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91e86e560d
linux/kernel/trace/trace.c
Steven Rostedt 91e86e560d tracing: Fix recursive user stack trace 
The user stack trace can fault when examining the trace. Which
would call the do_page_fault handler, which would trace again,
which would do the user stack trace, which would fault and call
do_page_fault again ...

Thus this is causing a recursive bug. We need to have a recursion
detector here.

[ Resubmitted by Jiri Olsa ]

[ Eric Dumazet recommended using __this_cpu_* instead of __get_cpu_* ]

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
LKML-Reference: <1289390172-9730-3-git-send-email-jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2010-11-12 21:20:08 -05:00

4639 lines
103 KiB
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/*
* ring buffer based function tracer
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
* Originally taken from the RT patch by:
* Arnaldo Carvalho de Melo <acme@redhat.com>
*
* Based on code from the latency_tracer, that is:
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
#include <linux/ring_buffer.h>
#include <generated/utsrelease.h>
#include <linux/stacktrace.h>
#include <linux/writeback.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/smp_lock.h>
#include <linux/notifier.h>
#include <linux/irqflags.h>
#include <linux/debugfs.h>
#include <linux/pagemap.h>
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/splice.h>
#include <linux/kdebug.h>
#include <linux/string.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/fs.h>
#include "trace.h"
#include "trace_output.h"
#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE)
/*
* On boot up, the ring buffer is set to the minimum size, so that
* we do not waste memory on systems that are not using tracing.
*/
int ring_buffer_expanded;
/*
* We need to change this state when a selftest is running.
* A selftest will lurk into the ring-buffer to count the
* entries inserted during the selftest although some concurrent
* insertions into the ring-buffer such as trace_printk could occurred
* at the same time, giving false positive or negative results.
*/
static bool __read_mostly tracing_selftest_running;
/*
* If a tracer is running, we do not want to run SELFTEST.
*/
bool __read_mostly tracing_selftest_disabled;
/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
{ }
};
static struct tracer_flags dummy_tracer_flags = {
.val = 0,
.opts = dummy_tracer_opt
};
static int dummy_set_flag(u32 old_flags, u32 bit, int set)
{
return 0;
}
/*
* Kill all tracing for good (never come back).
* It is initialized to 1 but will turn to zero if the initialization
* of the tracer is successful. But that is the only place that sets
* this back to zero.
*/
static int tracing_disabled = 1;
DEFINE_PER_CPU(int, ftrace_cpu_disabled);
static inline void ftrace_disable_cpu(void)
{
preempt_disable();
__this_cpu_inc(ftrace_cpu_disabled);
}
static inline void ftrace_enable_cpu(void)
{
__this_cpu_dec(ftrace_cpu_disabled);
preempt_enable();
}
cpumask_var_t __read_mostly tracing_buffer_mask;
/*
* ftrace_dump_on_oops - variable to dump ftrace buffer on oops
*
* If there is an oops (or kernel panic) and the ftrace_dump_on_oops
* is set, then ftrace_dump is called. This will output the contents
* of the ftrace buffers to the console. This is very useful for
* capturing traces that lead to crashes and outputing it to a
* serial console.
*
* It is default off, but you can enable it with either specifying
* "ftrace_dump_on_oops" in the kernel command line, or setting
* /proc/sys/kernel/ftrace_dump_on_oops
* Set 1 if you want to dump buffers of all CPUs
* Set 2 if you want to dump the buffer of the CPU that triggered oops
*/
enum ftrace_dump_mode ftrace_dump_on_oops;
static int tracing_set_tracer(const char *buf);
#define MAX_TRACER_SIZE 100
static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;
static int __init set_cmdline_ftrace(char *str)
{
strncpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
default_bootup_tracer = bootup_tracer_buf;
/* We are using ftrace early, expand it */
ring_buffer_expanded = 1;
return 1;
}
__setup("ftrace=", set_cmdline_ftrace);
static int __init set_ftrace_dump_on_oops(char *str)
{
if (*str++ != '=' || !*str) {
ftrace_dump_on_oops = DUMP_ALL;
return 1;
}
if (!strcmp("orig_cpu", str)) {
ftrace_dump_on_oops = DUMP_ORIG;
return 1;
}
return 0;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
unsigned long long ns2usecs(cycle_t nsec)
{
nsec += 500;
do_div(nsec, 1000);
return nsec;
}
/*
* The global_trace is the descriptor that holds the tracing
* buffers for the live tracing. For each CPU, it contains
* a link list of pages that will store trace entries. The
* page descriptor of the pages in the memory is used to hold
* the link list by linking the lru item in the page descriptor
* to each of the pages in the buffer per CPU.
*
* For each active CPU there is a data field that holds the
* pages for the buffer for that CPU. Each CPU has the same number
* of pages allocated for its buffer.
*/
static struct trace_array global_trace;
static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
int filter_current_check_discard(struct ring_buffer *buffer,
struct ftrace_event_call *call, void *rec,
struct ring_buffer_event *event)
{
return filter_check_discard(call, rec, buffer, event);
}
EXPORT_SYMBOL_GPL(filter_current_check_discard);
cycle_t ftrace_now(int cpu)
{
u64 ts;
/* Early boot up does not have a buffer yet */
if (!global_trace.buffer)
return trace_clock_local();
ts = ring_buffer_time_stamp(global_trace.buffer, cpu);
ring_buffer_normalize_time_stamp(global_trace.buffer, cpu, &ts);
return ts;
}
/*
* The max_tr is used to snapshot the global_trace when a maximum
* latency is reached. Some tracers will use this to store a maximum
* trace while it continues examining live traces.
*
* The buffers for the max_tr are set up the same as the global_trace.
* When a snapshot is taken, the link list of the max_tr is swapped
* with the link list of the global_trace and the buffers are reset for
* the global_trace so the tracing can continue.
*/
static struct trace_array max_tr;
static DEFINE_PER_CPU(struct trace_array_cpu, max_tr_data);
/* tracer_enabled is used to toggle activation of a tracer */
static int tracer_enabled = 1;
/**
* tracing_is_enabled - return tracer_enabled status
*
* This function is used by other tracers to know the status
* of the tracer_enabled flag. Tracers may use this function
* to know if it should enable their features when starting
* up. See irqsoff tracer for an example (start_irqsoff_tracer).
*/
int tracing_is_enabled(void)
{
return tracer_enabled;
}
/*
* trace_buf_size is the size in bytes that is allocated
* for a buffer. Note, the number of bytes is always rounded
* to page size.
*
* This number is purposely set to a low number of 16384.
* If the dump on oops happens, it will be much appreciated
* to not have to wait for all that output. Anyway this can be
* boot time and run time configurable.
*/
#define TRACE_BUF_SIZE_DEFAULT 1441792UL /* 16384 * 88 (sizeof(entry)) */
static unsigned long trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
/* trace_types holds a link list of available tracers. */
static struct tracer *trace_types __read_mostly;
/* current_trace points to the tracer that is currently active */
static struct tracer *current_trace __read_mostly;
/*
* trace_types_lock is used to protect the trace_types list.
*/
static DEFINE_MUTEX(trace_types_lock);
/*
* serialize the access of the ring buffer
*
* ring buffer serializes readers, but it is low level protection.
* The validity of the events (which returns by ring_buffer_peek() ..etc)
* are not protected by ring buffer.
*
* The content of events may become garbage if we allow other process consumes
* these events concurrently:
* A) the page of the consumed events may become a normal page
* (not reader page) in ring buffer, and this page will be rewrited
* by events producer.
* B) The page of the consumed events may become a page for splice_read,
* and this page will be returned to system.
*
* These primitives allow multi process access to different cpu ring buffer
* concurrently.
*
* These primitives don't distinguish read-only and read-consume access.
* Multi read-only access are also serialized.
*/
#ifdef CONFIG_SMP
static DECLARE_RWSEM(all_cpu_access_lock);
static DEFINE_PER_CPU(struct mutex, cpu_access_lock);
static inline void trace_access_lock(int cpu)
{
if (cpu == TRACE_PIPE_ALL_CPU) {
/* gain it for accessing the whole ring buffer. */
down_write(&all_cpu_access_lock);
} else {
/* gain it for accessing a cpu ring buffer. */
/* Firstly block other trace_access_lock(TRACE_PIPE_ALL_CPU). */
down_read(&all_cpu_access_lock);
/* Secondly block other access to this @cpu ring buffer. */
mutex_lock(&per_cpu(cpu_access_lock, cpu));
}
}
static inline void trace_access_unlock(int cpu)
{
if (cpu == TRACE_PIPE_ALL_CPU) {
up_write(&all_cpu_access_lock);
} else {
mutex_unlock(&per_cpu(cpu_access_lock, cpu));
up_read(&all_cpu_access_lock);
}
}
static inline void trace_access_lock_init(void)
{
int cpu;
for_each_possible_cpu(cpu)
mutex_init(&per_cpu(cpu_access_lock, cpu));
}
#else
static DEFINE_MUTEX(access_lock);
static inline void trace_access_lock(int cpu)
{
(void)cpu;
mutex_lock(&access_lock);
}
static inline void trace_access_unlock(int cpu)
{
(void)cpu;
mutex_unlock(&access_lock);
}
static inline void trace_access_lock_init(void)
{
}
#endif
/* trace_wait is a waitqueue for tasks blocked on trace_poll */
static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
/* trace_flags holds trace_options default values */
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD;
static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);
/**
* 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)
{
int cpu;
if (trace_flags & TRACE_ITER_BLOCK)
return;
/*
* The runqueue_is_locked() can fail, but this is the best we
* have for now:
*/
cpu = get_cpu();
if (!runqueue_is_locked(cpu))
wake_up(&trace_wait);
put_cpu();
}
static int __init set_buf_size(char *str)
{
unsigned long buf_size;
if (!str)
return 0;
buf_size = memparse(str, &str);
/* nr_entries can not be zero */
if (buf_size == 0)
return 0;
trace_buf_size = buf_size;
return 1;
}
__setup("trace_buf_size=", set_buf_size);
static int __init set_tracing_thresh(char *str)
{
unsigned long threshhold;
int ret;
if (!str)
return 0;
ret = strict_strtoul(str, 0, &threshhold);
if (ret < 0)
return 0;
tracing_thresh = threshhold * 1000;
return 1;
}
__setup("tracing_thresh=", set_tracing_thresh);
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
return nsecs / 1000;
}
/* These must match the bit postions in trace_iterator_flags */
static const char *trace_options[] = {
"print-parent",
"sym-offset",
"sym-addr",
"verbose",
"raw",
"hex",
"bin",
"block",
"stacktrace",
"trace_printk",
"ftrace_preempt",
"branch",
"annotate",
"userstacktrace",
"sym-userobj",
"printk-msg-only",
"context-info",
"latency-format",
"sleep-time",
"graph-time",
"record-cmd",
NULL
};
static struct {
u64 (*func)(void);
const char *name;
} trace_clocks[] = {
{ trace_clock_local, "local" },
{ trace_clock_global, "global" },
};
int trace_clock_id;
/*
* trace_parser_get_init - gets the buffer for trace parser
*/
int trace_parser_get_init(struct trace_parser *parser, int size)
{
memset(parser, 0, sizeof(*parser));
parser->buffer = kmalloc(size, GFP_KERNEL);
if (!parser->buffer)
return 1;
parser->size = size;
return 0;
}
/*
* trace_parser_put - frees the buffer for trace parser
*/
void trace_parser_put(struct trace_parser *parser)
{
kfree(parser->buffer);
}
/*
* trace_get_user - reads the user input string separated by space
* (matched by isspace(ch))
*
* For each string found the 'struct trace_parser' is updated,
* and the function returns.
*
* Returns number of bytes read.
*
* See kernel/trace/trace.h for 'struct trace_parser' details.
*/
int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char ch;
size_t read = 0;
ssize_t ret;
if (!*ppos)
trace_parser_clear(parser);
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
/*
* The parser is not finished with the last write,
* continue reading the user input without skipping spaces.
