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kernel-fxtec-pro1x/kernel/trace/trace.c
Steven Rostedt 77ae365eca ring-buffer: make lockless 
This patch converts the ring buffers into a completely lockless
buffer recording system. The read side still takes locks since
we still serialize readers. But the writers are the ones that
must be lockless (those can happen in NMIs).

The main change is to the "head_page" pointer. We write to the
tail, and read from the head. The "head_page" pointer in the cpu
buffer is now just a reference to where to look. The real head
page is now kept in the head_page->list->prev->next pointer.
That is, in the list head of the previous page we set flags.

The list pages are allocated to be aligned such that the lowest
significant bits are always zero pointing to the list. This gives
us play to put in flags to their pointers.

bit 0: set when the page is a head page
bit 1: set when the writer is moving the page (for overwrite mode)

cmpxchg is used to update the pointer.

When the writer wraps the buffer and the tail meets the head,
in overwrite mode, the writer must move the head page forward.
It first uses cmpxchg to change the pointer flag from 1 to 2.
Once this is done, the reader on another CPU will not take the
page from the buffer.

The writers need to protect against interrupts (we don't bother with
disabling interrupts because NMIs are allowed to write too).

After the writer sets the pointer flag to 2, it takes care to
manage interrupts coming in. This is discribed in detail within the
comments of the code.

 Changes in version 2:
  - Let reader reset entries value of header page.
  - Fix tail page passing commit page on reader page test.
  - Always increment entries and write counter in rb_tail_page_update
  - Add safety check in rb_set_commit_to_write to break out of infinite loop
  - add mask in rb_is_reader_page

[ Impact: lock free writing to the ring buffer ]

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-07-07 18:36:12 -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 <linux/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/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/gfp.h>
#include <linux/fs.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;
/*
* 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;
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 which cpu buffers are currently read in trace_pipe */
static cpumask_var_t tracing_reader_cpumask;
#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(const char *buf);
#define BOOTUP_TRACER_SIZE 100
static char bootup_tracer_buf[BOOTUP_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;
static int __init set_ftrace(char *str)
{
strncpy(bootup_tracer_buf, str, BOOTUP_TRACER_SIZE);
default_bootup_tracer = bootup_tracer_buf;
/* We are using ftrace early, expand it */
ring_buffer_expanded = 1;
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);
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 ftrace_event_call *call, void *rec,
struct ring_buffer_event *event)
{
return filter_check_discard(call, rec, global_trace.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_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_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
TRACE_ITER_GRAPH_TIME;
/**
* 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;
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);
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",
"trace_printk",
"ftrace_preempt",
"branch",
"annotate",
"userstacktrace",
"sym-userobj",
"printk-msg-only",
"context-info",
"latency-format",
"global-clock",
"sleep-time",
"graph-time",
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 /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];
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(tsk);
}
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;
}
/**
* 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 && ret != -EAGAIN);
__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)
__releases(kernel_lock)
__acquires(kernel_lock)
{
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;
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;
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);
if (ret || !default_bootup_tracer)
goto out_unlock;
if (strncmp(default_bootup_tracer, type->name, BOOTUP_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:
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 (type == current_trace && tracer_enabled) {
tracer_enabled = 0;
tracing_stop();
if (current_trace->stop)
current_trace->stop(&global_trace);
current_trace = &nop_trace;
}
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);
}
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 raw_spinlock_t trace_cmdline_lock = __RAW_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;
}
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) {
