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	unsigned int old_userobj;
25	int cnt = 0, cpu;
26
27	trace_init_global_iter(&iter);
28	iter.buffer_iter = buffer_iter;
29
30	for_each_tracing_cpu(cpu) {
31		atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
32	}
33
34	old_userobj = trace_flags;
35
36	/* don't look at user memory in panic mode */
37	trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
38
39	kdb_printf("Dumping ftrace buffer:\n");
40
41	/* reset all but tr, trace, and overruns */
42	memset(&iter.seq, 0,
43		   sizeof(struct trace_iterator) -
44		   offsetof(struct trace_iterator, seq));
45	iter.iter_flags |= TRACE_FILE_LAT_FMT;
46	iter.pos = -1;
47
48	if (cpu_file == RING_BUFFER_ALL_CPUS) {
49		for_each_tracing_cpu(cpu) {
50			iter.buffer_iter[cpu] =
51			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu);
52			ring_buffer_read_start(iter.buffer_iter[cpu]);
53			tracing_iter_reset(&iter, cpu);
54		}
55	} else {
56		iter.cpu_file = cpu_file;
57		iter.buffer_iter[cpu_file] =
58			ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file);
59		ring_buffer_read_start(iter.buffer_iter[cpu_file]);
60		tracing_iter_reset(&iter, cpu_file);
61	}
62
63	while (trace_find_next_entry_inc(&iter)) {
64		if (!cnt)
65			kdb_printf("---------------------------------\n");
66		cnt++;
67
68		if (!skip_lines) {
69			print_trace_line(&iter);
70			trace_printk_seq(&iter.seq);
71		} else {
72			skip_lines--;
73		}
74
75		if (KDB_FLAG(CMD_INTERRUPT))
76			goto out;
77	}
78
79	if (!cnt)
80		kdb_printf("   (ftrace buffer empty)\n");
81	else
82		kdb_printf("---------------------------------\n");
83
84out:
85	trace_flags = old_userobj;
86
87	for_each_tracing_cpu(cpu) {
88		atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
89	}
90
91	for_each_tracing_cpu(cpu) {
92		if (iter.buffer_iter[cpu]) {
93			ring_buffer_read_finish(iter.buffer_iter[cpu]);
94			iter.buffer_iter[cpu] = NULL;
95		}
96	}
97}
98
99/*
100 * kdb_ftdump - Dump the ftrace log buffer
101 */
102static int kdb_ftdump(int argc, const char **argv)
103{
104	int skip_lines = 0;
105	long cpu_file;
106	char *cp;
107
108	if (argc > 2)
109		return KDB_ARGCOUNT;
110
111	if (argc) {
112		skip_lines = simple_strtol(argv[1], &cp, 0);
113		if (*cp)
114			skip_lines = 0;
115	}
116
117	if (argc == 2) {
118		cpu_file = simple_strtol(argv[2], &cp, 0);
119		if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
120		    !cpu_online(cpu_file))
121			return KDB_BADINT;
122	} else {
123		cpu_file = RING_BUFFER_ALL_CPUS;
124	}
125
126	kdb_trap_printk++;
127	ftrace_dump_buf(skip_lines, cpu_file);
128	kdb_trap_printk--;
129
130	return 0;
131}
132
133static __init int kdb_ftrace_register(void)
134{
135	kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
136			    "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE);
137	return 0;
138}
139
140late_initcall(kdb_ftrace_register);
141