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linux/kernel/trace/ftrace.c

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/*
* Infrastructure for profiling code inserted by 'gcc -pg'.
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
*
* Originally ported from the -rt patch by:
* Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
*
* Based on code in the latency_tracer, that is:
*
* Copyright (C) 2004-2006 Ingo Molnar
* Copyright (C) 2004 William Lee Irwin III
*/
#include <linux/stop_machine.h>
#include <linux/clocksource.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/hardirq.h>
#include <linux/kthread.h>
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/ftrace.h>
#include <linux/sysctl.h>
#include <linux/ctype.h>
#include <linux/hash.h>
#include <linux/list.h>
#include <asm/ftrace.h>
#include "trace.h"
/* ftrace_enabled is a method to turn ftrace on or off */
int ftrace_enabled __read_mostly;
static int last_ftrace_enabled;
/*
* ftrace_disabled is set when an anomaly is discovered.
* ftrace_disabled is much stronger than ftrace_enabled.
*/
static int ftrace_disabled __read_mostly;
static DEFINE_SPINLOCK(ftrace_lock);
static DEFINE_MUTEX(ftrace_sysctl_lock);
static struct ftrace_ops ftrace_list_end __read_mostly =
{
.func = ftrace_stub,
};
static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
static void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
{
struct ftrace_ops *op = ftrace_list;
/* in case someone actually ports this to alpha! */
read_barrier_depends();
while (op != &ftrace_list_end) {
/* silly alpha */
read_barrier_depends();
op->func(ip, parent_ip);
op = op->next;
};
}
/**
* clear_ftrace_function - reset the ftrace function
*
* This NULLs the ftrace function and in essence stops
* tracing. There may be lag
*/
void clear_ftrace_function(void)
{
ftrace_trace_function = ftrace_stub;
}
static int __register_ftrace_function(struct ftrace_ops *ops)
{
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
ops->next = ftrace_list;
/*
* We are entering ops into the ftrace_list but another
* CPU might be walking that list. We need to make sure
* the ops->next pointer is valid before another CPU sees
* the ops pointer included into the ftrace_list.
*/
smp_wmb();
ftrace_list = ops;
if (ftrace_enabled) {
/*
* For one func, simply call it directly.
* For more than one func, call the chain.
*/
if (ops->next == &ftrace_list_end)
ftrace_trace_function = ops->func;
else
ftrace_trace_function = ftrace_list_func;
}
spin_unlock(&ftrace_lock);
return 0;
}
static int __unregister_ftrace_function(struct ftrace_ops *ops)
{
struct ftrace_ops **p;
int ret = 0;
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
/*
* If we are removing the last function, then simply point
* to the ftrace_stub.
*/
if (ftrace_list == ops && ops->next == &ftrace_list_end) {
ftrace_trace_function = ftrace_stub;
ftrace_list = &ftrace_list_end;
goto out;
}
for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
if (*p == ops)
break;
if (*p != ops) {
ret = -1;
goto out;
}
*p = (*p)->next;
if (ftrace_enabled) {
/* If we only have one func left, then call that directly */
if (ftrace_list == &ftrace_list_end ||
ftrace_list->next == &ftrace_list_end)
ftrace_trace_function = ftrace_list->func;
}
out:
spin_unlock(&ftrace_lock);
return ret;
}
#ifdef CONFIG_DYNAMIC_FTRACE
#ifndef CONFIG_FTRACE_MCOUNT_RECORD
/*
* The hash lock is only needed when the recording of the mcount
* callers are dynamic. That is, by the caller themselves and
* not recorded via the compilation.
*/
static DEFINE_SPINLOCK(ftrace_hash_lock);
#define ftrace_hash_lock(flags) spin_lock_irqsave(&ftrace_hash_lock, flags)
#define ftrace_hash_unlock(flags) \
spin_unlock_irqrestore(&ftrace_hash_lock, flags)
#else
/* This is protected via the ftrace_lock with MCOUNT_RECORD. */
#define ftrace_hash_lock(flags) do { (void)(flags); } while (0)
#define ftrace_hash_unlock(flags) do { } while(0)
#endif
/*
* Since MCOUNT_ADDR may point to mcount itself, we do not want
* to get it confused by reading a reference in the code as we
* are parsing on objcopy output of text. Use a variable for
* it instead.
