kernel-ark/kernel/trace/ftrace.c
Frederic Weisbecker 00f57f545a tracing/function-graph-tracer: fix a regression while suspend to disk
Impact: fix a crash while kernel image restore

When the function graph tracer is running and while suspend to disk, some racy
and dangerous things happen against this tracer.

The current task will save its registers including the stack pointer which
contains the return address hooked by the tracer. But the current task will
continue to enter other functions after that to save the memory, and then
it will store other return addresses, and finally loose the old depth which
matches the return address saved in the old stack (during the registers saving).

So on image restore, the code will return to wrong addresses.
And there are other things: on restore, the task will have it's "current"
pointer overwritten during registers restoring....switching from one task to
another... That would be insane to try to trace function graphs at these
stages.

This patch makes the function graph tracer listening on power events, making
it's tracing disabled for the current task (the one that performs the
hibernation work) while suspend/resume to disk, making the tracing safe
during hibernation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-01-21 15:21:30 +01:00

2142 lines
44 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/suspend.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/list.h>
#include <asm/ftrace.h>
#include "trace.h"
#define FTRACE_WARN_ON(cond) \
do { \
if (WARN_ON(cond)) \
ftrace_kill(); \
} while (0)
#define FTRACE_WARN_ON_ONCE(cond) \
do { \
if (WARN_ON_ONCE(cond)) \
ftrace_kill(); \
} while (0)
/* ftrace_enabled is a method to turn ftrace on or off */
int ftrace_enabled __read_mostly;
static int last_ftrace_enabled;
/* set when tracing only a pid */
struct pid *ftrace_pid_trace;
static struct pid * const ftrace_swapper_pid = &init_struct_pid;
/* Quick disabling of function tracer. */
int function_trace_stop;
/*
* 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 DEFINE_MUTEX(ftrace_start_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;
ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;
ftrace_func_t ftrace_pid_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;
};
}
static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
{
if (!test_tsk_trace_trace(current))
return;
ftrace_pid_function(ip, parent_ip);
}
static void set_ftrace_pid_function(ftrace_func_t func)
{
/* do not set ftrace_pid_function to itself! */
if (func != ftrace_pid_func)
ftrace_pid_function = func;
}
/**
* 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;
__ftrace_trace_function = ftrace_stub;
ftrace_pid_function = ftrace_stub;
}
#ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
/*
* For those archs that do not test ftrace_trace_stop in their
* mcount call site, we need to do it from C.
*/
static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
{
if (function_trace_stop)
return;
__ftrace_trace_function(ip, parent_ip);
}
#endif
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) {
ftrace_func_t func;
if (ops->next == &ftrace_list_end)
func = ops->func;
else
func = ftrace_list_func;
if (ftrace_pid_trace) {
set_ftrace_pid_function(func);
func = ftrace_pid_func;
}
/*
* For one func, simply call it directly.
* For more than one func, call the chain.
*/
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
ftrace_trace_function = func;
#else
__ftrace_trace_function = func;
ftrace_trace_function = ftrace_test_stop_func;
#endif
}
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->next == &ftrace_list_end) {
ftrace_func_t func = ftrace_list->func;
if (ftrace_pid_trace) {
set_ftrace_pid_function(func);
func = ftrace_pid_func;
}
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
ftrace_trace_function = func;
#else
__ftrace_trace_function = func;
#endif
}
}
out:
spin_unlock(&ftrace_lock);
return ret;
}
static void ftrace_update_pid_func(void)
{
