linux/kernel/trace/ftrace.c
Steven Rostedt 05736a427f ftrace: warn on failure to disable mcount callers
With the recent updates to ftrace, there should not be any failures when
modifying the code. If there is, then we need to warn about it.

This patch has a cleaned up version of the code that I used to discover
that the weak symbols were causing failures.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-10-14 10:38:11 +02:00

1873 lines
40 KiB
C

/*
* 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;
}