*/
static unsigned long mcount_addr = MCOUNT_ADDR;
static struct task_struct *ftraced_task;
enum {
FTRACE_ENABLE_CALLS = (1 << 0),
FTRACE_DISABLE_CALLS = (1 << 1),
FTRACE_UPDATE_TRACE_FUNC = (1 << 2),
FTRACE_ENABLE_MCOUNT = (1 << 3),
FTRACE_DISABLE_MCOUNT = (1 << 4),
};
static int ftrace_filtered;
static int tracing_on;
static int frozen_record_count;
static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
static DEFINE_MUTEX(ftraced_lock);
static DEFINE_MUTEX(ftrace_regex_lock);
struct ftrace_page {
struct ftrace_page *next;
unsigned long index;
struct dyn_ftrace records[];
};
#define ENTRIES_PER_PAGE \
((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
/* estimate from running different kernels */
#define NR_TO_INIT 10000
static struct ftrace_page *ftrace_pages_start;
static struct ftrace_page *ftrace_pages;
static int ftraced_trigger;
static int ftraced_suspend;
static int ftraced_stop;
static int ftrace_record_suspend;
static struct dyn_ftrace *ftrace_free_records;
#ifdef CONFIG_KPROBES
static inline void freeze_record(struct dyn_ftrace *rec)
{
if (!(rec->flags & FTRACE_FL_FROZEN)) {
rec->flags |= FTRACE_FL_FROZEN;
frozen_record_count++;
}
}
static inline void unfreeze_record(struct dyn_ftrace *rec)
{
if (rec->flags & FTRACE_FL_FROZEN) {
rec->flags &= ~FTRACE_FL_FROZEN;
frozen_record_count--;
}
}
static inline int record_frozen(struct dyn_ftrace *rec)
{
return rec->flags & FTRACE_FL_FROZEN;
}
#else
# define freeze_record(rec) ({ 0; })
# define unfreeze_record(rec) ({ 0; })
# define record_frozen(rec) ({ 0; })
#endif /* CONFIG_KPROBES */
int skip_trace(unsigned long ip)
{
unsigned long fl;
struct dyn_ftrace *rec;
struct hlist_node *t;
struct hlist_head *head;
if (frozen_record_count == 0)
return 0;
head = &ftrace_hash[hash_long(ip, FTRACE_HASHBITS)];
hlist_for_each_entry_rcu(rec, t, head, node) {
if (rec->ip == ip) {
if (record_frozen(rec)) {
if (rec->flags & FTRACE_FL_FAILED)
return 1;
if (!(rec->flags & FTRACE_FL_CONVERTED))
return 1;
if (!tracing_on || !ftrace_enabled)
return 1;
if (ftrace_filtered) {
fl = rec->flags & (FTRACE_FL_FILTER |
FTRACE_FL_NOTRACE);
if (!fl || (fl & FTRACE_FL_NOTRACE))
return 1;
}
}
break;
}
}
return 0;
}
static inline int
ftrace_ip_in_hash(unsigned long ip, unsigned long key)
{
struct dyn_ftrace *p;
struct hlist_node *t;
int found = 0;
hlist_for_each_entry_rcu(p, t, &ftrace_hash[key], node) {
if (p->ip == ip) {
found = 1;
break;
}
}
return found;
}
static inline void
ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
{
hlist_add_head_rcu(&node->node, &ftrace_hash[key]);
}
/* called from kstop_machine */
static inline void ftrace_del_hash(struct dyn_ftrace *node)
{
hlist_del(&node->node);
}
static void ftrace_free_rec(struct dyn_ftrace *rec)
{
rec->ip = (unsigned long)ftrace_free_records;
ftrace_free_records = rec;
rec->flags |= FTRACE_FL_FREE;
}
void ftrace_release(void *start, unsigned long size)
{
struct dyn_ftrace *rec;
struct ftrace_page *pg;
unsigned long s = (unsigned long)start;
unsigned long e = s + size;
int i;
if (ftrace_disabled || !start)
return;
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
if ((rec->ip >= s) && (rec->ip < e))
ftrace_free_rec(rec);
}
}
spin_unlock(&ftrace_lock);
}
static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
{
struct dyn_ftrace *rec;
/* First check for freed records */
if (ftrace_free_records) {
rec = ftrace_free_records;
if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
WARN_ON_ONCE(1);
ftrace_free_records = NULL;
ftrace_disabled = 1;
ftrace_enabled = 0;
return NULL;
}
ftrace_free_records = (void *)rec->ip;
memset(rec, 0, sizeof(*rec));
return rec;
}
if (ftrace_pages->index == ENTRIES_PER_PAGE) {
if (!ftrace_pages->next)
return NULL;
ftrace_pages = ftrace_pages->next;
}
return &ftrace_pages->records[ftrace_pages->index++];
}
static void
ftrace_record_ip(unsigned long ip)
{
struct dyn_ftrace *node;
unsigned long flags;
unsigned long key;
int resched;
int cpu;
if (!ftrace_enabled || ftrace_disabled)
return;
resched = need_resched();
preempt_disable_notrace();
/*
* We simply need to protect against recursion.
* Use the the raw version of smp_processor_id and not
* __get_cpu_var which can call debug hooks that can
* cause a recursive crash here.
*/
cpu = raw_smp_processor_id();
per_cpu(ftrace_shutdown_disable_cpu, cpu)++;
if (per_cpu(ftrace_shutdown_disable_cpu, cpu) != 1)
goto out;
if (unlikely(ftrace_record_suspend))
goto out;
key = hash_long(ip, FTRACE_HASHBITS);
WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
if (ftrace_ip_in_hash(ip, key))
goto out;
ftrace_hash_lock(flags);
/* This ip may have hit the hash before the lock */
if (ftrace_ip_in_hash(ip, key))
goto out_unlock;
node = ftrace_alloc_dyn_node(ip);
if (!node)
goto out_unlock;
node->ip = ip;
ftrace_add_hash(node, key);
ftraced_trigger = 1;
out_unlock:
ftrace_hash_unlock(flags);
out:
per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
/* prevent recursion with scheduler */
if (resched)
preempt_enable_no_resched_notrace();
else
preempt_enable_notrace();
}
#define FTRACE_ADDR ((long)(ftrace_caller))
static int
__ftrace_replace_code(struct dyn_ftrace *rec,
unsigned char *old, unsigned char *new, int enable)
{
unsigned long ip, fl;
ip = rec->ip;
if (ftrace_filtered && enable) {
/*
* If filtering is on:
*
* If this record is set to be filtered and
* is enabled then do nothing.
