
iter->trace->pipe_open(iter);
nonseekable_open(inode, filp);
out:
mutex_unlock(&trace_types_lock);
return ret;
fail:
kfree(iter->trace);
kfree(iter);
mutex_unlock(&trace_types_lock);
return ret;
}
static int tracing_release_pipe(struct inode *inode, struct file *file)
{
struct trace_iterator *iter = file->private_data;
mutex_lock(&trace_types_lock);
if (iter->trace->pipe_close)
iter->trace->pipe_close(iter);
mutex_unlock(&trace_types_lock);
free_cpumask_var(iter->started);
mutex_destroy(&iter->mutex);
kfree(iter->trace);
kfree(iter);
return 0;
}
static unsigned int
tracing_poll_pipe(struct file *filp, poll_table *poll_table)
{
struct trace_iterator *iter = filp->private_data;
if (trace_flags & TRACE_ITER_BLOCK) {
/*
* Always select as readable when in blocking mode
*/
return POLLIN | POLLRDNORM;
} else {
if (!trace_empty(iter))
return POLLIN | POLLRDNORM;
poll_wait(filp, &trace_wait, poll_table);
if (!trace_empty(iter))
return POLLIN | POLLRDNORM;
return 0;
}
}
void default_wait_pipe(struct trace_iterator *iter)
{
DEFINE_WAIT(wait);
prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
if (trace_empty(iter))
schedule();
finish_wait(&trace_wait, &wait);
}
/*
* This is a make-shift waitqueue.
* A tracer might use this callback on some rare cases:
*
* 1) the current tracer might hold the runqueue lock when it wakes up
* a reader, hence a deadlock (sched, function, and function graph tracers)
* 2) the function tracers, trace all functions, we don't want
* the overhead of calling wake_up and friends
* (and tracing them too)
*
* Anyway, this is really very primitive wakeup.
*/
void poll_wait_pipe(struct trace_iterator *iter)
{
set_current_state(TASK_INTERRUPTIBLE);
/* sleep for 100 msecs, and try again. */
schedule_timeout(HZ / 10);
}
/* Must be called with trace_types_lock mutex held. */
static int tracing_wait_pipe(struct file *filp)
{
struct trace_iterator *iter = filp->private_data;
while (trace_empty(iter)) {
if ((filp->f_flags & O_NONBLOCK)) {
return -EAGAIN;
}
mutex_unlock(&iter->mutex);
iter->trace->wait_pipe(iter);
mutex_lock(&iter->mutex);
if (signal_pending(current))
return -EINTR;
/*
* We block until we read something and tracing is disabled.
* We still block if tracing is disabled, but we have never
* read anything. This allows a user to cat this file, and
* then enable tracing. But after we have read something,
* we give an EOF when tracing is again disabled.
*
* iter->pos will be 0 if we haven't read anything.
*/
if (!tracer_enabled && iter->pos)
break;
}
return 1;
}
/*
* Consumer reader.
*/
static ssize_t
tracing_read_pipe(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_iterator *iter = filp->private_data;
static struct tracer *old_tracer;
ssize_t sret;
/* return any leftover data */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
return sret;
trace_seq_init(&iter->seq);
/* copy the tracer to avoid using a global lock all around */
mutex_lock(&trace_types_lock);
if (unlikely(old_tracer != current_trace && current_trace)) {
old_tracer = current_trace;
*iter->trace = *current_trace;
}
mutex_unlock(&trace_types_lock);
/*
* Avoid more than one consumer on a single file descriptor
* This is just a matter of traces coherency, the ring buffer itself
* is protected.
*/
mutex_lock(&iter->mutex);
if (iter->trace->read) {
sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
if (sret)
goto out;
}
waitagain:
sret = tracing_wait_pipe(filp);
if (sret <= 0)
goto out;
/* stop when tracing is finished */
if (trace_empty(iter)) {
sret = 0;
goto out;
}
if (cnt >= PAGE_SIZE)
cnt = PAGE_SIZE - 1;
/* reset all but tr, trace, and overruns */
memset(&iter->seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter->pos = -1;
trace_event_read_lock();
trace_access_lock(iter->cpu_file);
while (trace_find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
int len = iter->seq.len;
ret = print_trace_line(iter);
if (ret == TRACE_TYPE_PARTIAL_LINE) {
/* don't print partial lines */
iter->seq.len = len;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
if (iter->seq.len >= cnt)
break;
/*
* Setting the full flag means we reached the trace_seq buffer
* size and we should leave by partial output condition above.