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 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 (!__raw_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);
__raw_spin_unlock(&trace_cmdline_lock);
}
void trace_find_cmdline(int pid, char comm[])
{
unsigned map;
if (!pid) {
strcpy(comm, "<idle>");
return;
}
if (pid > PID_MAX_DEFAULT) {
strcpy(comm, "<...>");
return;
}
preempt_disable();
__raw_spin_lock(&trace_cmdline_lock);
map = map_pid_to_cmdline[pid];
if (map != NO_CMDLINE_MAP)
strcpy(comm, saved_cmdlines[map]);
else
strcpy(comm, "<...>");
__raw_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->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);
}
struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
int type,
unsigned long len,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
event = ring_buffer_lock_reserve(tr->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 void ftrace_trace_stack(struct trace_array *tr,
unsigned long flags, int skip, int pc);
static void ftrace_trace_userstack(struct trace_array *tr,
unsigned long flags, int pc);
static inline void __trace_buffer_unlock_commit(struct trace_array *tr,
struct ring_buffer_event *event,
unsigned long flags, int pc,
int wake)
{
ring_buffer_unlock_commit(tr->buffer, event);
ftrace_trace_stack(tr, flags, 6, pc);
ftrace_trace_userstack(tr, flags, pc);
if (wake)
trace_wake_up();
}
void trace_buffer_unlock_commit(struct trace_array *tr,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(tr, event, flags, pc, 1);
}
struct ring_buffer_event *
trace_current_buffer_lock_reserve(int type, unsigned long len,
unsigned long flags, int pc)
{
return trace_buffer_lock_reserve(&global_trace,
type, len, flags, pc);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
void trace_current_buffer_unlock_commit(struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(&global_trace, event, flags, pc, 1);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
void trace_nowake_buffer_unlock_commit(struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(&global_trace, event, flags, pc, 0);
}
EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
void trace_current_buffer_discard_commit(struct ring_buffer_event *event)
{
ring_buffer_discard_commit(global_trace.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_event *event;
struct ftrace_entry *entry;
/* If we are reading the ring buffer, don't trace */
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return;
event = trace_buffer_lock_reserve(tr, 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, tr->buffer, event))
ring_buffer_unlock_commit(tr->buffer, event);
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int __trace_graph_entry(struct trace_array *tr,
struct ftrace_graph_ent *trace,
unsigned long flags,
int pc)
{
struct ftrace_event_call *call = &event_funcgraph_entry;
struct ring_buffer_event *event;
struct ftrace_graph_ent_entry *entry;
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return 0;
event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_ENT,
sizeof(*entry), flags, pc);
if (!event)
return 0;
entry = ring_buffer_event_data(event);
entry->graph_ent = *trace;
if (!filter_current_check_discard(call, entry, event))
ring_buffer_unlock_commit(global_trace.buffer, event);
return 1;
}
static void __trace_graph_return(struct trace_array *tr,
struct ftrace_graph_ret *trace,
unsigned long flags,
int pc)
{
struct ftrace_event_call *call = &event_funcgraph_exit;
struct ring_buffer_event *event;
struct ftrace_graph_ret_entry *entry;
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return;
event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_RET,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->ret = *trace;
if (!filter_current_check_discard(call, entry, event))
ring_buffer_unlock_commit(global_trace.buffer, event);
}
#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, ip, parent_ip, flags, pc);
}
static void __ftrace_trace_stack(struct trace_array *tr,
unsigned long flags,
int skip, int pc)
{
#ifdef CONFIG_STACKTRACE
struct ftrace_event_call *call = &event_kernel_stack;
struct ring_buffer_event *event;
struct stack_entry *entry;
struct stack_trace trace;
event = trace_buffer_lock_reserve(tr, TRACE_STACK,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
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);
if (!filter_check_discard(call, entry, tr->buffer, event))
ring_buffer_unlock_commit(tr->buffer, event);
#endif
}
static void ftrace_trace_stack(struct trace_array *tr,
unsigned long flags,
int skip, int pc)
{
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
__ftrace_trace_stack(tr, flags, skip, pc);
}
void __trace_stack(struct trace_array *tr,
unsigned long flags,
int skip, int pc)
{
__ftrace_trace_stack(tr, flags, skip, pc);
}
static void ftrace_trace_userstack(struct trace_array *tr,