ftrace_func_t func;
/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
if (ftrace_trace_function == ftrace_stub)
goto out;
func = ftrace_trace_function;
if (ftrace_pid_trace) {
set_ftrace_pid_function(func);
func = ftrace_pid_func;
} else {
if (func == ftrace_pid_func)
func = ftrace_pid_function;
}
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
ftrace_trace_function = func;
#else
__ftrace_trace_function = func;
#endif
out:
spin_unlock(&ftrace_lock);
}
#ifdef CONFIG_DYNAMIC_FTRACE
#ifndef CONFIG_FTRACE_MCOUNT_RECORD
# error Dynamic ftrace depends on MCOUNT_RECORD
#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;
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),
FTRACE_START_FUNC_RET = (1 << 5),
FTRACE_STOP_FUNC_RET = (1 << 6),
};
static int ftrace_filtered;
static LIST_HEAD(ftrace_new_addrs);
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 struct dyn_ftrace *ftrace_free_records;
#ifdef CONFIG_KPROBES
static int frozen_record_count;
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 */
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))) {
FTRACE_WARN_ON_ONCE(1);
ftrace_free_records = NULL;
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) {
/* allocate another page */
ftrace_pages->next =
(void *)get_zeroed_page(GFP_KERNEL);
if (!ftrace_pages->next)
return NULL;
}
ftrace_pages = ftrace_pages->next;
}
return &ftrace_pages->records[ftrace_pages->index++];
}
static struct dyn_ftrace *
ftrace_record_ip(unsigned long ip)
{
struct dyn_ftrace *rec;
if (ftrace_disabled)
return NULL;
rec = ftrace_alloc_dyn_node(ip);
if (!rec)
return NULL;
rec->ip = ip;
list_add(&rec->list, &ftrace_new_addrs);
return rec;
}
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 void ftrace_bug(int failed, unsigned long ip)
{
switch (failed) {
case -EFAULT:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace faulted on modifying ");
print_ip_sym(ip);
break;
case -EINVAL:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace failed to modify ");
print_ip_sym(ip);
print_ip_ins(" actual: ", (unsigned char *)ip);
printk(KERN_CONT "\n");
break;
case -EPERM:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace faulted on writing ");
print_ip_sym(ip);
break;
default:
FTRACE_WARN_ON_ONCE(1);
pr_info("ftrace faulted on unknown error ");
print_ip_sym(ip);
}
}
static int
__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
{
unsigned long ip, fl;
unsigned long ftrace_addr;
ftrace_addr = (unsigned long)ftrace_caller;
ip = rec->ip;
/*
* If this record is not to be traced and
* it is not enabled then do nothing.
*
* If this record is not to be traced and
* it is enabled then disabled it.
*
*/
if (rec->flags & FTRACE_FL_NOTRACE) {
if (rec->flags & FTRACE_FL_ENABLED)
rec->flags &= ~FTRACE_FL_ENABLED;
else
return 0;
} else if (ftrace_filtered && enable) {
/*
* Filtering is on:
*/
fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);
/* Record is filtered and enabled, do nothing */
if (fl == (FTRACE_FL_FILTER | FTRACE_FL_ENABLED))
return 0;
/* Record is not filtered and is not enabled do nothing */
if (!fl)
return 0;
/* Record is not filtered but enabled, disable it */
if (fl == FTRACE_FL_ENABLED)
rec->flags &= ~FTRACE_FL_ENABLED;
else
/* Otherwise record is filtered but not enabled, enable it */
rec->flags |= FTRACE_FL_ENABLED;
} else {
/* Disable or not filtered */
if (enable) {
/* if record is enabled, do nothing */
if (rec->flags & FTRACE_FL_ENABLED)
return 0;
rec->flags |= FTRACE_FL_ENABLED;
} else {
/* if record is not enabled do nothing */
if (!(rec->flags & FTRACE_FL_ENABLED))
return 0;
rec->flags &= ~FTRACE_FL_ENABLED;
}
}
if (rec->flags & FTRACE_FL_ENABLED)
return ftrace_make_call(rec, ftrace_addr);
else
return ftrace_make_nop(NULL, rec, ftrace_addr);
}
static void ftrace_replace_code(int enable)
{
int i, failed;
struct dyn_ftrace *rec;
struct ftrace_page *pg;
for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
/*
* Skip over free records and records that have
* failed.
