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: Jason Wessel <jason.wessel@windriver.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> CC: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Jason Wessel
parent
3f0a55e357
commit
955b61e597
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@ -57,5 +57,8 @@ obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
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obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
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obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
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obj-$(CONFIG_EVENT_TRACING) += power-traces.o
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ifeq ($(CONFIG_TRACING),y)
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obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
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endif
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libftrace-y := ftrace.o
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@ -101,10 +101,7 @@ static inline void ftrace_enable_cpu(void)
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preempt_enable();
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}
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static cpumask_var_t __read_mostly tracing_buffer_mask;
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#define for_each_tracing_cpu(cpu) \
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for_each_cpu(cpu, tracing_buffer_mask)
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cpumask_var_t __read_mostly tracing_buffer_mask;
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/*
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* ftrace_dump_on_oops - variable to dump ftrace buffer on oops
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@ -1539,11 +1536,6 @@ int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
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}
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EXPORT_SYMBOL_GPL(trace_vprintk);
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enum trace_file_type {
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TRACE_FILE_LAT_FMT = 1,
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TRACE_FILE_ANNOTATE = 2,
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};
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static void trace_iterator_increment(struct trace_iterator *iter)
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{
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/* Don't allow ftrace to trace into the ring buffers */
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@ -1641,7 +1633,7 @@ struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
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}
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/* Find the next real entry, and increment the iterator to the next entry */
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static void *find_next_entry_inc(struct trace_iterator *iter)
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void *trace_find_next_entry_inc(struct trace_iterator *iter)
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{
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iter->ent = __find_next_entry(iter, &iter->cpu,
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&iter->lost_events, &iter->ts);
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@ -1676,19 +1668,19 @@ static void *s_next(struct seq_file *m, void *v, loff_t *pos)
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return NULL;
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if (iter->idx < 0)
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ent = find_next_entry_inc(iter);
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ent = trace_find_next_entry_inc(iter);
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else
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ent = iter;
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while (ent && iter->idx < i)
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ent = find_next_entry_inc(iter);
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ent = trace_find_next_entry_inc(iter);
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iter->pos = *pos;
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return ent;
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}
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static void tracing_iter_reset(struct trace_iterator *iter, int cpu)
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void tracing_iter_reset(struct trace_iterator *iter, int cpu)
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{
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struct trace_array *tr = iter->tr;
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struct ring_buffer_event *event;
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@ -2049,7 +2041,7 @@ int trace_empty(struct trace_iterator *iter)
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}
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/* Called with trace_event_read_lock() held. */
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static enum print_line_t print_trace_line(struct trace_iterator *iter)
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enum print_line_t print_trace_line(struct trace_iterator *iter)
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{
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enum print_line_t ret;
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@ -3211,7 +3203,7 @@ waitagain:
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trace_event_read_lock();
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trace_access_lock(iter->cpu_file);
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while (find_next_entry_inc(iter) != NULL) {
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while (trace_find_next_entry_inc(iter) != NULL) {
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enum print_line_t ret;
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int len = iter->seq.len;
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@ -3294,7 +3286,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
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if (ret != TRACE_TYPE_NO_CONSUME)
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trace_consume(iter);
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rem -= count;
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if (!find_next_entry_inc(iter)) {
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if (!trace_find_next_entry_inc(iter)) {
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rem = 0;
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iter->ent = NULL;
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break;
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@ -3350,7 +3342,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
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if (ret <= 0)
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goto out_err;
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if (!iter->ent && !find_next_entry_inc(iter)) {
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if (!iter->ent && !trace_find_next_entry_inc(iter)) {
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ret = -EFAULT;
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goto out_err;
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}
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@ -4414,7 +4406,7 @@ static struct notifier_block trace_die_notifier = {
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*/
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#define KERN_TRACE KERN_EMERG
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static void
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void
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trace_printk_seq(struct trace_seq *s)
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{
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/* Probably should print a warning here. */
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@ -4429,6 +4421,13 @@ trace_printk_seq(struct trace_seq *s)
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trace_seq_init(s);
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}
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void trace_init_global_iter(struct trace_iterator *iter)
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{
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iter->tr = &global_trace;
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iter->trace = current_trace;
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iter->cpu_file = TRACE_PIPE_ALL_CPU;
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}
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static void
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__ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
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{
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@ -4454,8 +4453,10 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
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if (disable_tracing)
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ftrace_kill();
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trace_init_global_iter(&iter);
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for_each_tracing_cpu(cpu) {
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atomic_inc(&global_trace.data[cpu]->disabled);
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atomic_inc(&iter.tr->data[cpu]->disabled);
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}
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old_userobj = trace_flags & TRACE_ITER_SYM_USEROBJ;
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@ -4504,7 +4505,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
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iter.iter_flags |= TRACE_FILE_LAT_FMT;
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iter.pos = -1;
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if (find_next_entry_inc(&iter) != NULL) {
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if (trace_find_next_entry_inc(&iter) != NULL) {
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int ret;
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ret = print_trace_line(&iter);
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@ -4526,7 +4527,7 @@ __ftrace_dump(bool disable_tracing, enum ftrace_dump_mode oops_dump_mode)
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trace_flags |= old_userobj;
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for_each_tracing_cpu(cpu) {
