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linux-pinenote/kernel/trace/trace.c
Steven Rostedt 5aa1ba6a6c ftrace: prevent ftrace_special from recursion 
Impact: stop ftrace_special from recursion

The ftrace_special is used to help debug areas of the kernel.
Because of this, if it is put in certain locations, the fact that
it allows recursion can become a problem if the kernel developer
using does not realize that.

This patch changes ftrace_special to not allow recursion into itself
to make it more robust.

It also changes from preempt disable interrupts disable to prevent
any loss of trace entries.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-11 09:40:29 +01:00

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/*
* ring buffer based function tracer
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
* Originally taken from the RT patch by:
* Arnaldo Carvalho de Melo <acme@redhat.com>
*
* Based on code from the latency_tracer, that is:
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
#include <linux/utsrelease.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/debugfs.h>
#include <linux/pagemap.h>
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include <linux/kdebug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/gfp.h>
#include <linux/fs.h>
#include <linux/kprobes.h>
#include <linux/writeback.h>
#include <linux/stacktrace.h>
#include <linux/ring_buffer.h>
#include <linux/irqflags.h>
#include "trace.h"
#define TRACE_BUFFER_FLAGS (RB_FL_OVERWRITE)
unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX;
unsigned long __read_mostly tracing_thresh;
/*
* Kill all tracing for good (never come back).
* It is initialized to 1 but will turn to zero if the initialization
* of the tracer is successful. But that is the only place that sets
* this back to zero.
*/
int tracing_disabled = 1;
static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);
static inline void ftrace_disable_cpu(void)
{
preempt_disable();
local_inc(&__get_cpu_var(ftrace_cpu_disabled));
}
static inline void ftrace_enable_cpu(void)
{
local_dec(&__get_cpu_var(ftrace_cpu_disabled));
preempt_enable();
}
static cpumask_t __read_mostly tracing_buffer_mask;
#define for_each_tracing_cpu(cpu) \
for_each_cpu_mask(cpu, tracing_buffer_mask)
/*
* ftrace_dump_on_oops - variable to dump ftrace buffer on oops
*
* If there is an oops (or kernel panic) and the ftrace_dump_on_oops
* is set, then ftrace_dump is called. This will output the contents
* of the ftrace buffers to the console. This is very useful for
* capturing traces that lead to crashes and outputing it to a
* serial console.
*
* It is default off, but you can enable it with either specifying
* "ftrace_dump_on_oops" in the kernel command line, or setting
* /proc/sys/kernel/ftrace_dump_on_oops to true.
*/
int ftrace_dump_on_oops;
static int tracing_set_tracer(char *buf);
static int __init set_ftrace(char *str)
{
tracing_set_tracer(str);
return 1;
}
__setup("ftrace", set_ftrace);
static int __init set_ftrace_dump_on_oops(char *str)
{
ftrace_dump_on_oops = 1;
return 1;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
long
ns2usecs(cycle_t nsec)
{
nsec += 500;
do_div(nsec, 1000);
return nsec;
}
cycle_t ftrace_now(int cpu)
{
u64 ts = ring_buffer_time_stamp(cpu);
ring_buffer_normalize_time_stamp(cpu, &ts);
return ts;
}
/*
* The global_trace is the descriptor that holds the tracing
* buffers for the live tracing. For each CPU, it contains
* a link list of pages that will store trace entries. The
* page descriptor of the pages in the memory is used to hold
* the link list by linking the lru item in the page descriptor
* to each of the pages in the buffer per CPU.
*
* For each active CPU there is a data field that holds the
* pages for the buffer for that CPU. Each CPU has the same number
* of pages allocated for its buffer.
*/
static struct trace_array global_trace;
static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);
/*
* The max_tr is used to snapshot the global_trace when a maximum
* latency is reached. Some tracers will use this to store a maximum
* trace while it continues examining live traces.
*
* The buffers for the max_tr are set up the same as the global_trace.
* When a snapshot is taken, the link list of the max_tr is swapped
* with the link list of the global_trace and the buffers are reset for
* the global_trace so the tracing can continue.
*/
static struct trace_array max_tr;
static DEFINE_PER_CPU(struct trace_array_cpu, max_data);
/* tracer_enabled is used to toggle activation of a tracer */
static int tracer_enabled = 1;
/**
* tracing_is_enabled - return tracer_enabled status
*
* This function is used by other tracers to know the status
* of the tracer_enabled flag. Tracers may use this function
* to know if it should enable their features when starting
* up. See irqsoff tracer for an example (start_irqsoff_tracer).
*/
int tracing_is_enabled(void)
{
return tracer_enabled;
}
/* function tracing enabled */
int ftrace_function_enabled;
/*
* trace_buf_size is the size in bytes that is allocated
* for a buffer. Note, the number of bytes is always rounded
* to page size.
*
* This number is purposely set to a low number of 16384.
* If the dump on oops happens, it will be much appreciated
* to not have to wait for all that output. Anyway this can be
* boot time and run time configurable.
*/
#define TRACE_BUF_SIZE_DEFAULT 1441792UL /* 16384 * 88 (sizeof(entry)) */
static unsigned long trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
/* trace_types holds a link list of available tracers. */
static struct tracer *trace_types __read_mostly;
/* current_trace points to the tracer that is currently active */
static struct tracer *current_trace __read_mostly;
/*
* max_tracer_type_len is used to simplify the allocating of
* buffers to read userspace tracer names. We keep track of
* the longest tracer name registered.
*/
static int max_tracer_type_len;
/*
* trace_types_lock is used to protect the trace_types list.
* This lock is also used to keep user access serialized.
* Accesses from userspace will grab this lock while userspace
* activities happen inside the kernel.
*/
static DEFINE_MUTEX(trace_types_lock);
/* trace_wait is a waitqueue for tasks blocked on trace_poll */
static DECLARE_WAIT_QUEUE_HEAD(trace_wait);
/* trace_flags holds iter_ctrl options */
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK;
/**
* trace_wake_up - wake up tasks waiting for trace input
*
* Simply wakes up any task that is blocked on the trace_wait
* queue. These is used with trace_poll for tasks polling the trace.
*/
void trace_wake_up(void)
{
/*
* The runqueue_is_locked() can fail, but this is the best we
* have for now:
*/
if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
wake_up(&trace_wait);
}
static int __init set_buf_size(char *str)
{
unsigned long buf_size;
int ret;
if (!str)
return 0;
ret = strict_strtoul(str, 0, &buf_size);
/* nr_entries can not be zero */
if (ret < 0 || buf_size == 0)
return 0;
trace_buf_size = buf_size;
return 1;
}
__setup("trace_buf_size=", set_buf_size);
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
return nsecs / 1000;
}
/*
* TRACE_ITER_SYM_MASK masks the options in trace_flags that
* control the output of kernel symbols.
*/
#define TRACE_ITER_SYM_MASK \
(TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
/* These must match the bit postions in trace_iterator_flags */
static const char *trace_options[] = {
"print-parent",
"sym-offset",
"sym-addr",
"verbose",
"raw",
"hex",
"bin",
"block",
"stacktrace",
"sched-tree",
"ftrace_printk",
"ftrace_preempt",
NULL
};
/*
* ftrace_max_lock is used to protect the swapping of buffers
* when taking a max snapshot. The buffers themselves are
* protected by per_cpu spinlocks. But the action of the swap
* needs its own lock.
*
* This is defined as a raw_spinlock_t in order to help
* with performance when lockdep debugging is enabled.
*/
static raw_spinlock_t ftrace_max_lock =
(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
/*
* Copy the new maximum trace into the separate maximum-trace
* structure. (this way the maximum trace is permanently saved,
* for later retrieval via /debugfs/tracing/latency_trace)
*/
static void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct trace_array_cpu *data = tr->data[cpu];
max_tr.cpu = cpu;
max_tr.time_start = data->preempt_timestamp;
data = max_tr.data[cpu];
data->saved_latency = tracing_max_latency;
memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
data->pid = tsk->pid;
data->uid = tsk->uid;
data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
data->policy = tsk->policy;
data->rt_priority = tsk->rt_priority;
/* record this tasks comm */
tracing_record_cmdline(current);
}
/**
* trace_seq_printf - sequence printing of trace information
* @s: trace sequence descriptor
* @fmt: printf format string
*
* The tracer may use either sequence operations or its own
* copy to user routines. To simplify formating of a trace
* trace_seq_printf is used to store strings into a special
* buffer (@s). Then the output may be either used by
* the sequencer or pulled into another buffer.
*/
int
trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
{
int len = (PAGE_SIZE - 1) - s->len;
va_list ap;
int ret;
if (!len)
return 0;
va_start(ap, fmt);
ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
va_end(ap);
/* If we can't write it all, don't bother writing anything */
if (ret >= len)
return 0;
s->len += ret;
return len;
}
/**
* trace_seq_puts - trace sequence printing of simple string
* @s: trace sequence descriptor
* @str: simple string to record
*
* The tracer may use either the sequence operations or its own
* copy to user routines. This function records a simple string
* into a special buffer (@s) for later retrieval by a sequencer
* or other mechanism.