*/
if (rec->flags & FTRACE_FL_FREE ||
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, enable);
if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
rec->flags |= FTRACE_FL_FAILED;
if ((system_state == SYSTEM_BOOTING) ||
!core_kernel_text(rec->ip)) {
ftrace_free_rec(rec);
} else
ftrace_bug(failed, rec->ip);
}
}
}
}
static int
ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
{
unsigned long ip;
int ret;
ip = rec->ip;
ret = ftrace_make_nop(mod, rec, mcount_addr);
if (ret) {
ftrace_bug(ret, ip);
rec->flags |= FTRACE_FL_FAILED;
return 0;
}
return 1;
}
static int __ftrace_modify_code(void *data)
{
int *command = data;
if (*command & FTRACE_ENABLE_CALLS)
ftrace_replace_code(1);
else if (*command & FTRACE_DISABLE_CALLS)
ftrace_replace_code(0);
if (*command & FTRACE_UPDATE_TRACE_FUNC)
ftrace_update_ftrace_func(ftrace_trace_function);
if (*command & FTRACE_START_FUNC_RET)
ftrace_enable_ftrace_graph_caller();
else if (*command & FTRACE_STOP_FUNC_RET)
ftrace_disable_ftrace_graph_caller();
return 0;
}
static void ftrace_run_update_code(int command)
{
stop_machine(__ftrace_modify_code, &command, NULL);
}
static ftrace_func_t saved_ftrace_func;
static int ftrace_start_up;
static void ftrace_startup_enable(int command)
{
if (saved_ftrace_func != ftrace_trace_function) {
saved_ftrace_func = ftrace_trace_function;
command |= FTRACE_UPDATE_TRACE_FUNC;
}
if (!command || !ftrace_enabled)
return;
ftrace_run_update_code(command);
}
static void ftrace_startup(int command)
{
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftrace_start_lock);
ftrace_start_up++;
command |= FTRACE_ENABLE_CALLS;
ftrace_startup_enable(command);
mutex_unlock(&ftrace_start_lock);
}
static void ftrace_shutdown(int command)
{
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftrace_start_lock);
ftrace_start_up--;
if (!ftrace_start_up)
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(&ftrace_start_lock);
}
static void ftrace_startup_sysctl(void)
{
int command = FTRACE_ENABLE_MCOUNT;
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftrace_start_lock);
/* Force update next time */
saved_ftrace_func = NULL;
/* ftrace_start_up is true if we want ftrace running */
if (ftrace_start_up)
command |= FTRACE_ENABLE_CALLS;
ftrace_run_update_code(command);
mutex_unlock(&ftrace_start_lock);
}
static void ftrace_shutdown_sysctl(void)
{
int command = FTRACE_DISABLE_MCOUNT;
if (unlikely(ftrace_disabled))
return;
mutex_lock(&ftrace_start_lock);
/* ftrace_start_up is true if ftrace is running */
if (ftrace_start_up)
command |= FTRACE_DISABLE_CALLS;
ftrace_run_update_code(command);
mutex_unlock(&ftrace_start_lock);
}
static cycle_t ftrace_update_time;
static unsigned long ftrace_update_cnt;
unsigned long ftrace_update_tot_cnt;
static int ftrace_update_code(struct module *mod)
{
struct dyn_ftrace *p, *t;
cycle_t start, stop;
start = ftrace_now(raw_smp_processor_id());
ftrace_update_cnt = 0;
list_for_each_entry_safe(p, t, &ftrace_new_addrs, list) {
/* If something went wrong, bail without enabling anything */
if (unlikely(ftrace_disabled))
return -1;
list_del_init(&p->list);
/* convert record (i.e, patch mcount-call with NOP) */
if (ftrace_code_disable(mod, p)) {
p->flags |= FTRACE_FL_CONVERTED;
ftrace_update_cnt++;
} else
ftrace_free_rec(p);
}
stop = ftrace_now(raw_smp_processor_id());
ftrace_update_time = stop - start;
ftrace_update_tot_cnt += ftrace_update_cnt;
return 0;
}
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 entries in %d pages\n",
num_to_init, cnt + 1);
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 {
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 {
iter->idx = -1;
}
} 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_FILTER) &&
!(rec->flags & FTRACE_FL_FILTER)) ||
((iter->flags & FTRACE_ITER_NOTRACE) &&
!(rec->flags & FTRACE_FL_NOTRACE))) {
rec = NULL;
goto retry;
}
}
spin_unlock(&ftrace_lock);
return rec;
}
static void *t_start(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
void *p = NULL;
if (*pos > 0) {
if (iter->idx < 0)
return p;
(*pos)--;
iter->idx--;
}
p = t_next(m, p, pos);
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;
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->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;
int not = 0;
if (buff[0] == '!') {
not = 1;
buff++;
len--;
}
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) {
if (not)
rec->flags &= ~flag;
else
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(&ftrace_start_lock);