* One of the trace_seq_* functions is not used properly.
*/
WARN_ONCE(iter->seq.full, "full flag set for trace type %d",
iter->ent->type);
}
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (iter->seq.readpos >= iter->seq.len)
trace_seq_init(&iter->seq);
/*
* If there was nothing to send to user, in spite of consuming trace
* entries, go back to wait for more entries.
*/
if (sret == -EBUSY)
goto waitagain;
out:
mutex_unlock(&iter->mutex);
return sret;
}
static void tracing_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
__free_page(buf->page);
}
static void tracing_spd_release_pipe(struct splice_pipe_desc *spd,
unsigned int idx)
{
__free_page(spd->pages[idx]);
}
static const struct pipe_buf_operations tracing_pipe_buf_ops = {
.can_merge = 0,
.map = generic_pipe_buf_map,
.unmap = generic_pipe_buf_unmap,
.confirm = generic_pipe_buf_confirm,
.release = tracing_pipe_buf_release,
.steal = generic_pipe_buf_steal,
.get = generic_pipe_buf_get,
};
static size_t
tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
{
size_t count;
int ret;
/* Seq buffer is page-sized, exactly what we need. */
for (;;) {
count = iter->seq.len;
ret = print_trace_line(iter);
count = iter->seq.len - count;
if (rem < count) {
rem = 0;
iter->seq.len -= count;
break;
}
if (ret == TRACE_TYPE_PARTIAL_LINE) {
iter->seq.len -= count;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
rem -= count;
if (!trace_find_next_entry_inc(iter)) {
rem = 0;
iter->ent = NULL;
break;
}
}
return rem;
}
static ssize_t tracing_splice_read_pipe(struct file *filp,
loff_t *ppos,
struct pipe_inode_info *pipe,
size_t len,
unsigned int flags)
{
struct page *pages_def[PIPE_DEF_BUFFERS];
struct partial_page partial_def[PIPE_DEF_BUFFERS];
struct trace_iterator *iter = filp->private_data;
struct splice_pipe_desc spd = {
.pages = pages_def,
.partial = partial_def,
.nr_pages = 0, /* This gets updated below. */
.flags = flags,
.ops = &tracing_pipe_buf_ops,
.spd_release = tracing_spd_release_pipe,
};
static struct tracer *old_tracer;
ssize_t ret;
size_t rem;
unsigned int i;
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
/* copy the tracer to avoid using a global lock all around */
mutex_lock(&trace_types_lock);
if (unlikely(old_tracer != current_trace && current_trace)) {
old_tracer = current_trace;
*iter->trace = *current_trace;
}
mutex_unlock(&trace_types_lock);
mutex_lock(&iter->mutex);
if (iter->trace->splice_read) {
ret = iter->trace->splice_read(iter, filp,
ppos, pipe, len, flags);
if (ret)
goto out_err;
}
ret = tracing_wait_pipe(filp);
if (ret <= 0)
goto out_err;
if (!iter->ent && !trace_find_next_entry_inc(iter)) {
ret = -EFAULT;
goto out_err;
}
trace_event_read_lock();
trace_access_lock(iter->cpu_file);
/* Fill as many pages as possible. */
for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
spd.pages[i] = alloc_page(GFP_KERNEL);
if (!spd.pages[i])
break;
rem = tracing_fill_pipe_page(rem, iter);
/* Copy the data into the page, so we can start over. */
ret = trace_seq_to_buffer(&iter->seq,
page_address(spd.pages[i]),
iter->seq.len);
if (ret < 0) {
__free_page(spd.pages[i]);
break;
}
spd.partial[i].offset = 0;
spd.partial[i].len = iter->seq.len;
trace_seq_init(&iter->seq);
}
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
mutex_unlock(&iter->mutex);
spd.nr_pages = i;
ret = splice_to_pipe(pipe, &spd);
out:
splice_shrink_spd(pipe, &spd);
return ret;
out_err:
mutex_unlock(&iter->mutex);
goto out;
}
static ssize_t
tracing_entries_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
char buf[96];
int r;
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded)
r = sprintf(buf, "%lu (expanded: %lu)\n",
tr->entries >> 10,
trace_buf_size >> 10);
else
r = sprintf(buf, "%lu\n", tr->entries >> 10);
mutex_unlock(&trace_types_lock);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_entries_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long val;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
/* must have at least 1 entry */