*/
if (!parser->cont) {
/* skip white space */
while (cnt && isspace(ch)) {
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
/* only spaces were written */
if (isspace(ch)) {
*ppos += read;
ret = read;
goto out;
}
parser->idx = 0;
}
/* read the non-space input */
while (cnt && !isspace(ch)) {
if (parser->idx < parser->size - 1)
parser->buffer[parser->idx++] = ch;
else {
ret = -EINVAL;
goto out;
}
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
/* We either got finished input or we have to wait for another call. */
if (isspace(ch)) {
parser->buffer[parser->idx] = 0;
parser->cont = false;
} else {
parser->cont = true;
parser->buffer[parser->idx++] = ch;
}
*ppos += read;
ret = read;
out:
return ret;
}
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
int len;
int ret;
if (!cnt)
return 0;
if (s->len <= s->readpos)
return -EBUSY;
len = s->len - s->readpos;
if (cnt > len)
cnt = len;
ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
if (ret == cnt)
return -EFAULT;
cnt -= ret;
s->readpos += cnt;
return cnt;
}
static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
void *ret;
if (s->len <= s->readpos)
return -EBUSY;
len = s->len - s->readpos;
if (cnt > len)
cnt = len;
ret = memcpy(buf, s->buffer + s->readpos, cnt);
if (!ret)
return -EFAULT;
s->readpos += cnt;
return cnt;
}
/*
* ftrace_max_lock is used to protect the swapping of buffers
* when taking a max snapshot. The buffers themselves are
* protected by per_cpu spinlocks. But the action of the swap
* needs its own lock.
*
* This is defined as a arch_spinlock_t in order to help
* with performance when lockdep debugging is enabled.
*
* It is also used in other places outside the update_max_tr
* so it needs to be defined outside of the
* CONFIG_TRACER_MAX_TRACE.
*/
static arch_spinlock_t ftrace_max_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
unsigned long __read_mostly tracing_thresh;
#ifdef CONFIG_TRACER_MAX_TRACE
unsigned long __read_mostly tracing_max_latency;
/*
* Copy the new maximum trace into the separate maximum-trace
* structure. (this way the maximum trace is permanently saved,
* for later retrieval via /sys/kernel/debug/tracing/latency_trace)
*/
static void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct trace_array_cpu *data = tr->data[cpu];
struct trace_array_cpu *max_data;
max_tr.cpu = cpu;
max_tr.time_start = data->preempt_timestamp;
max_data = max_tr.data[cpu];
max_data->saved_latency = tracing_max_latency;
max_data->critical_start = data->critical_start;
max_data->critical_end = data->critical_end;
memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
max_data->pid = tsk->pid;
max_data->uid = task_uid(tsk);
max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
max_data->policy = tsk->policy;
max_data->rt_priority = tsk->rt_priority;
/* record this tasks comm */
tracing_record_cmdline(tsk);
}
/**
* update_max_tr - snapshot all trace buffers from global_trace to max_tr
* @tr: tracer
* @tsk: the task with the latency
* @cpu: The cpu that initiated the trace.
*
* Flip the buffers between the @tr and the max_tr and record information
* about which task was the cause of this latency.
*/
void
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct ring_buffer *buf = tr->buffer;
if (trace_stop_count)
return;
WARN_ON_ONCE(!irqs_disabled());
if (!current_trace->use_max_tr) {
WARN_ON_ONCE(1);
return;
}
arch_spin_lock(&ftrace_max_lock);
tr->buffer = max_tr.buffer;
max_tr.buffer = buf;
__update_max_tr(tr, tsk, cpu);
arch_spin_unlock(&ftrace_max_lock);
}
/**
* update_max_tr_single - only copy one trace over, and reset the rest
* @tr - tracer
* @tsk - task with the latency
* @cpu - the cpu of the buffer to copy.
*
* Flip the trace of a single CPU buffer between the @tr and the max_tr.
*/
void
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
int ret;
if (trace_stop_count)
return;
WARN_ON_ONCE(!irqs_disabled());
if (!current_trace->use_max_tr) {
WARN_ON_ONCE(1);
return;
}
arch_spin_lock(&ftrace_max_lock);
ftrace_disable_cpu();
ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
if (ret == -EBUSY) {
/*
* We failed to swap the buffer due to a commit taking
* place on this CPU. We fail to record, but we reset
* the max trace buffer (no one writes directly to it)
* and flag that it failed.
*/
trace_array_printk(&max_tr, _THIS_IP_,
"Failed to swap buffers due to commit in progress\n");
}
ftrace_enable_cpu();
WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
__update_max_tr(tr, tsk, cpu);
arch_spin_unlock(&ftrace_max_lock);
}
#endif /* CONFIG_TRACER_MAX_TRACE */
/**
* register_tracer - register a tracer with the ftrace system.
* @type - the plugin for the tracer
*
* Register a new plugin tracer.
*/
int register_tracer(struct tracer *type)
__releases(kernel_lock)
__acquires(kernel_lock)
{
struct tracer *t;
int ret = 0;
if (!type->name) {
pr_info("Tracer must have a name\n");
return -1;
}
if (strlen(type->name) >= MAX_TRACER_SIZE) {
pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
return -1;
}
mutex_lock(&trace_types_lock);
tracing_selftest_running = true;
for (t = trace_types; t; t = t->next) {
if (strcmp(type->name, t->name) == 0) {
/* already found */
pr_info("Tracer %s already registered\n",
type->name);
ret = -1;
goto out;
}
}
if (!type->set_flag)
type->set_flag = &dummy_set_flag;
if (!type->flags)
type->flags = &dummy_tracer_flags;
else
if (!type->flags->opts)
type->flags->opts = dummy_tracer_opt;
if (!type->wait_pipe)
type->wait_pipe = default_wait_pipe;
#ifdef CONFIG_FTRACE_STARTUP_TEST
if (type->selftest && !tracing_selftest_disabled) {
struct tracer *saved_tracer = current_trace;
struct trace_array *tr = &global_trace;
/*
* Run a selftest on this tracer.
* Here we reset the trace buffer, and set the current
* tracer to be this tracer. The tracer can then run some
* internal tracing to verify that everything is in order.
* If we fail, we do not register this tracer.
*/
tracing_reset_online_cpus(tr);
current_trace = type;
/* the test is responsible for initializing and enabling */
pr_info("Testing tracer %s: ", type->name);
ret = type->selftest(type, tr);
/* the test is responsible for resetting too */
current_trace = saved_tracer;
if (ret) {
printk(KERN_CONT "FAILED!\n");
goto out;
}
/* Only reset on passing, to avoid touching corrupted buffers */
tracing_reset_online_cpus(tr);
printk(KERN_CONT "PASSED\n");
}
#endif
type->next = trace_types;
trace_types = type;
out:
tracing_selftest_running = false;
mutex_unlock(&trace_types_lock);
if (ret || !default_bootup_tracer)
goto out_unlock;
if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
goto out_unlock;
printk(KERN_INFO "Starting tracer '%s'\n", type->name);
/* Do we want this tracer to start on bootup? */
tracing_set_tracer(type->name);
default_bootup_tracer = NULL;
/* disable other selftests, since this will break it. */
tracing_selftest_disabled = 1;
#ifdef CONFIG_FTRACE_STARTUP_TEST
printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
type->name);
#endif
out_unlock:
return ret;
}
void unregister_tracer(struct tracer *type)
{
struct tracer **t;
mutex_lock(&trace_types_lock);
for (t = &trace_types; *t; t = &(*t)->next) {
if (*t == type)
goto found;
}
pr_info("Tracer %s not registered\n", type->name);
goto out;
found:
*t = (*t)->next;
if (type == current_trace && tracer_enabled) {
tracer_enabled = 0;
tracing_stop();
if (current_trace->stop)
current_trace->stop(&global_trace);
current_trace = &nop_trace;
}
out:
mutex_unlock(&trace_types_lock);
}
static void __tracing_reset(struct ring_buffer *buffer, int cpu)
{
ftrace_disable_cpu();
ring_buffer_reset_cpu(buffer, cpu);
ftrace_enable_cpu();
}
void tracing_reset(struct trace_array *tr, int cpu)
{
struct ring_buffer *buffer = tr->buffer;
ring_buffer_record_disable(buffer);
/* Make sure all commits have finished */
synchronize_sched();
__tracing_reset(buffer, cpu);
ring_buffer_record_enable(buffer);
}
void tracing_reset_online_cpus(struct trace_array *tr)
{
struct ring_buffer *buffer = tr->buffer;
int cpu;
ring_buffer_record_disable(buffer);
/* Make sure all commits have finished */
synchronize_sched();
tr->time_start = ftrace_now(tr->cpu);
for_each_online_cpu(cpu)
__tracing_reset(buffer, cpu);
ring_buffer_record_enable(buffer);
}
void tracing_reset_current(int cpu)
{
tracing_reset(&global_trace, cpu);
}
void tracing_reset_current_online_cpus(void)
{
tracing_reset_online_cpus(&global_trace);
}
#define SAVED_CMDLINES 128
#define NO_CMDLINE_MAP UINT_MAX
static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
static int cmdline_idx;
static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
/* temporary disable recording */
static atomic_t trace_record_cmdline_disabled __read_mostly;
static void trace_init_cmdlines(void)
{
memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
cmdline_idx = 0;
}
int is_tracing_stopped(void)
{
return trace_stop_count;
}
/**
* ftrace_off_permanent - disable all ftrace code permanently
*
* This should only be called when a serious anomally has
* been detected. This will turn off the function tracing,
* ring buffers, and other tracing utilites. It takes no
* locks and can be called from any context.
*/
void ftrace_off_permanent(void)
{
tracing_disabled = 1;
ftrace_stop();
tracing_off_permanent();
}
/**
* tracing_start - quick start of the tracer
*
* If tracing is enabled but was stopped by tracing_stop,
* this will start the tracer back up.
*/
void tracing_start(void)
{
struct ring_buffer *buffer;
unsigned long flags;
if (tracing_disabled)
return;
spin_lock_irqsave(&tracing_start_lock, flags);
if (--trace_stop_count) {
if (trace_stop_count < 0) {
/* Someone screwed up their debugging */
WARN_ON_ONCE(1);
trace_stop_count = 0;
}
goto out;
}
/* Prevent the buffers from switching */
arch_spin_lock(&ftrace_max_lock);
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
arch_spin_unlock(&ftrace_max_lock);
ftrace_start();
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
/**
* tracing_stop - quick stop of the tracer
*
* Light weight way to stop tracing. Use in conjunction with
* tracing_start.
*/
void tracing_stop(void)
{
struct ring_buffer *buffer;
unsigned long flags;
ftrace_stop();
spin_lock_irqsave(&tracing_start_lock, flags);
if (trace_stop_count++)
goto out;
/* Prevent the buffers from switching */
arch_spin_lock(&ftrace_max_lock);
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
arch_spin_unlock(&ftrace_max_lock);
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
void trace_stop_cmdline_recording(void);
static void trace_save_cmdline(struct task_struct *tsk)
{
unsigned pid, idx;
if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
return;
/*
* It's not the end of the world if we don't get
* the lock, but we also don't want to spin
* nor do we want to disable interrupts,
* so if we miss here, then better luck next time.
*/
if (!arch_spin_trylock(&trace_cmdline_lock))
return;
idx = map_pid_to_cmdline[tsk->pid];
if (idx == NO_CMDLINE_MAP) {
idx = (cmdline_idx + 1) % SAVED_CMDLINES;
/*
* Check whether the cmdline buffer at idx has a pid
* mapped. We are going to overwrite that entry so we
* need to clear the map_pid_to_cmdline. Otherwise we
* would read the new comm for the old pid.
