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linux/kernel/trace/trace.c
Steven Rostedt 745b1626dd trace: set max latency variable to zero on default 
Impact: trace max latencies on start of latency tracing

This patch sets the max latency to zero whenever one of the
irq variant tracers or the wakeup tracer is set to current tracer.

Most developers expect to see output when starting up a latency
tracer. But since the max_latency is already set to max, and
it takes a latency greater than max_latency to be recorded, there
is no trace. This is not the expected behavior and has even confused
myself.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-16 12:18:09 +01:00

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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/utsrelease.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/debugfs.h>
#include <linux/pagemap.h>
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/kdebug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/gfp.h>
#include <linux/fs.h>
#include <linux/kprobes.h>
#include <linux/writeback.h>
#include <linux/stacktrace.h>
#include <linux/ring_buffer.h>
#include <linux/irqflags.h>
#include "trace.h"
#include "trace_output.h"
#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE)
unsigned long __read_mostly tracing_max_latency;
unsigned long __read_mostly tracing_thresh;
/*
* 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 ftrace_printk could occurred
* at the same time, giving false positive or negative results.
*/
static bool __read_mostly tracing_selftest_running;
/* 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.
*/
int tracing_disabled = 1;
static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);
static inline void ftrace_disable_cpu(void)
{
preempt_disable();
local_inc(&__get_cpu_var(ftrace_cpu_disabled));
}
static inline void ftrace_enable_cpu(void)
{
local_dec(&__get_cpu_var(ftrace_cpu_disabled));
preempt_enable();
}
static cpumask_var_t __read_mostly tracing_buffer_mask;
#define for_each_tracing_cpu(cpu) \
for_each_cpu(cpu, 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 to true.
*/
int ftrace_dump_on_oops;
static int tracing_set_tracer(char *buf);
static int __init set_ftrace(char *str)
{
tracing_set_tracer(str);
return 1;
}
__setup("ftrace", set_ftrace);
static int __init set_ftrace_dump_on_oops(char *str)
{
ftrace_dump_on_oops = 1;
return 1;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
long
ns2usecs(cycle_t nsec)
{
nsec += 500;
do_div(nsec, 1000);
return nsec;
}
cycle_t ftrace_now(int cpu)
{
u64 ts = ring_buffer_time_stamp(cpu);
ring_buffer_normalize_time_stamp(cpu, &ts);
return ts;
}
/*
* 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);
/*
* 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_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;
/*
* max_tracer_type_len is used to simplify the allocating of
* buffers to read userspace tracer names. We keep track of
* the longest tracer name registered.
*/
static int max_tracer_type_len;
/*
* trace_types_lock is used to protect the trace_types list.
* This lock is also used to keep user access serialized.
* Accesses from userspace will grab this lock while userspace
* activities happen inside the kernel.
*/
static DEFINE_MUTEX(trace_types_lock);
/* 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_wake_up - wake up tasks waiting for trace input
*
* Simply wakes 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)
{
/*
* The runqueue_is_locked() can fail, but this is the best we
* have for now:
*/
if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
wake_up(&trace_wait);
}
static int __init set_buf_size(char *str)
{
unsigned long buf_size;
int ret;
if (!str)
return 0;
ret = strict_strtoul(str, 0, &buf_size);
/* nr_entries can not be zero */
if (ret < 0 || buf_size == 0)
return 0;
trace_buf_size = buf_size;
return 1;
}
__setup("trace_buf_size=", set_buf_size);
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",
"sched-tree",
"ftrace_printk",
"ftrace_preempt",
"branch",
"annotate",
"userstacktrace",
"sym-userobj",
"printk-msg-only",
NULL
};
/*
* 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 raw_spinlock_t in order to help
* with performance when lockdep debugging is enabled.
*/
static raw_spinlock_t ftrace_max_lock =
(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
/*
* Copy the new maximum trace into the separate maximum-trace
* structure. (this way the maximum trace is permanently saved,
* for later retrieval via /debugfs/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];
max_tr.cpu = cpu;
max_tr.time_start = data->preempt_timestamp;
data = max_tr.data[cpu];
data->saved_latency = tracing_max_latency;
memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
data->pid = tsk->pid;
data->uid = task_uid(tsk);
data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
data->policy = tsk->policy;
data->rt_priority = tsk->rt_priority;
/* record this tasks comm */
tracing_record_cmdline(current);
}
static void
trace_seq_reset(struct trace_seq *s)
{
s->len = 0;
s->readpos = 0;
}
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
int len;
int ret;
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)
return -EFAULT;
s->readpos += len;
return cnt;
}
static void
trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
s->buffer[len] = 0;
seq_puts(m, s->buffer);
trace_seq_reset(s);
}
/**
* 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;
WARN_ON_ONCE(!irqs_disabled());
__raw_spin_lock(&ftrace_max_lock);
tr->buffer = max_tr.buffer;
max_tr.buffer = buf;
ftrace_disable_cpu();
ring_buffer_reset(tr->buffer);
ftrace_enable_cpu();
__update_max_tr(tr, tsk, cpu);
__raw_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;
WARN_ON_ONCE(!irqs_disabled());
__raw_spin_lock(&ftrace_max_lock);
ftrace_disable_cpu();
ring_buffer_reset(max_tr.buffer);
ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
ftrace_enable_cpu();
WARN_ON_ONCE(ret);
__update_max_tr(tr, tsk, cpu);
__raw_spin_unlock(&ftrace_max_lock);
}
/**
* 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)
{
struct tracer *t;
int len;
int ret = 0;
if (!type->name) {
pr_info("Tracer must have a name\n");
return -1;
}
/*
* When this gets called we hold the BKL which means that
* preemption is disabled. Various trace selftests however
* need to disable and enable preemption for successful tests.