if (!val)
return -EINVAL;
/* value is in KB */
val <<= 10;
ret = tracing_resize_ring_buffer(val);
if (ret < 0)
return ret;
*ppos += cnt;
return cnt;
}
static ssize_t
tracing_free_buffer_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
/*
* There is no need to read what the user has written, this function
* is just to make sure that there is no error when "echo" is used
*/
*ppos += cnt;
return cnt;
}
static int
tracing_free_buffer_release(struct inode *inode, struct file *filp)
{
/* disable tracing ? */
if (trace_flags & TRACE_ITER_STOP_ON_FREE)
tracing_off();
/* resize the ring buffer to 0 */
tracing_resize_ring_buffer(0);
return 0;
}
static int mark_printk(const char *fmt, ...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = trace_vprintk(0, fmt, args);
va_end(args);
return ret;
}
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
{
char *buf;
size_t written;
if (tracing_disabled)
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
buf = kmalloc(cnt + 2, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
if (copy_from_user(buf, ubuf, cnt)) {
kfree(buf);
return -EFAULT;
}
if (buf[cnt-1] != '\n') {
buf[cnt] = '\n';
buf[cnt+1] = '\0';
} else
buf[cnt] = '\0';
written = mark_printk("%s", buf);
kfree(buf);
*fpos += written;
/* don't tell userspace we wrote more - it might confuse them */
if (written > cnt)
written = cnt;
return written;
}
static int tracing_clock_show(struct seq_file *m, void *v)
{
int i;
for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
seq_printf(m,
"%s%s%s%s", i ? " " : "",
i == trace_clock_id ? "[" : "", trace_clocks[i].name,
i == trace_clock_id ? "]" : "");
seq_putc(m, '\n');
return 0;
}
static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
{
char buf[64];
const char *clockstr;
int i;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
clockstr = strstrip(buf);
for (i = 0; i < ARRAY_SIZE(trace_clocks); i++) {
if (strcmp(trace_clocks[i].name, clockstr) == 0)
break;
}
if (i == ARRAY_SIZE(trace_clocks))
return -EINVAL;
trace_clock_id = i;
mutex_lock(&trace_types_lock);
ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
if (max_tr.buffer)
ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
mutex_unlock(&trace_types_lock);
*fpos += cnt;
return cnt;
}
static int tracing_clock_open(struct inode *inode, struct file *file)
{
if (tracing_disabled)
return -ENODEV;
return single_open(file, tracing_clock_show, NULL);
}
static const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
.write = tracing_max_lat_write,
.llseek = generic_file_llseek,
};
static const struct file_operations tracing_ctrl_fops = {
.open = tracing_open_generic,
.read = tracing_ctrl_read,
.write = tracing_ctrl_write,
.llseek = generic_file_llseek,
};
static const struct file_operations set_tracer_fops = {
.open = tracing_open_generic,
.read = tracing_set_trace_read,
.write = tracing_set_trace_write,
.llseek = generic_file_llseek,
};
static const struct file_operations tracing_pipe_fops = {
.open = tracing_open_pipe,
.poll = tracing_poll_pipe,
.read = tracing_read_pipe,
.splice_read = tracing_splice_read_pipe,
.release = tracing_release_pipe,
.llseek = no_llseek,
};
static const struct file_operations tracing_entries_fops = {
.open = tracing_open_generic,
.read = tracing_entries_read,
.write = tracing_entries_write,
.llseek = generic_file_llseek,
};
static const struct file_operations tracing_free_buffer_fops = {
.write = tracing_free_buffer_write,
.release = tracing_free_buffer_release,
};
static const struct file_operations tracing_mark_fops = {
.open = tracing_open_generic,
.write = tracing_mark_write,
.llseek = generic_file_llseek,
};
static const struct file_operations trace_clock_fops = {
.open = tracing_clock_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.write = tracing_clock_write,
};
struct ftrace_buffer_info {
struct trace_array *tr;
void *spare;
int cpu;
unsigned int read;
};
static int tracing_buffers_open(struct inode *inode, struct file *filp)
{