*/
pid = map_cmdline_to_pid[idx];
if (pid != NO_CMDLINE_MAP)
map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
map_cmdline_to_pid[idx] = tsk->pid;
map_pid_to_cmdline[tsk->pid] = idx;
cmdline_idx = idx;
}
memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
arch_spin_unlock(&trace_cmdline_lock);
}
void trace_find_cmdline(int pid, char comm[])
{
unsigned map;
if (!pid) {
strcpy(comm, "<idle>");
return;
}
if (WARN_ON_ONCE(pid < 0)) {
strcpy(comm, "<XXX>");
return;
}
if (pid > PID_MAX_DEFAULT) {
strcpy(comm, "<...>");
return;
}
preempt_disable();
arch_spin_lock(&trace_cmdline_lock);
map = map_pid_to_cmdline[pid];
if (map != NO_CMDLINE_MAP)
strcpy(comm, saved_cmdlines[map]);
else
strcpy(comm, "<...>");
arch_spin_unlock(&trace_cmdline_lock);
preempt_enable();
}
void tracing_record_cmdline(struct task_struct *tsk)
{
if (atomic_read(&trace_record_cmdline_disabled) || !tracer_enabled ||
!tracing_is_on())
return;
trace_save_cmdline(tsk);
}
void
tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
int pc)
{
struct task_struct *tsk = current;
entry->preempt_count = pc & 0xff;
entry->pid = (tsk) ? tsk->pid : 0;
entry->lock_depth = (tsk) ? tsk->lock_depth : 0;
entry->flags =
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
#else
TRACE_FLAG_IRQS_NOSUPPORT |
#endif
((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
}
EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
struct ring_buffer_event *
trace_buffer_lock_reserve(struct ring_buffer *buffer,
int type,
unsigned long len,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
event = ring_buffer_lock_reserve(buffer, len);
if (event != NULL) {
struct trace_entry *ent = ring_buffer_event_data(event);
tracing_generic_entry_update(ent, flags, pc);
ent->type = type;
}
return event;
}
static inline void
__trace_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc,
int wake)
{
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);
ftrace_trace_userstack(buffer, flags, pc);
if (wake)
trace_wake_up();
}
void trace_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
}
struct ring_buffer_event *
trace_current_buffer_lock_reserve(struct ring_buffer **current_rb,
int type, unsigned long len,
unsigned long flags, int pc)
{
*current_rb = global_trace.buffer;
return trace_buffer_lock_reserve(*current_rb,
type, len, flags, pc);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_lock_reserve);
void trace_current_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(buffer, event, flags, pc, 1);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_unlock_commit);
void trace_nowake_buffer_unlock_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event,
unsigned long flags, int pc)
{
__trace_buffer_unlock_commit(buffer, event, flags, pc, 0);
}
EXPORT_SYMBOL_GPL(trace_nowake_buffer_unlock_commit);
void trace_current_buffer_discard_commit(struct ring_buffer *buffer,
struct ring_buffer_event *event)
{
ring_buffer_discard_commit(buffer, event);
}
EXPORT_SYMBOL_GPL(trace_current_buffer_discard_commit);
void
trace_function(struct trace_array *tr,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
struct ftrace_event_call *call = &event_function;
struct ring_buffer *buffer = tr->buffer;
struct ring_buffer_event *event;
struct ftrace_entry *entry;
/* If we are reading the ring buffer, don't trace */
if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
return;
event = trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry),
flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->ip = ip;
entry->parent_ip = parent_ip;
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);
}
void
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
if (likely(!atomic_read(&data->disabled)))
trace_function(tr, ip, parent_ip, flags, pc);
}
#ifdef CONFIG_STACKTRACE
static void __ftrace_trace_stack(struct ring_buffer *buffer,
unsigned long flags,
int skip, int pc)
{
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(buffer, 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, buffer, event))
ring_buffer_unlock_commit(buffer, event);
}
void ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags,
int skip, int pc)
{
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
__ftrace_trace_stack(buffer, flags, skip, pc);
}
void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
int pc)
{
__ftrace_trace_stack(tr->buffer, flags, skip, pc);
}
/**
* trace_dump_stack - record a stack back trace in the trace buffer
*/
void trace_dump_stack(void)
{
unsigned long flags;
if (tracing_disabled || tracing_selftest_running)
return;
local_save_flags(flags);
/* skipping 3 traces, seems to get us at the caller of this function */
__ftrace_trace_stack(global_trace.buffer, flags, 3, preempt_count());
}
static DEFINE_PER_CPU(int, user_stack_count);
void
ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
{
struct ftrace_event_call *call = &event_user_stack;
struct ring_buffer_event *event;
struct userstack_entry *entry;
struct stack_trace trace;
if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
return;
/*
* NMIs can not handle page faults, even with fix ups.
* The save user stack can (and often does) fault.
*/
if (unlikely(in_nmi()))
return;
/*
* prevent recursion, since the user stack tracing may
* trigger other kernel events.
*/
preempt_disable();
if (__this_cpu_read(user_stack_count))
goto out;
__this_cpu_inc(user_stack_count);
event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
sizeof(*entry), flags, pc);
if (!event)
return;
entry = ring_buffer_event_data(event);
entry->tgid = current->tgid;
memset(&entry->caller, 0, sizeof(entry->caller));
trace.nr_entries = 0;
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.skip = 0;
trace.entries = entry->caller;
save_stack_trace_user(&trace);
if (!filter_check_discard(call, entry, buffer, event))
ring_buffer_unlock_commit(buffer, event);
__this_cpu_dec(user_stack_count);
out:
preempt_enable();
}
#ifdef UNUSED
static void __trace_userstack(struct trace_array *tr, unsigned long flags)
{
ftrace_trace_userstack(tr, flags, preempt_count());
}
#endif /* UNUSED */
#endif /* CONFIG_STACKTRACE */
/**
* trace_vbprintk - write binary msg to tracing buffer
*
*/
int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)
{
static arch_spinlock_t trace_buf_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
static u32 trace_buf[TRACE_BUF_SIZE];
struct ftrace_event_call *call = &event_bprint;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
struct bprint_entry *entry;
unsigned long flags;
int disable;
int cpu, len = 0, size, pc;
if (unlikely(tracing_selftest_running || tracing_disabled))
return 0;
/* Don't pollute graph traces with trace_vprintk internals */
pause_graph_tracing();
pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disable = atomic_inc_return(&data->disabled);
if (unlikely(disable != 1))
goto out;
/* Lockdep uses trace_printk for lock tracing */
local_irq_save(flags);
arch_spin_lock(&trace_buf_lock);
len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);
if (len > TRACE_BUF_SIZE || len < 0)
goto out_unlock;
size = sizeof(*entry) + sizeof(u32) * len;
buffer = tr->buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_BPRINT, size,
flags, pc);
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
entry->ip = ip;
entry->fmt = fmt;
memcpy(entry->buf, trace_buf, sizeof(u32) * len);
if (!filter_check_discard(call, entry, buffer, event)) {
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, flags, 6, pc);
}
out_unlock:
arch_spin_unlock(&trace_buf_lock);
local_irq_restore(flags);
out:
atomic_dec_return(&data->disabled);
preempt_enable_notrace();
unpause_graph_tracing();
return len;
}
EXPORT_SYMBOL_GPL(trace_vbprintk);
int trace_array_printk(struct trace_array *tr,
unsigned long ip, const char *fmt, ...)
{
int ret;
va_list ap;
if (!(trace_flags & TRACE_ITER_PRINTK))
return 0;
va_start(ap, fmt);
ret = trace_array_vprintk(tr, ip, fmt, ap);
va_end(ap);
return ret;
}
int trace_array_vprintk(struct trace_array *tr,
unsigned long ip, const char *fmt, va_list args)
{
static arch_spinlock_t trace_buf_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static char trace_buf[TRACE_BUF_SIZE];
struct ftrace_event_call *call = &event_print;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
struct trace_array_cpu *data;
int cpu, len = 0, size, pc;
struct print_entry *entry;
unsigned long irq_flags;
int disable;
if (tracing_disabled || tracing_selftest_running)
return 0;
pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disable = atomic_inc_return(&data->disabled);
if (unlikely(disable != 1))
goto out;
pause_graph_tracing();
raw_local_irq_save(irq_flags);
arch_spin_lock(&trace_buf_lock);
len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
size = sizeof(*entry) + len + 1;
buffer = tr->buffer;
event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, size,
irq_flags, pc);
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
entry->ip = ip;
memcpy(&entry->buf, trace_buf, len);
entry->buf[len] = '\0';
if (!filter_check_discard(call, entry, buffer, event)) {
ring_buffer_unlock_commit(buffer, event);
ftrace_trace_stack(buffer, irq_flags, 6, pc);
}
out_unlock:
arch_spin_unlock(&trace_buf_lock);
raw_local_irq_restore(irq_flags);
unpause_graph_tracing();
out:
atomic_dec_return(&data->disabled);
preempt_enable_notrace();
return len;
}
int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
{
return trace_array_vprintk(&global_trace, ip, fmt, args);
}
EXPORT_SYMBOL_GPL(trace_vprintk);
static void trace_iterator_increment(struct trace_iterator *iter)
{
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
iter->idx++;
if (iter->buffer_iter[iter->cpu])
ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
ftrace_enable_cpu();
}
static struct trace_entry *
peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts,
unsigned long *lost_events)
{
struct ring_buffer_event *event;
struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
if (buf_iter)
event = ring_buffer_iter_peek(buf_iter, ts);
else
event = ring_buffer_peek(iter->tr->buffer, cpu, ts,
lost_events);
ftrace_enable_cpu();
return event ? ring_buffer_event_data(event) : NULL;
}
static struct trace_entry *
__find_next_entry(struct trace_iterator *iter, int *ent_cpu,
unsigned long *missing_events, u64 *ent_ts)
{
struct ring_buffer *buffer = iter->tr->buffer;
struct trace_entry *ent, *next = NULL;
unsigned long lost_events = 0, next_lost = 0;
int cpu_file = iter->cpu_file;
u64 next_ts = 0, ts;
int next_cpu = -1;
int cpu;
/*
* If we are in a per_cpu trace file, don't bother by iterating over
* all cpu and peek directly.
*/
if (cpu_file > TRACE_PIPE_ALL_CPU) {
if (ring_buffer_empty_cpu(buffer, cpu_file))
return NULL;
ent = peek_next_entry(iter, cpu_file, ent_ts, missing_events);
if (ent_cpu)
*ent_cpu = cpu_file;
return ent;
}
for_each_tracing_cpu(cpu) {
if (ring_buffer_empty_cpu(buffer, cpu))
continue;
ent = peek_next_entry(iter, cpu, &ts, &lost_events);
/*
* Pick the entry with the smallest timestamp:
*/
if (ent && (!next || ts < next_ts)) {
next = ent;
next_cpu = cpu;
next_ts = ts;
next_lost = lost_events;
}
}
if (ent_cpu)
*ent_cpu = next_cpu;
if (ent_ts)
*ent_ts = next_ts;
if (missing_events)
*missing_events = next_lost;
return next;
}
/* Find the next real entry, without updating the iterator itself */
struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
int *ent_cpu, u64 *ent_ts)
{
return __find_next_entry(iter, ent_cpu, NULL, ent_ts);
}
/* Find the next real entry, and increment the iterator to the next entry */
void *trace_find_next_entry_inc(struct trace_iterator *iter)
{
iter->ent = __find_next_entry(iter, &iter->cpu,
&iter->lost_events, &iter->ts);
if (iter->ent)
trace_iterator_increment(iter);
return iter->ent ? iter : NULL;
}
static void trace_consume(struct trace_iterator *iter)
{
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts,
&iter->lost_events);
ftrace_enable_cpu();
}
static void *s_next(struct seq_file *m, void *v, loff_t *pos)
{
struct trace_iterator *iter = m->private;
int i = (int)*pos;
void *ent;
WARN_ON_ONCE(iter->leftover);
(*pos)++;
/* can't go backwards */
if (iter->idx > i)
return NULL;
if (iter->idx < 0)
ent = trace_find_next_entry_inc(iter);
else
ent = iter;
while (ent && iter->idx < i)
ent = trace_find_next_entry_inc(iter);
iter->pos = *pos;
return ent;
}
void tracing_iter_reset(struct trace_iterator *iter, int cpu)
{
struct trace_array *tr = iter->tr;
struct ring_buffer_event *event;
struct ring_buffer_iter *buf_iter;
unsigned long entries = 0;
u64 ts;
tr->data[cpu]->skipped_entries = 0;
if (!iter->buffer_iter[cpu])
return;
buf_iter = iter->buffer_iter[cpu];
ring_buffer_iter_reset(buf_iter);
/*
* We could have the case with the max latency tracers
* that a reset never took place on a cpu. This is evident
* by the timestamp being before the start of the buffer.
*/
while ((event = ring_buffer_iter_peek(buf_iter, &ts))) {
if (ts >= iter->tr->time_start)
break;
entries++;
ring_buffer_read(buf_iter, NULL);
}
tr->data[cpu]->skipped_entries = entries;
}
/*
* The current tracer is copied to avoid a global locking
* all around.