unsigned long flags, int pc)
{
#ifdef CONFIG_STACKTRACE
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;
event = trace_buffer_lock_reserve(tr, TRACE_USER_STACK,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
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, tr->buffer, event))
ring_buffer_unlock_commit(tr->buffer, event);
#endif
}
#ifdef UNUSED
static void __trace_userstack(struct trace_array *tr, unsigned long flags)
{
ftrace_trace_userstack(tr, flags, preempt_count());
}
#endif /* UNUSED */
static void
ftrace_trace_special(void *__tr,
unsigned long arg1, unsigned long arg2, unsigned long arg3,
int pc)
{
struct ring_buffer_event *event;
struct trace_array *tr = __tr;
struct special_entry *entry;
event = trace_buffer_lock_reserve(tr, TRACE_SPECIAL,
sizeof(*entry), 0, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->arg1 = arg1;
entry->arg2 = arg2;
entry->arg3 = arg3;
trace_buffer_unlock_commit(tr, event, 0, pc);
}
void
__trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
}
void
tracing_sched_switch_trace(struct trace_array *tr,
struct task_struct *prev,
struct task_struct *next,
unsigned long flags, int pc)
{
struct ftrace_event_call *call = &event_context_switch;
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
event = trace_buffer_lock_reserve(tr, TRACE_CTX,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
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);
if (!filter_check_discard(call, entry, tr->buffer, event))
trace_buffer_unlock_commit(tr, event, flags, pc);
}
void
tracing_sched_wakeup_trace(struct trace_array *tr,
struct task_struct *wakee,
struct task_struct *curr,
unsigned long flags, int pc)
{
struct ftrace_event_call *call = &event_wakeup;
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
event = trace_buffer_lock_reserve(tr, TRACE_WAKE,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
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);
if (!filter_check_discard(call, entry, tr->buffer, event))
ring_buffer_unlock_commit(tr->buffer, event);
ftrace_trace_stack(tr, flags, 6, pc);
ftrace_trace_userstack(tr, flags, pc);
}
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, 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 ret;
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();
ret = __trace_graph_entry(tr, trace, flags, pc);
} else {
ret = 0;
}
/* 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 ret;
}
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, trace, flags, pc);
}
if (!trace->depth)
clear_tsk_trace_graph(current);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
/**
* trace_vbprintk - write binary msg to tracing buffer
*
*/
int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
{
static raw_spinlock_t trace_buf_lock =
(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
static u32 trace_buf[TRACE_BUF_SIZE];
struct ftrace_event_call *call = &event_bprint;
struct ring_buffer_event *event;
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
struct bprint_entry *entry;
unsigned long flags;
int disable;
int resched;
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();
resched = ftrace_preempt_disable();
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);
__raw_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;
event = trace_buffer_lock_reserve(tr, 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, tr->buffer, event))
ring_buffer_unlock_commit(tr->buffer, event);
out_unlock:
__raw_spin_unlock(&trace_buf_lock);
local_irq_restore(flags);
out:
atomic_dec_return(&data->disabled);
ftrace_preempt_enable(resched);
unpause_graph_tracing();
return len;
}
EXPORT_SYMBOL_GPL(trace_vbprintk);
int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
{
static raw_spinlock_t trace_buf_lock = __RAW_SPIN_LOCK_UNLOCKED;
static char trace_buf[TRACE_BUF_SIZE];
struct ftrace_event_call *call = &event_print;
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;
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);
__raw_spin_lock(&trace_buf_lock);
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 = trace_buffer_lock_reserve(tr, 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, tr->buffer, event))
ring_buffer_unlock_commit(tr->buffer, event);
out_unlock:
__raw_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;
}
EXPORT_SYMBOL_GPL(trace_vprintk);
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;
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);
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);
/*
* 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 */
struct trace_entry *trace_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;
}
/*
* No necessary locking here. The worst thing which can
* happen is loosing events consumed at the same time
* by a trace_pipe reader.
* Other than that, we don't risk to crash the ring buffer
* because it serializes the readers.