*/
static int
trace_seq_puts(struct trace_seq *s, const char *str)
{
int len = strlen(str);
if (len > ((PAGE_SIZE - 1) - s->len))
return 0;
memcpy(s->buffer + s->len, str, len);
s->len += len;
return len;
}
static int
trace_seq_putc(struct trace_seq *s, unsigned char c)
{
if (s->len >= (PAGE_SIZE - 1))
return 0;
s->buffer[s->len++] = c;
return 1;
}
static int
trace_seq_putmem(struct trace_seq *s, void *mem, size_t len)
{
if (len > ((PAGE_SIZE - 1) - s->len))
return 0;
memcpy(s->buffer + s->len, mem, len);
s->len += len;
return len;
}
#define MAX_MEMHEX_BYTES 8
#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
static int
trace_seq_putmem_hex(struct trace_seq *s, void *mem, size_t len)
{
unsigned char hex[HEX_CHARS];
unsigned char *data = mem;
int i, j;
#ifdef __BIG_ENDIAN
for (i = 0, j = 0; i < len; i++) {
#else
for (i = len-1, j = 0; i >= 0; i--) {
#endif
hex[j++] = hex_asc_hi(data[i]);
hex[j++] = hex_asc_lo(data[i]);
}
hex[j++] = ' ';
return trace_seq_putmem(s, hex, j);
}
static void
trace_seq_reset(struct trace_seq *s)
{
s->len = 0;
s->readpos = 0;
}
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
int len;
int ret;
if (s->len <= s->readpos)
return -EBUSY;
len = s->len - s->readpos;
if (cnt > len)
cnt = len;
ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
if (ret)
return -EFAULT;
s->readpos += len;
return cnt;
}
static void
trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;
s->buffer[len] = 0;
seq_puts(m, s->buffer);
trace_seq_reset(s);
}
/**
* update_max_tr - snapshot all trace buffers from global_trace to max_tr
* @tr: tracer
* @tsk: the task with the latency
* @cpu: The cpu that initiated the trace.
*
* Flip the buffers between the @tr and the max_tr and record information
* about which task was the cause of this latency.
*/
void
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
struct ring_buffer *buf = tr->buffer;
WARN_ON_ONCE(!irqs_disabled());
__raw_spin_lock(&ftrace_max_lock);
tr->buffer = max_tr.buffer;
max_tr.buffer = buf;
ftrace_disable_cpu();
ring_buffer_reset(tr->buffer);
ftrace_enable_cpu();
__update_max_tr(tr, tsk, cpu);
__raw_spin_unlock(&ftrace_max_lock);
}
/**
* update_max_tr_single - only copy one trace over, and reset the rest
* @tr - tracer
* @tsk - task with the latency
* @cpu - the cpu of the buffer to copy.
*
* Flip the trace of a single CPU buffer between the @tr and the max_tr.
*/
void
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
int ret;
WARN_ON_ONCE(!irqs_disabled());
__raw_spin_lock(&ftrace_max_lock);
ftrace_disable_cpu();
ring_buffer_reset(max_tr.buffer);
ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);
ftrace_enable_cpu();
WARN_ON_ONCE(ret);
__update_max_tr(tr, tsk, cpu);
__raw_spin_unlock(&ftrace_max_lock);
}
/**
* register_tracer - register a tracer with the ftrace system.
* @type - the plugin for the tracer
*
* Register a new plugin tracer.
*/
int register_tracer(struct tracer *type)
{
struct tracer *t;
int len;
int ret = 0;
if (!type->name) {
pr_info("Tracer must have a name\n");
return -1;
}
mutex_lock(&trace_types_lock);
for (t = trace_types; t; t = t->next) {
if (strcmp(type->name, t->name) == 0) {
/* already found */
pr_info("Trace %s already registered\n",
type->name);
ret = -1;
goto out;
}
}
#ifdef CONFIG_FTRACE_STARTUP_TEST
if (type->selftest) {
struct tracer *saved_tracer = current_trace;
struct trace_array *tr = &global_trace;
int i;
/*
* Run a selftest on this tracer.
* Here we reset the trace buffer, and set the current
* tracer to be this tracer. The tracer can then run some
* internal tracing to verify that everything is in order.
* If we fail, we do not register this tracer.
*/
for_each_tracing_cpu(i) {
tracing_reset(tr, i);
}
current_trace = type;
/* the test is responsible for initializing and enabling */
pr_info("Testing tracer %s: ", type->name);
ret = type->selftest(type, tr);
/* the test is responsible for resetting too */
current_trace = saved_tracer;
if (ret) {
printk(KERN_CONT "FAILED!\n");
goto out;
}
/* Only reset on passing, to avoid touching corrupted buffers */
for_each_tracing_cpu(i) {
tracing_reset(tr, i);
}
printk(KERN_CONT "PASSED\n");
}
#endif
type->next = trace_types;
trace_types = type;
len = strlen(type->name);
if (len > max_tracer_type_len)
max_tracer_type_len = len;
out:
mutex_unlock(&trace_types_lock);
return ret;
}
void unregister_tracer(struct tracer *type)
{
struct tracer **t;
int len;
mutex_lock(&trace_types_lock);
for (t = &trace_types; *t; t = &(*t)->next) {
if (*t == type)
goto found;
}
pr_info("Trace %s not registered\n", type->name);
goto out;
found:
*t = (*t)->next;
if (strlen(type->name) != max_tracer_type_len)
goto out;
max_tracer_type_len = 0;
for (t = &trace_types; *t; t = &(*t)->next) {
len = strlen((*t)->name);
if (len > max_tracer_type_len)
max_tracer_type_len = len;
}
out:
mutex_unlock(&trace_types_lock);
}
void tracing_reset(struct trace_array *tr, int cpu)
{
ftrace_disable_cpu();
ring_buffer_reset_cpu(tr->buffer, cpu);
ftrace_enable_cpu();
}
#define SAVED_CMDLINES 128
static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
static int cmdline_idx;
static DEFINE_SPINLOCK(trace_cmdline_lock);
/* temporary disable recording */
atomic_t trace_record_cmdline_disabled __read_mostly;
static void trace_init_cmdlines(void)
{
memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
cmdline_idx = 0;
}
static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);
/**
* tracing_start - quick start of the tracer
*
* If tracing is enabled but was stopped by tracing_stop,
* this will start the tracer back up.
*/
void tracing_start(void)
{
struct ring_buffer *buffer;
unsigned long flags;
if (tracing_disabled)
return;
spin_lock_irqsave(&tracing_start_lock, flags);
if (--trace_stop_count)
goto out;
if (trace_stop_count < 0) {
/* Someone screwed up their debugging */
WARN_ON_ONCE(1);
trace_stop_count = 0;
goto out;
}
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_enable(buffer);
ftrace_start();
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
/**
* tracing_stop - quick stop of the tracer
*
* Light weight way to stop tracing. Use in conjunction with
* tracing_start.
*/
void tracing_stop(void)
{
struct ring_buffer *buffer;
unsigned long flags;
ftrace_stop();
spin_lock_irqsave(&tracing_start_lock, flags);
if (trace_stop_count++)
goto out;
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
out:
spin_unlock_irqrestore(&tracing_start_lock, flags);
}
void trace_stop_cmdline_recording(void);
static void trace_save_cmdline(struct task_struct *tsk)
{
unsigned map;
unsigned idx;
if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
return;
/*
* It's not the end of the world if we don't get
* the lock, but we also don't want to spin
* nor do we want to disable interrupts,
* so if we miss here, then better luck next time.