* So we drop the BKL here and grab it after the tests again.
*/
unlock_kernel();
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("Trace %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;
#ifdef CONFIG_FTRACE_STARTUP_TEST
if (type->selftest) {
struct tracer *saved_tracer = current_trace;
struct trace_array *tr = &global_trace;
int i;
/*
* 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.
*/
for_each_tracing_cpu(i)
tracing_reset(tr, i);
current_trace = type;
/* 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 */
for_each_tracing_cpu(i)
tracing_reset(tr, i);
printk(KERN_CONT "PASSED\n");
}
#endif
type->next = trace_types;
trace_types = type;
len = strlen(type->name);
if (len > max_tracer_type_len)
max_tracer_type_len = len;
out:
tracing_selftest_running = false;
mutex_unlock(&trace_types_lock);
lock_kernel();
return ret;
}
void unregister_tracer(struct tracer *type)
{
struct tracer **t;
int len;
mutex_lock(&trace_types_lock);
for (t = &trace_types; *t; t = &(*t)->next) {
if (*t == type)
goto found;
}
pr_info("Trace %s not registered\n", type->name);
goto out;
found:
*t = (*t)->next;
if (strlen(type->name) != max_tracer_type_len)
goto out;
max_tracer_type_len = 0;
for (t = &trace_types; *t; t = &(*t)->next) {
len = strlen((*t)->name);
if (len > max_tracer_type_len)
max_tracer_type_len = len;
}
out:
mutex_unlock(&trace_types_lock);
}
void tracing_reset(struct trace_array *tr, int cpu)
{
ftrace_disable_cpu();
ring_buffer_reset_cpu(tr->buffer, cpu);
ftrace_enable_cpu();
}
void tracing_reset_online_cpus(struct trace_array *tr)
{
int cpu;
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
tracing_reset(tr, cpu);
}
#define SAVED_CMDLINES 128
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 DEFINE_SPINLOCK(trace_cmdline_lock);
/* temporary disable recording */
atomic_t trace_record_cmdline_disabled __read_mostly;
static void trace_init_cmdlines(void)
{
memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
cmdline_idx = 0;
}
static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);
/**
* 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)
goto out;
if (trace_stop_count < 0) {
/* Someone screwed up their debugging */
WARN_ON_ONCE(1);
trace_stop_count = 0;
goto out;
}
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
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;
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
void trace_stop_cmdline_recording(void);
static void trace_save_cmdline(struct task_struct *tsk)
{
unsigned map;
unsigned 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 (!spin_trylock(&trace_cmdline_lock))
return;
idx = map_pid_to_cmdline[tsk->pid];
if (idx >= SAVED_CMDLINES) {
idx = (cmdline_idx + 1) % SAVED_CMDLINES;
map = map_cmdline_to_pid[idx];
if (map <= PID_MAX_DEFAULT)
map_pid_to_cmdline[map] = (unsigned)-1;
map_pid_to_cmdline[tsk->pid] = idx;
cmdline_idx = idx;
}
memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
spin_unlock(&trace_cmdline_lock);
}
char *trace_find_cmdline(int pid)
{
char *cmdline = "<...>";
unsigned map;
if (!pid)
return "<idle>";
if (pid > PID_MAX_DEFAULT)
goto out;
map = map_pid_to_cmdline[pid];
if (map >= SAVED_CMDLINES)
goto out;
cmdline = saved_cmdlines[map];
out:
return cmdline;
}
void tracing_record_cmdline(struct task_struct *tsk)
{
if (atomic_read(&trace_record_cmdline_disabled))
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->tgid = (tsk) ? tsk->tgid : 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);
}
void
trace_function(struct trace_array *tr, struct trace_array_cpu *data,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
struct ring_buffer_event *event;
struct ftrace_entry *entry;
unsigned long irq_flags;
/* If we are reading the ring buffer, don't trace */
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_FN;
entry->ip = ip;
entry->parent_ip = parent_ip;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static void __trace_graph_entry(struct trace_array *tr,
struct trace_array_cpu *data,
struct ftrace_graph_ent *trace,
unsigned long flags,
int pc)
{
struct ring_buffer_event *event;
struct ftrace_graph_ent_entry *entry;
unsigned long irq_flags;
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return;
event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_GRAPH_ENT;
entry->graph_ent = *trace;
ring_buffer_unlock_commit(global_trace.buffer, event, irq_flags);
}
static void __trace_graph_return(struct trace_array *tr,
struct trace_array_cpu *data,
struct ftrace_graph_ret *trace,
unsigned long flags,
int pc)
{
struct ring_buffer_event *event;
struct ftrace_graph_ret_entry *entry;
unsigned long irq_flags;
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return;
event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_GRAPH_RET;
entry->ret = *trace;
ring_buffer_unlock_commit(global_trace.buffer, event, irq_flags);
}
#endif
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, data, ip, parent_ip, flags, pc);
}
static void __ftrace_trace_stack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags,
int skip, int pc)
{
#ifdef CONFIG_STACKTRACE
struct ring_buffer_event *event;
struct stack_entry *entry;
struct stack_trace trace;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_STACK;
memset(&entry->caller, 0, sizeof(entry->caller));
trace.nr_entries = 0;
