Commit 955b61e5 authored by Jason Wessel's avatar Jason Wessel
Browse files

ftrace,kdb: Extend kdb to be able to dump the ftrace buffer



Add in a helper function to allow the kdb shell to dump the ftrace
buffer.

Modify trace.c to expose the capability to iterate over the ftrace
buffer in a read only capacity.
Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
parent 3f0a55e3
......@@ -57,5 +57,8 @@ obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
obj-$(CONFIG_EVENT_TRACING) += power-traces.o
ifeq ($(CONFIG_TRACING),y)
obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
endif
libftrace-y := ftrace.o
......@@ -101,10 +101,7 @@ static inline void ftrace_enable_cpu(void)
preempt_enable();
}
static cpumask_var_t __read_mostly tracing_buffer_mask;
#define for_each_tracing_cpu(cpu) \
for_each_cpu(cpu, tracing_buffer_mask)
cpumask_var_t __read_mostly tracing_buffer_mask;
/*
* ftrace_dump_on_oops - variable to dump ftrace buffer on oops
......@@ -1539,11 +1536,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
}
EXPORT_SYMBOL_GPL(trace_vprintk);
enum trace_file_type {
TRACE_FILE_LAT_FMT = 1,
TRACE_FILE_ANNOTATE = 2,
};
static void trace_iterator_increment(struct trace_iterator *iter)
{
/* Don't allow ftrace to trace into the ring buffers */
......@@ -1641,7 +1633,7 @@ struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
}
/* Find the next real entry, and increment the iterator to the next entry */
static void *find_next_entry_inc(struct trace_iterator *iter)
void *trace_find_next_entry_inc(struct trace_iterator *iter)
{
iter->ent = __find_next_entry(iter, &iter->cpu,
&iter->lost_events, &iter->ts);
......@@ -1676,19 +1668,19 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
return NULL;
if (iter->idx < 0)
ent = find_next_entry_inc(iter);
ent = trace_find_next_entry_inc(iter);
else
ent = iter;
while (ent && iter->idx < i)
ent = find_next_entry_inc(iter);
ent = trace_find_next_entry_inc(iter);
iter->pos = *pos;
return ent;
}
static void tracing_iter_reset(struct trace_iterator *iter, int cpu)
void tracing_iter_reset(struct trace_iterator *iter, int cpu)
{
struct trace_array *tr = iter->tr;
struct ring_buffer_event *event;
......@@ -2049,7 +2041,7 @@ int trace_empty(struct trace_iterator *iter)
}
/* Called with trace_event_read_lock() held. */
static enum print_line_t print_trace_line(struct trace_iterator *iter)
enum print_line_t print_trace_line(struct trace_iterator *iter)
{
enum print_line_t ret;
......@@ -3211,7 +3203,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf,
trace_event_read_lock();
trace_access_lock(iter->cpu_file);
while (find_next_entry_inc(iter) != NULL) {
while (trace_find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
int len = iter->seq.len;
......@@ -3294,7 +3286,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
rem -= count;
if (!find_next_entry_inc(iter)) {
if (!trace_find_next_entry_inc(iter)) {
rem = 0;
iter->ent = NULL;
break;
......@@ -3350,7 +3342,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
if (ret <= 0)
goto out_err;
if (!iter->ent && !find_next_entry_inc(iter)) {
if (!iter->ent && !trace_find_next_entry_inc(iter)) {
ret = -EFAULT;
goto out_err;
}
......@@ -4414,7 +4406,7 @@ static struct notifier_block trace_die_notifier = {
*/
#define KERN_TRACE KERN_EMERG
static void
void
trace_printk_seq(struct trace_seq *s)
{
/* Probably should print a warning here. */
......@@ -4429,6 +4421,13 @@ trace_printk_seq(struct trace_seq *s)
trace_seq_init(s);
}
void trace_init_global_iter(struct trace_iterator *iter)
{
iter->tr = &global_trace;
iter->trace = current_trace;
iter->cpu_file = TRACE_PIPE_ALL_CPU;
}
static void
__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
{
......@@ -4454,8 +4453,10 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
if (disable_tracing)
ftrace_kill();
trace_init_global_iter(&iter);
for_each_tracing_cpu(cpu) {
atomic_inc(&global_trace.data[cpu]->disabled);
atomic_inc(&iter.tr->data[cpu]->disabled);
}
old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