*/
if (!spin_trylock(&trace_cmdline_lock))
return;
idx = map_pid_to_cmdline[tsk->pid];
if (idx >= SAVED_CMDLINES) {
idx = (cmdline_idx + 1) % SAVED_CMDLINES;
map = map_cmdline_to_pid[idx];
if (map <= PID_MAX_DEFAULT)
map_pid_to_cmdline[map] = (unsigned)-1;
map_pid_to_cmdline[tsk->pid] = idx;
cmdline_idx = idx;
}
memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
spin_unlock(&trace_cmdline_lock);
}
static char *trace_find_cmdline(int pid)
{
char *cmdline = "<...>";
unsigned map;
if (!pid)
return "<idle>";
if (pid > PID_MAX_DEFAULT)
goto out;
map = map_pid_to_cmdline[pid];
if (map >= SAVED_CMDLINES)
goto out;
cmdline = saved_cmdlines[map];
out:
return cmdline;
}
void tracing_record_cmdline(struct task_struct *tsk)
{
if (atomic_read(&trace_record_cmdline_disabled))
return;
trace_save_cmdline(tsk);
}
void
tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
int pc)
{
struct task_struct *tsk = current;
entry->preempt_count = pc & 0xff;
entry->pid = (tsk) ? tsk->pid : 0;
entry->flags =
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
#else
TRACE_FLAG_IRQS_NOSUPPORT |
#endif
((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
}
void
trace_function(struct trace_array *tr, struct trace_array_cpu *data,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
struct ring_buffer_event *event;
struct ftrace_entry *entry;
unsigned long irq_flags;
/* If we are reading the ring buffer, don't trace */
if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
return;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_FN;
entry->ip = ip;
entry->parent_ip = parent_ip;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
}
void
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
int pc)
{
if (likely(!atomic_read(&data->disabled)))
trace_function(tr, data, ip, parent_ip, flags, pc);
}
static void ftrace_trace_stack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags,
int skip, int pc)
{
#ifdef CONFIG_STACKTRACE
struct ring_buffer_event *event;
struct stack_entry *entry;
struct stack_trace trace;
unsigned long irq_flags;
if (!(trace_flags & TRACE_ITER_STACKTRACE))
return;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_STACK;
memset(&entry->caller, 0, sizeof(entry->caller));
trace.nr_entries = 0;
trace.max_entries = FTRACE_STACK_ENTRIES;
trace.skip = skip;
trace.entries = entry->caller;
save_stack_trace(&trace);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
#endif
}
void __trace_stack(struct trace_array *tr,
struct trace_array_cpu *data,
unsigned long flags,
int skip)
{
ftrace_trace_stack(tr, data, flags, skip, preempt_count());
}
static void
ftrace_trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3,
int pc)
{
struct ring_buffer_event *event;
struct trace_array_cpu *data = __data;
struct trace_array *tr = __tr;
struct special_entry *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, 0, pc);
entry->ent.type = TRACE_SPECIAL;
entry->arg1 = arg1;
entry->arg2 = arg2;
entry->arg3 = arg3;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, irq_flags, 4, pc);
trace_wake_up();
}
void
__trace_special(void *__tr, void *__data,
unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
ftrace_trace_special(__tr, __data, arg1, arg2, arg3, preempt_count());
}
void
tracing_sched_switch_trace(struct trace_array *tr,
struct trace_array_cpu *data,
struct task_struct *prev,
struct task_struct *next,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_CTX;
entry->prev_pid = prev->pid;
entry->prev_prio = prev->prio;
entry->prev_state = prev->state;
entry->next_pid = next->pid;
entry->next_prio = next->prio;
entry->next_state = next->state;
entry->next_cpu = task_cpu(next);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 5, pc);
}
void
tracing_sched_wakeup_trace(struct trace_array *tr,
struct trace_array_cpu *data,
struct task_struct *wakee,
struct task_struct *curr,
unsigned long flags, int pc)
{
struct ring_buffer_event *event;
struct ctx_switch_entry *entry;
unsigned long irq_flags;
event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
&irq_flags);
if (!event)
return;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_WAKE;
entry->prev_pid = curr->pid;
entry->prev_prio = curr->prio;
entry->prev_state = curr->state;
entry->next_pid = wakee->pid;
entry->next_prio = wakee->prio;
entry->next_state = wakee->state;
entry->next_cpu = task_cpu(wakee);
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
ftrace_trace_stack(tr, data, flags, 6, pc);
trace_wake_up();
}
void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
unsigned long flags;
int cpu;
int pc;
if (tracing_disabled)
return;
pc = preempt_count();
local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
if (likely(atomic_inc_return(&data->disabled) == 1))
ftrace_trace_special(tr, data, arg1, arg2, arg3, pc);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
#ifdef CONFIG_FUNCTION_TRACER
static void
function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu, resched;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
pc = preempt_count();
resched = ftrace_preempt_disable();
local_save_flags(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1))
trace_function(tr, data, ip, parent_ip, flags, pc);
atomic_dec(&data->disabled);
ftrace_preempt_enable(resched);
}
static void
function_trace_call(unsigned long ip, unsigned long parent_ip)
{
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
unsigned long flags;
long disabled;
int cpu;
int pc;
if (unlikely(!ftrace_function_enabled))
return;
/*
* Need to use raw, since this must be called before the
* recursive protection is performed.
*/
raw_local_irq_save(flags);
cpu = raw_smp_processor_id();
data = tr->data[cpu];
disabled = atomic_inc_return(&data->disabled);
if (likely(disabled == 1)) {
pc = preempt_count();
trace_function(tr, data, ip, parent_ip, flags, pc);
}
atomic_dec(&data->disabled);
raw_local_irq_restore(flags);
}
static struct ftrace_ops trace_ops __read_mostly =
{
.func = function_trace_call,
};
void tracing_start_function_trace(void)
{
ftrace_function_enabled = 0;
if (trace_flags & TRACE_ITER_PREEMPTONLY)
trace_ops.func = function_trace_call_preempt_only;
else
trace_ops.func = function_trace_call;
register_ftrace_function(&trace_ops);
ftrace_function_enabled = 1;
}
void tracing_stop_function_trace(void)
{
ftrace_function_enabled = 0;
unregister_ftrace_function(&trace_ops);
}
#endif
enum trace_file_type {
TRACE_FILE_LAT_FMT = 1,
};
static void trace_iterator_increment(struct trace_iterator *iter, int cpu)
{
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
iter->idx++;
if (iter->buffer_iter[iter->cpu])
ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
ftrace_enable_cpu();
}
static struct trace_entry *
peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts)
{
struct ring_buffer_event *event;
struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
if (buf_iter)
event = ring_buffer_iter_peek(buf_iter, ts);
else
event = ring_buffer_peek(iter->tr->buffer, cpu, ts);
ftrace_enable_cpu();
return event ? ring_buffer_event_data(event) : NULL;
}
static struct trace_entry *
__find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
{
struct ring_buffer *buffer = iter->tr->buffer;
struct trace_entry *ent, *next = NULL;
u64 next_ts = 0, ts;
int next_cpu = -1;
int cpu;
for_each_tracing_cpu(cpu) {
if (ring_buffer_empty_cpu(buffer, cpu))
continue;
ent = peek_next_entry(iter, cpu, &ts);
/*
* Pick the entry with the smallest timestamp:
*/
if (ent && (!next || ts < next_ts)) {
next = ent;
next_cpu = cpu;
next_ts = ts;
}
}
if (ent_cpu)
*ent_cpu = next_cpu;
if (ent_ts)
*ent_ts = next_ts;
return next;
}
/* Find the next real entry, without updating the iterator itself */
static struct trace_entry *
find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
{
return __find_next_entry(iter, ent_cpu, ent_ts);
}
/* Find the next real entry, and increment the iterator to the next entry */
static void *find_next_entry_inc(struct trace_iterator *iter)
{
iter->ent = __find_next_entry(iter, &iter->cpu, &iter->ts);
if (iter->ent)
trace_iterator_increment(iter, iter->cpu);
return iter->ent ? iter : NULL;
}
static void trace_consume(struct trace_iterator *iter)
{
/* Don't allow ftrace to trace into the ring buffers */
ftrace_disable_cpu();
ring_buffer_consume(iter->tr->buffer, iter->cpu, &iter->ts);
ftrace_enable_cpu();
}
static void *s_next(struct seq_file *m, void *v, loff_t *pos)
{
struct trace_iterator *iter = m->private;
int i = (int)*pos;
void *ent;
(*pos)++;
/* can't go backwards */
if (iter->idx > i)
return NULL;
if (iter->idx < 0)
ent = find_next_entry_inc(iter);
else
ent = iter;
while (ent && iter->idx < i)
ent = find_next_entry_inc(iter);
iter->pos = *pos;
return ent;
}
static void *s_start(struct seq_file *m, loff_t *pos)
{
struct trace_iterator *iter = m->private;
void *p = NULL;
loff_t l = 0;
int cpu;
mutex_lock(&trace_types_lock);
if (!current_trace || current_trace != iter->trace) {
mutex_unlock(&trace_types_lock);
return NULL;
}
atomic_inc(&trace_record_cmdline_disabled);
if (*pos != iter->pos) {
iter->ent = NULL;
iter->cpu = 0;
iter->idx = -1;
ftrace_disable_cpu();
for_each_tracing_cpu(cpu) {
ring_buffer_iter_reset(iter->buffer_iter[cpu]);
}
ftrace_enable_cpu();
for (p = iter; p && l < *pos; p = s_next(m, p, &l))
;
} else {
l = *pos - 1;
p = s_next(m, p, &l);
}
return p;
}
static void s_stop(struct seq_file *m, void *p)
{
atomic_dec(&trace_record_cmdline_disabled);
mutex_unlock(&trace_types_lock);
}
#ifdef CONFIG_KRETPROBES
static inline const char *kretprobed(const char *name)
{
static const char tramp_name[] = "kretprobe_trampoline";
