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Date: Thu, 14 Jan 2010 08:59:36 -0600
From: Jason Wessel <jason.wessel@...driver.com>
To: linux-kernel@...r.kernel.org
Cc: kgdb-bugreport@...ts.sourceforge.net, mingo@...e.hu,
Jason Wessel <jason.wessel@...driver.com>,
Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH 40/40] 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.
CC: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
---
Documentation/DocBook/kgdb.tmpl | 3 +-
kernel/trace/Makefile | 3 +
kernel/trace/trace.c | 48 +++++++---------
kernel/trace/trace.h | 17 ++++++
kernel/trace/trace_kdb.c | 116 +++++++++++++++++++++++++++++++++++++++
5 files changed, 160 insertions(+), 27 deletions(-)
create mode 100644 kernel/trace/trace_kdb.c
diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl
index bbf4a22..b01b5b1 100644
--- a/Documentation/DocBook/kgdb.tmpl
+++ b/Documentation/DocBook/kgdb.tmpl
@@ -675,7 +675,8 @@ Task Addr Pid Parent [*] cpu State Thread Command
<itemizedlist>
<listitem><para>A simple shell</para></listitem>
<listitem><para>The kdb core command set</para></listitem>
- <listitem><para>A registration API to register additional kdb shell commands.</para></listitem>
+ <listitem><para>A registration API to register additional kdb shell commands.</para>
+ <para>A good example of a self contained kdb module is the "ftdump" command for dumping the ftrace buffer. See: kernel/trace/trace_kdb.c</para></listitem>
<listitem><para>The implementation for kdb_printf() which emit messages directly to I/O drivers, bypassing the kernel log.</para></listitem>
<listitem><para>SW / HW breakpoint management for the kdb shell</para></listitem>
</itemizedlist>
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index cd9ecd8..c48a28f 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -56,5 +56,8 @@ 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 0df1b0f..b3c786a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -100,14 +100,11 @@ static inline void ftrace_enable_cpu(void)
preempt_enable();
}
-static cpumask_var_t __read_mostly tracing_buffer_mask;
+cpumask_var_t __read_mostly tracing_buffer_mask;
/* Define which cpu buffers are currently read in trace_pipe */
static cpumask_var_t tracing_reader_cpumask;
-#define for_each_tracing_cpu(cpu) \
- for_each_cpu(cpu, tracing_buffer_mask)
-
/*
* ftrace_dump_on_oops - variable to dump ftrace buffer on oops
*
@@ -1409,11 +1406,6 @@ 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 */
@@ -1503,7 +1495,7 @@ 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->ts);
@@ -1536,12 +1528,12 @@ 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;
@@ -1878,7 +1870,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
return event ? event->binary(iter, 0) : TRACE_TYPE_HANDLED;
}
-static int trace_empty(struct trace_iterator *iter)
+int trace_empty(struct trace_iterator *iter)
{
int cpu;
@@ -1909,7 +1901,7 @@ static 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;
@@ -3074,7 +3066,7 @@ waitagain:
iter->pos = -1;
trace_event_read_lock();
- 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;
@@ -3156,7 +3148,7 @@ 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;
@@ -3209,7 +3201,7 @@ 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;
}
@@ -4262,7 +4254,7 @@ 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. */
@@ -4277,6 +4269,13 @@ 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)
{
static arch_spinlock_t ftrace_dump_lock =
@@ -4301,8 +4300,10 @@ static void __ftrace_dump(bool disable_tracing)
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;
@@ -4312,11 +4313,6 @@ static void __ftrace_dump(bool disable_tracing)
printk(KERN_TRACE "Dumping ftrace buffer:\n");
- /* Simulate the iterator */
- iter.tr = &global_trace;
- iter.trace = current_trace;
- iter.cpu_file = TRACE_PIPE_ALL_CPU;
-
/*
* We need to stop all tracing on all CPUS to read the
* the next buffer. This is a bit expensive, but is
@@ -4338,7 +4334,7 @@ static void __ftrace_dump(bool disable_tracing)
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);
@@ -4359,7 +4355,7 @@ static void __ftrace_dump(bool disable_tracing)
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 4df6a77..563e6f8 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -352,6 +352,12 @@ 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 default_wait_pipe(struct trace_iterator *iter);
void poll_wait_pipe(struct trace_iterator *iter);
@@ -391,6 +397,15 @@ 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);
@@ -483,6 +498,8 @@ 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..9227ff3
--- /dev/null
+++ b/kernel/trace/trace_kdb.c
@@ -0,0 +1,116 @@
+/*
+ * 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_start(iter.tr->buffer, 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);
--
1.6.3.1.9.g95405b
--
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