*
* 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)
ring_buffer_iter_reset(iter->buffer_iter[cpu]);
} else
ring_buffer_iter_reset(iter->buffer_iter[cpu_file]);
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);
}
trace_event_read_lock();
return p;
}
static void s_stop(struct seq_file *m, void *p)
{
atomic_dec(&trace_record_cmdline_disabled);
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, "# |||| / \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 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);
/* 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->trace(iter, sym_flags);
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->raw(iter, 0);
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->hex(iter, 0);
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->binary(iter, 0) : TRACE_TYPE_HANDLED;
}
static 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. */
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_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);
}
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)
{
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 (!alloc_cpumask_var(&iter->started, GFP_KERNEL))
goto fail;
cpumask_clear(iter->started);
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;
if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
for_each_tracing_cpu(cpu) {
iter->buffer_iter[cpu] =
ring_buffer_read_start(iter->tr->buffer, cpu);
}
} else {
cpu = iter->cpu_file;
iter->buffer_iter[cpu] =
ring_buffer_read_start(iter->tr->buffer, cpu);
}
/* TODO stop tracer */
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;
/* stop the trace while dumping */
tracing_stop();
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);
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 = (struct seq_file *)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_APPEND)) {
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 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 const struct file_operations tracing_fops = {
.open = tracing_open,
.read = seq_read,
.write = tracing_write_stub,
.llseek = seq_lseek,
.release = tracing_release,
};
static const 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;
err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
if (err)
goto err_unlock;
mutex_lock(&tracing_cpumask_update_lock);
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:
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,
};
static ssize_t
tracing_trace_options_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct tracer_opt *trace_opts;
u32 tracer_flags;
int len = 0;
char *buf;
int r = 0;
int i;
/* calculate max size */
for (i = 0; trace_options[i]; i++) {
len += strlen(trace_options[i]);
len += 3; /* "no" and newline */
}
mutex_lock(&trace_types_lock);
tracer_flags = current_trace->flags->val;
trace_opts = current_trace->flags->opts;
/*
* 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 newline */
}
/* +2 for \n and \0 */
buf = kmalloc(len + 2, GFP_KERNEL);
if (!buf) {
mutex_unlock(&trace_types_lock);
return -ENOMEM;
}
for (i = 0; trace_options[i]; i++) {
if (trace_flags & (1 << i))
r += sprintf(buf + r, "%s\n", trace_options[i]);
else
r += sprintf(buf + r, "no%s\n", trace_options[i]);
}
for (i = 0; trace_opts[i].name; i++) {
if (tracer_flags & trace_opts[i].bit)
r += sprintf(buf + r, "%s\n",
trace_opts[i].name);
else
r += sprintf(buf + r, "no%s\n",
trace_opts[i].name);
}
mutex_unlock(&trace_types_lock);
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 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_GLOBAL_CLK) {
u64 (*func)(void);
if (enabled)
func = trace_clock_global;
else
func = trace_clock_local;
mutex_lock(&trace_types_lock);
ring_buffer_set_clock(global_trace.buffer, func);
if (max_tr.buffer)
ring_buffer_set_clock(max_tr.buffer, func);
mutex_unlock(&trace_types_lock);
}
}
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) {
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;
}
filp->f_pos += cnt;
return cnt;
}
static const 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"
"# 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,
};
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,
};
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];
unsigned 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);
}
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;
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;
}
global_trace.entries = size;
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);