int size = sizeof(tramp_name);
if (strncmp(tramp_name, name, size) == 0)
return "[unknown/kretprobe'd]";
return name;
}
#else
static inline const char *kretprobed(const char *name)
{
return name;
}
#endif /* CONFIG_KRETPROBES */
static int
seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
{
#ifdef CONFIG_KALLSYMS
char str[KSYM_SYMBOL_LEN];
const char *name;
kallsyms_lookup(address, NULL, NULL, NULL, str);
name = kretprobed(str);
return trace_seq_printf(s, fmt, name);
#endif
return 1;
}
static int
seq_print_sym_offset(struct trace_seq *s, const char *fmt,
unsigned long address)
{
#ifdef CONFIG_KALLSYMS
char str[KSYM_SYMBOL_LEN];
const char *name;
sprint_symbol(str, address);
name = kretprobed(str);
return trace_seq_printf(s, fmt, name);
#endif
return 1;
}
#ifndef CONFIG_64BIT
# define IP_FMT "%08lx"
#else
# define IP_FMT "%016lx"
#endif
static int
seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
{
int ret;
if (!ip)
return trace_seq_printf(s, "0");
if (sym_flags & TRACE_ITER_SYM_OFFSET)
ret = seq_print_sym_offset(s, "%s", ip);
else
ret = seq_print_sym_short(s, "%s", ip);
if (!ret)
return 0;
if (sym_flags & TRACE_ITER_SYM_ADDR)
ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
return ret;
}
static void print_lat_help_header(struct seq_file *m)
{
seq_puts(m, "# _------=> CPU# \n");
seq_puts(m, "# / _-----=> irqs-off \n");
seq_puts(m, "# | / _----=> need-resched \n");
seq_puts(m, "# || / _---=> hardirq/softirq \n");
seq_puts(m, "# ||| / _--=> preempt-depth \n");
seq_puts(m, "# |||| / \n");
seq_puts(m, "# ||||| delay \n");
seq_puts(m, "# cmd pid ||||| time | caller \n");
seq_puts(m, "# \\ / ||||| \\ | / \n");
}
static void print_func_help_header(struct seq_file *m)
{
seq_puts(m, "# TASK-PID CPU# TIMESTAMP FUNCTION\n");
seq_puts(m, "# | | | | |\n");
}
static void
print_trace_header(struct seq_file *m, struct trace_iterator *iter)
{
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_array *tr = iter->tr;
struct trace_array_cpu *data = tr->data[tr->cpu];
struct tracer *type = current_trace;
unsigned long total;
unsigned long entries;
const char *name = "preemption";
if (type)
name = type->name;
entries = ring_buffer_entries(iter->tr->buffer);
total = entries +
ring_buffer_overruns(iter->tr->buffer);
seq_printf(m, "%s latency trace v1.1.5 on %s\n",
name, UTS_RELEASE);
seq_puts(m, "-----------------------------------"
"---------------------------------\n");
seq_printf(m, " latency: %lu us, #%lu/%lu, CPU#%d |"
" (M:%s VP:%d, KP:%d, SP:%d HP:%d",
nsecs_to_usecs(data->saved_latency),
entries,
total,
tr->cpu,
#if defined(CONFIG_PREEMPT_NONE)
"server",
#elif defined(CONFIG_PREEMPT_VOLUNTARY)
"desktop",
#elif defined(CONFIG_PREEMPT)
"preempt",
#else
"unknown",
#endif
/* These are reserved for later use */
0, 0, 0, 0);
#ifdef CONFIG_SMP
seq_printf(m, " #P:%d)\n", num_online_cpus());
#else
seq_puts(m, ")\n");
#endif
seq_puts(m, " -----------------\n");
seq_printf(m, " | task: %.16s-%d "
"(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
data->comm, data->pid, data->uid, data->nice,
data->policy, data->rt_priority);
seq_puts(m, " -----------------\n");
if (data->critical_start) {
seq_puts(m, " => started at: ");
seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
trace_print_seq(m, &iter->seq);
seq_puts(m, "\n => ended at: ");
seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
trace_print_seq(m, &iter->seq);
seq_puts(m, "\n");
}
seq_puts(m, "\n");
}
static void
lat_print_generic(struct trace_seq *s, struct trace_entry *entry, int cpu)
{
int hardirq, softirq;
char *comm;
comm = trace_find_cmdline(entry->pid);
trace_seq_printf(s, "%8.8s-%-5d ", comm, entry->pid);
trace_seq_printf(s, "%3d", cpu);
trace_seq_printf(s, "%c%c",
(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
(entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' : '.',
((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
if (hardirq && softirq) {
trace_seq_putc(s, 'H');
} else {
if (hardirq) {
trace_seq_putc(s, 'h');
} else {
if (softirq)
trace_seq_putc(s, 's');
else
trace_seq_putc(s, '.');
}
}
if (entry->preempt_count)
trace_seq_printf(s, "%x", entry->preempt_count);
else
trace_seq_puts(s, ".");
}
unsigned long preempt_mark_thresh = 100;
static void
lat_print_timestamp(struct trace_seq *s, u64 abs_usecs,
unsigned long rel_usecs)
{
trace_seq_printf(s, " %4lldus", abs_usecs);
if (rel_usecs > preempt_mark_thresh)
trace_seq_puts(s, "!: ");
else if (rel_usecs > 1)
trace_seq_puts(s, "+: ");
else
trace_seq_puts(s, " : ");
}
static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;
/*
* The message is supposed to contain an ending newline.
* If the printing stops prematurely, try to add a newline of our own.
*/
void trace_seq_print_cont(struct trace_seq *s, struct trace_iterator *iter)
{
struct trace_entry *ent;
struct trace_field_cont *cont;
bool ok = true;
ent = peek_next_entry(iter, iter->cpu, NULL);
if (!ent || ent->type != TRACE_CONT) {
trace_seq_putc(s, '\n');
return;
}
do {
cont = (struct trace_field_cont *)ent;
if (ok)
ok = (trace_seq_printf(s, "%s", cont->buf) > 0);
ftrace_disable_cpu();
if (iter->buffer_iter[iter->cpu])
ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);
else
ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
ftrace_enable_cpu();
ent = peek_next_entry(iter, iter->cpu, NULL);
} while (ent && ent->type == TRACE_CONT);
if (!ok)
trace_seq_putc(s, '\n');
}
static void test_cpu_buff_start(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
if (cpu_isset(iter->cpu, iter->started))
return;
cpu_set(iter->cpu, iter->started);
trace_seq_printf(s, "##### CPU %u buffer started ####\n", iter->cpu);
}
static enum print_line_t
print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
{
struct trace_seq *s = &iter->seq;
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_entry *next_entry;
unsigned long verbose = (trace_flags & TRACE_ITER_VERBOSE);
struct trace_entry *entry = iter->ent;
unsigned long abs_usecs;
unsigned long rel_usecs;
u64 next_ts;
char *comm;
int S, T;
int i;
unsigned state;
if (entry->type == TRACE_CONT)
return TRACE_TYPE_HANDLED;
test_cpu_buff_start(iter);
next_entry = find_next_entry(iter, NULL, &next_ts);
if (!next_entry)
next_ts = iter->ts;
rel_usecs = ns2usecs(next_ts - iter->ts);
abs_usecs = ns2usecs(iter->ts - iter->tr->time_start);
if (verbose) {
comm = trace_find_cmdline(entry->pid);
trace_seq_printf(s, "%16s %5d %3d %d %08x %08x [%08lx]"
" %ld.%03ldms (+%ld.%03ldms): ",
comm,
entry->pid, cpu, entry->flags,
entry->preempt_count, trace_idx,
ns2usecs(iter->ts),
abs_usecs/1000,
abs_usecs % 1000, rel_usecs/1000,
rel_usecs % 1000);
} else {
lat_print_generic(s, entry, cpu);
lat_print_timestamp(s, abs_usecs, rel_usecs);
}
switch (entry->type) {
case TRACE_FN: {
struct ftrace_entry *field;
trace_assign_type(field, entry);
seq_print_ip_sym(s, field->ip, sym_flags);
trace_seq_puts(s, " (");
seq_print_ip_sym(s, field->parent_ip, sym_flags);
trace_seq_puts(s, ")\n");
break;
}
case TRACE_CTX:
case TRACE_WAKE: {
struct ctx_switch_entry *field;
trace_assign_type(field, entry);
T = field->next_state < sizeof(state_to_char) ?
state_to_char[field->next_state] : 'X';
state = field->prev_state ?
__ffs(field->prev_state) + 1 : 0;
S = state < sizeof(state_to_char) - 1 ? state_to_char[state] : 'X';
comm = trace_find_cmdline(field->next_pid);
trace_seq_printf(s, " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",
field->prev_pid,
field->prev_prio,
S, entry->type == TRACE_CTX ? "==>" : " +",
field->next_cpu,
field->next_pid,
field->next_prio,
T, comm);
break;
}
case TRACE_SPECIAL: {
struct special_entry *field;
trace_assign_type(field, entry);
trace_seq_printf(s, "# %ld %ld %ld\n",
field->arg1,
field->arg2,
field->arg3);
break;
}
case TRACE_STACK: {
struct stack_entry *field;
trace_assign_type(field, entry);
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
if (i)
trace_seq_puts(s, " <= ");
seq_print_ip_sym(s, field->caller[i], sym_flags);
}
trace_seq_puts(s, "\n");
break;
}
case TRACE_PRINT: {
struct print_entry *field;
trace_assign_type(field, entry);
seq_print_ip_sym(s, field->ip, sym_flags);
trace_seq_printf(s, ": %s", field->buf);
if (entry->flags & TRACE_FLAG_CONT)
trace_seq_print_cont(s, iter);
break;
}
default:
trace_seq_printf(s, "Unknown type %d\n", entry->type);
}
return TRACE_TYPE_HANDLED;
}
static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
struct trace_entry *entry;
unsigned long usec_rem;
unsigned long long t;
unsigned long secs;
char *comm;
int ret;
int S, T;
int i;
entry = iter->ent;
if (entry->type == TRACE_CONT)
return TRACE_TYPE_HANDLED;
test_cpu_buff_start(iter);
comm = trace_find_cmdline(iter->ent->pid);
t = ns2usecs(iter->ts);
usec_rem = do_div(t, 1000000ULL);
secs = (unsigned long)t;
ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, "[%03d] ", iter->cpu);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
switch (entry->type) {
case TRACE_FN: {
struct ftrace_entry *field;
trace_assign_type(field, entry);
ret = seq_print_ip_sym(s, field->ip, sym_flags);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
if ((sym_flags & TRACE_ITER_PRINT_PARENT) &&
field->parent_ip) {
ret = trace_seq_printf(s, " <-");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
ret = seq_print_ip_sym(s,
field->parent_ip,
sym_flags);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = trace_seq_printf(s, "\n");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_CTX:
case TRACE_WAKE: {
struct ctx_switch_entry *field;
trace_assign_type(field, entry);
S = field->prev_state < sizeof(state_to_char) ?