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.skip = skip;
trace.entries = entry->caller;
save_stack_trace(&trace);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
#endif
}
static void ftrace_trace_stack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags,
int skip, int pc)
{
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
__ftrace_trace_stack(tr, data, flags, skip, pc);
}
void __trace_stack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags,
int skip, int pc)
{
__ftrace_trace_stack(tr, data, flags, skip, pc);
}
static void ftrace_trace_userstack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags, int pc)
{
#ifdef CONFIG_STACKTRACE
struct ring_buffer_event *event;
struct userstack_entry *entry;
struct stack_trace trace;
unsigned long irq_flags;
if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
return;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_USER_STACK;
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);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
#endif
}
void __trace_userstack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags)
{
ftrace_trace_userstack(tr, data, flags, preempt_count());
}
static void
ftrace_trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3,
int pc)
{
struct ring_buffer_event *event;
struct trace_array_cpu *data = __data;
struct trace_array *tr = __tr;
struct special_entry *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, pc);
entry->ent.type = TRACE_SPECIAL;
entry->arg1 = arg1;
entry->arg2 = arg2;
entry->arg3 = arg3;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, irq_flags, 4, pc);
ftrace_trace_userstack(tr, data, irq_flags, pc);
trace_wake_up();
}
void
__trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
ftrace_trace_special(__tr, __data, arg1, arg2, arg3, preempt_count());
}
void
tracing_sched_switch_trace(struct trace_array *tr,
struct trace_array_cpu *data,
struct task_struct *prev,
struct task_struct *next,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_CTX;
entry->prev_pid = prev->pid;
entry->prev_prio = prev->prio;
entry->prev_state = prev->state;
entry->next_pid = next->pid;
entry->next_prio = next->prio;
entry->next_state = next->state;
entry->next_cpu = task_cpu(next);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 5, pc);
ftrace_trace_userstack(tr, data, flags, pc);
}
void
tracing_sched_wakeup_trace(struct trace_array *tr,
struct trace_array_cpu *data,
struct task_struct *wakee,
struct task_struct *curr,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_WAKE;
entry->prev_pid = curr->pid;
entry->prev_prio = curr->prio;
entry->prev_state = curr->state;
entry->next_pid = wakee->pid;
entry->next_prio = wakee->prio;
entry->next_state = wakee->state;
entry->next_cpu = task_cpu(wakee);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 6, pc);
ftrace_trace_userstack(tr, data, flags, pc);
trace_wake_up();
}
void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
unsigned long flags;
int cpu;
int pc;
if (tracing_disabled)
return;
pc = preempt_count();
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
if (likely(atomic_inc_return(&data->disabled) == 1))
ftrace_trace_special(tr, data, arg1, arg2, arg3, pc);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
int trace_graph_entry(struct ftrace_graph_ent *trace)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
if (!ftrace_trace_task(current))
return 0;
if (!ftrace_graph_addr(trace->func))
return 0;
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
__trace_graph_entry(tr, data, trace, flags, pc);
}
/* Only do the atomic if it is not already set */
if (!test_tsk_trace_graph(current))
set_tsk_trace_graph(current);
atomic_dec(&data->disabled);
local_irq_restore(flags);
return 1;
}
void trace_graph_return(struct ftrace_graph_ret *trace)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
__trace_graph_return(tr, data, trace, flags, pc);
}
if (!trace->depth)
clear_tsk_trace_graph(current);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
enum trace_file_type {
TRACE_FILE_LAT_FMT = 1,
TRACE_FILE_ANNOTATE = 2,
};
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)
{
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);
ftrace_enable_cpu();
return event ? ring_buffer_event_data(event) : NULL;
}
static struct trace_entry *
__find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
{
struct ring_buffer *buffer = iter->tr->buffer;
struct trace_entry *ent, *next = NULL;
u64 next_ts = 0, ts;
int next_cpu = -1;
int cpu;
for_each_tracing_cpu(cpu) {
if (ring_buffer_empty_cpu(buffer, cpu))
continue;
ent = peek_next_entry(iter, cpu, &ts);
/*
* Pick the entry with the smallest timestamp:
*/
if (ent && (!next || ts < next_ts)) {
next = ent;
next_cpu = cpu;
next_ts = ts;
}
}
if (ent_cpu)
*ent_cpu = next_cpu;
if (ent_ts)
*ent_ts = next_ts;
return next;
}
/* Find the next real entry, without updating the iterator itself */
static struct trace_entry *
find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
{
return __find_next_entry(iter, ent_cpu, ent_ts);
}
/* Find the next real entry, and increment the iterator to the next entry */
static void *find_next_entry_inc(struct trace_iterator *iter)
{
iter->ent = __find_next_entry(iter, &iter->cpu, &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);
