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Date: Thu, 27 May 2010 16:51:12 -0500
From: Jason Wessel <jason.wessel@...driver.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org,
Jason Wessel <jason.wessel@...driver.com>,
Frederic Weisbecker <fweisbec@...il.com>,
Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH] 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.
CC: Frederic Weisbecker <fweisbec@...il.com>
CC: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
---
kernel/trace/Makefile | 5 ++
kernel/trace/trace.c | 43 +++++++++--------
kernel/trace/trace.h | 19 +++++++
kernel/trace/trace_kdb.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 165 insertions(+), 21 deletions(-)
create mode 100644 kernel/trace/trace_kdb.c
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index ffb1a5b..74ffb84 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -1,5 +1,7 @@
# Do not instrument the tracer itself:
+CFLAGS_trace_kdb.o += -O0
+CFLAGS_trace.o += -O0
ifdef CONFIG_FUNCTION_TRACER
ORIG_CFLAGS := $(KBUILD_CFLAGS)
@@ -57,5 +59,8 @@ obj-$(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
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8a76339..ce22b5b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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;
@@ -2048,7 +2040,7 @@ 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;
@@ -3210,7 +3202,7 @@ waitagain:
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;
@@ -3293,7 +3285,7 @@ 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;
@@ -3349,7 +3341,7 @@ 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;
}
@@ -4419,7 +4411,7 @@ 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. */
@@ -4434,6 +4426,13 @@ 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)
{
@@ -4459,8 +4458,10 @@ __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;
@@ -4509,7 +4510,7 @@ __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);
@@ -4531,7 +4532,7 @@ __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();
}
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d1ce0be..450b2c8 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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;
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
new file mode 100644
index 0000000..44cbda2
--- /dev/null
+++ b/kernel/trace/trace_kdb.c
@@ -0,0 +1,119 @@
+/*
+ * kdb helper for dumping the ftrace buffer
+ *
+ * Copyright (C) 2010 Jason Wessel <jason.wessel@...driver.com>
+ *
+ * ftrace_dump_buf based on ftrace_dump:
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@...hat.com>
+ * Copyright (C) 2008 Ingo Molnar <mingo@...hat.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);
--
1.6.3.3
--
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