......@@ -4504,7 +4505,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;
if (find_next_entry_inc(&iter) != NULL) {
if (trace_find_next_entry_inc(&iter) != NULL) {
int ret;
ret = print_trace_line(&iter);
......@@ -4526,7 +4527,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
trace_flags |= old_userobj;
for_each_tracing_cpu(cpu) {
atomic_dec(&global_trace.data[cpu]->disabled);
atomic_dec(&iter.tr->data[cpu]->disabled);
}
tracing_on();
}
......
......@@ -338,6 +338,14 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
int *ent_cpu, u64 *ent_ts);
int trace_empty(struct trace_iterator *iter);
void *trace_find_next_entry_inc(struct trace_iterator *iter);
void trace_init_global_iter(struct trace_iterator *iter);
void tracing_iter_reset(struct trace_iterator *iter, int cpu);
void default_wait_pipe(struct trace_iterator *iter);
void poll_wait_pipe(struct trace_iterator *iter);
......@@ -380,6 +388,15 @@ void tracing_start_sched_switch_record(void);
int register_tracer(struct tracer *type);
void unregister_tracer(struct tracer *type);
int is_tracing_stopped(void);
enum trace_file_type {
TRACE_FILE_LAT_FMT = 1,
TRACE_FILE_ANNOTATE = 2,
};
extern cpumask_var_t __read_mostly tracing_buffer_mask;
#define for_each_tracing_cpu(cpu) \
for_each_cpu(cpu, tracing_buffer_mask)
extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
......@@ -471,6 +488,8 @@ trace_array_vprintk(struct trace_array *tr,
unsigned long ip, const char *fmt, va_list args);
int trace_array_printk(struct trace_array *tr,
unsigned long ip, const char *fmt, ...);
void trace_printk_seq(struct trace_seq *s);
enum print_line_t print_trace_line(struct trace_iterator *iter);
extern unsigned long trace_flags;
......
/*
* kdb helper for dumping the ftrace buffer
*
* Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
*
* ftrace_dump_buf based on ftrace_dump:
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
*/
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/kdb.h>
#include <linux/ftrace.h>
#include "../debug/kdb/kdb_private.h"
#include "trace.h"
#include "trace_output.h"
static void ftrace_dump_buf(int skip_lines)
{
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
unsigned int old_userobj;
int cnt = 0, cpu;
trace_init_global_iter(&iter);
for_each_tracing_cpu(cpu) {
atomic_inc(&iter.tr->data[cpu]->disabled);
}
old_userobj = trace_flags;
/* don't look at user memory in panic mode */
trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
kdb_printf("Dumping ftrace buffer:\n");
/* reset all but tr, trace, and overruns */
memset(&iter.seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;
for_each_tracing_cpu(cpu) {
iter.buffer_iter[cpu] =
ring_buffer_read_prepare(iter.tr->buffer, cpu);
ring_buffer_read_start(iter.buffer_iter[cpu]);
tracing_iter_reset(&iter, cpu);
}
if (!trace_empty(&iter))
trace_find_next_entry_inc(&iter);
while (!trace_empty(&iter)) {
if (!cnt)
kdb_printf("---------------------------------\n");
cnt++;
if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines)
print_trace_line(&iter);
if (!skip_lines)
trace_printk_seq(&iter.seq);
else
skip_lines--;
if (KDB_FLAG(CMD_INTERRUPT))
goto out;
}
if (!cnt)
kdb_printf(" (ftrace buffer empty)\n");
else
kdb_printf("---------------------------------\n");
out:
trace_flags = old_userobj;
for_each_tracing_cpu(cpu) {
atomic_dec(&iter.tr->data[cpu]->disabled);
}
for_each_tracing_cpu(cpu)
if (iter.buffer_iter[cpu])
ring_buffer_read_finish(iter.buffer_iter[cpu]);
}
/*
* kdb_ftdump - Dump the ftrace log buffer
*/
static int kdb_ftdump(int argc, const char **argv)
{
int skip_lines = 0;
char *cp;
if (argc > 1)
return KDB_ARGCOUNT;
if (argc) {
skip_lines = simple_strtol(argv[1], &cp, 0);
if (*cp)
skip_lines = 0;
}
kdb_trap_printk++;
ftrace_dump_buf(skip_lines);
kdb_trap_printk--;
return 0;
}
static __init int kdb_ftrace_register(void)
{
kdb_register_repeat("ftdump", kdb_ftdump, "", "Dump ftrace log",
0, KDB_REPEAT_NONE);
return 0;
}
late_initcall(kdb_ftrace_register);
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