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;
(*pos)++;
/* can't go backwards */
if (iter->idx > i)
return NULL;
if (iter->idx < 0)
ent = find_next_entry_inc(iter);
else
ent = iter;
while (ent && iter->idx < i)
ent = find_next_entry_inc(iter);
iter->pos = *pos;
return ent;
}
static void *s_start(struct seq_file *m, loff_t *pos)
{
struct trace_iterator *iter = m->private;
void *p = NULL;
loff_t l = 0;
int cpu;
mutex_lock(&trace_types_lock);
if (!current_trace || current_trace != iter->trace) {
mutex_unlock(&trace_types_lock);
return NULL;
}
atomic_inc(&trace_record_cmdline_disabled);
if (*pos != iter->pos) {
iter->ent = NULL;
iter->cpu = 0;
iter->idx = -1;
ftrace_disable_cpu();
for_each_tracing_cpu(cpu) {
ring_buffer_iter_reset(iter->buffer_iter[cpu]);
}
ftrace_enable_cpu();
for (p = iter; p && l < *pos; p = s_next(m, p, &l))
;
} else {
l = *pos - 1;
p = s_next(m, p, &l);
}
return p;
}
static void s_stop(struct seq_file *m, void *p)
{
atomic_dec(&trace_record_cmdline_disabled);
mutex_unlock(&trace_types_lock);
}
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, "# |||| / \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");
}
static 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 total;
unsigned long entries;
const char *name = "preemption";
if (type)
name = type->name;
entries = ring_buffer_entries(iter->tr->buffer);
total = entries +
ring_buffer_overruns(iter->tr->buffer);
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");
}
seq_puts(m, "\n");
}
static void
lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
{
int hardirq, softirq;
char *comm;
comm = trace_find_cmdline(entry->pid);
trace_seq_printf(s, "%8.8s-%-5d ", comm, entry->pid);
trace_seq_printf(s, "%3d", cpu);
trace_seq_printf(s, "%c%c",
(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
(entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' : '.',
((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
if (hardirq && softirq) {
trace_seq_putc(s, 'H');
} else {
if (hardirq) {
trace_seq_putc(s, 'h');
} else {
if (softirq)
trace_seq_putc(s, 's');
else
trace_seq_putc(s, '.');
}
}
if (entry->preempt_count)
trace_seq_printf(s, "%x", entry->preempt_count);
else
trace_seq_puts(s, ".");
}
unsigned long preempt_mark_thresh = 100;
static void
lat_print_timestamp(struct trace_seq *s, u64 abs_usecs,
unsigned long rel_usecs)
{
trace_seq_printf(s, " %4lldus", abs_usecs);
if (rel_usecs > preempt_mark_thresh)
trace_seq_puts(s, "!: ");
else if (rel_usecs > 1)
trace_seq_puts(s, "+: ");
else
trace_seq_puts(s, " : ");
}
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;
cpumask_set_cpu(iter->cpu, iter->started);
trace_seq_printf(s, "##### CPU %u buffer started ####\n", iter->cpu);
}
static enum print_line_t
print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
{
struct trace_seq *s = &iter->seq;
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_entry *next_entry;
struct trace_event *event;
unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
struct trace_entry *entry = iter->ent;
unsigned long abs_usecs;
unsigned long rel_usecs;
u64 next_ts;
char *comm;
int ret;
test_cpu_buff_start(iter);
next_entry = find_next_entry(iter, NULL, &next_ts);
if (!next_entry)
next_ts = iter->ts;
rel_usecs = ns2usecs(next_ts - iter->ts);
abs_usecs = ns2usecs(iter->ts - iter->tr->time_start);
if (verbose) {
comm = trace_find_cmdline(entry->pid);
trace_seq_printf(s, "%16s %5d %3d %d %08x %08x [%08lx]"
" %ld.%03ldms (+%ld.%03ldms): ",
comm,
entry->pid, cpu, entry->flags,
entry->preempt_count, trace_idx,
ns2usecs(iter->ts),
abs_usecs/1000,
abs_usecs % 1000, rel_usecs/1000,
rel_usecs % 1000);
} else {
lat_print_generic(s, entry, cpu);
lat_print_timestamp(s, abs_usecs, rel_usecs);
}
event = ftrace_find_event(entry->type);
if (event && event->latency_trace) {
ret = event->latency_trace(s, entry, sym_flags);
if (ret)
return ret;
return TRACE_TYPE_HANDLED;
}
trace_seq_printf(s, "Unknown type %d\n", entry->type);
return TRACE_TYPE_HANDLED;
}
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;
unsigned long usec_rem;
unsigned long long t;
unsigned long secs;
char *comm;
int ret;
entry = iter->ent;
test_cpu_buff_start(iter);
comm = trace_find_cmdline(iter->ent->pid);
t = ns2usecs(iter->ts);
usec_rem = do_div(t, 1000000ULL);
secs = (unsigned long)t;
ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, "[%03d] ", iter->cpu);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
event = ftrace_find_event(entry->type);
if (event && event->trace) {
ret = event->trace(s, entry, sym_flags);
if (ret)
return ret;
return TRACE_TYPE_HANDLED;
}
ret = trace_seq_printf(s, "Unknown type %d\n", entry->type);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
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;
int ret;
entry = iter->ent;
ret = trace_seq_printf(s, "%d %d %llu ",
entry->pid, iter->cpu, iter->ts);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
event = ftrace_find_event(entry->type);
if (event && event->raw) {
ret = event->raw(s, entry, 0);
if (ret)
return ret;
return TRACE_TYPE_HANDLED;
}
ret = trace_seq_printf(s, "%d ?\n", entry->type);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
return TRACE_TYPE_HANDLED;
}
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;
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 && event->hex)
