1/*
2 * kdb helper for dumping the ftrace buffer
3 *
4 * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
5 *
6 * ftrace_dump_buf based on ftrace_dump:
7 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
8 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
9 *
10 */
11#include <linux/init.h>
12#include <linux/kgdb.h>
13#include <linux/kdb.h>
14#include <linux/ftrace.h>
15
16#include "trace.h"
17#include "trace_output.h"
18
19static void ftrace_dump_buf(int skip_lines, long cpu_file)
20{
21	/* use static because iter can be a bit big for the stack */
22	static struct trace_iterator iter;
23	static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS];
24	struct trace_array *tr;
25	unsigned int old_userobj;
26	int cnt = 0, cpu;
27
28	trace_init_global_iter(&iter);
29	iter.buffer_iter = buffer_iter;
30	tr = iter.tr;
31
32	for_each_tracing_cpu(cpu) {
33		atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
34	}
35
36	old_userobj = tr->trace_flags;
37
38	/* don't look at user memory in panic mode */
39	tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
40
41	kdb_printf("Dumping ftrace buffer:\n");
42
43	/* reset all but tr, trace, and overruns */
44	memset(&iter.seq, 0,
45		   sizeof(struct trace_iterator) -
46		   offsetof(struct trace_iterator, seq));
47	iter.iter_flags |= TRACE_FILE_LAT_FMT;
48	iter.pos = -1;
49
50	if (cpu_file == RING_BUFFER_ALL_CPUS) {
51		for_each_tracing_cpu(cpu) {
52			iter.buffer_iter[cpu] =
53			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu);
54			ring_buffer_read_start(iter.buffer_iter[cpu]);
55			tracing_iter_reset(&iter, cpu);
56		}
57	} else {
58		iter.cpu_file = cpu_file;
59		iter.buffer_iter[cpu_file] =
60			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file);
61		ring_buffer_read_start(iter.buffer_iter[cpu_file]);
62		tracing_iter_reset(&iter, cpu_file);
63	}
64
65	while (trace_find_next_entry_inc(&iter)) {
66		if (!cnt)
67			kdb_printf("---------------------------------\n");
68		cnt++;
69
70		if (!skip_lines) {
71			print_trace_line(&iter);
72			trace_printk_seq(&iter.seq);
73		} else {
74			skip_lines--;
75		}
76
77		if (KDB_FLAG(CMD_INTERRUPT))
78			goto out;
79	}
80
81	if (!cnt)
82		kdb_printf("   (ftrace buffer empty)\n");
83	else
84		kdb_printf("---------------------------------\n");
85
86out:
87	tr->trace_flags = old_userobj;
88
89	for_each_tracing_cpu(cpu) {
90		atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
91	}
92
93	for_each_tracing_cpu(cpu) {
94		if (iter.buffer_iter[cpu]) {
95			ring_buffer_read_finish(iter.buffer_iter[cpu]);
96			iter.buffer_iter[cpu] = NULL;
97		}
98	}
99}
100
101/*
102 * kdb_ftdump - Dump the ftrace log buffer
103 */
104static int kdb_ftdump(int argc, const char **argv)
105{
106	int skip_lines = 0;
107	long cpu_file;
108	char *cp;
109
110	if (argc > 2)
111		return KDB_ARGCOUNT;
112
113	if (argc) {
114		skip_lines = simple_strtol(argv[1], &cp, 0);
115		if (*cp)
116			skip_lines = 0;
117	}
118
119	if (argc == 2) {
120		cpu_file = simple_strtol(argv[2], &cp, 0);
121		if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
122		    !cpu_online(cpu_file))
123			return KDB_BADINT;
124	} else {
125		cpu_file = RING_BUFFER_ALL_CPUS;
126	}
127
128	kdb_trap_printk++;
129	ftrace_dump_buf(skip_lines, cpu_file);
130	kdb_trap_printk--;
131
132	return 0;
133}
134
135static __init int kdb_ftrace_register(void)
136{
137	kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
138			    "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE);
139	return 0;
140}
141
142late_initcall(kdb_ftrace_register);
143