destroy_trace_option_files(topts);
current_trace = t;
topts = create_trace_option_files(current_trace);
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_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)
{
unsigned long *ptr = filp->private_data;
char buf[64];
unsigned 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 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);
/* We only allow one reader per cpu */
if (cpu_file == TRACE_PIPE_ALL_CPU) {
if (!cpumask_empty(tracing_reader_cpumask)) {
ret = -EBUSY;
goto out;
}
cpumask_setall(tracing_reader_cpumask);
} else {
if (!cpumask_test_cpu(cpu_file, tracing_reader_cpumask))
cpumask_set_cpu(cpu_file, tracing_reader_cpumask);
else {
ret = -EBUSY;
goto out;
}
}
/* 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);
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->cpu_file == TRACE_PIPE_ALL_CPU)
cpumask_clear(tracing_reader_cpumask);
else
cpumask_clear_cpu(iter->cpu_file, tracing_reader_cpumask);
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();
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;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
if (iter->seq.len >= cnt)
break;
}
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, inspite 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 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;
}
trace_consume(iter);
rem -= count;
if (!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[PIPE_BUFFERS];
struct partial_page partial[PIPE_BUFFERS];
struct trace_iterator *iter = filp->private_data;
struct splice_pipe_desc spd = {
.pages = pages,
.partial = partial,
.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;
/* 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 && !find_next_entry_inc(iter)) {
ret = -EFAULT;
goto out_err;
}
trace_event_read_lock();
/* Fill as many pages as possible. */
for (i = 0, rem = len; i < PIPE_BUFFERS && rem; i++) {
pages[i] = alloc_page(GFP_KERNEL);
if (!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(pages[i]),
iter->seq.len);
if (ret < 0) {
__free_page(pages[i]);
break;
}
partial[i].offset = 0;
partial[i].len = iter->seq.len;
trace_seq_init(&iter->seq);
}
trace_event_read_unlock();
mutex_unlock(&iter->mutex);
spd.nr_pages = i;
return splice_to_pipe(pipe, &spd);
out_err:
mutex_unlock(&iter->mutex);
return ret;
}
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;
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 = tracing_resize_ring_buffer(val);
if (ret < 0) {
cnt = ret;
goto out;
}
}
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, 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 const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
.write = tracing_max_lat_write,
};
static const struct file_operations tracing_ctrl_fops = {
.open = tracing_open_generic,
.read = tracing_ctrl_read,
.write = tracing_ctrl_write,
};
static const struct file_operations set_tracer_fops = {
.open = tracing_open_generic,
.read = tracing_set_trace_read,
.write = tracing_set_trace_write,
};
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,
};
static const struct file_operations tracing_entries_fops = {
.open = tracing_open_generic,
.read = tracing_entries_read,
.write = tracing_entries_write,
};
static const struct file_operations tracing_mark_fops = {
.open = tracing_open_generic,
.write = tracing_mark_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;
unsigned int pos;
ssize_t ret;
size_t size;
if (!count)
return 0;
if (!info->spare)
info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
if (!info->spare)
return -ENOMEM;
/* Do we have previous read data to read? */
if (info->read < PAGE_SIZE)
goto read;
info->read = 0;
ret = ring_buffer_read_page(info->tr->buffer,
&info->spare,
count,
info->cpu, 0);
if (ret < 0)
return 0;
pos = ring_buffer_page_len(info->spare);
if (pos < PAGE_SIZE)
memset(info->spare + pos, 0, PAGE_SIZE - pos);
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 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[PIPE_BUFFERS];
struct page *pages[PIPE_BUFFERS];
struct splice_pipe_desc spd = {
.pages = pages,
.partial = partial,
.flags = flags,
.ops = &buffer_pipe_buf_ops,
.spd_release = buffer_spd_release,
};
struct buffer_ref *ref;
int entries, size, i;
size_t ret;
if (*ppos & (PAGE_SIZE - 1)) {
WARN_ONCE(1, "Ftrace: previous read must page-align\n");
return -EINVAL;
}
if (len & (PAGE_SIZE - 1)) {
WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
if (len < PAGE_SIZE)
return -EINVAL;
len &= PAGE_MASK;
}