event->hex(s, entry, 0);
SEQ_PUT_FIELD_RET(s, newline);
return TRACE_TYPE_HANDLED;
}
static enum print_line_t print_printk_msg_only(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry = iter->ent;
struct print_entry *field;
int ret;
trace_assign_type(field, entry);
ret = trace_seq_printf(s, field->buf);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
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;
SEQ_PUT_FIELD_RET(s, entry->pid);
SEQ_PUT_FIELD_RET(s, entry->cpu);
SEQ_PUT_FIELD_RET(s, iter->ts);
event = ftrace_find_event(entry->type);
if (event && event->binary)
event->binary(s, entry, 0);
return TRACE_TYPE_HANDLED;
}
static int trace_empty(struct trace_iterator *iter)
{
int cpu;
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;
}
static enum print_line_t print_trace_line(struct trace_iterator *iter)
{
enum print_line_t ret;
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_PRINT &&
trace_flags & TRACE_ITER_PRINTK &&
trace_flags & TRACE_ITER_PRINTK_MSGONLY)
return 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);
if (iter->iter_flags & TRACE_FILE_LAT_FMT)
return print_lat_fmt(iter, iter->idx, iter->cpu);
return print_trace_fmt(iter);
}
static int s_show(struct seq_file *m, void *v)
{
struct trace_iterator *iter = v;
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 if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
/* print nothing if the buffers are empty */
if (trace_empty(iter))
return 0;
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);
}
} else {
print_trace_line(iter);
trace_print_seq(m, &iter->seq);
}
return 0;
}
static 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, int *ret)
{
struct trace_iterator *iter;
struct seq_file *m;
int cpu;
if (tracing_disabled) {
*ret = -ENODEV;
return NULL;
}
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter) {
*ret = -ENOMEM;
goto out;
}
mutex_lock(&trace_types_lock);
if (current_trace && current_trace->print_max)
iter->tr = &max_tr;
else
iter->tr = inode->i_private;
iter->trace = current_trace;
iter->pos = -1;
/* 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;
for_each_tracing_cpu(cpu) {
iter->buffer_iter[cpu] =
ring_buffer_read_start(iter->tr->buffer, cpu);
if (!iter->buffer_iter[cpu])
goto fail_buffer;
}
/* TODO stop tracer */
*ret = seq_open(file, &tracer_seq_ops);
if (*ret)
goto fail_buffer;
m = file->private_data;
m->private = iter;
/* stop the trace while dumping */
tracing_stop();
mutex_unlock(&trace_types_lock);
out:
return iter;
fail_buffer:
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
mutex_unlock(&trace_types_lock);
kfree(iter);
return ERR_PTR(-ENOMEM);
}
int tracing_open_generic(struct inode *inode, struct file *filp)
{
if (tracing_disabled)
return -ENODEV;
filp->private_data = inode->i_private;
return 0;
}
int tracing_release(struct inode *inode, struct file *file)
{
struct seq_file *m = (struct seq_file *)file->private_data;
struct trace_iterator *iter = m->private;
int cpu;
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);
kfree(iter);
return 0;
}
static int tracing_open(struct inode *inode, struct file *file)
{
int ret;
__tracing_open(inode, file, &ret);
return ret;
}
static int tracing_lt_open(struct inode *inode, struct file *file)
{
struct trace_iterator *iter;
int ret;
iter = __tracing_open(inode, file, &ret);
if (!ret)
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 = m->private;
(*pos)++;
if (t)
t = t->next;
m->private = t;
return t;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct tracer *t = m->private;
loff_t l = 0;
mutex_lock(&trace_types_lock);
for (; 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 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)
{
int ret;
if (tracing_disabled)
return -ENODEV;
ret = seq_open(file, &show_traces_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = trace_types;
}
return ret;
}
static struct file_operations tracing_fops = {
.open = tracing_open,
.read = seq_read,
.llseek = seq_lseek,
.release = tracing_release,
};
static struct file_operations tracing_lt_fops = {
.open = tracing_lt_open,
.read = seq_read,
.llseek = seq_lseek,
.release = tracing_release,
};
static struct file_operations show_traces_fops = {
.open = show_traces_open,
.read = seq_read,
.release = seq_release,
};
/*
* 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;
mutex_lock(&tracing_cpumask_update_lock);
err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
if (err)
goto err_unlock;
local_irq_disable();
__raw_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);
}
}
__raw_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:
mutex_unlock(&tracing_cpumask_update_lock);
free_cpumask_var(tracing_cpumask);
return err;
}
static struct file_operations tracing_cpumask_fops = {
.open = tracing_open_generic,
.read = tracing_cpumask_read,
.write = tracing_cpumask_write,
};
static ssize_t
tracing_trace_options_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
int i;
char *buf;
int r = 0;
int len = 0;
u32 tracer_flags = current_trace->flags->val;
struct tracer_opt *trace_opts = current_trace->flags->opts;
/* calulate max size */
for (i = 0; trace_options[i]; i++) {
len += strlen(trace_options[i]);
len += 3; /* "no" and space */
}
/*
* Increase the size with names of options specific
* of the current tracer.