int cpu = (int)(long)inode->i_private;
struct ftrace_buffer_info *info;
if (tracing_disabled)
return -ENODEV;
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return -ENOMEM;
info->tr = &global_trace;
info->cpu = cpu;
info->spare = NULL;
/* Force reading ring buffer for first read */
info->read = (unsigned int)-1;
filp->private_data = info;
return nonseekable_open(inode, filp);
}
static ssize_t
tracing_buffers_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
struct ftrace_buffer_info *info = filp->private_data;
ssize_t ret;
size_t size;
if (!count)
return 0;
if (!info->spare)
info->spare = ring_buffer_alloc_read_page(info->tr->buffer, info->cpu);
if (!info->spare)
return -ENOMEM;
/* Do we have previous read data to read? */
if (info->read < PAGE_SIZE)
goto read;
info->read = 0;
trace_access_lock(info->cpu);
ret = ring_buffer_read_page(info->tr->buffer,
&info->spare,
count,
info->cpu, 0);
trace_access_unlock(info->cpu);
if (ret < 0)
return 0;
read:
size = PAGE_SIZE - info->read;
if (size > count)
size = count;
ret = copy_to_user(ubuf, info->spare + info->read, size);
if (ret == size)
return -EFAULT;
size -= ret;
*ppos += size;
info->read += size;
return size;
}
static int tracing_buffers_release(struct inode *inode, struct file *file)
{
struct ftrace_buffer_info *info = file->private_data;
if (info->spare)
ring_buffer_free_read_page(info->tr->buffer, info->spare);
kfree(info);
return 0;
}
struct buffer_ref {
struct ring_buffer *buffer;
void *page;
int ref;
};
static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct buffer_ref *ref = (struct buffer_ref *)buf->private;
if (--ref->ref)
return;
ring_buffer_free_read_page(ref->buffer, ref->page);
kfree(ref);
buf->private = 0;
}
static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
return 1;
}
static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct buffer_ref *ref = (struct buffer_ref *)buf->private;
ref->ref++;
}
/* Pipe buffer operations for a buffer. */
static const struct pipe_buf_operations buffer_pipe_buf_ops = {
.can_merge = 0,
.map = generic_pipe_buf_map,
.unmap = generic_pipe_buf_unmap,
.confirm = generic_pipe_buf_confirm,
.release = buffer_pipe_buf_release,
.steal = buffer_pipe_buf_steal,
.get = buffer_pipe_buf_get,
};
/*
* Callback from splice_to_pipe(), if we need to release some pages
* at the end of the spd in case we error'ed out in filling the pipe.
*/
static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
{
struct buffer_ref *ref =
(struct buffer_ref *)spd->partial[i].private;
if (--ref->ref)
return;
ring_buffer_free_read_page(ref->buffer, ref->page);
kfree(ref);
spd->partial[i].private = 0;
}
static ssize_t
tracing_buffers_splice_read(struct file *file, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
struct ftrace_buffer_info *info = file->private_data;
struct partial_page partial_def[PIPE_DEF_BUFFERS];
struct page *pages_def[PIPE_DEF_BUFFERS];
struct splice_pipe_desc spd = {
.pages = pages_def,
.partial = partial_def,
.flags = flags,
.ops = &buffer_pipe_buf_ops,
.spd_release = buffer_spd_release,
};
struct buffer_ref *ref;
int entries, size, i;
size_t ret;
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
if (*ppos & (PAGE_SIZE - 1)) {
WARN_ONCE(1, "Ftrace: previous read must page-align\n");
ret = -EINVAL;
goto out;
}
if (len & (PAGE_SIZE - 1)) {
WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
if (len < PAGE_SIZE) {
ret = -EINVAL;
goto out;
}
len &= PAGE_MASK;
}
trace_access_lock(info->cpu);
entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
struct page *page;
int r;
ref = kzalloc(sizeof(*ref), GFP_KERNEL);
if (!ref)
break;
ref->ref = 1;
ref->buffer = info->tr->buffer;
ref->page = ring_buffer_alloc_read_page(ref->buffer, info->cpu);
if (!ref->page) {
kfree(ref);
break;
}
r = ring_buffer_read_page(ref->buffer, &ref->page,
len, info->cpu, 1);
if (r < 0) {
ring_buffer_free_read_page(ref->buffer, ref->page);
kfree(ref);
break;
}
/*
* zero out any left over data, this is going to
* user land.