if (ftrace_start_up && ftrace_enabled)
ftrace_run_update_code(FTRACE_ENABLE_CALLS);
mutex_unlock(&ftrace_start_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 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,
};
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static DEFINE_MUTEX(graph_lock);
int ftrace_graph_count;
unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
static void *
g_next(struct seq_file *m, void *v, loff_t *pos)
{
unsigned long *array = m->private;
int index = *pos;
(*pos)++;
if (index >= ftrace_graph_count)
return NULL;
return &array[index];
}
static void *g_start(struct seq_file *m, loff_t *pos)
{
void *p = NULL;
mutex_lock(&graph_lock);
p = g_next(m, p, pos);
return p;
}
static void g_stop(struct seq_file *m, void *p)
{
mutex_unlock(&graph_lock);
}
static int g_show(struct seq_file *m, void *v)
{
unsigned long *ptr = v;
char str[KSYM_SYMBOL_LEN];
if (!ptr)
return 0;
kallsyms_lookup(*ptr, NULL, NULL, NULL, str);
seq_printf(m, "%s\n", str);
return 0;
}
static struct seq_operations ftrace_graph_seq_ops = {
.start = g_start,
.next = g_next,
.stop = g_stop,
.show = g_show,
};
static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
int ret = 0;
if (unlikely(ftrace_disabled))
return -ENODEV;
mutex_lock(&graph_lock);
if ((file->f_mode & FMODE_WRITE) &&
!(file->f_flags & O_APPEND)) {
ftrace_graph_count = 0;
memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
}
if (file->f_mode & FMODE_READ) {
ret = seq_open(file, &ftrace_graph_seq_ops);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = ftrace_graph_funcs;
}
} else
file->private_data = ftrace_graph_funcs;
mutex_unlock(&graph_lock);
return ret;
}
static ssize_t
ftrace_graph_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 int
ftrace_set_func(unsigned long *array, int idx, char *buffer)
{
char str[KSYM_SYMBOL_LEN];
struct dyn_ftrace *rec;
struct ftrace_page *pg;
int found = 0;
int i, j;
if (ftrace_disabled)
return -ENODEV;
/* 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->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
continue;
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
if (strcmp(str, buffer) == 0) {
found = 1;
for (j = 0; j < idx; j++)
if (array[j] == rec->ip) {
found = 0;
break;
}
if (found)
array[idx] = rec->ip;
break;
}
}
}
spin_unlock(&ftrace_lock);
return found ? 0 : -EINVAL;
}
static ssize_t
ftrace_graph_write(struct file *file, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
unsigned char buffer[FTRACE_BUFF_MAX+1];
unsigned long *array;
size_t read = 0;
ssize_t ret;
int index = 0;
char ch;
if (!cnt || cnt < 0)
return 0;
mutex_lock(&graph_lock);
if (ftrace_graph_count >= FTRACE_GRAPH_MAX_FUNCS) {
ret = -EBUSY;
goto out;
}
if (file->f_mode & FMODE_READ) {
struct seq_file *m = file->private_data;
array = m->private;
} else
array = file->private_data;
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
/* skip white space */
while (cnt && isspace(ch)) {
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
if (isspace(ch)) {
*ppos += read;
ret = read;
goto out;
}
while (cnt && !isspace(ch)) {
if (index < FTRACE_BUFF_MAX)
buffer[index++] = ch;
else {
ret = -EINVAL;
goto out;
}
ret = get_user(ch, ubuf++);
if (ret)
goto out;
read++;
cnt--;
}
buffer[index] = 0;
/* we allow only one at a time */
ret = ftrace_set_func(array, ftrace_graph_count, buffer);
if (ret)
goto out;
ftrace_graph_count++;
file->f_pos += read;
ret = read;
out:
mutex_unlock(&graph_lock);
return ret;
}
static const struct file_operations ftrace_graph_fops = {
.open = ftrace_graph_open,
.read = ftrace_graph_read,
.write = ftrace_graph_write,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
{
struct dentry *entry;
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");
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
entry = debugfs_create_file("set_graph_function", 0444, d_tracer,
NULL,
&ftrace_graph_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'set_graph_function' entry\n");
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
return 0;
}
static int ftrace_convert_nops(struct module *mod,
unsigned long *start,
unsigned long *end)
{
unsigned long *p;
unsigned long addr;
unsigned long flags;
mutex_lock(&ftrace_start_lock);
p = start;
while (p < end) {
addr = ftrace_call_adjust(*p++);
/*
* Some architecture linkers will pad between
* the different mcount_loc sections of different
* object files to satisfy alignments.
* Skip any NULL pointers.