*
* If this record is set to be filtered and
* it is not enabled, enable it.
*
* If this record is not set to be filtered
* and it is not enabled do nothing.
*
* If this record is set not to trace then
* do nothing.
*
* If this record is set not to trace and
* it is enabled then disable it.
*
* If this record is not set to be filtered and
* it is enabled, disable it.
*/
fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE |
FTRACE_FL_ENABLED);
if ((fl == (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
(fl == (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE)) ||
!fl || (fl == FTRACE_FL_NOTRACE))
return 0;
/*
* If it is enabled disable it,
* otherwise enable it!
*/
if (fl & FTRACE_FL_ENABLED) {
/* swap new and old */
new = old;
old = ftrace_call_replace(ip, FTRACE_ADDR);
rec->flags &= ~FTRACE_FL_ENABLED;
} else {
new = ftrace_call_replace(ip, FTRACE_ADDR);
rec->flags |= FTRACE_FL_ENABLED;
}
} else {
if (enable) {
/*
* If this record is set not to trace and is
* not enabled, do nothing.
*/
fl = rec->flags & (FTRACE_FL_NOTRACE | FTRACE_FL_ENABLED);
if (fl == FTRACE_FL_NOTRACE)
return 0;
new = ftrace_call_replace(ip, FTRACE_ADDR);
} else
old = ftrace_call_replace(ip, FTRACE_ADDR);
if (enable) {
if (rec->flags & FTRACE_FL_ENABLED)
return 0;
rec->flags |= FTRACE_FL_ENABLED;
} else {
if (!(rec->flags & FTRACE_FL_ENABLED))
return 0;
rec->flags &= ~FTRACE_FL_ENABLED;
}
}
return ftrace_modify_code(ip, old, new);
}
static void ftrace_replace_code(int enable)
{
int i, failed;
unsigned char *new = NULL, *old = NULL;
struct dyn_ftrace *rec;
struct ftrace_page *pg;
if (enable)
old = ftrace_nop_replace();
else
new = ftrace_nop_replace();
for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
/* don't modify code that has already faulted */
if (rec->flags & FTRACE_FL_FAILED)
continue;
/* ignore updates to this record's mcount site */
if (get_kprobe((void *)rec->ip)) {
freeze_record(rec);
continue;
} else {
unfreeze_record(rec);
}
failed = __ftrace_replace_code(rec, old, new, enable);
if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
rec->flags |= FTRACE_FL_FAILED;
if ((system_state == SYSTEM_BOOTING) ||
!core_kernel_text(rec->ip)) {
ftrace_del_hash(rec);
ftrace_free_rec(rec);
}
}
}
}
}
static void ftrace_shutdown_replenish(void)
{
if (ftrace_pages->next)
return;
/* allocate another page */
ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
}
static void print_ip_ins(const char *fmt, unsigned char *p)
{
int i;
printk(KERN_CONT "%s", fmt);
for (i = 0; i < MCOUNT_INSN_SIZE; i++)
printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
}
static int
ftrace_code_disable(struct dyn_ftrace *rec)
{
unsigned long ip;
unsigned char *nop, *call;
int failed;
ip = rec->ip;
nop = ftrace_nop_replace();
call = ftrace_call_replace(ip, mcount_addr);
failed = ftrace_modify_code(ip, call, nop);
if (failed) {
switch (failed) {
case 1:
WARN_ON_ONCE(1);
pr_info("ftrace faulted on modifying ");
print_ip_sym(ip);
break;
case 2:
WARN_ON_ONCE(1);
pr_info("ftrace failed to modify ");
print_ip_sym(ip);
print_ip_ins(" expected: ", call);
print_ip_ins(" actual: ", (unsigned char *)ip);
print_ip_ins(" replace: ", nop);
printk(KERN_CONT "\n");
break;
}
rec->flags |= FTRACE_FL_FAILED;
return 0;
}
return 1;
}
static int __ftrace_update_code(void *ignore);
static int __ftrace_modify_code(void *data)
{
unsigned long addr;
int *command = data;
if (*command & FTRACE_ENABLE_CALLS) {
/*
* Update any recorded ips now that we have the
* machine stopped
*/
__ftrace_update_code(NULL);
ftrace_replace_code(1);
tracing_on = 1;
} else if (*command & FTRACE_DISABLE_CALLS) {
ftrace_replace_code(0);
tracing_on = 0;
}
if (*command & FTRACE_UPDATE_TRACE_FUNC)
ftrace_update_ftrace_func(ftrace_trace_function);
if (*command & FTRACE_ENABLE_MCOUNT) {
addr = (unsigned long)ftrace_record_ip;
ftrace_mcount_set(&addr);
} else if (*command & FTRACE_DISABLE_MCOUNT) {
addr = (unsigned long)ftrace_stub;
ftrace_mcount_set(&addr);
}
return 0;
}
static void ftrace_run_update_code(int command)
{
stop_machine(__ftrace_modify_code, &command, NULL);
}
void ftrace_disable_daemon(void)
{
/* Stop the daemon from calling kstop_machine */
mutex_lock(&ftraced_lock);
ftraced_stop = 1;
mutex_unlock(&ftraced_lock);
ftrace_force_update();
}
void ftrace_enable_daemon(void)
{
mutex_lock(&ftraced_lock);
ftraced_stop = 0;
mutex_unlock(&ftraced_lock);
ftrace_force_update();