state_to_char[field->prev_state] : 'X';
T = field->next_state < sizeof(state_to_char) ?
state_to_char[field->next_state] : 'X';
ret = trace_seq_printf(s, " %5d:%3d:%c %s [%03d] %5d:%3d:%c\n",
field->prev_pid,
field->prev_prio,
S,
entry->type == TRACE_CTX ? "==>" : " +",
field->next_cpu,
field->next_pid,
field->next_prio,
T);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_SPECIAL: {
struct special_entry *field;
trace_assign_type(field, entry);
ret = trace_seq_printf(s, "# %ld %ld %ld\n",
field->arg1,
field->arg2,
field->arg3);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_STACK: {
struct stack_entry *field;
trace_assign_type(field, entry);
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
if (i) {
ret = trace_seq_puts(s, " <= ");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = seq_print_ip_sym(s, field->caller[i],
sym_flags);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
}
ret = trace_seq_puts(s, "\n");
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_PRINT: {
struct print_entry *field;
trace_assign_type(field, entry);
seq_print_ip_sym(s, field->ip, sym_flags);
trace_seq_printf(s, ": %s", field->buf);
if (entry->flags & TRACE_FLAG_CONT)
trace_seq_print_cont(s, iter);
break;
}
}
return TRACE_TYPE_HANDLED;
}
static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
{
struct trace_seq *s = &iter->seq;
struct trace_entry *entry;
int ret;
int S, T;
entry = iter->ent;
if (entry->type == TRACE_CONT)
return TRACE_TYPE_HANDLED;
ret = trace_seq_printf(s, "%d %d %llu ",
entry->pid, iter->cpu, iter->ts);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
switch (entry->type) {
case TRACE_FN: {
struct ftrace_entry *field;
trace_assign_type(field, entry);
ret = trace_seq_printf(s, "%x %x\n",
field->ip,
field->parent_ip);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_CTX:
case TRACE_WAKE: {
struct ctx_switch_entry *field;
trace_assign_type(field, entry);
S = field->prev_state < sizeof(state_to_char) ?
state_to_char[field->prev_state] : 'X';
T = field->next_state < sizeof(state_to_char) ?
state_to_char[field->next_state] : 'X';
if (entry->type == TRACE_WAKE)
S = '+';
ret = trace_seq_printf(s, "%d %d %c %d %d %d %c\n",
field->prev_pid,
field->prev_prio,
S,
field->next_cpu,
field->next_pid,
field->next_prio,
T);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_SPECIAL:
case TRACE_STACK: {
struct special_entry *field;
trace_assign_type(field, entry);
ret = trace_seq_printf(s, "# %ld %ld %ld\n",
field->arg1,
field->arg2,
field->arg3);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;
break;
}
case TRACE_PRINT: {
struct print_entry *field;
trace_assign_type(field, entry);
trace_seq_printf(s, "# %lx %s", field->ip, field->buf);
if (entry->flags & TRACE_FLAG_CONT)
trace_seq_print_cont(s, iter);
break;
}
}
return TRACE_TYPE_HANDLED;
}
#define SEQ_PUT_FIELD_RET(s, x) \
do { \
if (!trace_seq_putmem(s, &(x), sizeof(x))) \
return 0; \
} while (0)
#define SEQ_PUT_HEX_FIELD_RET(s, x) \
do { \
BUILD_BUG_ON(sizeof(x) > MAX_MEMHEX_BYTES); \
if (!trace_seq_putmem_hex(s, &(x), sizeof(x))) \
return 0; \
} while (0)
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;
int S, T;
entry = iter->ent;
if (entry->type == TRACE_CONT)
return TRACE_TYPE_HANDLED;
SEQ_PUT_HEX_FIELD_RET(s, entry->pid);
SEQ_PUT_HEX_FIELD_RET(s, iter->cpu);
SEQ_PUT_HEX_FIELD_RET(s, iter->ts);
switch (entry->type) {
case TRACE_FN: {
struct ftrace_entry *field;
trace_assign_type(field, entry);
SEQ_PUT_HEX_FIELD_RET(s, field->ip);
SEQ_PUT_HEX_FIELD_RET(s, field->parent_ip);
break;
}
case TRACE_CTX:
case TRACE_WAKE: {
struct ctx_switch_entry *field;
trace_assign_type(field, entry);
S = field->prev_state < sizeof(state_to_char) ?
state_to_char[field->prev_state] : 'X';
T = field->next_state < sizeof(state_to_char) ?
state_to_char[field->next_state] : 'X';
if (entry->type == TRACE_WAKE)
S = '+';
SEQ_PUT_HEX_FIELD_RET(s, field->prev_pid);
SEQ_PUT_HEX_FIELD_RET(s, field->prev_prio);
SEQ_PUT_HEX_FIELD_RET(s, S);
SEQ_PUT_HEX_FIELD_RET(s, field->next_cpu);
SEQ_PUT_HEX_FIELD_RET(s, field->next_pid);
SEQ_PUT_HEX_FIELD_RET(s, field->next_prio);
SEQ_PUT_HEX_FIELD_RET(s, T);
break;
}
case TRACE_SPECIAL:
case TRACE_STACK: {
struct special_entry *field;
trace_assign_type(field, entry);
SEQ_PUT_HEX_FIELD_RET(s, field->arg1);
SEQ_PUT_HEX_FIELD_RET(s, field->arg2);
SEQ_PUT_HEX_FIELD_RET(s, field->arg3);
break;
}
}
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;
entry = iter->ent;
if (entry->type == TRACE_CONT)
return TRACE_TYPE_HANDLED;
SEQ_PUT_FIELD_RET(s, entry->pid);
SEQ_PUT_FIELD_RET(s, entry->cpu);
SEQ_PUT_FIELD_RET(s, iter->ts);
switch (entry->type) {
case TRACE_FN: {
struct ftrace_entry *field;
trace_assign_type(field, entry);
SEQ_PUT_FIELD_RET(s, field->ip);
SEQ_PUT_FIELD_RET(s, field->parent_ip);
break;
}
case TRACE_CTX: {
struct ctx_switch_entry *field;
trace_assign_type(field, entry);
SEQ_PUT_FIELD_RET(s, field->prev_pid);
SEQ_PUT_FIELD_RET(s, field->prev_prio);
SEQ_PUT_FIELD_RET(s, field->prev_state);
SEQ_PUT_FIELD_RET(s, field->next_pid);
SEQ_PUT_FIELD_RET(s, field->next_prio);
SEQ_PUT_FIELD_RET(s, field->next_state);
break;
}
case TRACE_SPECIAL:
case TRACE_STACK: {
struct special_entry *field;
trace_assign_type(field, entry);
SEQ_PUT_FIELD_RET(s, field->arg1);
SEQ_PUT_FIELD_RET(s, field->arg2);
SEQ_PUT_FIELD_RET(s, field->arg3);
break;
}
}
return 1;
}
static int trace_empty(struct trace_iterator *iter)
{
int cpu;
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu]) {
if (!ring_buffer_iter_empty(iter->buffer_iter[cpu]))
return 0;
} else {
if (!ring_buffer_empty_cpu(iter->tr->buffer, cpu))
return 0;
}
}
return 1;
}
static enum print_line_t print_trace_line(struct trace_iterator *iter)
{
enum print_line_t ret;
if (iter->trace && iter->trace->print_line) {
ret = iter->trace->print_line(iter);
if (ret != TRACE_TYPE_UNHANDLED)
return ret;
}
if (trace_flags & TRACE_ITER_BIN)
return print_bin_fmt(iter);
if (trace_flags & TRACE_ITER_HEX)
return print_hex_fmt(iter);
if (trace_flags & TRACE_ITER_RAW)
return print_raw_fmt(iter);
if (iter->iter_flags & TRACE_FILE_LAT_FMT)
return print_lat_fmt(iter, iter->idx, iter->cpu);
return print_trace_fmt(iter);
}
static int s_show(struct seq_file *m, void *v)
{
struct trace_iterator *iter = v;
if (iter->ent == NULL) {
if (iter->tr) {
seq_printf(m, "# tracer: %s\n", iter->trace->name);
seq_puts(m, "#\n");
}
if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
/* print nothing if the buffers are empty */
if (trace_empty(iter))
return 0;
print_trace_header(m, iter);
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_lat_help_header(m);
} else {
if (!(trace_flags & TRACE_ITER_VERBOSE))
print_func_help_header(m);
}
} else {
print_trace_line(iter);
trace_print_seq(m, &iter->seq);
}
return 0;
}
static struct seq_operations tracer_seq_ops = {
.start = s_start,
.next = s_next,
.stop = s_stop,
.show = s_show,
};
static struct trace_iterator *
__tracing_open(struct inode *inode, struct file *file, int *ret)
{
struct trace_iterator *iter;
struct seq_file *m;
int cpu;
if (tracing_disabled) {
*ret = -ENODEV;
return NULL;
}
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter) {
*ret = -ENOMEM;
goto out;
}
mutex_lock(&trace_types_lock);
if (current_trace && current_trace->print_max)
iter->tr = &max_tr;
else
iter->tr = inode->i_private;
iter->trace = current_trace;
iter->pos = -1;
for_each_tracing_cpu(cpu) {
iter->buffer_iter[cpu] =
ring_buffer_read_start(iter->tr->buffer, cpu);
if (!iter->buffer_iter[cpu])
goto fail_buffer;
}
/* TODO stop tracer */
*ret = seq_open(file, &tracer_seq_ops);
if (*ret)
goto fail_buffer;
m = file->private_data;
m->private = iter;
/* stop the trace while dumping */
tracing_stop();
if (iter->trace && iter->trace->open)
iter->trace->open(iter);
mutex_unlock(&trace_types_lock);
out:
return iter;
fail_buffer:
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
mutex_unlock(&trace_types_lock);
return ERR_PTR(-ENOMEM);
}
int tracing_open_generic(struct inode *inode, struct file *filp)
{
if (tracing_disabled)
return -ENODEV;
filp->private_data = inode->i_private;
return 0;
}
int tracing_release(struct inode *inode, struct file *file)
{
struct seq_file *m = (struct seq_file *)file->private_data;
struct trace_iterator *iter = m->private;
int cpu;
mutex_lock(&trace_types_lock);
for_each_tracing_cpu(cpu) {
if (iter->buffer_iter[cpu])
ring_buffer_read_finish(iter->buffer_iter[cpu]);
}
if (iter->trace && iter->trace->close)
iter->trace->close(iter);
/* reenable tracing if it was previously enabled */
tracing_start();
mutex_unlock(&trace_types_lock);
seq_release(inode, file);
kfree(iter);
return 0;
}
static int tracing_open(struct inode *inode, struct file *file)
{
int ret;
__tracing_open(inode, file, &ret);
return ret;
}
static int tracing_lt_open(struct inode *inode, struct file *file)