*/
if (!addr)
continue;
ftrace_record_ip(addr);
}
/* disable interrupts to prevent kstop machine */
local_irq_save(flags);
ftrace_update_code(mod);
local_irq_restore(flags);
mutex_unlock(&ftrace_start_lock);
return 0;
}
void ftrace_init_module(struct module *mod,
unsigned long *start, unsigned long *end)
{
if (ftrace_disabled || start == end)
return;
ftrace_convert_nops(mod, 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(NULL,
__start_mcount_loc,
__stop_mcount_loc);
return;
failed:
ftrace_disabled = 1;
}
#else
static int __init ftrace_nodyn_init(void)
{
ftrace_enabled = 1;
return 0;
}
device_initcall(ftrace_nodyn_init);
static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
static inline void ftrace_startup_enable(int command) { }
/* Keep as macros so we do not need to define the commands */
# define ftrace_startup(command) do { } while (0)
# define ftrace_shutdown(command) do { } while (0)
# define ftrace_startup_sysctl() do { } while (0)
# define ftrace_shutdown_sysctl() do { } while (0)
#endif /* CONFIG_DYNAMIC_FTRACE */
static ssize_t
ftrace_pid_read(struct file *file, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
char buf[64];
int r;
if (ftrace_pid_trace == ftrace_swapper_pid)
r = sprintf(buf, "swapper tasks\n");
else if (ftrace_pid_trace)
r = sprintf(buf, "%u\n", pid_nr(ftrace_pid_trace));
else
r = sprintf(buf, "no pid\n");
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
static void clear_ftrace_swapper(void)
{
struct task_struct *p;
int cpu;
get_online_cpus();
for_each_online_cpu(cpu) {
p = idle_task(cpu);
clear_tsk_trace_trace(p);
}
put_online_cpus();
}
static void set_ftrace_swapper(void)
{
struct task_struct *p;
int cpu;
get_online_cpus();
for_each_online_cpu(cpu) {
p = idle_task(cpu);
set_tsk_trace_trace(p);
}
put_online_cpus();
}
static void clear_ftrace_pid(struct pid *pid)
{
struct task_struct *p;
do_each_pid_task(pid, PIDTYPE_PID, p) {
clear_tsk_trace_trace(p);
} while_each_pid_task(pid, PIDTYPE_PID, p);
put_pid(pid);
}
static void set_ftrace_pid(struct pid *pid)
{
struct task_struct *p;
do_each_pid_task(pid, PIDTYPE_PID, p) {
set_tsk_trace_trace(p);
} while_each_pid_task(pid, PIDTYPE_PID, p);
}
static void clear_ftrace_pid_task(struct pid **pid)
{
if (*pid == ftrace_swapper_pid)
clear_ftrace_swapper();
else
clear_ftrace_pid(*pid);
*pid = NULL;
}
static void set_ftrace_pid_task(struct pid *pid)
{
if (pid == ftrace_swapper_pid)
set_ftrace_swapper();
else
set_ftrace_pid(pid);
}
static ssize_t
ftrace_pid_write(struct file *filp, const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct pid *pid;
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_strtol(buf, 10, &val);
if (ret < 0)
return ret;
mutex_lock(&ftrace_start_lock);
if (val < 0) {
/* disable pid tracing */
if (!ftrace_pid_trace)
goto out;
clear_ftrace_pid_task(&ftrace_pid_trace);
} else {
/* swapper task is special */
if (!val) {
pid = ftrace_swapper_pid;
if (pid == ftrace_pid_trace)
goto out;
} else {
pid = find_get_pid(val);
if (pid == ftrace_pid_trace) {
put_pid(pid);
goto out;
}
}
if (ftrace_pid_trace)
clear_ftrace_pid_task(&ftrace_pid_trace);
if (!pid)
goto out;
ftrace_pid_trace = pid;
set_ftrace_pid_task(ftrace_pid_trace);
}
/* update the function call */
ftrace_update_pid_func();
ftrace_startup_enable(0);
out:
mutex_unlock(&ftrace_start_lock);
return cnt;
}
static struct file_operations ftrace_pid_fops = {
.read = ftrace_pid_read,
.write = ftrace_pid_write,
};
static __init int ftrace_init_debugfs(void)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
if (!d_tracer)
return 0;
ftrace_init_dyn_debugfs(d_tracer);
entry = debugfs_create_file("set_ftrace_pid", 0644, d_tracer,
NULL, &ftrace_pid_fops);
if (!entry)
pr_warning("Could not create debugfs "
"'set_ftrace_pid' entry\n");
return 0;
}
fs_initcall(ftrace_init_debugfs);
/**
* ftrace_kill - kill ftrace
*