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);
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);
}
spd.nr_pages = i;
/* did we read anything? */
if (!spd.nr_pages) {
if (flags & SPLICE_F_NONBLOCK)
ret = -EAGAIN;
else
ret = 0;
/* TODO: block */
return ret;
}
ret = splice_to_pipe(pipe, &spd);
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,
};
#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,
};
#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;
/* strlen(cpu) + MAX(log10(cpu)) + '\0' */
char cpu_dir[7];
if (cpu > 999 || cpu < 0)
return;
sprintf(cpu_dir, "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;
char buf[64];
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;
ret = 0;
switch (val) {
case 0:
/* do nothing if already cleared */
if (!(topt->flags->val & topt->opt->bit))
break;
mutex_lock(&trace_types_lock);
if (current_trace->set_flag)
ret = current_trace->set_flag(topt->flags->val,
topt->opt->bit, 0);
mutex_unlock(&trace_types_lock);
if (ret)
return ret;
topt->flags->val &= ~topt->opt->bit;
break;
case 1:
/* do nothing if already set */
if (topt->flags->val & topt->opt->bit)
break;
mutex_lock(&trace_types_lock);
if (current_trace->set_flag)
ret = current_trace->set_flag(topt->flags->val,
topt->opt->bit, 1);
mutex_unlock(&trace_types_lock);
if (ret)
return ret;
topt->flags->val |= topt->opt->bit;
break;
default:
return -EINVAL;
}
*ppos += cnt;
return cnt;
}
static const struct file_operations trace_options_fops = {
.open = tracing_open_generic,
.read = trace_options_read,
.write = trace_options_write,
};
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;
char buf[64];
unsigned 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;
switch (val) {
case 0:
trace_flags &= ~(1 << index);
break;
case 1:
trace_flags |= 1 << index;
break;
default:
return -EINVAL;
}
*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,
};
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;
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);
trace_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency, &tracing_max_lat_fops);
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("trace_marker", 0220, d_tracer,
NULL, &tracing_mark_fops);
trace_create_file("saved_cmdlines", 0444, d_tracer,
NULL, &tracing_saved_cmdlines_fops);
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
#endif
#ifdef CONFIG_SYSPROF_TRACER
init_tracer_sysprof_debugfs(d_tracer);
#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();
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_init(s);
}
static void __ftrace_dump(bool disable_tracing)
{
static raw_spinlock_t ftrace_dump_lock =
(raw_spinlock_t)__RAW_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);
__raw_spin_lock(&ftrace_dump_lock);
if (dump_ran)
goto out;
dump_ran = 1;
tracing_off();
if (disable_tracing)
ftrace_kill();
for_each_tracing_cpu(cpu) {
atomic_inc(&global_trace.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;
printk(KERN_TRACE "Dumping ftrace buffer:\n");
/* Simulate the iterator */
iter.tr = &global_trace;
iter.trace = current_trace;
iter.cpu_file = TRACE_PIPE_ALL_CPU;
/*
* 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");
/* Re-enable tracing if requested */
if (!disable_tracing) {
trace_flags |= old_userobj;
for_each_tracing_cpu(cpu) {
atomic_dec(&global_trace.data[cpu]->disabled);
}
tracing_on();
}
out:
__raw_spin_unlock(&ftrace_dump_lock);
local_irq_restore(flags);
}
/* By default: disable tracing after the dump */
void ftrace_dump(void)
{
__ftrace_dump(true);
}
__init static int tracer_alloc_buffers(void)
{
struct trace_array_cpu *data;
int ring_buf_size;
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;
if (!alloc_cpumask_var(&tracing_reader_cpumask, GFP_KERNEL))
goto out_free_tracing_cpumask;
/* 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;
cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
cpumask_copy(tracing_cpumask, cpu_all_mask);
cpumask_clear(tracing_reader_cpumask);
/* TODO: make the number of buffers hot pluggable with CPUS */
global_trace.buffer = ring_buffer_alloc(ring_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(ring_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);
current_trace = &nop_trace;
#ifdef CONFIG_BOOT_TRACER
register_tracer(&boot_tracer);
#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);
return 0;
out_free_cpumask:
free_cpumask_var(tracing_reader_cpumask);
out_free_tracing_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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