}
static ftrace_func_t saved_ftrace_func;
static void ftrace_startup(void)
{
int command = 0;
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftraced_lock);
ftraced_suspend++;
if (ftraced_suspend == 1)
command |= FTRACE_ENABLE_CALLS;
if (saved_ftrace_func != ftrace_trace_function) {
saved_ftrace_func = ftrace_trace_function;
command |= FTRACE_UPDATE_TRACE_FUNC;
}
if (!command || !ftrace_enabled)
goto out;
ftrace_run_update_code(command);
out:
mutex_unlock(&ftraced_lock);
}
static void ftrace_shutdown(void)
{
int command = 0;
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftraced_lock);
ftraced_suspend--;
if (!ftraced_suspend)
command |= FTRACE_DISABLE_CALLS;
if (saved_ftrace_func != ftrace_trace_function) {
saved_ftrace_func = ftrace_trace_function;
command |= FTRACE_UPDATE_TRACE_FUNC;
}
if (!command || !ftrace_enabled)
goto out;
ftrace_run_update_code(command);
out:
mutex_unlock(&ftraced_lock);
}
static void ftrace_startup_sysctl(void)
{
int command = FTRACE_ENABLE_MCOUNT;
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftraced_lock);
/* Force update next time */
saved_ftrace_func = NULL;
/* ftraced_suspend is true if we want ftrace running */
if (ftraced_suspend)
command |= FTRACE_ENABLE_CALLS;
ftrace_run_update_code(command);
mutex_unlock(&ftraced_lock);
}
static void ftrace_shutdown_sysctl(void)
{
int command = FTRACE_DISABLE_MCOUNT;
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftraced_lock);
/* ftraced_suspend is true if ftrace is running */
if (ftraced_suspend)
command |= FTRACE_DISABLE_CALLS;
ftrace_run_update_code(command);
mutex_unlock(&ftraced_lock);
}
static cycle_t ftrace_update_time;
static unsigned long ftrace_update_cnt;
unsigned long ftrace_update_tot_cnt;
static int __ftrace_update_code(void *ignore)
{
int i, save_ftrace_enabled;
cycle_t start, stop;
struct dyn_ftrace *p;
struct hlist_node *t, *n;
struct hlist_head *head, temp_list;
/* Don't be recording funcs now */
ftrace_record_suspend++;
save_ftrace_enabled = ftrace_enabled;
ftrace_enabled = 0;
start = ftrace_now(raw_smp_processor_id());
ftrace_update_cnt = 0;
/* No locks needed, the machine is stopped! */
for (i = 0; i < FTRACE_HASHSIZE; i++) {
INIT_HLIST_HEAD(&temp_list);
head = &ftrace_hash[i];
/* all CPUS are stopped, we are safe to modify code */
hlist_for_each_entry_safe(p, t, n, head, node) {
/* Skip over failed records which have not been
* freed. */
if (p->flags & FTRACE_FL_FAILED)
continue;
/* Unconverted records are always at the head of the
* hash bucket. Once we encounter a converted record,
* simply skip over to the next bucket. Saves ftraced
* some processor cycles (ftrace does its bid for
* global warming :-p ). */
if (p->flags & (FTRACE_FL_CONVERTED))
break;
/* Ignore updates to this record's mcount site.
* Reintroduce this record at the head of this
* bucket to attempt to "convert" it again if
* the kprobe on it is unregistered before the
* next run. */
if (get_kprobe((void *)p->ip)) {
ftrace_del_hash(p);
INIT_HLIST_NODE(&p->node);
hlist_add_head(&p->node, &temp_list);
freeze_record(p);
continue;
} else {
unfreeze_record(p);
}
/* convert record (i.e, patch mcount-call with NOP) */
if (ftrace_code_disable(p)) {
p->flags |= FTRACE_FL_CONVERTED;
ftrace_update_cnt++;
} else {
if ((system_state == SYSTEM_BOOTING) ||
!core_kernel_text(p->ip)) {
ftrace_del_hash(p);
ftrace_free_rec(p);
}
}
}
hlist_for_each_entry_safe(p, t, n, &temp_list, node) {
hlist_del(&p->node);
INIT_HLIST_NODE(&p->node);
hlist_add_head(&p->node, head);
}
}
stop = ftrace_now(raw_smp_processor_id());
ftrace_update_time = stop - start;
ftrace_update_tot_cnt += ftrace_update_cnt;
ftraced_trigger = 0;
ftrace_enabled = save_ftrace_enabled;
ftrace_record_suspend--;
return 0;
}
static int ftrace_update_code(void)
{
if (unlikely(ftrace_disabled) ||
!ftrace_enabled || !ftraced_trigger)
return 0;
stop_machine(__ftrace_update_code, NULL, NULL);
return 1;
}
static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
{
struct ftrace_page *pg;
int cnt;
int i;
/* allocate a few pages */
ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
if (!ftrace_pages_start)
return -1;
/*
* Allocate a few more pages.
*
* TODO: have some parser search vmlinux before
* final linking to find all calls to ftrace.
* Then we can:
* a) know how many pages to allocate.
* and/or
* b) set up the table then.
*
* The dynamic code is still necessary for
* modules.