*/
size = ring_buffer_page_len(ref->page);
if (size < PAGE_SIZE)
memset(ref->page + size, 0, PAGE_SIZE - size);
page = virt_to_page(ref->page);
spd.pages[i] = page;
spd.partial[i].len = PAGE_SIZE;
spd.partial[i].offset = 0;
spd.partial[i].private = (unsigned long)ref;
spd.nr_pages++;
*ppos += PAGE_SIZE;
entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
}
trace_access_unlock(info->cpu);
spd.nr_pages = i;
/* did we read anything? */
if (!spd.nr_pages) {
if (flags & SPLICE_F_NONBLOCK)
ret = -EAGAIN;
else
ret = 0;
/* TODO: block */
goto out;
}
ret = splice_to_pipe(pipe, &spd);
splice_shrink_spd(pipe, &spd);
out:
return ret;
}
static const struct file_operations tracing_buffers_fops = {
.open = tracing_buffers_open,
.read = tracing_buffers_read,
.release = tracing_buffers_release,
.splice_read = tracing_buffers_splice_read,
.llseek = no_llseek,
};
static ssize_t
tracing_stats_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
unsigned long cpu = (unsigned long)filp->private_data;
struct trace_array *tr = &global_trace;
struct trace_seq *s;
unsigned long cnt;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
trace_seq_init(s);
cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
trace_seq_printf(s, "entries: %ld\n", cnt);
cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
trace_seq_printf(s, "overrun: %ld\n", cnt);
cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
trace_seq_printf(s, "commit overrun: %ld\n", cnt);
count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
kfree(s);
return count;
}
static const struct file_operations tracing_stats_fops = {
.open = tracing_open_generic,
.read = tracing_stats_read,
.llseek = generic_file_llseek,
};
#ifdef CONFIG_DYNAMIC_FTRACE
int __weak ftrace_arch_read_dyn_info(char *buf, int size)
{
return 0;
}
static ssize_t
tracing_read_dyn_info(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
static char ftrace_dyn_info_buffer[1024];
static DEFINE_MUTEX(dyn_info_mutex);
unsigned long *p = filp->private_data;
char *buf = ftrace_dyn_info_buffer;
int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
int r;
mutex_lock(&dyn_info_mutex);
r = sprintf(buf, "%ld ", *p);
r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
buf[r++] = '\n';
r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
mutex_unlock(&dyn_info_mutex);
return r;
}
static const struct file_operations tracing_dyn_info_fops = {
.open = tracing_open_generic,
.read = tracing_read_dyn_info,
.llseek = generic_file_llseek,
};
#endif
static struct dentry *d_tracer;
struct dentry *tracing_init_dentry(void)
{
static int once;
if (d_tracer)
return d_tracer;
if (!debugfs_initialized())
return NULL;
d_tracer = debugfs_create_dir("tracing", NULL);
if (!d_tracer && !once) {
once = 1;
pr_warning("Could not create debugfs directory 'tracing'\n");
return NULL;
}
return d_tracer;
}
static struct dentry *d_percpu;
struct dentry *tracing_dentry_percpu(void)
{
static int once;
struct dentry *d_tracer;
if (d_percpu)
return d_percpu;
d_tracer = tracing_init_dentry();
if (!d_tracer)
return NULL;
d_percpu = debugfs_create_dir("per_cpu", d_tracer);
if (!d_percpu && !once) {
once = 1;
pr_warning("Could not create debugfs directory 'per_cpu'\n");
return NULL;
}
return d_percpu;
}
static void tracing_init_debugfs_percpu(long cpu)
{
struct dentry *d_percpu = tracing_dentry_percpu();
struct dentry *d_cpu;
char cpu_dir[30]; /* 30 characters should be more than enough */
snprintf(cpu_dir, 30, "cpu%ld", cpu);
d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
if (!d_cpu) {
pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);
return;
}
/* per cpu trace_pipe */
trace_create_file("trace_pipe", 0444, d_cpu,
(void *) cpu, &tracing_pipe_fops);
/* per cpu trace */
trace_create_file("trace", 0644, d_cpu,
(void *) cpu, &tracing_fops);
trace_create_file("trace_pipe_raw", 0444, d_cpu,
(void *) cpu, &tracing_buffers_fops);
trace_create_file("stats", 0444, d_cpu,
(void *) cpu, &tracing_stats_fops);
}
#ifdef CONFIG_FTRACE_SELFTEST
/* Let selftest have access to static functions in this file */
#include "trace_selftest.c"
#endif
struct trace_option_dentry {
struct tracer_opt *opt;