* 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(void)
{
ftrace_disabled = 1;
ftrace_enabled = 0;
clear_ftrace_function();
}
/**
* 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(0);
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(0);
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;
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static atomic_t ftrace_graph_active;
static struct notifier_block ftrace_suspend_notifier;
int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
{
return 0;
}
/* The callbacks that hook a function */
trace_func_graph_ret_t ftrace_graph_return =
(trace_func_graph_ret_t)ftrace_stub;
trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
{
int i;
int ret = 0;
unsigned long flags;
int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;
struct task_struct *g, *t;
for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
ret_stack_list[i] = kmalloc(FTRACE_RETFUNC_DEPTH
* sizeof(struct ftrace_ret_stack),
GFP_KERNEL);
if (!ret_stack_list[i]) {
start = 0;
end = i;
ret = -ENOMEM;
goto free;
}
}
read_lock_irqsave(&tasklist_lock, flags);
do_each_thread(g, t) {
if (start == end) {
ret = -EAGAIN;
goto unlock;
}
if (t->ret_stack == NULL) {
t->curr_ret_stack = -1;
/* Make sure IRQs see the -1 first: */
barrier();
t->ret_stack = ret_stack_list[start++];
atomic_set(&t->tracing_graph_pause, 0);
atomic_set(&t->trace_overrun, 0);
}
} while_each_thread(g, t);
unlock:
read_unlock_irqrestore(&tasklist_lock, flags);
free:
for (i = start; i < end; i++)
kfree(ret_stack_list[i]);
return ret;
}
/* Allocate a return stack for each task */
static int start_graph_tracing(void)
{
struct ftrace_ret_stack **ret_stack_list;
int ret;
ret_stack_list = kmalloc(FTRACE_RETSTACK_ALLOC_SIZE *
sizeof(struct ftrace_ret_stack *),
GFP_KERNEL);
if (!ret_stack_list)
return -ENOMEM;
do {
ret = alloc_retstack_tasklist(ret_stack_list);
} while (ret == -EAGAIN);
kfree(ret_stack_list);
return ret;
}
/*
* Hibernation protection.
* The state of the current task is too much unstable during
* suspend/restore to disk. We want to protect against that.
*/
static int
ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
void *unused)
{
switch (state) {
case PM_HIBERNATION_PREPARE:
pause_graph_tracing();
break;
case PM_POST_HIBERNATION:
unpause_graph_tracing();
break;
}
return NOTIFY_DONE;
}
int register_ftrace_graph(trace_func_graph_ret_t retfunc,
trace_func_graph_ent_t entryfunc)
{
int ret = 0;
mutex_lock(&ftrace_sysctl_lock);
ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
register_pm_notifier(&ftrace_suspend_notifier);
atomic_inc(&ftrace_graph_active);
ret = start_graph_tracing();
if (ret) {
atomic_dec(&ftrace_graph_active);
goto out;
}
ftrace_graph_return = retfunc;
ftrace_graph_entry = entryfunc;
ftrace_startup(FTRACE_START_FUNC_RET);
out:
mutex_unlock(&ftrace_sysctl_lock);
return ret;
}
void unregister_ftrace_graph(void)
{
mutex_lock(&ftrace_sysctl_lock);
atomic_dec(&ftrace_graph_active);
ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
ftrace_graph_entry = ftrace_graph_entry_stub;
ftrace_shutdown(FTRACE_STOP_FUNC_RET);
unregister_pm_notifier(&ftrace_suspend_notifier);
mutex_unlock(&ftrace_sysctl_lock);
}
/* Allocate a return stack for newly created task */
void ftrace_graph_init_task(struct task_struct *t)
{
if (atomic_read(&ftrace_graph_active)) {
t->ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
* sizeof(struct ftrace_ret_stack),
GFP_KERNEL);
if (!t->ret_stack)
return;
t->curr_ret_stack = -1;
atomic_set(&t->tracing_graph_pause, 0);
atomic_set(&t->trace_overrun, 0);
} else
t->ret_stack = NULL;
}
void ftrace_graph_exit_task(struct task_struct *t)
{
struct ftrace_ret_stack *ret_stack = t->ret_stack;
t->ret_stack = NULL;
/* NULL must become visible to IRQs before we free it: */
barrier();
kfree(ret_stack);
}
void ftrace_graph_stop(void)
{
ftrace_stop();
}
#endif