*/
pg = ftrace_pages = ftrace_pages_start;
cnt = num_to_init / ENTRIES_PER_PAGE;
pr_info("ftrace: allocating %ld hash entries in %d pages\n",
num_to_init, cnt);
for (i = 0; i < cnt; i++) {
pg->next = (void *)get_zeroed_page(GFP_KERNEL);
/* If we fail, we'll try later anyway */
if (!pg->next)
break;
pg = pg->next;
}
return 0;
}
enum {
FTRACE_ITER_FILTER = (1 << 0),
FTRACE_ITER_CONT = (1 << 1),
FTRACE_ITER_NOTRACE = (1 << 2),
FTRACE_ITER_FAILURES = (1 << 3),
};
#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
struct ftrace_iterator {
loff_t pos;
struct ftrace_page *pg;
unsigned idx;
unsigned flags;
unsigned char buffer[FTRACE_BUFF_MAX+1];
unsigned buffer_idx;
unsigned filtered;
};
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
struct dyn_ftrace *rec = NULL;
(*pos)++;
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
retry:
if (iter->idx >= iter->pg->index) {
if (iter->pg->next) {
iter->pg = iter->pg->next;
iter->idx = 0;
goto retry;
}
} else {
rec = &iter->pg->records[iter->idx++];
if ((rec->flags & FTRACE_FL_FREE) ||
(!(iter->flags & FTRACE_ITER_FAILURES) &&
(rec->flags & FTRACE_FL_FAILED)) ||
((iter->flags & FTRACE_ITER_FAILURES) &&
!(rec->flags & FTRACE_FL_FAILED)) ||
((iter->flags & FTRACE_ITER_NOTRACE) &&
!(rec->flags & FTRACE_FL_NOTRACE))) {
rec = NULL;
goto retry;
}
}
spin_unlock(&ftrace_lock);
iter->pos = *pos;
return rec;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
void *p = NULL;
loff_t l = -1;
if (*pos != iter->pos) {
for (p = t_next(m, p, &l); p && l < *pos; p = t_next(m, p, &l))
;
} else {
l = *pos;
p = t_next(m, p, &l);
}
return p;
}
static void t_stop(struct seq_file *m, void *p)
{
}
static int t_show(struct seq_file *m, void *v)
{
struct dyn_ftrace *rec = v;
char str[KSYM_SYMBOL_LEN];
if (!rec)
return 0;
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
seq_printf(m, "%s\n", str);
return 0;
}
static struct seq_operations show_ftrace_seq_ops = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = t_show,
};
static int
ftrace_avail_open(struct inode *inode, struct file *file)
{
struct ftrace_iterator *iter;
int ret;
if (unlikely(ftrace_disabled))
return -ENODEV;
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
iter->pg = ftrace_pages_start;
iter->pos = -1;
ret = seq_open(file, &show_ftrace_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = iter;
} else {
kfree(iter);
}
return ret;
}
int ftrace_avail_release(struct inode *inode, struct file *file)
{
struct seq_file *m = (struct seq_file *)file->private_data;
struct ftrace_iterator *iter = m->private;
seq_release(inode, file);
kfree(iter);
return 0;
}
static int
ftrace_failures_open(struct inode *inode, struct file *file)
{
int ret;
struct seq_file *m;
struct ftrace_iterator *iter;
ret = ftrace_avail_open(inode, file);
if (!ret) {
m = (struct seq_file *)file->private_data;
iter = (struct ftrace_iterator *)m->private;
iter->flags = FTRACE_ITER_FAILURES;
}
return ret;
}
static void ftrace_filter_reset(int enable)
{
struct ftrace_page *pg;
struct dyn_ftrace *rec;
unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
unsigned i;
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
if (enable)
ftrace_filtered = 0;
pg = ftrace_pages_start;
while (pg) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
if (rec->flags & FTRACE_FL_FAILED)
continue;
rec->flags &= ~type;
}
pg = pg->next;
}
spin_unlock(&ftrace_lock);
}
static int
ftrace_regex_open(struct inode *inode, struct file *file, int enable)
{
struct ftrace_iterator *iter;
int ret = 0;
if (unlikely(ftrace_disabled))
return -ENODEV;
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
mutex_lock(&ftrace_regex_lock);
if ((file->f_mode & FMODE_WRITE) &&
!(file->f_flags & O_APPEND))
ftrace_filter_reset(enable);
if (file->f_mode & FMODE_READ) {
iter->pg = ftrace_pages_start;
iter->pos = -1;
iter->flags = enable ? FTRACE_ITER_FILTER :
FTRACE_ITER_NOTRACE;
ret = seq_open(file, &show_ftrace_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = iter;
} else
kfree(iter);
} else
file->private_data = iter;
mutex_unlock(&ftrace_regex_lock);
return ret;
}
static int
ftrace_filter_open(struct inode *inode, struct file *file)
{
return ftrace_regex_open(inode, file, 1);
}
static int
ftrace_notrace_open(struct inode *inode, struct file *file)
{
return ftrace_regex_open(inode, file, 0);