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atomic_dec(&global_trace.data[cpu]->disabled);
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atomic_dec(&iter.tr->data[cpu]->disabled);
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}
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tracing_on();
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}
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@ -338,6 +338,14 @@ struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
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struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
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int *ent_cpu, u64 *ent_ts);
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int trace_empty(struct trace_iterator *iter);
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void *trace_find_next_entry_inc(struct trace_iterator *iter);
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void trace_init_global_iter(struct trace_iterator *iter);
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void tracing_iter_reset(struct trace_iterator *iter, int cpu);
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void default_wait_pipe(struct trace_iterator *iter);
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void poll_wait_pipe(struct trace_iterator *iter);
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@ -380,6 +388,15 @@ void tracing_start_sched_switch_record(void);
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int register_tracer(struct tracer *type);
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void unregister_tracer(struct tracer *type);
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int is_tracing_stopped(void);
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enum trace_file_type {
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TRACE_FILE_LAT_FMT = 1,
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TRACE_FILE_ANNOTATE = 2,
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};
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extern cpumask_var_t __read_mostly tracing_buffer_mask;
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#define for_each_tracing_cpu(cpu) \
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for_each_cpu(cpu, tracing_buffer_mask)
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extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
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@ -471,6 +488,8 @@ trace_array_vprintk(struct trace_array *tr,
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unsigned long ip, const char *fmt, va_list args);
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int trace_array_printk(struct trace_array *tr,
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unsigned long ip, const char *fmt, ...);
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void trace_printk_seq(struct trace_seq *s);
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enum print_line_t print_trace_line(struct trace_iterator *iter);
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extern unsigned long trace_flags;
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119
kernel/trace/trace_kdb.c
Normal file
119
kernel/trace/trace_kdb.c
Normal file
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@ -0,0 +1,119 @@
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/*
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* kdb helper for dumping the ftrace buffer
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*
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* Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
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*
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* ftrace_dump_buf based on ftrace_dump:
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
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*
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*/
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#include <linux/init.h>
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#include <linux/kgdb.h>
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#include <linux/kdb.h>
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#include <linux/ftrace.h>
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#include "../debug/kdb/kdb_private.h"
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#include "trace.h"
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#include "trace_output.h"
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static void ftrace_dump_buf(int skip_lines)
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{
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/* use static because iter can be a bit big for the stack */
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static struct trace_iterator iter;
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unsigned int old_userobj;
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int cnt = 0, cpu;
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trace_init_global_iter(&iter);
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for_each_tracing_cpu(cpu) {
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atomic_inc(&iter.tr->data[cpu]->disabled);
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}
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old_userobj = trace_flags;
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/* don't look at user memory in panic mode */
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trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
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kdb_printf("Dumping ftrace buffer:\n");
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/* reset all but tr, trace, and overruns */
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memset(&iter.seq, 0,
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sizeof(struct trace_iterator) -
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offsetof(struct trace_iterator, seq));
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iter.iter_flags |= TRACE_FILE_LAT_FMT;
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iter.pos = -1;
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for_each_tracing_cpu(cpu) {
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iter.buffer_iter[cpu] =
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ring_buffer_read_prepare(iter.tr->buffer, cpu);
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ring_buffer_read_start(iter.buffer_iter[cpu]);
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tracing_iter_reset(&iter, cpu);
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}
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if (!trace_empty(&iter))
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trace_find_next_entry_inc(&iter);
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while (!trace_empty(&iter)) {
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if (!cnt)
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kdb_printf("---------------------------------\n");
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cnt++;
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if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines)
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print_trace_line(&iter);
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if (!skip_lines)
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trace_printk_seq(&iter.seq);
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else
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skip_lines--;
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if (KDB_FLAG(CMD_INTERRUPT))
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goto out;
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}
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if (!cnt)
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kdb_printf(" (ftrace buffer empty)\n");
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else
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kdb_printf("---------------------------------\n");
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out:
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trace_flags = old_userobj;
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for_each_tracing_cpu(cpu) {
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atomic_dec(&iter.tr->data[cpu]->disabled);
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}
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for_each_tracing_cpu(cpu)
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if (iter.buffer_iter[cpu])
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ring_buffer_read_finish(iter.buffer_iter[cpu]);
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}
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/*
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* kdb_ftdump - Dump the ftrace log buffer
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*/
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static int kdb_ftdump(int argc, const char **argv)
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{
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int skip_lines = 0;
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char *cp;
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if (argc > 1)
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return KDB_ARGCOUNT;
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if (argc) {
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skip_lines = simple_strtol(argv[1], &cp, 0);
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if (*cp)
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skip_lines = 0;
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}
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kdb_trap_printk++;
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ftrace_dump_buf(skip_lines);
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kdb_trap_printk--;
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return 0;
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}
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static __init int kdb_ftrace_register(void)
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{
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kdb_register_repeat("ftdump", kdb_ftdump, "", "Dump ftrace log",
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0, KDB_REPEAT_NONE);
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return 0;
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}
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late_initcall(kdb_ftrace_register);
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