1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * kdb helper for dumping the ftrace buffer
4 *
5 * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
6 *
7 * ftrace_dump_buf based on ftrace_dump:
8 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
9 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
10 *
11 */
12 #include <linux/init.h>
13 #include <linux/kgdb.h>
14 #include <linux/kdb.h>
15 #include <linux/ftrace.h>
16
17 #include "trace.h"
18 #include "trace_output.h"
19
ftrace_dump_buf(int skip_lines,long cpu_file)20 static void ftrace_dump_buf(int skip_lines, long cpu_file)
21 {
22 /* use static because iter can be a bit big for the stack */
23 static struct trace_iterator iter;
24 static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS];
25 struct trace_array *tr;
26 unsigned int old_userobj;
27 int cnt = 0, cpu;
28
29 trace_init_global_iter(&iter);
30 iter.buffer_iter = buffer_iter;
31 tr = iter.tr;
32
33 for_each_tracing_cpu(cpu) {
34 atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
35 }
36
37 old_userobj = tr->trace_flags;
38
39 /* don't look at user memory in panic mode */
40 tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
41
42 kdb_printf("Dumping ftrace buffer:\n");
43
44 trace_iterator_reset(&iter);
45 iter.iter_flags |= TRACE_FILE_LAT_FMT;
46
47 if (cpu_file == RING_BUFFER_ALL_CPUS) {
48 for_each_tracing_cpu(cpu) {
49 iter.buffer_iter[cpu] =
50 ring_buffer_read_prepare(iter.trace_buffer->buffer,
51 cpu, GFP_ATOMIC);
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,
59 cpu_file, GFP_ATOMIC);
60 ring_buffer_read_start(iter.buffer_iter[cpu_file]);
61 tracing_iter_reset(&iter, cpu_file);
62 }
63
64 while (trace_find_next_entry_inc(&iter)) {
65 if (!cnt)
66 kdb_printf("---------------------------------\n");
67 cnt++;
68
69 if (!skip_lines) {
70 print_trace_line(&iter);
71 trace_printk_seq(&iter.seq);
72 } else {
73 skip_lines--;
74 }
75
76 if (KDB_FLAG(CMD_INTERRUPT))
77 goto out;
78 }
79
80 if (!cnt)
81 kdb_printf(" (ftrace buffer empty)\n");
82 else
83 kdb_printf("---------------------------------\n");
84
85 out:
86 tr->trace_flags = old_userobj;
87
88 for_each_tracing_cpu(cpu) {
89 atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
90 }
91
92 for_each_tracing_cpu(cpu) {
93 if (iter.buffer_iter[cpu]) {
94 ring_buffer_read_finish(iter.buffer_iter[cpu]);
95 iter.buffer_iter[cpu] = NULL;
96 }
97 }
98 }
99
100 /*
101 * kdb_ftdump - Dump the ftrace log buffer
102 */
kdb_ftdump(int argc,const char ** argv)103 static int kdb_ftdump(int argc, const char **argv)
104 {
105 int skip_lines = 0;
106 long cpu_file;
107 char *cp;
108
109 if (argc > 2)
110 return KDB_ARGCOUNT;
111
112 if (argc) {
113 skip_lines = simple_strtol(argv[1], &cp, 0);
114 if (*cp)
115 skip_lines = 0;
116 }
117
118 if (argc == 2) {
119 cpu_file = simple_strtol(argv[2], &cp, 0);
120 if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
121 !cpu_online(cpu_file))
122 return KDB_BADINT;
123 } else {
124 cpu_file = RING_BUFFER_ALL_CPUS;
125 }
126
127 kdb_trap_printk++;
128 ftrace_dump_buf(skip_lines, cpu_file);
129 kdb_trap_printk--;
130
131 return 0;
132 }
133
kdb_ftrace_register(void)134 static __init int kdb_ftrace_register(void)
135 {
136 kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
137 "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE);
138 return 0;
139 }
140
141 late_initcall(kdb_ftrace_register);
142