*/
static void *s_start(struct seq_file *m, loff_t *pos)
{
struct trace_iterator *iter = m->private;
static struct tracer *old_tracer;
int cpu_file = iter->cpu_file;
void *p = NULL;
loff_t l = 0;
int cpu;
/* copy the tracer to avoid using a global lock all around */
mutex_lock(&trace_types_lock);
if (unlikely(old_tracer != current_trace && current_trace)) {
old_tracer = current_trace;
*iter->trace = *current_trace;
}
mutex_unlock(&trace_types_lock);
atomic_inc(&trace_record_cmdline_disabled);
if (*pos != iter->pos) {
iter->ent = NULL;
iter->cpu = 0;
iter->idx = -1;
ftrace_disable_cpu();
if (cpu_file == TRACE_PIPE_ALL_CPU) {
for_each_tracing_cpu(cpu)
tracing_iter_reset(iter, cpu);
} else
tracing_iter_reset(iter, cpu_file);
ftrace_enable_cpu();
iter->leftover = 0;
for (p = iter; p && l < *pos; p = s_next(m, p, &l))
;
} else {
/*
* If we overflowed the seq_file before, then we want
* to just reuse the trace_seq buffer again.
*/
if (iter->leftover)
p = iter;
else {
l = *pos - 1;
p = s_next(m, p, &l);
}
}
trace_event_read_lock();
trace_access_lock(cpu_file);
return p;
}
static void s_stop(struct seq_file *m, void *p)
{
struct trace_iterator *iter = m->private;
atomic_dec(&trace_record_cmdline_disabled);
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
}
static void print_lat_help_header(struct seq_file *m)
{
seq_puts(m, "# _------=> CPU# \n");
seq_puts(m, "# / _-----=> irqs-off \n");
seq_puts(m, "# | / _----=> need-resched \n");
seq_puts(m, "# || / _---=> hardirq/softirq \n");
seq_puts(m, "# ||| / _--=> preempt-depth \n");
seq_puts(m, "# |||| /_--=> lock-depth \n");
seq_puts(m, "# |||||/ delay \n");
seq_puts(m, "# cmd pid |||||| time | caller \n");
seq_puts(m, "# \\ / |||||| \\ | / \n");
}
static void print_func_help_header(struct seq_file *m)
{
seq_puts(m, "# TASK-PID CPU# TIMESTAMP FUNCTION\n");
seq_puts(m, "# | | | | |\n");
}
void
print_trace_header(struct seq_file *m, struct trace_iterator *iter)
{
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_array *tr = iter->tr;
struct trace_array_cpu *data = tr->data[tr->cpu];
struct tracer *type = current_trace;
unsigned long entries = 0;
unsigned long total = 0;
unsigned long count;
const char *name = "preemption";
int cpu;
if (type)
name = type->name;
for_each_tracing_cpu(cpu) {
count = ring_buffer_entries_cpu(tr->buffer, cpu);
/*
* If this buffer has skipped entries, then we hold all
* entries for the trace and we need to ignore the
* ones before the time stamp.
*/
if (tr->data[cpu]->skipped_entries) {
count -= tr->data[cpu]->skipped_entries;
/* total is the same as the entries */
total += count;
} else
total += count +
ring_buffer_overrun_cpu(tr->buffer, cpu);
entries += count;
}
seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
name, UTS_RELEASE);
seq_puts(m, "# -----------------------------------"
"---------------------------------\n");
seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
" (M:%s VP:%d, KP:%d, SP:%d HP:%d",
nsecs_to_usecs(data->saved_latency),
entries,
total,
tr->cpu,
#if defined(CONFIG_PREEMPT_NONE)
"server",
#elif defined(CONFIG_PREEMPT_VOLUNTARY)
"desktop",
#elif defined(CONFIG_PREEMPT)
"preempt",
#else
"unknown",
#endif
/* These are reserved for later use */
0, 0, 0, 0);
#ifdef CONFIG_SMP
seq_printf(m, " #P:%d)\n", num_online_cpus());
#else
seq_puts(m, ")\n");
#endif
seq_puts(m, "# -----------------\n");
seq_printf(m, "# | task: %.16s-%d "
"(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
data->comm, data->pid, data->uid, data->nice,
data->policy, data->rt_priority);
seq_puts(m, "# -----------------\n");
if (data->critical_start) {
seq_puts(m, "# => started at: ");
seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
trace_print_seq(m, &iter->seq);
seq_puts(m, "\n# => ended at: ");
seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
trace_print_seq(m, &iter->seq);
seq_puts(m, "\n#\n");
}
seq_puts(m, "#\n");
}
static void test_cpu_buff_start(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
if (!(trace_flags & TRACE_ITER_ANNOTATE))
return;
if (!(iter->iter_flags & TRACE_FILE_ANNOTATE))
return;
if (cpumask_test_cpu(iter->cpu, iter->started))
return;
if (iter->tr->data[iter->cpu]->skipped_entries)
return;
cpumask_set_cpu(iter->cpu, iter->started);
/* Don't print started cpu buffer for the first entry of the trace */
if (iter->idx > 1)
trace_seq_printf(s, "##### CPU %u buffer started ####\n",
iter->cpu);
}
static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
test_cpu_buff_start(iter);
event = ftrace_find_event(entry->type);
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
if (!trace_print_lat_context(iter))
goto partial;
} else {
if (!trace_print_context(iter))
goto partial;
}
}
if (event)
return event->funcs->trace(iter, sym_flags, event);
if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
goto partial;
return TRACE_TYPE_HANDLED;
partial:
return TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
if (!trace_seq_printf(s, "%d %d %llu ",
entry->pid, iter->cpu, iter->ts))
goto partial;
}
event = ftrace_find_event(entry->type);
if (event)
return event->funcs->raw(iter, 0, event);
if (!trace_seq_printf(s, "%d ?\n", entry->type))
goto partial;
return TRACE_TYPE_HANDLED;
partial:
return TRACE_TYPE_PARTIAL_LINE;
}
static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
unsigned char newline = '\n';
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
}
event = ftrace_find_event(entry->type);
if (event) {
enum print_line_t ret = event->funcs->hex(iter, 0, event);
if (ret != TRACE_TYPE_HANDLED)
return ret;
}
SEQ_PUT_FIELD_RET(s, newline);
return TRACE_TYPE_HANDLED;
}
static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry;
struct trace_event *event;
entry = iter->ent;
if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
SEQ_PUT_FIELD_RET(s, entry->pid);
SEQ_PUT_FIELD_RET(s, iter->cpu);
SEQ_PUT_FIELD_RET(s, iter->ts);
}
event = ftrace_find_event(entry->type);
return event ? event->funcs->binary(iter, 0, event) :
TRACE_TYPE_HANDLED;
}
int trace_empty(struct trace_iterator *iter)
{
int cpu;
/* If we are looking at one CPU buffer, only check that one */
if (iter->cpu_file != TRACE_PIPE_ALL_CPU) {
cpu = iter->cpu_file;
if (iter->buffer_iter[cpu]) {
if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
return 0;
} else {
if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
return 0;
}
return 1;
}
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu]) {
if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
return 0;
} else {
if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
return 0;
}
}
return 1;
}
/* Called with trace_event_read_lock() held. */
enum print_line_t print_trace_line(struct trace_iterator *iter)
{
enum print_line_t ret;
if (iter->lost_events)
trace_seq_printf(&iter->seq, "CPU:%d [LOST %lu EVENTS]\n",
iter->cpu, iter->lost_events);
if (iter->trace && iter->trace->print_line) {
ret = iter->trace->print_line(iter);
if (ret != TRACE_TYPE_UNHANDLED)
return ret;
}
if (iter->ent->type == TRACE_BPRINT &&
trace_flags & TRACE_ITER_PRINTK &&
trace_flags & TRACE_ITER_PRINTK_MSGONLY)
return trace_print_bprintk_msg_only(iter);
if (iter->ent->type == TRACE_PRINT &&
trace_flags & TRACE_ITER_PRINTK &&
trace_flags & TRACE_ITER_PRINTK_MSGONLY)
return trace_print_printk_msg_only(iter);
if (trace_flags & TRACE_ITER_BIN)
return print_bin_fmt(iter);
if (trace_flags & TRACE_ITER_HEX)
return print_hex_fmt(iter);
if (trace_flags & TRACE_ITER_RAW)
return print_raw_fmt(iter);
return print_trace_fmt(iter);
}
void trace_default_header(struct seq_file *m)
{
struct trace_iterator *iter = m->private;
if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
/* print nothing if the buffers are empty */
if (trace_empty(iter))
return;
print_trace_header(m, iter);
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_lat_help_header(m);
} else {
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_func_help_header(m);
}
}
static int s_show(struct seq_file *m, void *v)
{
struct trace_iterator *iter = v;
int ret;
if (iter->ent == NULL) {
if (iter->tr) {
seq_printf(m, "# tracer: %s\n", iter->trace->name);
seq_puts(m, "#\n");
}
if (iter->trace && iter->trace->print_header)
iter->trace->print_header(m);
else
trace_default_header(m);
} else if (iter->leftover) {
/*
* If we filled the seq_file buffer earlier, we
* want to just show it now.
*/
ret = trace_print_seq(m, &iter->seq);
/* ret should this time be zero, but you never know */
iter->leftover = ret;
} else {
print_trace_line(iter);
ret = trace_print_seq(m, &iter->seq);
/*
* If we overflow the seq_file buffer, then it will
* ask us for this data again at start up.
* Use that instead.
* ret is 0 if seq_file write succeeded.
* -1 otherwise.
*/
iter->leftover = ret;
}
return 0;
}
static const struct seq_operations tracer_seq_ops = {
.start = s_start,
.next = s_next,
.stop = s_stop,
.show = s_show,
};
static struct trace_iterator *
__tracing_open(struct inode *inode, struct file *file)
{
long cpu_file = (long) inode->i_private;
void *fail_ret = ERR_PTR(-ENOMEM);
struct trace_iterator *iter;
struct seq_file *m;
int cpu, ret;
if (tracing_disabled)
return ERR_PTR(-ENODEV);
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return ERR_PTR(-ENOMEM);
/*
* We make a copy of the current tracer to avoid concurrent
* changes on it while we are reading.