*/
for (i = 0; trace_opts[i].name; i++) {
len += strlen(trace_opts[i].name);
len += 3; /* "no" and space */
}
/* +2 for \n and \0 */
buf = kmalloc(len + 2, GFP_KERNEL);
if (!buf)
return -ENOMEM;
for (i = 0; trace_options[i]; i++) {
if (trace_flags & (1 << i))
r += sprintf(buf + r, "%s ", trace_options[i]);
else
r += sprintf(buf + r, "no%s ", trace_options[i]);
}
for (i = 0; trace_opts[i].name; i++) {
if (tracer_flags & trace_opts[i].bit)
r += sprintf(buf + r, "%s ",
trace_opts[i].name);
else
r += sprintf(buf + r, "no%s ",
trace_opts[i].name);
}
r += sprintf(buf + r, "\n");
WARN_ON(r >= len + 2);
r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
kfree(buf);
return r;
}
/* Try to assign a tracer specific option */
static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
{
struct tracer_flags *trace_flags = trace->flags;
struct tracer_opt *opts = NULL;
int ret = 0, i = 0;
int len;
for (i = 0; trace_flags->opts[i].name; i++) {
opts = &trace_flags->opts[i];
len = strlen(opts->name);
if (strncmp(cmp, opts->name, len) == 0) {
ret = trace->set_flag(trace_flags->val,
opts->bit, !neg);
break;
}
}
/* Not found */
if (!trace_flags->opts[i].name)
return -EINVAL;
/* Refused to handle */
if (ret)
return ret;
if (neg)
trace_flags->val &= ~opts->bit;
else
trace_flags->val |= opts->bit;
return 0;
}
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 = buf;
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;
if (strncmp(buf, "no", 2) == 0) {
neg = 1;
cmp += 2;
}
for (i = 0; trace_options[i]; i++) {
int len = strlen(trace_options[i]);
if (strncmp(cmp, trace_options[i], len) == 0) {
if (neg)
trace_flags &= ~(1 << i);
else
trace_flags |= (1 << i);
break;
}
}
/* If no option could be set, test the specific tracer options */
if (!trace_options[i]) {
ret = set_tracer_option(current_trace, cmp, neg);
if (ret)
return ret;
}
filp->f_pos += cnt;
return cnt;
}
static struct file_operations tracing_iter_fops = {
.open = tracing_open_generic,
.read = tracing_trace_options_read,
.write = tracing_trace_options_write,
};
static const char readme_msg[] =
"tracing mini-HOWTO:\n\n"
"# mkdir /debug\n"
"# mount -t debugfs nodev /debug\n\n"
"# cat /debug/tracing/available_tracers\n"
"wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
"# cat /debug/tracing/current_tracer\n"
"none\n"
"# echo sched_switch > /debug/tracing/current_tracer\n"
"# cat /debug/tracing/current_tracer\n"
"sched_switch\n"
"# cat /debug/tracing/trace_options\n"
"noprint-parent nosym-offset nosym-addr noverbose\n"
"# echo print-parent > /debug/tracing/trace_options\n"
"# echo 1 > /debug/tracing/tracing_enabled\n"
"# cat /debug/tracing/trace > /tmp/trace.txt\n"
"echo 0 > /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 struct file_operations tracing_readme_fops = {
.open = tracing_open_generic,
.read = tracing_readme_read,
};
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;
char buf[64];
long val;
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
val = !!val;
mutex_lock(&trace_types_lock);
if (tracer_enabled ^ val) {
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);
filp->f_pos += 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_type_len+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);
}
static int tracing_set_tracer(char *buf)
{
struct trace_array *tr = &global_trace;
struct tracer *t;
int ret = 0;
mutex_lock(&trace_types_lock);
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);
current_trace = t;
if (t->init) {
ret = t->init(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_type_len+1];
int i;
size_t ret;
int err;
ret = cnt;
if (cnt > max_tracer_type_len)
cnt = max_tracer_type_len;
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;
filp->f_pos += 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)
{
long *ptr = filp->private_data;
char buf[64];
long val;
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
*ptr = val * 1000;
return cnt;
}
static atomic_t tracing_reader;
static int tracing_open_pipe(struct inode *inode, struct file *filp)
{
struct trace_iterator *iter;
if (tracing_disabled)
return -ENODEV;
/* We only allow for reader of the pipe */
if (atomic_inc_return(&tracing_reader) != 1) {
atomic_dec(&tracing_reader);
return -EBUSY;
}
/* create a buffer to store the information to pass to userspace */
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
kfree(iter);
return -ENOMEM;
}
mutex_lock(&trace_types_lock);
/* trace pipe does not show start of buffer */
cpumask_setall(iter->started);
iter->tr = &global_trace;
iter->trace = current_trace;
filp->private_data = iter;
if (iter->trace->pipe_open)
iter->trace->pipe_open(iter);
mutex_unlock(&trace_types_lock);
return 0;
}
static int tracing_release_pipe(struct inode *inode, struct file *file)
{
struct trace_iterator *iter = file->private_data;
free_cpumask_var(iter->started);
kfree(iter);
atomic_dec(&tracing_reader);
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;
}
}
/*
* 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;
ssize_t sret;
/* return any leftover data */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
return sret;
trace_seq_reset(&iter->seq);
mutex_lock(&trace_types_lock);
if (iter->trace->read) {
sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
if (sret)
goto out;
}
waitagain:
sret = 0;
while (trace_empty(iter)) {
if ((filp->f_flags & O_NONBLOCK)) {
sret = -EAGAIN;
goto out;
}
/*
* This is a make-shift waitqueue. The reason we don't use
* an actual wait queue is because:
* 1) we only ever have one waiter
* 2) the tracing, traces 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.