{
struct trace_iterator *iter;
int ret;
iter = __tracing_open(inode, file, &ret);
if (!ret)
iter->iter_flags |= TRACE_FILE_LAT_FMT;
return ret;
}
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct tracer *t = m->private;
(*pos)++;
if (t)
t = t->next;
m->private = t;
return t;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct tracer *t = m->private;
loff_t l = 0;
mutex_lock(&trace_types_lock);
for (; t && l < *pos; t = t_next(m, t, &l))
;
return t;
}
static void t_stop(struct seq_file *m, void *p)
{
mutex_unlock(&trace_types_lock);
}
static int t_show(struct seq_file *m, void *v)
{
struct tracer *t = v;
if (!t)
return 0;
seq_printf(m, "%s", t->name);
if (t->next)
seq_putc(m, ' ');
else
seq_putc(m, '\n');
return 0;
}
static struct seq_operations show_traces_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int show_traces_open(struct inode *inode, struct file *file)
{
int ret;
if (tracing_disabled)
return -ENODEV;
ret = seq_open(file, &show_traces_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = trace_types;
}
return ret;
}
static struct file_operations tracing_fops = {
.open = tracing_open,
.read = seq_read,
.llseek = seq_lseek,
.release = tracing_release,
};
static struct file_operations tracing_lt_fops = {
.open = tracing_lt_open,
.read = seq_read,
.llseek = seq_lseek,
.release = tracing_release,
};
static struct file_operations show_traces_fops = {
.open = show_traces_open,
.read = seq_read,
.release = seq_release,
};
/*
* Only trace on a CPU if the bitmask is set:
*/
static cpumask_t tracing_cpumask = CPU_MASK_ALL;
/*
* When tracing/tracing_cpu_mask is modified then this holds
* the new bitmask we are about to install:
*/
static cpumask_t tracing_cpumask_new;
/*
* 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;
mutex_lock(&tracing_cpumask_update_lock);
err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
if (err)
goto err_unlock;
raw_local_irq_disable();
__raw_spin_lock(&ftrace_max_lock);
for_each_tracing_cpu(cpu) {
/*
* Increase/decrease the disabled counter if we are
* about to flip a bit in the cpumask:
*/
if (cpu_isset(cpu, tracing_cpumask) &&
!cpu_isset(cpu, tracing_cpumask_new)) {
atomic_inc(&global_trace.data[cpu]->disabled);
}
if (!cpu_isset(cpu, tracing_cpumask) &&
cpu_isset(cpu, tracing_cpumask_new)) {
atomic_dec(&global_trace.data[cpu]->disabled);
}
}
__raw_spin_unlock(&ftrace_max_lock);
raw_local_irq_enable();
tracing_cpumask = tracing_cpumask_new;
mutex_unlock(&tracing_cpumask_update_lock);
return count;
err_unlock:
mutex_unlock(&tracing_cpumask_update_lock);
return err;
}
static struct file_operations tracing_cpumask_fops = {
.open = tracing_open_generic,
.read = tracing_cpumask_read,
.write = tracing_cpumask_write,
};
static ssize_t
tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char *buf;
int r = 0;
int len = 0;
int i;
/* calulate max size */
for (i = 0; trace_options[i]; i++) {
len += strlen(trace_options[i]);
len += 3; /* "no" and space */
}
/* +2 for \n and \0 */
buf = kmalloc(len + 2, GFP_KERNEL);
if (!buf)
return -ENOMEM;
for (i = 0; trace_options[i]; i++) {
if (trace_flags & (1 << i))
r += sprintf(buf + r, "%s ", trace_options[i]);
else
r += sprintf(buf + r, "no%s ", trace_options[i]);
}
r += sprintf(buf + r, "\n");
WARN_ON(r >= len + 2);
r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
kfree(buf);
return r;
}
static ssize_t
tracing_iter_ctrl_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
char *cmp = buf;
int neg = 0;
int i;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
if (strncmp(buf, "no", 2) == 0) {
neg = 1;
cmp += 2;
}
for (i = 0; trace_options[i]; i++) {
int len = strlen(trace_options[i]);
if (strncmp(cmp, trace_options[i], len) == 0) {
if (neg)
trace_flags &= ~(1 << i);
else
trace_flags |= (1 << i);
break;
}
}
/*
* If no option could be set, return an error:
*/
if (!trace_options[i])
return -EINVAL;
filp->f_pos += cnt;
return cnt;
}
static struct file_operations tracing_iter_fops = {
.open = tracing_open_generic,
.read = tracing_iter_ctrl_read,
.write = tracing_iter_ctrl_write,
};
static const char readme_msg[] =
"tracing mini-HOWTO:\n\n"
"# mkdir /debug\n"
"# mount -t debugfs nodev /debug\n\n"
"# cat /debug/tracing/available_tracers\n"
"wakeup preemptirqsoff preemptoff irqsoff ftrace sched_switch none\n\n"
"# cat /debug/tracing/current_tracer\n"
"none\n"
"# echo sched_switch > /debug/tracing/current_tracer\n"
"# cat /debug/tracing/current_tracer\n"
"sched_switch\n"
"# cat /debug/tracing/iter_ctrl\n"
"noprint-parent nosym-offset nosym-addr noverbose\n"
"# echo print-parent > /debug/tracing/iter_ctrl\n"
"# echo 1 > /debug/tracing/tracing_enabled\n"
"# cat /debug/tracing/trace > /tmp/trace.txt\n"
"echo 0 > /debug/tracing/tracing_enabled\n"
;
static ssize_t
tracing_readme_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return simple_read_from_buffer(ubuf, cnt, ppos,
readme_msg, strlen(readme_msg));
}
static struct file_operations tracing_readme_fops = {
.open = tracing_open_generic,
.read = tracing_readme_read,
};
static ssize_t
tracing_ctrl_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
int r;
r = sprintf(buf, "%u\n", tracer_enabled);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_ctrl_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
char buf[64];
long val;
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
val = !!val;
mutex_lock(&trace_types_lock);
if (tracer_enabled ^ val) {
if (val) {
tracer_enabled = 1;
if (current_trace->start)
current_trace->start(tr);
tracing_start();
} else {
tracer_enabled = 0;
tracing_stop();
if (current_trace->stop)
current_trace->stop(tr);
}
}
mutex_unlock(&trace_types_lock);
filp->f_pos += cnt;
return cnt;
}
static ssize_t
tracing_set_trace_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[max_tracer_type_len+2];
int r;
mutex_lock(&trace_types_lock);
if (current_trace)
r = sprintf(buf, "%s\n", current_trace->name);
else
r = sprintf(buf, "\n");
mutex_unlock(&trace_types_lock);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static int tracing_set_tracer(char *buf)
{
struct trace_array *tr = &global_trace;
struct tracer *t;
int ret = 0;
mutex_lock(&trace_types_lock);
for (t = trace_types; t; t = t->next) {
if (strcmp(t->name, buf) == 0)
break;
}
if (!t) {
ret = -EINVAL;
goto out;
}
if (t == current_trace)
goto out;
if (current_trace && current_trace->reset)
current_trace->reset(tr);
current_trace = t;
if (t->init)
t->init(tr);
out:
mutex_unlock(&trace_types_lock);
return ret;
}
static ssize_t
tracing_set_trace_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[max_tracer_type_len+1];
int i;
size_t ret;
if (cnt > max_tracer_type_len)
cnt = max_tracer_type_len;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
/* strip ending whitespace. */
for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
buf[i] = 0;
ret = tracing_set_tracer(buf);
if (!ret)
ret = cnt;
if (ret > 0)
filp->f_pos += ret;
return ret;
}
static ssize_t
tracing_max_lat_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned long *ptr = filp->private_data;
char buf[64];
int r;
r = snprintf(buf, sizeof(buf), "%ld\n",
*ptr == (unsigned long)-1 ? -1 : nsecs_to_usecs(*ptr));
if (r > sizeof(buf))
r = sizeof(buf);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
tracing_max_lat_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
long *ptr = filp->private_data;
char buf[64];
long val;
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
*ptr = val * 1000;
return cnt;
}
static atomic_t tracing_reader;
static int tracing_open_pipe(struct inode *inode, struct file *filp)
{
struct trace_iterator *iter;
if (tracing_disabled)
return -ENODEV;
/* We only allow for reader of the pipe */
if (atomic_inc_return(&tracing_reader) != 1) {
atomic_dec(&tracing_reader);
return -EBUSY;
}
/* create a buffer to store the information to pass to userspace */
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
mutex_lock(&trace_types_lock);
/* trace pipe does not show start of buffer */
cpus_setall(iter->started);
iter->tr = &global_trace;
iter->trace = current_trace;
filp->private_data = iter;
if (iter->trace->pipe_open)
iter->trace->pipe_open(iter);
mutex_unlock(&trace_types_lock);
return 0;
}
static int tracing_release_pipe(struct inode *inode, struct file *file)
{
struct trace_iterator *iter = file->private_data;
kfree(iter);
atomic_dec(&tracing_reader);
return 0;
}
static unsigned int
tracing_poll_pipe(struct file *filp, poll_table *poll_table)
{
struct trace_iterator *iter = filp->private_data;
if (trace_flags & TRACE_ITER_BLOCK) {
/*
* Always select as readable when in blocking mode
*/
return POLLIN | POLLRDNORM;
} else {
if (!trace_empty(iter))
return POLLIN | POLLRDNORM;
poll_wait(filp, &trace_wait, poll_table);
if (!trace_empty(iter))
return POLLIN | POLLRDNORM;
return 0;
}
}
/*
* Consumer reader.