*/
mutex_lock(&trace_types_lock);
iter->trace = kzalloc(sizeof(*iter->trace), GFP_KERNEL);
if (!iter->trace)
goto fail;
if (current_trace)
*iter->trace = *current_trace;
if (!zalloc_cpumask_var(&iter->started, GFP_KERNEL))
goto fail;
if (current_trace && current_trace->print_max)
iter->tr = &max_tr;
else
iter->tr = &global_trace;
iter->pos = -1;
mutex_init(&iter->mutex);
iter->cpu_file = cpu_file;
/* Notify the tracer early; before we stop tracing. */
if (iter->trace && iter->trace->open)
iter->trace->open(iter);
/* Annotate start of buffers if we had overruns */
if (ring_buffer_overruns(iter->tr->buffer))
iter->iter_flags |= TRACE_FILE_ANNOTATE;
/* stop the trace while dumping */
tracing_stop();
if (iter->cpu_file == TRACE_PIPE_ALL_CPU) {
for_each_tracing_cpu(cpu) {
iter->buffer_iter[cpu] =
ring_buffer_read_prepare(iter->tr->buffer, cpu);
}
ring_buffer_read_prepare_sync();
for_each_tracing_cpu(cpu) {
ring_buffer_read_start(iter->buffer_iter[cpu]);
tracing_iter_reset(iter, cpu);
}
} else {
cpu = iter->cpu_file;
iter->buffer_iter[cpu] =
ring_buffer_read_prepare(iter->tr->buffer, cpu);
ring_buffer_read_prepare_sync();
ring_buffer_read_start(iter->buffer_iter[cpu]);
tracing_iter_reset(iter, cpu);
}
ret = seq_open(file, &tracer_seq_ops);
if (ret < 0) {
fail_ret = ERR_PTR(ret);
goto fail_buffer;
}
m = file->private_data;
m->private = iter;
mutex_unlock(&trace_types_lock);
return iter;
fail_buffer:
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
free_cpumask_var(iter->started);
tracing_start();
fail:
mutex_unlock(&trace_types_lock);
kfree(iter->trace);
kfree(iter);
return fail_ret;
}
int tracing_open_generic(struct inode *inode, struct file *filp)
{
if (tracing_disabled)
return -ENODEV;
filp->private_data = inode->i_private;
return 0;
}
static int tracing_release(struct inode *inode, struct file *file)
{
struct seq_file *m = file->private_data;
struct trace_iterator *iter;
int cpu;
if (!(file->f_mode & FMODE_READ))
return 0;
iter = m->private;
mutex_lock(&trace_types_lock);
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
if (iter->trace && iter->trace->close)
iter->trace->close(iter);
/* reenable tracing if it was previously enabled */
tracing_start();
mutex_unlock(&trace_types_lock);
seq_release(inode, file);
mutex_destroy(&iter->mutex);
free_cpumask_var(iter->started);
kfree(iter->trace);
kfree(iter);
return 0;
}
static int tracing_open(struct inode *inode, struct file *file)
{
struct trace_iterator *iter;
int ret = 0;
/* If this file was open for write, then erase contents */
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC)) {
long cpu = (long) inode->i_private;
if (cpu == TRACE_PIPE_ALL_CPU)
tracing_reset_online_cpus(&global_trace);
else
tracing_reset(&global_trace, cpu);
}
if (file->f_mode & FMODE_READ) {
iter = __tracing_open(inode, file);
if (IS_ERR(iter))
ret = PTR_ERR(iter);
else if (trace_flags & TRACE_ITER_LATENCY_FMT)
iter->iter_flags |= TRACE_FILE_LAT_FMT;
}
return ret;
}
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct tracer *t = v;
(*pos)++;
if (t)
t = t->next;
return t;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct tracer *t;
loff_t l = 0;
mutex_lock(&trace_types_lock);
for (t = trace_types; t && l < *pos; t = t_next(m, t, &l))
;
return t;
}
static void t_stop(struct seq_file *m, void *p)
{
mutex_unlock(&trace_types_lock);
}
static int t_show(struct seq_file *m, void *v)
{
struct tracer *t = v;
if (!t)
return 0;
seq_printf(m, "%s", t->name);
if (t->next)
seq_putc(m, ' ');
else
seq_putc(m, '\n');
return 0;
}
static const struct seq_operations show_traces_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int show_traces_open(struct inode *inode, struct file *file)
{
if (tracing_disabled)
return -ENODEV;
return seq_open(file, &show_traces_seq_ops);
}
static ssize_t
tracing_write_stub(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
return count;
}
static 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,
.llseek = seq_lseek,
};
/*
* Only trace on a CPU if the bitmask is set:
*/
static cpumask_var_t tracing_cpumask;
/*
* The tracer itself will not take this lock, but still we want
* to provide a consistent cpumask to user-space:
*/
static DEFINE_MUTEX(tracing_cpumask_update_lock);
/*
* Temporary storage for the character representation of the
* CPU bitmask (and one more byte for the newline):
*/
static char mask_str[NR_CPUS + 1];
static ssize_t
tracing_cpumask_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
int len;
mutex_lock(&tracing_cpumask_update_lock);
len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
if (count - len < 2) {
count = -EINVAL;
goto out_err;
}
len += sprintf(mask_str + len, "\n");
count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
out_err:
mutex_unlock(&tracing_cpumask_update_lock);
return count;
}
static ssize_t
tracing_cpumask_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
int err, cpu;
cpumask_var_t tracing_cpumask_new;
if (!alloc_cpumask_var(&tracing_cpumask_new, GFP_KERNEL))
return -ENOMEM;
err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
if (err)
goto err_unlock;
mutex_lock(&tracing_cpumask_update_lock);
local_irq_disable();
arch_spin_lock(&ftrace_max_lock);
for_each_tracing_cpu(cpu) {
/*
* Increase/decrease the disabled counter if we are
* about to flip a bit in the cpumask:
*/
if (cpumask_test_cpu(cpu, tracing_cpumask) &&
!cpumask_test_cpu(cpu, tracing_cpumask_new)) {
atomic_inc(&global_trace.data[cpu]->disabled);
}
if (!cpumask_test_cpu(cpu, tracing_cpumask) &&
cpumask_test_cpu(cpu, tracing_cpumask_new)) {
atomic_dec(&global_trace.data[cpu]->disabled);
}
}
arch_spin_unlock(&ftrace_max_lock);
local_irq_enable();
cpumask_copy(tracing_cpumask, tracing_cpumask_new);
mutex_unlock(&tracing_cpumask_update_lock);
free_cpumask_var(tracing_cpumask_new);
return count;
err_unlock:
free_cpumask_var(tracing_cpumask_new);
return err;
}
static const struct file_operations tracing_cpumask_fops = {
.open = tracing_open_generic,
.read = tracing_cpumask_read,
.write = tracing_cpumask_write,
.llseek = generic_file_llseek,
};
static int tracing_trace_options_show(struct seq_file *m, void *v)
{
struct tracer_opt *trace_opts;
u32 tracer_flags;
int i;
mutex_lock(&trace_types_lock);
tracer_flags = current_trace->flags->val;
trace_opts = current_trace->flags->opts;
for (i = 0; trace_options[i]; i++) {
if (trace_flags & (1 << i))
seq_printf(m, "%s\n", trace_options[i]);
else
seq_printf(m, "no%s\n", trace_options[i]);
}
for (i = 0; trace_opts[i].name; i++) {
if (tracer_flags & trace_opts[i].bit)
seq_printf(m, "%s\n", trace_opts[i].name);
else
seq_printf(m, "no%s\n", trace_opts[i].name);
}
mutex_unlock(&trace_types_lock);
return 0;
}
static int __set_tracer_option(struct tracer *trace,
struct tracer_flags *tracer_flags,
struct tracer_opt *opts, int neg)
{
int ret;
ret = trace->set_flag(tracer_flags->val, opts->bit, !neg);
if (ret)
return ret;
if (neg)
tracer_flags->val &= ~opts->bit;
else
tracer_flags->val |= opts->bit;
return 0;
}
/* Try to assign a tracer specific option */
static int set_tracer_option(struct tracer *trace, char *cmp, int neg)
{
struct tracer_flags *tracer_flags = trace->flags;
struct tracer_opt *opts = NULL;
int i;
for (i = 0; tracer_flags->opts[i].name; i++) {
opts = &tracer_flags->opts[i];
if (strcmp(cmp, opts->name) == 0)
return __set_tracer_option(trace, trace->flags,
opts, neg);
}
return -EINVAL;
}
static void set_tracer_flags(unsigned int mask, int enabled)
{
/* do nothing if flag is already set */
if (!!(trace_flags & mask) == !!enabled)
return;
if (enabled)
trace_flags |= mask;
else
trace_flags &= ~mask;
if (mask == TRACE_ITER_RECORD_CMD)
trace_event_enable_cmd_record(enabled);
}
static ssize_t
tracing_trace_options_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
char *cmp;
int neg = 0;
int ret;
int i;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
cmp = strstrip(buf);
if (strncmp(cmp, "no", 2) == 0) {
neg = 1;
cmp += 2;
}
for (i = 0; trace_options[i]; i++) {
if (strcmp(cmp, trace_options[i]) == 0) {
set_tracer_flags(1 << i, !neg);
break;
}
}
/* If no option could be set, test the specific tracer options */
if (!trace_options[i]) {
mutex_lock(&trace_types_lock);
ret = set_tracer_option(current_trace, cmp, neg);
mutex_unlock(&trace_types_lock);
if (ret)
return ret;
}
*ppos += cnt;
return cnt;
}
static int tracing_trace_options_open(struct inode *inode, struct file *file)
{
if (tracing_disabled)
return -ENODEV;
return single_open(file, tracing_trace_options_show, NULL);
}
static const struct file_operations tracing_iter_fops = {
.open = tracing_trace_options_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.write = tracing_trace_options_write,
};
static const char readme_msg[] =
"tracing mini-HOWTO:\n\n"
"# mount -t debugfs nodev /sys/kernel/debug\n\n"
"# cat /sys/kernel/debug/tracing/available_tracers\n"
"wakeup preemptirqsoff preemptoff irqsoff function sched_switch nop\n\n"
"# cat /sys/kernel/debug/tracing/current_tracer\n"
"nop\n"
"# echo sched_switch > /sys/kernel/debug/tracing/current_tracer\n"
"# cat /sys/kernel/debug/tracing/current_tracer\n"
"sched_switch\n"
"# cat /sys/kernel/debug/tracing/trace_options\n"
"noprint-parent nosym-offset nosym-addr noverbose\n"
"# echo print-parent > /sys/kernel/debug/tracing/trace_options\n"
"# echo 1 > /sys/kernel/debug/tracing/tracing_enabled\n"
"# cat /sys/kernel/debug/tracing/trace > /tmp/trace.txt\n"
"# echo 0 > /sys/kernel/debug/tracing/tracing_enabled\n"
;
static ssize_t
tracing_readme_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return simple_read_from_buffer(ubuf, cnt, ppos,
readme_msg, strlen(readme_msg));
}
static const struct file_operations tracing_readme_fops = {
.open = tracing_open_generic,
.read = tracing_readme_read,
.llseek = generic_file_llseek,
};
static ssize_t
tracing_saved_cmdlines_read(struct file *file, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char *buf_comm;
char *file_buf;
char *buf;
int len = 0;
int pid;
int i;
file_buf = kmalloc(SAVED_CMDLINES*(16+TASK_COMM_LEN), GFP_KERNEL);
if (!file_buf)
return -ENOMEM;
buf_comm = kmalloc(TASK_COMM_LEN, GFP_KERNEL);
if (!buf_comm) {
kfree(file_buf);
return -ENOMEM;
}
buf = file_buf;
for (i = 0; i < SAVED_CMDLINES; i++) {
int r;
pid = map_cmdline_to_pid[i];
if (pid == -1 || pid == NO_CMDLINE_MAP)
continue;
trace_find_cmdline(pid, buf_comm);
r = sprintf(buf, "%d %s\n", pid, buf_comm);
buf += r;
len += r;
}
len = simple_read_from_buffer(ubuf, cnt, ppos,
file_buf, len);
kfree(file_buf);
kfree(buf_comm);
return len;
}
static const struct file_operations tracing_saved_cmdlines_fops = {
.open = tracing_open_generic,
.read = tracing_saved_cmdlines_read,
.llseek = generic_file_llseek,
};
static ssize_t
tracing_ctrl_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
int r;
r = sprintf(buf, "%u\n", tracer_enabled);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_ctrl_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
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);
*ppos += cnt;
return cnt;
}
static ssize_t
tracing_set_trace_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[MAX_TRACER_SIZE+2];
int r;
mutex_lock(&trace_types_lock);
if (current_trace)
r = sprintf(buf, "%s\n", current_trace->name);
else
r = sprintf(buf, "\n");
mutex_unlock(&trace_types_lock);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
int tracer_init(struct tracer *t, struct trace_array *tr)
{
tracing_reset_online_cpus(tr);
return t->init(tr);
}
static int tracing_resize_ring_buffer(unsigned long size)
{
int ret;
/*
* If kernel or user changes the size of the ring buffer
* we use the size that was given, and we can forget about
* expanding it later.
*/
ring_buffer_expanded = 1;
ret = ring_buffer_resize(global_trace.buffer, size);
if (ret < 0)
return ret;
if (!current_trace->use_max_tr)
goto out;
ret = ring_buffer_resize(max_tr.buffer, size);
if (ret < 0) {
int r;
r = ring_buffer_resize(global_trace.buffer,
global_trace.entries);
if (r < 0) {
/*
* AARGH! We are left with different
* size max buffer!!!!
* The max buffer is our "snapshot" buffer.
* When a tracer needs a snapshot (one of the
* latency tracers), it swaps the max buffer
* with the saved snap shot. We succeeded to
* update the size of the main buffer, but failed to
* update the size of the max buffer. But when we tried
* to reset the main buffer to the original size, we
* failed there too. This is very unlikely to
* happen, but if it does, warn and kill all
* tracing.
*/
WARN_ON(1);
tracing_disabled = 1;
}
return ret;
}
max_tr.entries = size;
out:
global_trace.entries = size;
return ret;
}
/**
* tracing_update_buffers - used by tracing facility to expand ring buffers
*
* To save on memory when the tracing is never used on a system with it
* configured in. The ring buffers are set to a minimum size. But once
* a user starts to use the tracing facility, then they need to grow
* to their default size.