struct tracer_flags *flags;
struct dentry *entry;
};
static ssize_t
trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
struct trace_option_dentry *topt = filp->private_data;
char *buf;
if (topt->flags->val & topt->opt->bit)
buf = "1\n";
else
buf = "0\n";
return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}
static ssize_t
trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
{
struct trace_option_dentry *topt = filp->private_data;
unsigned long val;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
if (val != 0 && val != 1)
return -EINVAL;
if (!!(topt->flags->val & topt->opt->bit) != val) {
mutex_lock(&trace_types_lock);
ret = __set_tracer_option(current_trace, topt->flags,
topt->opt, !val);
mutex_unlock(&trace_types_lock);
if (ret)
return ret;
}
*ppos += cnt;
return cnt;
}
static const struct file_operations trace_options_fops = {
.open = tracing_open_generic,
.read = trace_options_read,
.write = trace_options_write,
.llseek = generic_file_llseek,
};
static ssize_t
trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
long index = (long)filp->private_data;
char *buf;
if (trace_flags & (1 << index))
buf = "1\n";
else
buf = "0\n";
return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}
static ssize_t
trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
{
long index = (long)filp->private_data;
unsigned long val;
int ret;
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
if (val != 0 && val != 1)
return -EINVAL;
set_tracer_flags(1 << index, val);
*ppos += cnt;
return cnt;
}
static const struct file_operations trace_options_core_fops = {
.open = tracing_open_generic,
.read = trace_options_core_read,
.write = trace_options_core_write,
.llseek = generic_file_llseek,
};
struct dentry *trace_create_file(const char *name,
mode_t mode,
struct dentry *parent,
void *data,
const struct file_operations *fops)
{
struct dentry *ret;
ret = debugfs_create_file(name, mode, parent, data, fops);
if (!ret)
pr_warning("Could not create debugfs '%s' entry\n", name);
return ret;
}
static struct dentry *trace_options_init_dentry(void)
{
struct dentry *d_tracer;
static struct dentry *t_options;
if (t_options)
return t_options;
d_tracer = tracing_init_dentry();
if (!d_tracer)
return NULL;
t_options = debugfs_create_dir("options", d_tracer);
if (!t_options) {
pr_warning("Could not create debugfs directory 'options'\n");
return NULL;
}
return t_options;
}
static void
create_trace_option_file(struct trace_option_dentry *topt,
struct tracer_flags *flags,
struct tracer_opt *opt)
{
struct dentry *t_options;
t_options = trace_options_init_dentry();
if (!t_options)
return;
topt->flags = flags;
topt->opt = opt;
topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
&trace_options_fops);
}
static struct trace_option_dentry *
create_trace_option_files(struct tracer *tracer)
{
struct trace_option_dentry *topts;
struct tracer_flags *flags;
struct tracer_opt *opts;
int cnt;
if (!tracer)
return NULL;
flags = tracer->flags;
if (!flags || !flags->opts)
return NULL;
opts = flags->opts;
for (cnt = 0; opts[cnt].name; cnt++)
;
topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
if (!topts)
return NULL;
for (cnt = 0; opts[cnt].name; cnt++)
create_trace_option_file(&topts[cnt], flags,
&opts[cnt]);
return topts;
}
static void
destroy_trace_option_files(struct trace_option_dentry *topts)
{
int cnt;
if (!topts)
return;
for (cnt = 0; topts[cnt].opt; cnt++) {
if (topts[cnt].entry)
debugfs_remove(topts[cnt].entry);
}
kfree(topts);
}
static struct dentry *
create_trace_option_core_file(const char *option, long index)
{
struct dentry *t_options;
t_options = trace_options_init_dentry();
if (!t_options)
return NULL;
return trace_create_file(option, 0644, t_options, (void *)index,
&trace_options_core_fops);
}
static __init void create_trace_options_dir(void)
{
struct dentry *t_options;
int i;
t_options = trace_options_init_dentry();
if (!t_options)
return;
for (i = 0; trace_options[i]; i++)
create_trace_option_core_file(trace_options[i], i);
}
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
int cpu;
trace_access_lock_init();
d_tracer = tracing_init_dentry();