*/
set_current_state(TASK_INTERRUPTIBLE);
iter->tr->waiter = current;
mutex_unlock(&trace_types_lock);
/* sleep for 100 msecs, and try again. */
schedule_timeout(HZ/10);
mutex_lock(&trace_types_lock);
iter->tr->waiter = NULL;
if (signal_pending(current)) {
sret = -EINTR;
goto out;
}
if (iter->trace != current_trace)
goto out;
/*
* 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;
continue;
}
/* stop when tracing is finished */
if (trace_empty(iter))
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;
while (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;
}
trace_consume(iter);
if (iter->seq.len >= cnt)
break;
}
/* 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_reset(&iter->seq);
/*
* If there was nothing to send to user, inspite of consuming trace
* entries, go back to wait for more entries.
*/
if (sret == -EBUSY)
goto waitagain;
out:
mutex_unlock(&trace_types_lock);
return sret;
}
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[64];
int r;
r = sprintf(buf, "%lu\n", tr->entries >> 10);
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;
char buf[64];
int ret, cpu;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
/* must have at least 1 entry */
if (!val)
return -EINVAL;
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);
}
/* value is in KB */
val <<= 10;
if (val != global_trace.entries) {
ret = ring_buffer_resize(global_trace.buffer, val);
if (ret < 0) {
cnt = ret;
goto out;
}
ret = ring_buffer_resize(max_tr.buffer, val);
if (ret < 0) {
int r;
cnt = ret;
r = ring_buffer_resize(global_trace.buffer,
global_trace.entries);
if (r < 0) {
/* AARGH! We are left with different
* size max buffer!!!! */
WARN_ON(1);
tracing_disabled = 1;
}
goto out;
}
global_trace.entries = val;
}
filp->f_pos += cnt;
/* If check pages failed, return ENOMEM */
if (tracing_disabled)
cnt = -ENOMEM;
out:
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();
max_tr.entries = global_trace.entries;
mutex_unlock(&trace_types_lock);
return cnt;
}
static int mark_printk(const char *fmt, ...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = trace_vprintk(0, -1, 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;
char *end;
if (tracing_disabled)
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
buf = kmalloc(cnt + 1, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
if (copy_from_user(buf, ubuf, cnt)) {
kfree(buf);
return -EFAULT;
}
/* Cut from the first nil or newline. */
buf[cnt] = '\0';
end = strchr(buf, '\n');
if (end)
*end = '\0';
cnt = mark_printk("%s\n", buf);
kfree(buf);
*fpos += cnt;
return cnt;
}
static struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
.write = tracing_max_lat_write,
};
static struct file_operations tracing_ctrl_fops = {
.open = tracing_open_generic,
.read = tracing_ctrl_read,
.write = tracing_ctrl_write,
};
static struct file_operations set_tracer_fops = {
.open = tracing_open_generic,
.read = tracing_set_trace_read,
.write = tracing_set_trace_write,
};
static struct file_operations tracing_pipe_fops = {
.open = tracing_open_pipe,
.poll = tracing_poll_pipe,
.read = tracing_read_pipe,
.release = tracing_release_pipe,
};
static struct file_operations tracing_entries_fops = {
.open = tracing_open_generic,
.read = tracing_entries_read,
.write = tracing_entries_write,
};
static struct file_operations tracing_mark_fops = {
.open = tracing_open_generic,
.write = tracing_mark_write,
};
#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 struct file_operations tracing_dyn_info_fops = {
.open = tracing_open_generic,
.read = tracing_read_dyn_info,
};
#endif
static struct dentry *d_tracer;
struct dentry *tracing_init_dentry(void)
{
static int once;
if (d_tracer)
return d_tracer;
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;
}
#ifdef CONFIG_FTRACE_SELFTEST
/* Let selftest have access to static functions in this file */
#include "trace_selftest.c"
#endif
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
entry = debugfs_create_file("tracing_enabled", 0644, d_tracer,
&global_trace, &tracing_ctrl_fops);
if (!entry)
pr_warning("Could not create debugfs 'tracing_enabled' entry\n");
entry = debugfs_create_file("trace_options", 0644, d_tracer,
NULL, &tracing_iter_fops);
if (!entry)
pr_warning("Could not create debugfs 'trace_options' entry\n");
entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,
NULL, &tracing_cpumask_fops);
if (!entry)
pr_warning("Could not create debugfs 'tracing_cpumask' entry\n");
entry = debugfs_create_file("latency_trace", 0444, d_tracer,
&global_trace, &tracing_lt_fops);
if (!entry)
pr_warning("Could not create debugfs 'latency_trace' entry\n");
entry = debugfs_create_file("trace", 0444, d_tracer,
&global_trace, &tracing_fops);
if (!entry)
pr_warning("Could not create debugfs 'trace' entry\n");
entry = debugfs_create_file("available_tracers", 0444, d_tracer,
&global_trace, &show_traces_fops);
if (!entry)
pr_warning("Could not create debugfs 'available_tracers' entry\n");
entry = debugfs_create_file("current_tracer", 0444, d_tracer,
&global_trace, &set_tracer_fops);
if (!entry)
pr_warning("Could not create debugfs 'current_tracer' entry\n");
entry = debugfs_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency,