*
* This function is to be called when a tracer is about to be used.
*/
int tracing_update_buffers(void)
{
int ret = 0;
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded)
ret = tracing_resize_ring_buffer(trace_buf_size);
mutex_unlock(&trace_types_lock);
return ret;
}
struct trace_option_dentry;
static struct trace_option_dentry *
create_trace_option_files(struct tracer *tracer);
static void
destroy_trace_option_files(struct trace_option_dentry *topts);
static int tracing_set_tracer(const char *buf)
{
static struct trace_option_dentry *topts;
struct trace_array *tr = &global_trace;
struct tracer *t;
int ret = 0;
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded) {
ret = tracing_resize_ring_buffer(trace_buf_size);
if (ret < 0)
goto out;
ret = 0;
}
for (t = trace_types; t; t = t->next) {
if (strcmp(t->name, buf) == 0)
break;
}
if (!t) {
ret = -EINVAL;
goto out;
}
if (t == current_trace)
goto out;
trace_branch_disable();
if (current_trace && current_trace->reset)
current_trace->reset(tr);
if (current_trace && current_trace->use_max_tr) {
/*
* We don't free the ring buffer. instead, resize it because
* The max_tr ring buffer has some state (e.g. ring->clock) and
* we want preserve it.
*/
ring_buffer_resize(max_tr.buffer, 1);
max_tr.entries = 1;
}
destroy_trace_option_files(topts);
current_trace = t;
topts = create_trace_option_files(current_trace);
if (current_trace->use_max_tr) {
ret = ring_buffer_resize(max_tr.buffer, global_trace.entries);
if (ret < 0)
goto out;
max_tr.entries = global_trace.entries;
}
if (t->init) {
ret = tracer_init(t, tr);
if (ret)
goto out;
}
trace_branch_enable(tr);
out:
mutex_unlock(&trace_types_lock);
return ret;
}
static ssize_t
tracing_set_trace_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[MAX_TRACER_SIZE+1];
int i;
size_t ret;
int err;
ret = cnt;
if (cnt > MAX_TRACER_SIZE)
cnt = MAX_TRACER_SIZE;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
/* strip ending whitespace. */
for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
buf[i] = 0;
err = tracing_set_tracer(buf);
if (err)
return err;
*ppos += ret;
return ret;
}
static ssize_t
tracing_max_lat_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long *ptr = filp->private_data;
char buf[64];
int r;
r = snprintf(buf, sizeof(buf), "%ld\n",
*ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
if (r > sizeof(buf))
r = sizeof(buf);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_max_lat_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long *ptr = filp->private_data;
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);
/* create a buffer to store the information to pass to userspace */
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter) {
ret = -ENOMEM;
goto out;
}
/*
* We make a copy of the current tracer to avoid concurrent
* changes on it while we are reading.
*/
iter->trace = kmalloc(sizeof(*iter->trace), GFP_KERNEL);
if (!iter->trace) {
ret = -ENOMEM;
goto fail;
}
if (current_trace)
*iter->trace = *current_trace;
if (!alloc_cpumask_var(&iter->started, GFP_KERNEL)) {
ret = -ENOMEM;
goto fail;
}
/* trace pipe does not show start of buffer */
cpumask_setall(iter->started);
if (trace_flags & TRACE_ITER_LATENCY_FMT)
iter->iter_flags |= TRACE_FILE_LAT_FMT;
iter->cpu_file = cpu_file;
iter->tr = &global_trace;
mutex_init(&iter->mutex);
filp->private_data = iter;
if (iter->trace->pipe_open)
iter->trace->pipe_open(iter);
nonseekable_open(inode, filp);
out:
mutex_unlock(&trace_types_lock);
return ret;
fail:
kfree(iter->trace);
kfree(iter);
mutex_unlock(&trace_types_lock);
return ret;
}
static int tracing_release_pipe(struct inode *inode, struct file *file)
{
struct trace_iterator *iter = file->private_data;
mutex_lock(&trace_types_lock);
if (iter->trace->pipe_close)
iter->trace->pipe_close(iter);
mutex_unlock(&trace_types_lock);
free_cpumask_var(iter->started);
mutex_destroy(&iter->mutex);
kfree(iter->trace);
kfree(iter);
return 0;
}
static unsigned int
tracing_poll_pipe(struct file *filp, poll_table *poll_table)
{
struct trace_iterator *iter = filp->private_data;
if (trace_flags & TRACE_ITER_BLOCK) {
/*
* Always select as readable when in blocking mode
*/
return POLLIN | POLLRDNORM;
} else {
if (!trace_empty(iter))
return POLLIN | POLLRDNORM;
poll_wait(filp, &trace_wait, poll_table);
if (!trace_empty(iter))
return POLLIN | POLLRDNORM;
return 0;
}
}
void default_wait_pipe(struct trace_iterator *iter)
{
DEFINE_WAIT(wait);
prepare_to_wait(&trace_wait, &wait, TASK_INTERRUPTIBLE);
if (trace_empty(iter))
schedule();
finish_wait(&trace_wait, &wait);
}
/*
* This is a make-shift waitqueue.
* A tracer might use this callback on some rare cases:
*
* 1) the current tracer might hold the runqueue lock when it wakes up
* a reader, hence a deadlock (sched, function, and function graph tracers)
* 2) the function tracers, trace all functions, we don't want
* the overhead of calling wake_up and friends
* (and tracing them too)
*
* Anyway, this is really very primitive wakeup.
*/
void poll_wait_pipe(struct trace_iterator *iter)
{
set_current_state(TASK_INTERRUPTIBLE);
/* sleep for 100 msecs, and try again. */
schedule_timeout(HZ / 10);
}
/* Must be called with trace_types_lock mutex held. */
static int tracing_wait_pipe(struct file *filp)
{
struct trace_iterator *iter = filp->private_data;
while (trace_empty(iter)) {
if ((filp->f_flags & O_NONBLOCK)) {
return -EAGAIN;
}
mutex_unlock(&iter->mutex);
iter->trace->wait_pipe(iter);
mutex_lock(&iter->mutex);
if (signal_pending(current))
return -EINTR;
/*
* We block until we read something and tracing is disabled.
* We still block if tracing is disabled, but we have never
* read anything. This allows a user to cat this file, and
* then enable tracing. But after we have read something,
* we give an EOF when tracing is again disabled.
*
* iter->pos will be 0 if we haven't read anything.
*/
if (!tracer_enabled && iter->pos)
break;
}
return 1;
}
/*
* Consumer reader.
*/
static ssize_t
tracing_read_pipe(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_iterator *iter = filp->private_data;
static struct tracer *old_tracer;
ssize_t sret;
/* return any leftover data */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
return sret;
trace_seq_init(&iter->seq);
/* copy the tracer to avoid using a global lock all around */
mutex_lock(&trace_types_lock);
if (unlikely(old_tracer != current_trace && current_trace)) {
old_tracer = current_trace;
*iter->trace = *current_trace;
}
mutex_unlock(&trace_types_lock);
/*
* Avoid more than one consumer on a single file descriptor
* This is just a matter of traces coherency, the ring buffer itself
* is protected.
*/
mutex_lock(&iter->mutex);
if (iter->trace->read) {
sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
if (sret)
goto out;
}
waitagain:
sret = tracing_wait_pipe(filp);
if (sret <= 0)
goto out;
/* stop when tracing is finished */
if (trace_empty(iter)) {
sret = 0;
goto out;
}
if (cnt >= PAGE_SIZE)
cnt = PAGE_SIZE - 1;
/* reset all but tr, trace, and overruns */
memset(&iter->seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter->pos = -1;
trace_event_read_lock();
trace_access_lock(iter->cpu_file);
while (trace_find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
int len = iter->seq.len;
ret = print_trace_line(iter);
if (ret == TRACE_TYPE_PARTIAL_LINE) {
/* don't print partial lines */
iter->seq.len = len;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
if (iter->seq.len >= cnt)
break;
}
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (iter->seq.readpos >= iter->seq.len)
trace_seq_init(&iter->seq);
/*
* If there was nothing to send to user, 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 const struct pipe_buf_operations tracing_pipe_buf_ops = {
.can_merge = 0,
.map = generic_pipe_buf_map,
.unmap = generic_pipe_buf_unmap,
.confirm = generic_pipe_buf_confirm,
.release = tracing_pipe_buf_release,
.steal = generic_pipe_buf_steal,
.get = generic_pipe_buf_get,
};
static size_t
tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
{
size_t count;
int ret;
/* Seq buffer is page-sized, exactly what we need. */
for (;;) {
count = iter->seq.len;
ret = print_trace_line(iter);
count = iter->seq.len - count;
if (rem < count) {
rem = 0;
iter->seq.len -= count;
break;
}
if (ret == TRACE_TYPE_PARTIAL_LINE) {
iter->seq.len -= count;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
rem -= count;
if (!trace_find_next_entry_inc(iter)) {
rem = 0;
iter->ent = NULL;
break;
}
}
return rem;
}
static ssize_t tracing_splice_read_pipe(struct file *filp,
loff_t *ppos,
struct pipe_inode_info *pipe,
size_t len,
unsigned int flags)
{
struct page *pages_def[PIPE_DEF_BUFFERS];
struct partial_page partial_def[PIPE_DEF_BUFFERS];
struct trace_iterator *iter = filp->private_data;
struct splice_pipe_desc spd = {
.pages = pages_def,
.partial = partial_def,
.nr_pages = 0, /* This gets updated below. */
.flags = flags,
.ops = &tracing_pipe_buf_ops,
.spd_release = tracing_spd_release_pipe,
};
static struct tracer *old_tracer;
ssize_t ret;
size_t rem;
unsigned int i;
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
/* copy the tracer to avoid using a global lock all around */
mutex_lock(&trace_types_lock);
if (unlikely(old_tracer != current_trace && current_trace)) {
old_tracer = current_trace;
*iter->trace = *current_trace;
}
mutex_unlock(&trace_types_lock);
mutex_lock(&iter->mutex);
if (iter->trace->splice_read) {
ret = iter->trace->splice_read(iter, filp,
ppos, pipe, len, flags);
if (ret)
goto out_err;
}
ret = tracing_wait_pipe(filp);
if (ret <= 0)
goto out_err;
if (!iter->ent && !trace_find_next_entry_inc(iter)) {
ret = -EFAULT;
goto out_err;
}
trace_event_read_lock();
trace_access_lock(iter->cpu_file);
/* Fill as many pages as possible. */
for (i = 0, rem = len; i < pipe->buffers && rem; i++) {
spd.pages[i] = alloc_page(GFP_KERNEL);
if (!spd.pages[i])
break;
rem = tracing_fill_pipe_page(rem, iter);
/* Copy the data into the page, so we can start over. */
ret = trace_seq_to_buffer(&iter->seq,
page_address(spd.pages[i]),
iter->seq.len);
if (ret < 0) {
__free_page(spd.pages[i]);
break;
}
spd.partial[i].offset = 0;
spd.partial[i].len = iter->seq.len;
trace_seq_init(&iter->seq);
}
trace_access_unlock(iter->cpu_file);
trace_event_read_unlock();
mutex_unlock(&iter->mutex);
spd.nr_pages = i;
ret = splice_to_pipe(pipe, &spd);
out:
splice_shrink_spd(pipe, &spd);
return ret;
out_err:
mutex_unlock(&iter->mutex);
goto out;
}
static ssize_t
tracing_entries_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
char buf[96];
int r;
mutex_lock(&trace_types_lock);
if (!ring_buffer_expanded)
r = sprintf(buf, "%lu (expanded: %lu)\n",
tr->entries >> 10,
trace_buf_size >> 10);
else
r = sprintf(buf, "%lu\n", tr->entries >> 10);
mutex_unlock(&trace_types_lock);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_entries_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long val;
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;
}
}
*ppos += 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();
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;
size_t written;
if (tracing_disabled)
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