trace_create_file("tracing_enabled", 0644, d_tracer,
&global_trace, &tracing_ctrl_fops);
trace_create_file("trace_options", 0644, d_tracer,
NULL, &tracing_iter_fops);
trace_create_file("tracing_cpumask", 0644, d_tracer,
NULL, &tracing_cpumask_fops);
trace_create_file("trace", 0644, d_tracer,
(void *) TRACE_PIPE_ALL_CPU, &tracing_fops);
trace_create_file("available_tracers", 0444, d_tracer,
&global_trace, &show_traces_fops);
trace_create_file("current_tracer", 0644, d_tracer,
&global_trace, &set_tracer_fops);
#ifdef CONFIG_TRACER_MAX_TRACE
trace_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency, &tracing_max_lat_fops);
#endif
trace_create_file("tracing_thresh", 0644, d_tracer,
&tracing_thresh, &tracing_max_lat_fops);
trace_create_file("README", 0444, d_tracer,
NULL, &tracing_readme_fops);
trace_create_file("trace_pipe", 0444, d_tracer,
(void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
trace_create_file("buffer_size_kb", 0644, d_tracer,
&global_trace, &tracing_entries_fops);
trace_create_file("free_buffer", 0644, d_tracer,
&global_trace, &tracing_free_buffer_fops);
trace_create_file("trace_marker", 0220, d_tracer,
NULL, &tracing_mark_fops);
trace_create_file("saved_cmdlines", 0444, d_tracer,
NULL, &tracing_saved_cmdlines_fops);
trace_create_file("trace_clock", 0644, d_tracer, NULL,
&trace_clock_fops);
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
#endif
create_trace_options_dir();
for_each_tracing_cpu(cpu)
tracing_init_debugfs_percpu(cpu);
return 0;
}
static int trace_panic_handler(struct notifier_block *this,
unsigned long event, void *unused)
{
if (ftrace_dump_on_oops)
ftrace_dump(ftrace_dump_on_oops);
return NOTIFY_OK;
}
static struct notifier_block trace_panic_notifier = {
.notifier_call = trace_panic_handler,
.next = NULL,
.priority = 150 /* priority: INT_MAX >= x >= 0 */
};
static int trace_die_handler(struct notifier_block *self,
unsigned long val,
void *data)
{
switch (val) {
case DIE_OOPS:
if (ftrace_dump_on_oops)
ftrace_dump(ftrace_dump_on_oops);
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block trace_die_notifier = {
.notifier_call = trace_die_handler,
.priority = 200
};
/*
* printk is set to max of 1024, we really don't need it that big.
* Nothing should be printing 1000 characters anyway.
*/
#define TRACE_MAX_PRINT 1000
/*
* Define here KERN_TRACE so that we have one place to modify
* it if we decide to change what log level the ftrace dump
* should be at.
*/
#define KERN_TRACE KERN_EMERG
void
trace_printk_seq(struct trace_seq *s)
{
/* Probably should print a warning here. */
if (s->len >= 1000)
s->len = 1000;
/* should be zero ended, but we are paranoid. */
s->buffer[s->len] = 0;
printk(KERN_TRACE "%s", s->buffer);
trace_seq_init(s);
}
void trace_init_global_iter(struct trace_iterator *iter)
{
iter->tr = &global_trace;
iter->trace = current_trace;
iter->cpu_file = TRACE_PIPE_ALL_CPU;
}
static void
__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
{
static arch_spinlock_t ftrace_dump_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
unsigned int old_userobj;
static int dump_ran;
unsigned long flags;
int cnt = 0, cpu;
/* only one dump */
local_irq_save(flags);
arch_spin_lock(&ftrace_dump_lock);
if (dump_ran)
goto out;
dump_ran = 1;
tracing_off();
if (disable_tracing)
ftrace_kill();
trace_init_global_iter(&iter);
for_each_tracing_cpu(cpu) {
atomic_inc(&iter.tr->data[cpu]->disabled);
}
old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
/* don't look at user memory in panic mode */
trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
/* Simulate the iterator */
iter.tr = &global_trace;
iter.trace = current_trace;
switch (oops_dump_mode) {
case DUMP_ALL:
iter.cpu_file = TRACE_PIPE_ALL_CPU;
break;
case DUMP_ORIG:
iter.cpu_file = raw_smp_processor_id();
break;
case DUMP_NONE:
goto out_enable;
default:
printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n");
iter.cpu_file = TRACE_PIPE_ALL_CPU;
}
printk(KERN_TRACE "Dumping ftrace buffer:\n");
/*
* We need to stop all tracing on all CPUS to read the
* the next buffer. This is a bit expensive, but is
* not done often. We fill all what we can read,
* and then release the locks again.