}
static ssize_t
ftrace_regex_read(struct file *file, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
if (file->f_mode & FMODE_READ)
return seq_read(file, ubuf, cnt, ppos);
else
return -EPERM;
}
static loff_t
ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
{
loff_t ret;
if (file->f_mode & FMODE_READ)
ret = seq_lseek(file, offset, origin);
else
file->f_pos = ret = 1;
return ret;
}
enum {
MATCH_FULL,
MATCH_FRONT_ONLY,
MATCH_MIDDLE_ONLY,
MATCH_END_ONLY,
};
static void
ftrace_match(unsigned char *buff, int len, int enable)
{
char str[KSYM_SYMBOL_LEN];
char *search = NULL;
struct ftrace_page *pg;
struct dyn_ftrace *rec;
int type = MATCH_FULL;
unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
unsigned i, match = 0, search_len = 0;
for (i = 0; i < len; i++) {
if (buff[i] == '*') {
if (!i) {
search = buff + i + 1;
type = MATCH_END_ONLY;
search_len = len - (i + 1);
} else {
if (type == MATCH_END_ONLY) {
type = MATCH_MIDDLE_ONLY;
} else {
match = i;
type = MATCH_FRONT_ONLY;
}
buff[i] = 0;
break;
}
}
}
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
if (enable)
ftrace_filtered = 1;
pg = ftrace_pages_start;
while (pg) {
for (i = 0; i < pg->index; i++) {
int matched = 0;
char *ptr;
rec = &pg->records[i];
if (rec->flags & FTRACE_FL_FAILED)
continue;
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
switch (type) {
case MATCH_FULL:
if (strcmp(str, buff) == 0)
matched = 1;
break;
case MATCH_FRONT_ONLY:
if (memcmp(str, buff, match) == 0)
matched = 1;
break;
case MATCH_MIDDLE_ONLY:
if (strstr(str, search))
matched = 1;
break;
case MATCH_END_ONLY:
ptr = strstr(str, search);
if (ptr && (ptr[search_len] == 0))
matched = 1;
break;
}
if (matched)
rec->flags |= flag;
}
pg = pg->next;
}
spin_unlock(&ftrace_lock);
}
static ssize_t
ftrace_regex_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos, int enable)
{
struct ftrace_iterator *iter;
char ch;
size_t read = 0;
ssize_t ret;
if (!cnt || cnt < 0)
return 0;
mutex_lock(&ftrace_regex_lock);
if (file->f_mode & FMODE_READ) {
struct seq_file *m = file->private_data;
iter = m->private;
} else
iter = file->private_data;
if (!*ppos) {
iter->flags &= ~FTRACE_ITER_CONT;
iter->buffer_idx = 0;
}
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
if (!(iter->flags & ~FTRACE_ITER_CONT)) {
/* skip white space */
while (cnt && isspace(ch)) {
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
if (isspace(ch)) {
file->f_pos += read;
ret = read;
goto out;
}
iter->buffer_idx = 0;
}
while (cnt && !isspace(ch)) {
if (iter->buffer_idx < FTRACE_BUFF_MAX)
iter->buffer[iter->buffer_idx++] = ch;
else {
ret = -EINVAL;
goto out;
}
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
if (isspace(ch)) {
iter->filtered++;
iter->buffer[iter->buffer_idx] = 0;
ftrace_match(iter->buffer, iter->buffer_idx, enable);
iter->buffer_idx = 0;
} else
iter->flags |= FTRACE_ITER_CONT;
file->f_pos += read;
ret = read;
out:
mutex_unlock(&ftrace_regex_lock);
return ret;
}
static ssize_t
ftrace_filter_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
}
static ssize_t
ftrace_notrace_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
}
static void
ftrace_set_regex(unsigned char *buf, int len, int reset, int enable)
{
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftrace_regex_lock);
if (reset)
ftrace_filter_reset(enable);
if (buf)
ftrace_match(buf, len, enable);
mutex_unlock(&ftrace_regex_lock);
}
/**
* ftrace_set_filter - set a function to filter on in ftrace
* @buf - the string that holds the function filter text.
* @len - the length of the string.
* @reset - non zero to reset all filters before applying this filter.
*
* Filters denote which functions should be enabled when tracing is enabled.
* If @buf is NULL and reset is set, all functions will be enabled for tracing.
*/
void ftrace_set_filter(unsigned char *buf, int len, int reset)
{
ftrace_set_regex(buf, len, reset, 1);
}
/**
* ftrace_set_notrace - set a function to not trace in ftrace
* @buf - the string that holds the function notrace text.
* @len - the length of the string.
* @reset - non zero to reset all filters before applying this filter.
*
* Notrace Filters denote which functions should not be enabled when tracing
* is enabled. If @buf is NULL and reset is set, all functions will be enabled
* for tracing.