*/
static ssize_t
tracing_read_pipe(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_iterator *iter = filp->private_data;
ssize_t sret;
/* return any leftover data */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (sret != -EBUSY)
return sret;
trace_seq_reset(&iter->seq);
mutex_lock(&trace_types_lock);
if (iter->trace->read) {
sret = iter->trace->read(iter, filp, ubuf, cnt, ppos);
if (sret)
goto out;
}
waitagain:
sret = 0;
while (trace_empty(iter)) {
if ((filp->f_flags & O_NONBLOCK)) {
sret = -EAGAIN;
goto out;
}
/*
* This is a make-shift waitqueue. The reason we don't use
* an actual wait queue is because:
* 1) we only ever have one waiter
* 2) the tracing, traces all functions, we don't want
* the overhead of calling wake_up and friends
* (and tracing them too)
* Anyway, this is really very primitive wakeup.
*/
set_current_state(TASK_INTERRUPTIBLE);
iter->tr->waiter = current;
mutex_unlock(&trace_types_lock);
/* sleep for 100 msecs, and try again. */
schedule_timeout(HZ/10);
mutex_lock(&trace_types_lock);
iter->tr->waiter = NULL;
if (signal_pending(current)) {
sret = -EINTR;
goto out;
}
if (iter->trace != current_trace)
goto out;
/*
* We block until we read something and tracing is disabled.
* We still block if tracing is disabled, but we have never
* read anything. This allows a user to cat this file, and
* then enable tracing. But after we have read something,
* we give an EOF when tracing is again disabled.
*
* iter->pos will be 0 if we haven't read anything.
*/
if (!tracer_enabled && iter->pos)
break;
continue;
}
/* stop when tracing is finished */
if (trace_empty(iter))
goto out;
if (cnt >= PAGE_SIZE)
cnt = PAGE_SIZE - 1;
/* reset all but tr, trace, and overruns */
memset(&iter->seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter->pos = -1;
while (find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
int len = iter->seq.len;
ret = print_trace_line(iter);
if (ret == TRACE_TYPE_PARTIAL_LINE) {
/* don't print partial lines */
iter->seq.len = len;
break;
}
trace_consume(iter);
if (iter->seq.len >= cnt)
break;
}
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
if (iter->seq.readpos >= iter->seq.len)
trace_seq_reset(&iter->seq);
/*
* If there was nothing to send to user, inspite of consuming trace
* entries, go back to wait for more entries.
*/
if (sret == -EBUSY)
goto waitagain;
out:
mutex_unlock(&trace_types_lock);
return sret;
}
static ssize_t
tracing_entries_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
char buf[64];
int r;
r = sprintf(buf, "%lu\n", tr->entries);
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);
}
if (val != global_trace.entries) {
ret = ring_buffer_resize(global_trace.buffer, val);
if (ret < 0) {
cnt = ret;
goto out;
}
ret = ring_buffer_resize(max_tr.buffer, val);
if (ret < 0) {
int r;
cnt = ret;
r = ring_buffer_resize(global_trace.buffer,
global_trace.entries);
if (r < 0) {
/* AARGH! We are left with different
* size max buffer!!!! */
WARN_ON(1);
tracing_disabled = 1;
}
goto out;
}
global_trace.entries = val;
}
filp->f_pos += cnt;
/* If check pages failed, return ENOMEM */
if (tracing_disabled)
cnt = -ENOMEM;
out:
for_each_tracing_cpu(cpu) {
if (global_trace.data[cpu])
atomic_dec(&global_trace.data[cpu]->disabled);
if (max_tr.data[cpu])
atomic_dec(&max_tr.data[cpu]->disabled);
}
tracing_start();
max_tr.entries = global_trace.entries;
mutex_unlock(&trace_types_lock);
return cnt;
}
static int mark_printk(const char *fmt, ...)
{
int ret;
va_list args;
va_start(args, fmt);
ret = trace_vprintk(0, fmt, args);
va_end(args);
return ret;
}
static ssize_t
tracing_mark_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *fpos)
{
char *buf;
char *end;
if (tracing_disabled)
return -EINVAL;
if (cnt > TRACE_BUF_SIZE)
cnt = TRACE_BUF_SIZE;
buf = kmalloc(cnt + 1, GFP_KERNEL);
if (buf == NULL)
return -ENOMEM;
if (copy_from_user(buf, ubuf, cnt)) {
kfree(buf);
return -EFAULT;
}
/* Cut from the first nil or newline. */
buf[cnt] = '\0';
end = strchr(buf, '\n');
if (end)
*end = '\0';
cnt = mark_printk("%s\n", buf);
kfree(buf);
*fpos += cnt;
return cnt;
}
static struct file_operations tracing_max_lat_fops = {
.open = tracing_open_generic,
.read = tracing_max_lat_read,
.write = tracing_max_lat_write,
};
static struct file_operations tracing_ctrl_fops = {
.open = tracing_open_generic,
.read = tracing_ctrl_read,
.write = tracing_ctrl_write,
};
static struct file_operations set_tracer_fops = {
.open = tracing_open_generic,
.read = tracing_set_trace_read,
.write = tracing_set_trace_write,
};
static struct file_operations tracing_pipe_fops = {
.open = tracing_open_pipe,
.poll = tracing_poll_pipe,
.read = tracing_read_pipe,
.release = tracing_release_pipe,
};
static struct file_operations tracing_entries_fops = {
.open = tracing_open_generic,
.read = tracing_entries_read,
.write = tracing_entries_write,
};
static struct file_operations tracing_mark_fops = {
.open = tracing_open_generic,
.write = tracing_mark_write,
};
#ifdef CONFIG_DYNAMIC_FTRACE
int __weak ftrace_arch_read_dyn_info(char *buf, int size)
{
return 0;
}
static ssize_t
tracing_read_dyn_info(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
static char ftrace_dyn_info_buffer[1024];
static DEFINE_MUTEX(dyn_info_mutex);
unsigned long *p = filp->private_data;
char *buf = ftrace_dyn_info_buffer;
int size = ARRAY_SIZE(ftrace_dyn_info_buffer);
int r;
mutex_lock(&dyn_info_mutex);
r = sprintf(buf, "%ld ", *p);
r += ftrace_arch_read_dyn_info(buf+r, (size-1)-r);
buf[r++] = '\n';
r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
mutex_unlock(&dyn_info_mutex);
return r;
}
static struct file_operations tracing_dyn_info_fops = {
.open = tracing_open_generic,
.read = tracing_read_dyn_info,
};
#endif
static struct dentry *d_tracer;
struct dentry *tracing_init_dentry(void)
{
static int once;
if (d_tracer)
return d_tracer;
d_tracer = debugfs_create_dir("tracing", NULL);
if (!d_tracer && !once) {
once = 1;
pr_warning("Could not create debugfs directory 'tracing'\n");
return NULL;
}
return d_tracer;
}
#ifdef CONFIG_FTRACE_SELFTEST
/* Let selftest have access to static functions in this file */
#include "trace_selftest.c"
#endif
static __init int tracer_init_debugfs(void)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
entry = debugfs_create_file("tracing_enabled", 0644, d_tracer,
&global_trace, &tracing_ctrl_fops);
if (!entry)
pr_warning("Could not create debugfs 'tracing_enabled' entry\n");
entry = debugfs_create_file("iter_ctrl", 0644, d_tracer,
NULL, &tracing_iter_fops);
if (!entry)
pr_warning("Could not create debugfs 'iter_ctrl' entry\n");
entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,
NULL, &tracing_cpumask_fops);
if (!entry)
pr_warning("Could not create debugfs 'tracing_cpumask' entry\n");
entry = debugfs_create_file("latency_trace", 0444, d_tracer,
&global_trace, &tracing_lt_fops);
if (!entry)
pr_warning("Could not create debugfs 'latency_trace' entry\n");
entry = debugfs_create_file("trace", 0444, d_tracer,
&global_trace, &tracing_fops);
if (!entry)
pr_warning("Could not create debugfs 'trace' entry\n");