*/
while (!trace_empty(&iter)) {
if (!cnt)
printk(KERN_TRACE "---------------------------------\n");
cnt++;
/* reset all but tr, trace, and overruns */
memset(&iter.seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;
if (trace_find_next_entry_inc(&iter) != NULL) {
int ret;
ret = print_trace_line(&iter);
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(&iter);
}
trace_printk_seq(&iter.seq);
}
if (!cnt)
printk(KERN_TRACE " (ftrace buffer empty)\n");
else
printk(KERN_TRACE "---------------------------------\n");
out_enable:
/* Re-enable tracing if requested */
if (!disable_tracing) {
trace_flags |= old_userobj;
for_each_tracing_cpu(cpu) {
atomic_dec(&iter.tr->data[cpu]->disabled);
}
tracing_on();
}
out:
arch_spin_unlock(&ftrace_dump_lock);
local_irq_restore(flags);
}
/* By default: disable tracing after the dump */
void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
{
__ftrace_dump(true, oops_dump_mode);
}
__init static int tracer_alloc_buffers(void)
{
int ring_buf_size;
enum ring_buffer_flags rb_flags;
int i;
int ret = -ENOMEM;
if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
goto out;
if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
goto out_free_buffer_mask;
/* To save memory, keep the ring buffer size to its minimum */
if (ring_buffer_expanded)
ring_buf_size = trace_buf_size;
else
ring_buf_size = 1;
rb_flags = trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
cpumask_copy(tracing_cpumask, cpu_all_mask);
/* TODO: make the number of buffers hot pluggable with CPUS */
global_trace.buffer = ring_buffer_alloc(ring_buf_size, rb_flags);
if (!global_trace.buffer) {
printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
WARN_ON(1);
goto out_free_cpumask;
}
global_trace.entries = ring_buffer_size(global_trace.buffer);
#ifdef CONFIG_TRACER_MAX_TRACE
max_tr.buffer = ring_buffer_alloc(1, rb_flags);
if (!max_tr.buffer) {
printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
WARN_ON(1);
ring_buffer_free(global_trace.buffer);
goto out_free_cpumask;
}
max_tr.entries = 1;
#endif
/* Allocate the first page for all buffers */
for_each_tracing_cpu(i) {
global_trace.data[i] = &per_cpu(global_trace_cpu, i);
max_tr.data[i] = &per_cpu(max_tr_data, i);
}
trace_init_cmdlines();
register_tracer(&nop_trace);
current_trace = &nop_trace;
/* All seems OK, enable tracing */
tracing_disabled = 0;
atomic_notifier_chain_register(&panic_notifier_list,
&trace_panic_notifier);
register_die_notifier(&trace_die_notifier);
return 0;
out_free_cpumask:
free_cpumask_var(tracing_cpumask);
out_free_buffer_mask:
free_cpumask_var(tracing_buffer_mask);
out:
return ret;
}
__init static int clear_boot_tracer(void)
{
/*
* The default tracer at boot buffer is an init section.
* This function is called in lateinit. If we did not
* find the boot tracer, then clear it out, to prevent
* later registration from accessing the buffer that is
* about to be freed.
*/
if (!default_bootup_tracer)
return 0;
printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
default_bootup_tracer);
default_bootup_tracer = NULL;
return 0;
}
early_initcall(tracer_alloc_buffers);
fs_initcall(tracer_init_debugfs);
late_initcall(clear_boot_tracer);
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