buf = kmalloc(cnt + 2, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
if (copy_from_user(buf, ubuf, cnt)) {
kfree(buf);
return -EFAULT;
}
if (buf[cnt-1] != '\n') {
buf[cnt] = '\n';
buf[cnt+1] = '\0';
} else
buf[cnt] = '\0';
written = mark_printk("%s", buf);
kfree(buf);
*fpos += written;
/* don't tell userspace we wrote more - it might confuse them */
if (written > cnt)
written = cnt;
return written;
}
static int tracing_clock_show(struct seq_file *m, void *v)
{
int i;
for (i = 0; i < ARRAY_SIZE(trace_clocks); i++)
seq_printf(m,
"%s%s%s%s", i ? " " : "",
i == trace_clock_id ? "[" : "", trace_clocks[i].name,
i == trace_clock_id ? "]" : "");
seq_putc(m, '\n');
return 0;
}
static ssize_t tracing_clock_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
{
char buf[64];
const char *clockstr;
int i;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
clockstr = strstrip(buf);
for (i = 0; i < ARRAY_SIZE(trace_clocks); i++) {
if (strcmp(trace_clocks[i].name, clockstr) == 0)
break;
}
if (i == ARRAY_SIZE(trace_clocks))
return -EINVAL;
trace_clock_id = i;
mutex_lock(&trace_types_lock);
ring_buffer_set_clock(global_trace.buffer, trace_clocks[i].func);
if (max_tr.buffer)
ring_buffer_set_clock(max_tr.buffer, trace_clocks[i].func);
mutex_unlock(&trace_types_lock);
*fpos += cnt;
return cnt;
}
static int tracing_clock_open(struct inode *inode, struct file *file)
{
if (tracing_disabled)
return -ENODEV;
return single_open(file, tracing_clock_show, NULL);
}
static const struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
.write = tracing_max_lat_write,
.llseek = generic_file_llseek,
};
static const struct file_operations tracing_ctrl_fops = {
.open = tracing_open_generic,
.read = tracing_ctrl_read,
.write = tracing_ctrl_write,
.llseek = generic_file_llseek,
};
static const struct file_operations set_tracer_fops = {
.open = tracing_open_generic,
.read = tracing_set_trace_read,
.write = tracing_set_trace_write,
.llseek = generic_file_llseek,
};
static const struct file_operations tracing_pipe_fops = {
.open = tracing_open_pipe,
.poll = tracing_poll_pipe,
.read = tracing_read_pipe,
.splice_read = tracing_splice_read_pipe,
.release = tracing_release_pipe,
.llseek = no_llseek,
};
static const struct file_operations tracing_entries_fops = {
.open = tracing_open_generic,
.read = tracing_entries_read,
.write = tracing_entries_write,
.llseek = generic_file_llseek,
};
static const struct file_operations tracing_mark_fops = {
.open = tracing_open_generic,
.write = tracing_mark_write,
.llseek = generic_file_llseek,
};
static const struct file_operations trace_clock_fops = {
.open = tracing_clock_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.write = tracing_clock_write,
};
struct ftrace_buffer_info {
struct trace_array *tr;
void *spare;
int cpu;
unsigned int read;
};
static int tracing_buffers_open(struct inode *inode, struct file *filp)
{
int cpu = (int)(long)inode->i_private;
struct ftrace_buffer_info *info;
if (tracing_disabled)
return -ENODEV;
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info)
return -ENOMEM;
info->tr = &global_trace;
info->cpu = cpu;
info->spare = NULL;
/* Force reading ring buffer for first read */
info->read = (unsigned int)-1;
filp->private_data = info;
return nonseekable_open(inode, filp);
}
static ssize_t
tracing_buffers_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
struct ftrace_buffer_info *info = filp->private_data;
ssize_t ret;
size_t size;
if (!count)
return 0;
if (!info->spare)
info->spare = ring_buffer_alloc_read_page(info->tr->buffer);
if (!info->spare)
return -ENOMEM;
/* Do we have previous read data to read? */
if (info->read < PAGE_SIZE)
goto read;
info->read = 0;
trace_access_lock(info->cpu);
ret = ring_buffer_read_page(info->tr->buffer,
&info->spare,
count,
info->cpu, 0);
trace_access_unlock(info->cpu);
if (ret < 0)
return 0;
read:
size = PAGE_SIZE - info->read;
if (size > count)
size = count;
ret = copy_to_user(ubuf, info->spare + info->read, size);
if (ret == size)
return -EFAULT;
size -= ret;
*ppos += size;
info->read += size;
return size;
}
static int tracing_buffers_release(struct inode *inode, struct file *file)
{
struct ftrace_buffer_info *info = file->private_data;
if (info->spare)
ring_buffer_free_read_page(info->tr->buffer, info->spare);
kfree(info);
return 0;
}
struct buffer_ref {
struct ring_buffer *buffer;
void *page;
int ref;
};
static void buffer_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct buffer_ref *ref = (struct buffer_ref *)buf->private;
if (--ref->ref)
return;
ring_buffer_free_read_page(ref->buffer, ref->page);
kfree(ref);
buf->private = 0;
}
static int buffer_pipe_buf_steal(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
return 1;
}
static void buffer_pipe_buf_get(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct buffer_ref *ref = (struct buffer_ref *)buf->private;
ref->ref++;
}
/* Pipe buffer operations for a buffer. */
static const struct pipe_buf_operations buffer_pipe_buf_ops = {
.can_merge = 0,
.map = generic_pipe_buf_map,
.unmap = generic_pipe_buf_unmap,
.confirm = generic_pipe_buf_confirm,
.release = buffer_pipe_buf_release,
.steal = buffer_pipe_buf_steal,
.get = buffer_pipe_buf_get,
};
/*
* Callback from splice_to_pipe(), if we need to release some pages
* at the end of the spd in case we error'ed out in filling the pipe.
*/
static void buffer_spd_release(struct splice_pipe_desc *spd, unsigned int i)
{
struct buffer_ref *ref =
(struct buffer_ref *)spd->partial[i].private;
if (--ref->ref)
return;
ring_buffer_free_read_page(ref->buffer, ref->page);
kfree(ref);
spd->partial[i].private = 0;
}
static ssize_t
tracing_buffers_splice_read(struct file *file, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
struct ftrace_buffer_info *info = file->private_data;
struct partial_page partial_def[PIPE_DEF_BUFFERS];
struct page *pages_def[PIPE_DEF_BUFFERS];
struct splice_pipe_desc spd = {
.pages = pages_def,
.partial = partial_def,
.flags = flags,
.ops = &buffer_pipe_buf_ops,
.spd_release = buffer_spd_release,
};
struct buffer_ref *ref;
int entries, size, i;
size_t ret;
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
if (*ppos & (PAGE_SIZE - 1)) {
WARN_ONCE(1, "Ftrace: previous read must page-align\n");
ret = -EINVAL;
goto out;
}
if (len & (PAGE_SIZE - 1)) {
WARN_ONCE(1, "Ftrace: splice_read should page-align\n");
if (len < PAGE_SIZE) {
ret = -EINVAL;
goto out;
}
len &= PAGE_MASK;
}
trace_access_lock(info->cpu);
entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
for (i = 0; i < pipe->buffers && len && entries; i++, len -= PAGE_SIZE) {
struct page *page;
int r;
ref = kzalloc(sizeof(*ref), GFP_KERNEL);
if (!ref)
break;
ref->ref = 1;
ref->buffer = info->tr->buffer;
ref->page = ring_buffer_alloc_read_page(ref->buffer);
if (!ref->page) {
kfree(ref);
break;
}
r = ring_buffer_read_page(ref->buffer, &ref->page,
len, info->cpu, 1);
if (r < 0) {
ring_buffer_free_read_page(ref->buffer,
ref->page);
kfree(ref);
break;
}
/*
* zero out any left over data, this is going to
* user land.
*/
size = ring_buffer_page_len(ref->page);
if (size < PAGE_SIZE)
memset(ref->page + size, 0, PAGE_SIZE - size);
page = virt_to_page(ref->page);
spd.pages[i] = page;
spd.partial[i].len = PAGE_SIZE;
spd.partial[i].offset = 0;
spd.partial[i].private = (unsigned long)ref;
spd.nr_pages++;
*ppos += PAGE_SIZE;
entries = ring_buffer_entries_cpu(info->tr->buffer, info->cpu);
}
trace_access_unlock(info->cpu);
spd.nr_pages = i;
/* did we read anything? */
if (!spd.nr_pages) {
if (flags & SPLICE_F_NONBLOCK)
ret = -EAGAIN;
else
ret = 0;
/* TODO: block */
goto out;
}
ret = splice_to_pipe(pipe, &spd);
splice_shrink_spd(pipe, &spd);
out:
return ret;
}
static const struct file_operations tracing_buffers_fops = {
.open = tracing_buffers_open,
.read = tracing_buffers_read,
.release = tracing_buffers_release,
.splice_read = tracing_buffers_splice_read,
.llseek = no_llseek,
};
static ssize_t
tracing_stats_read(struct file *filp, char __user *ubuf,
size_t count, loff_t *ppos)
{
unsigned long cpu = (unsigned long)filp->private_data;
struct trace_array *tr = &global_trace;
struct trace_seq *s;
unsigned long cnt;
s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
return -ENOMEM;
trace_seq_init(s);
cnt = ring_buffer_entries_cpu(tr->buffer, cpu);
trace_seq_printf(s, "entries: %ld\n", cnt);
cnt = ring_buffer_overrun_cpu(tr->buffer, cpu);
trace_seq_printf(s, "overrun: %ld\n", cnt);
cnt = ring_buffer_commit_overrun_cpu(tr->buffer, cpu);
trace_seq_printf(s, "commit overrun: %ld\n", cnt);
count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
kfree(s);
return count;
}
static const struct file_operations tracing_stats_fops = {
.open = tracing_open_generic,
.read = tracing_stats_read,
.llseek = generic_file_llseek,
};
#ifdef CONFIG_DYNAMIC_FTRACE
int __weak ftrace_arch_read_dyn_info(char *buf, int size)
{
return 0;
}
static ssize_t
tracing_read_dyn_info(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
static char ftrace_dyn_info_buffer[1024];
static DEFINE_MUTEX(dyn_info_mutex);
unsigned long *p = filp->private_data;
char *buf = ftrace_dyn_info_buffer;
int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
int r;
mutex_lock(&dyn_info_mutex);
r = sprintf(buf, "%ld ", *p);
r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
buf[r++] = '\n';
r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
mutex_unlock(&dyn_info_mutex);
return r;
}
static const struct file_operations tracing_dyn_info_fops = {
.open = tracing_open_generic,
.read = tracing_read_dyn_info,
.llseek = generic_file_llseek,
};
#endif
static struct dentry *d_tracer;
struct dentry *tracing_init_dentry(void)
{
static int once;
if (d_tracer)
return d_tracer;
if (!debugfs_initialized())
return NULL;
d_tracer = debugfs_create_dir("tracing", NULL);
if (!d_tracer && !once) {
once = 1;
pr_warning("Could not create debugfs directory 'tracing'\n");
return NULL;
}
return d_tracer;
}
static struct dentry *d_percpu;
struct dentry *tracing_dentry_percpu(void)
{
static int once;
struct dentry *d_tracer;
if (d_percpu)
return d_percpu;
d_tracer = tracing_init_dentry();
if (!d_tracer)
return NULL;
d_percpu = debugfs_create_dir("per_cpu", d_tracer);
if (!d_percpu && !once) {
once = 1;
pr_warning("Could not create debugfs directory 'per_cpu'\n");
return NULL;
}
return d_percpu;
}
static void tracing_init_debugfs_percpu(long cpu)
{
struct dentry *d_percpu = tracing_dentry_percpu();
struct dentry *d_cpu;
char cpu_dir[30]; /* 30 characters should be more than enough */
snprintf(cpu_dir, 30, "cpu%ld", cpu);
d_cpu = debugfs_create_dir(cpu_dir, d_percpu);
if (!d_cpu) {
pr_warning("Could not create debugfs '%s' entry\n", cpu_dir);
return;
}
/* per cpu trace_pipe */
trace_create_file("trace_pipe", 0444, d_cpu,
(void *) cpu, &tracing_pipe_fops);
/* per cpu trace */
trace_create_file("trace", 0644, d_cpu,
(void *) cpu, &tracing_fops);
trace_create_file("trace_pipe_raw", 0444, d_cpu,
(void *) cpu, &tracing_buffers_fops);
trace_create_file("stats", 0444, d_cpu,
(void *) cpu, &tracing_stats_fops);
}
#ifdef CONFIG_FTRACE_SELFTEST
/* Let selftest have access to static functions in this file */
#include "trace_selftest.c"
#endif
struct trace_option_dentry {
