Root/kernel/trace/trace_kdb.c

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

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