entry = debugfs_create_file("available_tracers", 0444, d_tracer,
&global_trace, &show_traces_fops);
if (!entry)
pr_warning("Could not create debugfs 'available_tracers' entry\n");
entry = debugfs_create_file("current_tracer", 0444, d_tracer,
&global_trace, &set_tracer_fops);
if (!entry)
pr_warning("Could not create debugfs 'current_tracer' entry\n");
entry = debugfs_create_file("tracing_max_latency", 0644, d_tracer,
&tracing_max_latency,
&tracing_max_lat_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'tracing_max_latency' entry\n");
entry = debugfs_create_file("tracing_thresh", 0644, d_tracer,
&tracing_thresh, &tracing_max_lat_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'tracing_thresh' entry\n");
entry = debugfs_create_file("README", 0644, d_tracer,
NULL, &tracing_readme_fops);
if (!entry)
pr_warning("Could not create debugfs 'README' entry\n");
entry = debugfs_create_file("trace_pipe", 0644, d_tracer,
NULL, &tracing_pipe_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'trace_pipe' entry\n");
entry = debugfs_create_file("trace_entries", 0644, d_tracer,
&global_trace, &tracing_entries_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'trace_entries' entry\n");
entry = debugfs_create_file("trace_marker", 0220, d_tracer,
NULL, &tracing_mark_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'trace_marker' entry\n");
#ifdef CONFIG_DYNAMIC_FTRACE
entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,
&ftrace_update_tot_cnt,
&tracing_dyn_info_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'dyn_ftrace_total_info' entry\n");
#endif
#ifdef CONFIG_SYSPROF_TRACER
init_tracer_sysprof_debugfs(d_tracer);
#endif
return 0;
}
int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
{
static DEFINE_SPINLOCK(trace_buf_lock);
static char trace_buf[TRACE_BUF_SIZE];
struct ring_buffer_event *event;
struct trace_array *tr = &global_trace;
struct trace_array_cpu *data;
struct print_entry *entry;
unsigned long flags, irq_flags;
int cpu, len = 0, size, pc;
if (tracing_disabled)
return 0;
pc = preempt_count();
preempt_disable_notrace();
cpu = raw_smp_processor_id();
data = tr->data[cpu];
if (unlikely(atomic_read(&data->disabled)))
goto out;
spin_lock_irqsave(&trace_buf_lock, flags);
len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
len = min(len, TRACE_BUF_SIZE-1);
trace_buf[len] = 0;
size = sizeof(*entry) + len + 1;
event = ring_buffer_lock_reserve(tr->buffer, size, &irq_flags);
if (!event)
goto out_unlock;
entry = ring_buffer_event_data(event);
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_PRINT;
entry->ip = ip;
memcpy(&entry->buf, trace_buf, len);
entry->buf[len] = 0;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
out_unlock:
spin_unlock_irqrestore(&trace_buf_lock, flags);
out:
preempt_enable_notrace();
return len;
}
EXPORT_SYMBOL_GPL(trace_vprintk);
int __ftrace_printk(unsigned long ip, const char *fmt, ...)
{
int ret;
va_list ap;
if (!(trace_flags & TRACE_ITER_PRINTK))
return 0;
va_start(ap, fmt);
ret = trace_vprintk(ip, fmt, ap);
va_end(ap);
return ret;
}
EXPORT_SYMBOL_GPL(__ftrace_printk);
static int trace_panic_handler(struct notifier_block *this,
unsigned long event, void *unused)
{
if (ftrace_dump_on_oops)
ftrace_dump();
return NOTIFY_OK;
}
static struct notifier_block trace_panic_notifier = {
.notifier_call = trace_panic_handler,
.next = NULL,
.priority = 150 /* priority: INT_MAX >= x >= 0 */
};
static int trace_die_handler(struct notifier_block *self,
unsigned long val,
void *data)
{
switch (val) {
case DIE_OOPS:
if (ftrace_dump_on_oops)
ftrace_dump();
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block trace_die_notifier = {
.notifier_call = trace_die_handler,
.priority = 200
};
/*
* printk is set to max of 1024, we really don't need it that big.
* Nothing should be printing 1000 characters anyway.
*/
#define TRACE_MAX_PRINT 1000
/*
* Define here KERN_TRACE so that we have one place to modify
* it if we decide to change what log level the ftrace dump
* should be at.
*/
#define KERN_TRACE KERN_INFO
static void
trace_printk_seq(struct trace_seq *s)
{
/* Probably should print a warning here. */
if (s->len >= 1000)
s->len = 1000;
/* should be zero ended, but we are paranoid. */
s->buffer[s->len] = 0;
printk(KERN_TRACE "%s", s->buffer);
trace_seq_reset(s);
}
void ftrace_dump(void)
{
static DEFINE_SPINLOCK(ftrace_dump_lock);
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
static cpumask_t mask;
static int dump_ran;
unsigned long flags;
int cnt = 0, cpu;
/* only one dump */
spin_lock_irqsave(&ftrace_dump_lock, flags);
if (dump_ran)
goto out;
dump_ran = 1;
/* No turning back! */
ftrace_kill();
for_each_tracing_cpu(cpu) {
atomic_inc(&global_trace.data[cpu]->disabled);
}
printk(KERN_TRACE "Dumping ftrace buffer:\n");
iter.tr = &global_trace;
iter.trace = current_trace;
/*
* We need to stop all tracing on all CPUS to read the
* the next buffer. This is a bit expensive, but is
* not done often. We fill all what we can read,
* and then release the locks again.
*/
cpus_clear(mask);
while (!trace_empty(&iter)) {
if (!cnt)
printk(KERN_TRACE "---------------------------------\n");
cnt++;
/* reset all but tr, trace, and overruns */
memset(&iter.seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;
if (find_next_entry_inc(&iter) != NULL) {
print_trace_line(&iter);
trace_consume(&iter);
}
trace_printk_seq(&iter.seq);
}
if (!cnt)
printk(KERN_TRACE " (ftrace buffer empty)\n");
else
printk(KERN_TRACE "---------------------------------\n");
out:
spin_unlock_irqrestore(&ftrace_dump_lock, flags);
}
__init static int tracer_alloc_buffers(void)
{
struct trace_array_cpu *data;
int i;
/* TODO: make the number of buffers hot pluggable with CPUS */
tracing_buffer_mask = cpu_possible_map;
global_trace.buffer = ring_buffer_alloc(trace_buf_size,
TRACE_BUFFER_FLAGS);
if (!global_trace.buffer) {
printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
WARN_ON(1);
return 0;
}
global_trace.entries = ring_buffer_size(global_trace.buffer);
#ifdef CONFIG_TRACER_MAX_TRACE
max_tr.buffer = ring_buffer_alloc(trace_buf_size,
TRACE_BUFFER_FLAGS);
if (!max_tr.buffer) {
printk(KERN_ERR "tracer: failed to allocate max ring buffer!\n");
WARN_ON(1);
ring_buffer_free(global_trace.buffer);
return 0;
}
max_tr.entries = ring_buffer_size(max_tr.buffer);
WARN_ON(max_tr.entries != global_trace.entries);
#endif
/* Allocate the first page for all buffers */
for_each_tracing_cpu(i) {
data = global_trace.data[i] = &per_cpu(global_trace_cpu, i);
max_tr.data[i] = &per_cpu(max_data, i);
}
trace_init_cmdlines();
register_tracer(&nop_trace);
#ifdef CONFIG_BOOT_TRACER
register_tracer(&boot_tracer);
current_trace = &boot_tracer;
current_trace->init(&global_trace);
#else
current_trace = &nop_trace;
#endif
/* All seems OK, enable tracing */
tracing_disabled = 0;
atomic_notifier_chain_register(&panic_notifier_list,
&trace_panic_notifier);
register_die_notifier(&trace_die_notifier);
return 0;
}
early_initcall(tracer_alloc_buffers);
fs_initcall(tracer_init_debugfs);
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