struct tracer_opt *opt;
struct tracer_flags *flags;
struct dentry *entry;
};
static ssize_t
trace_options_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
struct trace_option_dentry *topt = filp->private_data;
char *buf;
if (topt->flags->val & topt->opt->bit)
buf = "1\n";
else
buf = "0\n";
return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}
static ssize_t
trace_options_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
{
struct trace_option_dentry *topt = filp->private_data;
unsigned long val;
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;
if (val != 0 && val != 1)
return -EINVAL;
if (!!(topt->flags->val & topt->opt->bit) != val) {
mutex_lock(&trace_types_lock);
ret = __set_tracer_option(current_trace, topt->flags,
topt->opt, !val);
mutex_unlock(&trace_types_lock);
if (ret)
return ret;
}
*ppos += cnt;
return cnt;
}
static const struct file_operations trace_options_fops = {
.open = tracing_open_generic,
.read = trace_options_read,
.write = trace_options_write,
.llseek = generic_file_llseek,
};
static ssize_t
trace_options_core_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
long index = (long)filp->private_data;
char *buf;
if (trace_flags & (1 << index))
buf = "1\n";
else
buf = "0\n";
return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}
static ssize_t
trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
{
long index = (long)filp->private_data;
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;
if (val != 0 && val != 1)
return -EINVAL;
set_tracer_flags(1 << index, val);
*ppos += cnt;
return cnt;
}
static const struct file_operations trace_options_core_fops = {
.open = tracing_open_generic,
.read = trace_options_core_read,
.write = trace_options_core_write,
.llseek = generic_file_llseek,
};
struct dentry *trace_create_file(const char *name,
mode_t mode,
struct dentry *parent,
void *data,
const struct file_operations *fops)
{
struct dentry *ret;
ret = debugfs_create_file(name, mode, parent, data, fops);
if (!ret)
pr_warning("Could not create debugfs '%s' entry\n", name);
return ret;
}
static struct dentry *trace_options_init_dentry(void)
{
struct dentry *d_tracer;
static struct dentry *t_options;
if (t_options)
return t_options;
d_tracer = tracing_init_dentry();
if (!d_tracer)
return NULL;
t_options = debugfs_create_dir("options", d_tracer);
if (!t_options) {
pr_warning("Could not create debugfs directory 'options'\n");
return NULL;
}
return t_options;
}
static void
create_trace_option_file(struct trace_option_dentry *topt,
struct tracer_flags *flags,
struct tracer_opt *opt)
{
struct dentry *t_options;
t_options = trace_options_init_dentry();
if (!t_options)
return;
topt->flags = flags;
topt->opt = opt;
topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
&trace_options_fops);
}
static struct trace_option_dentry *
create_trace_option_files(struct tracer *tracer)
{
struct trace_option_dentry *topts;
struct tracer_flags *flags;
struct tracer_opt *opts;
int cnt;
if (!tracer)
return NULL;
flags = tracer->flags;
if (!flags || !flags->opts)
return NULL;
opts = flags->opts;
for (cnt = 0; opts[cnt].name; cnt++)
;
topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
if (!topts)
return NULL;
for (cnt = 0; opts[cnt].name; cnt++)
create_trace_option_file(&topts[cnt], flags,
&opts[cnt]);
return topts;
}
static void
destroy_trace_option_files(struct trace_option_dentry *topts)
{
int cnt;
if (!topts)
return;
for (cnt = 0; topts[cnt].opt; cnt++) {
if (topts[cnt].entry)
debugfs_remove(topts[cnt].entry);
}
kfree(topts);
}
static struct dentry *
create_trace_option_core_file(const char *option, long index)
{
struct dentry *t_options;
t_options = trace_options_init_dentry();
if (!t_options)
return NULL;
return trace_create_file(option, 0644, t_options, (void *)index,
&trace_options_core_fops);
}
static __init void create_trace_options_dir(void)
{
struct dentry *t_options;
int i;
t_options = trace_options_init_dentry();
if (!t_options)
return;
for (i = 0; trace_options[i]; i++)
create_trace_option_core_file(trace_options[i], i);
}
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
int cpu;
trace_access_lock_init();
d_tracer = tracing_init_dentry();
trace_create_file("tracing_enabled", 0644, d_tracer,
&global_trace, &tracing_ctrl_fops);
trace_create_file("trace_options", 0644, d_tracer,
NULL, &tracing_iter_fops);
trace_create_file("tracing_cpumask", 0644, d_tracer,
NULL, &tracing_cpumask_fops);
trace_create_file("trace", 0644, d_tracer,
(void *) TRACE_PIPE_ALL_CPU, &tracing_fops);
trace_create_file("available_tracers", 0444, d_tracer,
&global_trace, &show_traces_fops);
trace_create_file("current_tracer", 0644, d_tracer,
&global_trace, &set_tracer_fops);
#ifdef CONFIG_TRACER_MAX_TRACE
trace_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency, &tracing_max_lat_fops);
#endif
trace_create_file("tracing_thresh", 0644, d_tracer,
&tracing_thresh, &tracing_max_lat_fops);
trace_create_file("README", 0444, d_tracer,
NULL, &tracing_readme_fops);
trace_create_file("trace_pipe", 0444, d_tracer,
(void *) TRACE_PIPE_ALL_CPU, &tracing_pipe_fops);
trace_create_file("buffer_size_kb", 0644, d_tracer,
&global_trace, &tracing_entries_fops);
trace_create_file("trace_marker", 0220, d_tracer,
NULL, &tracing_mark_fops);
trace_create_file("saved_cmdlines", 0444, d_tracer,
NULL, &tracing_saved_cmdlines_fops);
trace_create_file("trace_clock", 0644, d_tracer, NULL,
&trace_clock_fops);
#ifdef CONFIG_DYNAMIC_FTRACE
trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
#endif
create_trace_options_dir();
for_each_tracing_cpu(cpu)
tracing_init_debugfs_percpu(cpu);
return 0;
}
static int trace_panic_handler(struct notifier_block *this,
unsigned long event, void *unused)
{
if (ftrace_dump_on_oops)
ftrace_dump(ftrace_dump_on_oops);
return NOTIFY_OK;
}
static struct notifier_block trace_panic_notifier = {
.notifier_call = trace_panic_handler,
.next = NULL,
.priority = 150 /* priority: INT_MAX >= x >= 0 */
};
static int trace_die_handler(struct notifier_block *self,
unsigned long val,
void *data)
{
switch (val) {
case DIE_OOPS:
if (ftrace_dump_on_oops)
ftrace_dump(ftrace_dump_on_oops);
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block trace_die_notifier = {
.notifier_call = trace_die_handler,
.priority = 200
};
/*
* printk is set to max of 1024, we really don't need it that big.
* Nothing should be printing 1000 characters anyway.
*/
#define TRACE_MAX_PRINT 1000
/*
* Define here KERN_TRACE so that we have one place to modify
* it if we decide to change what log level the ftrace dump
* should be at.
*/
#define KERN_TRACE KERN_EMERG
void
trace_printk_seq(struct trace_seq *s)
{
/* Probably should print a warning here. */
if (s->len >= 1000)
s->len = 1000;
/* should be zero ended, but we are paranoid. */
s->buffer[s->len] = 0;
printk(KERN_TRACE "%s", s->buffer);
trace_seq_init(s);
}
void trace_init_global_iter(struct trace_iterator *iter)
{
iter->tr = &global_trace;
iter->trace = current_trace;
iter->cpu_file = TRACE_PIPE_ALL_CPU;
}
static void
__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
{
static arch_spinlock_t ftrace_dump_lock =
(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
unsigned int old_userobj;
static int dump_ran;
unsigned long flags;
int cnt = 0, cpu;
/* only one dump */
local_irq_save(flags);
arch_spin_lock(&ftrace_dump_lock);
if (dump_ran)
goto out;
dump_ran = 1;
tracing_off();
if (disable_tracing)
ftrace_kill();
trace_init_global_iter(&iter);
for_each_tracing_cpu(cpu) {
atomic_inc(&iter.tr->data[cpu]->disabled);
}
old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
/* don't look at user memory in panic mode */
trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
/* Simulate the iterator */
iter.tr = &global_trace;
iter.trace = current_trace;
switch (oops_dump_mode) {
case DUMP_ALL:
iter.cpu_file = TRACE_PIPE_ALL_CPU;
break;
case DUMP_ORIG:
iter.cpu_file = raw_smp_processor_id();
break;
case DUMP_NONE:
goto out_enable;
default:
printk(KERN_TRACE "Bad dumping mode, switching to all CPUs dump\n");
iter.cpu_file = TRACE_PIPE_ALL_CPU;
}
printk(KERN_TRACE "Dumping ftrace buffer:\n");
/*
* We need to stop all tracing on all CPUS to read the
* the next buffer. This is a bit expensive, but is
* not done often. We fill all what we can read,
* and then release the locks again.
*/
while (!trace_empty(&iter)) {
if (!cnt)
printk(KERN_TRACE "---------------------------------\n");
cnt++;
/* reset all but tr, trace, and overruns */
memset(&iter.seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;
if (trace_find_next_entry_inc(&iter) != NULL) {
int ret;
ret = print_trace_line(&iter);
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(&iter);
}
trace_printk_seq(&iter.seq);
}
if (!cnt)
printk(KERN_TRACE " (ftrace buffer empty)\n");
else
printk(KERN_TRACE "---------------------------------\n");
out_enable:
/* Re-enable tracing if requested */
if (!disable_tracing) {
trace_flags |= old_userobj;
for_each_tracing_cpu(cpu) {
atomic_dec(&iter.tr->data[cpu]->disabled);
}
tracing_on();
}
out:
arch_spin_unlock(&ftrace_dump_lock);
local_irq_restore(flags);
}
/* By default: disable tracing after the dump */
void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
{
__ftrace_dump(true, oops_dump_mode);
}
__init static int tracer_alloc_buffers(void)
{
int ring_buf_size;
int i;
int ret = -ENOMEM;
if (!alloc_cpumask_var(&tracing_buffer_mask, GFP_KERNEL))
goto out;
if (!alloc_cpumask_var(&tracing_cpumask, GFP_KERNEL))
goto out_free_buffer_mask;
/* To save memory, keep the ring buffer size to its minimum */
if (ring_buffer_expanded)
ring_buf_size = trace_buf_size;
else
ring_buf_size = 1;
cpumask_copy(tracing_buffer_mask, cpu_possible_mask);
cpumask_copy(tracing_cpumask, cpu_all_mask);
/* TODO: make the number of buffers hot pluggable with CPUS */
global_trace.buffer = ring_buffer_alloc(ring_buf_size,
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(1, 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 = 1;
#endif
/* Allocate the first page for all buffers */
for_each_tracing_cpu(i) {
global_trace.data[i] = &per_cpu(global_trace_cpu, i);
max_tr.data[i] = &per_cpu(max_tr_data, i);
}
trace_init_cmdlines();
register_tracer(&nop_trace);
current_trace = &nop_trace;
/* All seems OK, enable tracing */
tracing_disabled = 0;
atomic_notifier_chain_register(&panic_notifier_list,
&trace_panic_notifier);
register_die_notifier(&trace_die_notifier);
return 0;
out_free_cpumask:
free_cpumask_var(tracing_cpumask);
out_free_buffer_mask:
free_cpumask_var(tracing_buffer_mask);
out:
return ret;
}
__init static int clear_boot_tracer(void)
{
/*
* The default tracer at boot buffer is an init section.
* This function is called in lateinit. If we did not
* find the boot tracer, then clear it out, to prevent
* later registration from accessing the buffer that is
* about to be freed.
*/
if (!default_bootup_tracer)
return 0;
printk(KERN_INFO "ftrace bootup tracer '%s' not registered.\n",
default_bootup_tracer);
default_bootup_tracer = NULL;
return 0;
}
early_initcall(tracer_alloc_buffers);
fs_initcall(tracer_init_debugfs);
late_initcall(clear_boot_tracer);
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