*/
void ftrace_set_notrace(unsigned char *buf, int len, int reset)
{
ftrace_set_regex(buf, len, reset, 0);
}
static int
ftrace_regex_release(struct inode *inode, struct file *file, int enable)
{
struct seq_file *m = (struct seq_file *)file->private_data;
struct ftrace_iterator *iter;
mutex_lock(&ftrace_regex_lock);
if (file->f_mode & FMODE_READ) {
iter = m->private;
seq_release(inode, file);
} else
iter = file->private_data;
if (iter->buffer_idx) {
iter->filtered++;
iter->buffer[iter->buffer_idx] = 0;
ftrace_match(iter->buffer, iter->buffer_idx, enable);
}
mutex_lock(&ftrace_sysctl_lock);
mutex_lock(&ftraced_lock);
if (iter->filtered && ftraced_suspend && ftrace_enabled)
ftrace_run_update_code(FTRACE_ENABLE_CALLS);
mutex_unlock(&ftraced_lock);
mutex_unlock(&ftrace_sysctl_lock);
kfree(iter);
mutex_unlock(&ftrace_regex_lock);
return 0;
}
static int
ftrace_filter_release(struct inode *inode, struct file *file)
{
return ftrace_regex_release(inode, file, 1);
}
static int
ftrace_notrace_release(struct inode *inode, struct file *file)
{
return ftrace_regex_release(inode, file, 0);
}
static ssize_t
ftraced_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
/* don't worry about races */
char *buf = ftraced_stop ? "disabled\n" : "enabled\n";
int r = strlen(buf);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static ssize_t
ftraced_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
long val;
int ret;
if (cnt >= sizeof(buf))
return -EINVAL;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
if (strncmp(buf, "enable", 6) == 0)
val = 1;
else if (strncmp(buf, "disable", 7) == 0)
val = 0;
else {
buf[cnt] = 0;
ret = strict_strtoul(buf, 10, &val);
if (ret < 0)
return ret;
val = !!val;
}
if (val)
ftrace_enable_daemon();
else
ftrace_disable_daemon();
filp->f_pos += cnt;
return cnt;
}
static struct file_operations ftrace_avail_fops = {
.open = ftrace_avail_open,
.read = seq_read,
.llseek = seq_lseek,
.release = ftrace_avail_release,
};
static struct file_operations ftrace_failures_fops = {
.open = ftrace_failures_open,
.read = seq_read,
.llseek = seq_lseek,
.release = ftrace_avail_release,
};
static struct file_operations ftrace_filter_fops = {
.open = ftrace_filter_open,
.read = ftrace_regex_read,
.write = ftrace_filter_write,
.llseek = ftrace_regex_lseek,
.release = ftrace_filter_release,
};
static struct file_operations ftrace_notrace_fops = {
.open = ftrace_notrace_open,
.read = ftrace_regex_read,
.write = ftrace_notrace_write,
.llseek = ftrace_regex_lseek,
.release = ftrace_notrace_release,
};
static struct file_operations ftraced_fops = {
.open = tracing_open_generic,
.read = ftraced_read,
.write = ftraced_write,
};
/**
* ftrace_force_update - force an update to all recording ftrace functions
*/
int ftrace_force_update(void)
{
int ret = 0;
if (unlikely(ftrace_disabled))
return -ENODEV;
mutex_lock(&ftrace_sysctl_lock);
mutex_lock(&ftraced_lock);
/*
* If ftraced_trigger is not set, then there is nothing
* to update.
*/
if (ftraced_trigger && !ftrace_update_code())
ret = -EBUSY;
mutex_unlock(&ftraced_lock);
mutex_unlock(&ftrace_sysctl_lock);
return ret;
}
static void ftrace_force_shutdown(void)
{
struct task_struct *task;
int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;
mutex_lock(&ftraced_lock);
task = ftraced_task;
ftraced_task = NULL;
ftraced_suspend = -1;
ftrace_run_update_code(command);
mutex_unlock(&ftraced_lock);
if (task)
kthread_stop(task);
}
static __init int ftrace_init_debugfs(void)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
entry = debugfs_create_file("available_filter_functions", 0444,
d_tracer, NULL, &ftrace_avail_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'available_filter_functions' entry\n");
entry = debugfs_create_file("failures", 0444,
d_tracer, NULL, &ftrace_failures_fops);
if (!entry)
pr_warning("Could not create debugfs 'failures' entry\n");
entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
NULL, &ftrace_filter_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'set_ftrace_filter' entry\n");
entry = debugfs_create_file("set_ftrace_notrace", 0644, d_tracer,
NULL, &ftrace_notrace_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'set_ftrace_notrace' entry\n");
entry = debugfs_create_file("ftraced_enabled", 0644, d_tracer,
NULL, &ftraced_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'ftraced_enabled' entry\n");
return 0;
}
fs_initcall(ftrace_init_debugfs);
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
static int ftrace_convert_nops(unsigned long *start,
unsigned long *end)
{
unsigned long *p;
unsigned long addr;
unsigned long flags;
p = start;
while (p < end) {
addr = ftrace_call_adjust(*p++);
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
ftrace_record_ip(addr);
spin_unlock(&ftrace_lock);
ftrace_shutdown_replenish();
}
/* p is ignored */
local_irq_save(flags);
__ftrace_update_code(p);
local_irq_restore(flags);
return 0;
}
void ftrace_init_module(unsigned long *start, unsigned long *end)
{
if (ftrace_disabled || start == end)
return;
ftrace_convert_nops(start, end);
}
extern unsigned long __start_mcount_loc[];