&tracing_max_lat_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'tracing_max_latency' entry\n");
entry = debugfs_create_file("tracing_thresh", 0644, d_tracer,
&tracing_thresh, &tracing_max_lat_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'tracing_thresh' entry\n");
entry = debugfs_create_file("README", 0644, d_tracer,
NULL, &tracing_readme_fops);
if (!entry)
pr_warning("Could not create debugfs 'README' entry\n");
entry = debugfs_create_file("trace_pipe", 0644, d_tracer,
NULL, &tracing_pipe_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'trace_pipe' entry\n");
entry = debugfs_create_file("buffer_size_kb", 0644, d_tracer,
&global_trace, &tracing_entries_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'buffer_size_kb' entry\n");
entry = debugfs_create_file("trace_marker", 0220, d_tracer,
NULL, &tracing_mark_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'trace_marker' entry\n");
#ifdef CONFIG_DYNAMIC_FTRACE
entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt,
&tracing_dyn_info_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'dyn_ftrace_total_info' entry\n");
#endif
#ifdef CONFIG_SYSPROF_TRACER
init_tracer_sysprof_debugfs(d_tracer);
#endif
return 0;
}
int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args)
{
static DEFINE_SPINLOCK(trace_buf_lock);
static char trace_buf[TRACE_BUF_SIZE];
struct ring_buffer_event *event;
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
int cpu, len = 0, size, pc;
struct print_entry *entry;
unsigned long irq_flags;
if (tracing_disabled || tracing_selftest_running)
return 0;
pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
if (unlikely(atomic_read(&data->disabled)))
goto out;
pause_graph_tracing();
spin_lock_irqsave(&trace_buf_lock, irq_flags);
len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
len = min(len, TRACE_BUF_SIZE-1);
trace_buf[len] = 0;
size = sizeof(*entry) + len + 1;
event = ring_buffer_lock_reserve(tr->buffer, size, &irq_flags);
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, irq_flags, pc);
entry->ent.type = TRACE_PRINT;
entry->ip = ip;
entry->depth = depth;
memcpy(&entry->buf, trace_buf, len);
entry->buf[len] = 0;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
out_unlock:
spin_unlock_irqrestore(&trace_buf_lock, irq_flags);
unpause_graph_tracing();
out:
preempt_enable_notrace();
return len;
}
EXPORT_SYMBOL_GPL(trace_vprintk);
int __ftrace_printk(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_vprintk(ip, task_curr_ret_stack(current), fmt, ap);
va_end(ap);
return ret;
}
EXPORT_SYMBOL_GPL(__ftrace_printk);
static int trace_panic_handler(struct notifier_block *this,
unsigned long event, void *unused)
{
if (ftrace_dump_on_oops)
ftrace_dump();
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();
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
static 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_reset(s);
}
void ftrace_dump(void)
{
static DEFINE_SPINLOCK(ftrace_dump_lock);
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
static int dump_ran;
unsigned long flags;
int cnt = 0, cpu;
/* only one dump */
spin_lock_irqsave(&ftrace_dump_lock, flags);
if (dump_ran)
goto out;
dump_ran = 1;
/* No turning back! */
tracing_off();
ftrace_kill();
for_each_tracing_cpu(cpu) {
atomic_inc(&global_trace.data[cpu]->disabled);
}
/* don't look at user memory in panic mode */
trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
printk(KERN_TRACE "Dumping ftrace buffer:\n");
iter.tr = &global_trace;
iter.trace = current_trace;
/*
* 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 (find_next_entry_inc(&iter) != NULL) {
print_trace_line(&iter);
trace_consume(&iter);
}
trace_printk_seq(&iter.seq);
}
if (!cnt)
printk(KERN_TRACE " (ftrace buffer empty)\n");
else
printk(KERN_TRACE "---------------------------------\n");
out:
spin_unlock_irqrestore(&ftrace_dump_lock, flags);
}
__init static int tracer_alloc_buffers(void)
{
struct trace_array_cpu *data;
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;
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(trace_buf_size,
TRACE_BUFFER_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(trace_buf_size,
TRACE_BUFFER_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 = ring_buffer_size(max_tr.buffer);
WARN_ON(max_tr.entries != global_trace.entries);
#endif
/* Allocate the first page for all buffers */
for_each_tracing_cpu(i) {
data = global_trace.data[i] = &per_cpu(global_trace_cpu, i);
max_tr.data[i] = &per_cpu(max_data, i);
}
trace_init_cmdlines();
register_tracer(&nop_trace);
#ifdef CONFIG_BOOT_TRACER
register_tracer(&boot_tracer);
current_trace = &boot_tracer;
current_trace->init(&global_trace);
#else
current_trace = &nop_trace;
#endif
/* All seems OK, enable tracing */
tracing_disabled = 0;
atomic_notifier_chain_register(&panic_notifier_list,
&trace_panic_notifier);
register_die_notifier(&trace_die_notifier);
ret = 0;
out_free_cpumask:
free_cpumask_var(tracing_cpumask);
out_free_buffer_mask:
free_cpumask_var(tracing_buffer_mask);
out:
return ret;
}
early_initcall(tracer_alloc_buffers);
fs_initcall(tracer_init_debugfs);
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