extern unsigned long __stop_mcount_loc[];
void __init ftrace_init(void)
{
unsigned long count, addr, flags;
int ret;
/* Keep the ftrace pointer to the stub */
addr = (unsigned long)ftrace_stub;
local_irq_save(flags);
ftrace_dyn_arch_init(&addr);
local_irq_restore(flags);
/* ftrace_dyn_arch_init places the return code in addr */
if (addr)
goto failed;
count = __stop_mcount_loc - __start_mcount_loc;
ret = ftrace_dyn_table_alloc(count);
if (ret)
goto failed;
last_ftrace_enabled = ftrace_enabled = 1;
ret = ftrace_convert_nops(__start_mcount_loc,
__stop_mcount_loc);
return;
failed:
ftrace_disabled = 1;
}
#else /* CONFIG_FTRACE_MCOUNT_RECORD */
static int ftraced(void *ignore)
{
unsigned long usecs;
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
/* check once a second */
schedule_timeout(HZ);
if (unlikely(ftrace_disabled))
continue;
mutex_lock(&ftrace_sysctl_lock);
mutex_lock(&ftraced_lock);
if (!ftraced_suspend && !ftraced_stop &&
ftrace_update_code()) {
usecs = nsecs_to_usecs(ftrace_update_time);
if (ftrace_update_tot_cnt > 100000) {
ftrace_update_tot_cnt = 0;
pr_info("hm, dftrace overflow: %lu change%s"
" (%lu total) in %lu usec%s\n",
ftrace_update_cnt,
ftrace_update_cnt != 1 ? "s" : "",
ftrace_update_tot_cnt,
usecs, usecs != 1 ? "s" : "");
ftrace_disabled = 1;
WARN_ON_ONCE(1);
}
}
mutex_unlock(&ftraced_lock);
mutex_unlock(&ftrace_sysctl_lock);
ftrace_shutdown_replenish();
}
__set_current_state(TASK_RUNNING);
return 0;
}
static int __init ftrace_dynamic_init(void)
{
struct task_struct *p;
unsigned long addr;
int ret;
addr = (unsigned long)ftrace_record_ip;
stop_machine(ftrace_dyn_arch_init, &addr, NULL);
/* ftrace_dyn_arch_init places the return code in addr */
if (addr) {
ret = (int)addr;
goto failed;
}
ret = ftrace_dyn_table_alloc(NR_TO_INIT);
if (ret)
goto failed;
p = kthread_run(ftraced, NULL, "ftraced");
if (IS_ERR(p)) {
ret = -1;
goto failed;
}
last_ftrace_enabled = ftrace_enabled = 1;
ftraced_task = p;
return 0;
failed:
ftrace_disabled = 1;
return ret;
}
core_initcall(ftrace_dynamic_init);
#endif /* CONFIG_FTRACE_MCOUNT_RECORD */
#else
# define ftrace_startup() do { } while (0)
# define ftrace_shutdown() do { } while (0)
# define ftrace_startup_sysctl() do { } while (0)
# define ftrace_shutdown_sysctl() do { } while (0)
# define ftrace_force_shutdown() do { } while (0)
#endif /* CONFIG_DYNAMIC_FTRACE */
/**
* ftrace_kill_atomic - kill ftrace from critical sections
*
* This function should be used by panic code. It stops ftrace
* but in a not so nice way. If you need to simply kill ftrace
* from a non-atomic section, use ftrace_kill.
*/
void ftrace_kill_atomic(void)
{
ftrace_disabled = 1;
ftrace_enabled = 0;
#ifdef CONFIG_DYNAMIC_FTRACE
ftraced_suspend = -1;
#endif
clear_ftrace_function();
}
/**
* ftrace_kill - totally shutdown ftrace
*
* This is a safety measure. If something was detected that seems
* wrong, calling this function will keep ftrace from doing
* any more modifications, and updates.
* used when something went wrong.
*/
void ftrace_kill(void)
{
mutex_lock(&ftrace_sysctl_lock);
ftrace_disabled = 1;
ftrace_enabled = 0;
clear_ftrace_function();
mutex_unlock(&ftrace_sysctl_lock);
/* Try to totally disable ftrace */
ftrace_force_shutdown();
}
/**
* register_ftrace_function - register a function for profiling
* @ops - ops structure that holds the function for profiling.
*
* Register a function to be called by all functions in the
* kernel.
*
* Note: @ops->func and all the functions it calls must be labeled
* with "notrace", otherwise it will go into a
* recursive loop.
*/
int register_ftrace_function(struct ftrace_ops *ops)
{
int ret;
if (unlikely(ftrace_disabled))
return -1;
mutex_lock(&ftrace_sysctl_lock);
ret = __register_ftrace_function(ops);
ftrace_startup();
mutex_unlock(&ftrace_sysctl_lock);
return ret;
}
/**
* unregister_ftrace_function - unresgister a function for profiling.
* @ops - ops structure that holds the function to unregister
*
* Unregister a function that was added to be called by ftrace profiling.
*/
int unregister_ftrace_function(struct ftrace_ops *ops)
{
int ret;
mutex_lock(&ftrace_sysctl_lock);
ret = __unregister_ftrace_function(ops);
ftrace_shutdown();
mutex_unlock(&ftrace_sysctl_lock);
return ret;
}
int
ftrace_enable_sysctl(struct ctl_table *table, int write,
struct file *file, void __user *buffer, size_t *lenp,
loff_t *ppos)
{
int ret;
if (unlikely(ftrace_disabled))
return -ENODEV;
mutex_lock(&ftrace_sysctl_lock);
ret = proc_dointvec(table, write, file, buffer, lenp, ppos);
if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
goto out;
last_ftrace_enabled = ftrace_enabled;
if (ftrace_enabled) {
ftrace_startup_sysctl();
/* we are starting ftrace again */
if (ftrace_list != &ftrace_list_end) {
if (ftrace_list->next == &ftrace_list_end)
ftrace_trace_function = ftrace_list->func;
else
ftrace_trace_function = ftrace_list_func;
}
} else {
/* stopping ftrace calls (just send to ftrace_stub) */
ftrace_trace_function = ftrace_stub;
ftrace_shutdown_sysctl();
}
out:
mutex_unlock(&ftrace_sysctl_lock);
return ret;
}
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