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 | |
20 | static struct trace_iterator iter; |
21 | static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS]; |
22 | |
23 | static void ftrace_dump_buf(int skip_entries, long cpu_file) |
24 | { |
25 | struct trace_array *tr; |
26 | unsigned int old_userobj; |
27 | int cnt = 0, cpu; |
28 | |
29 | tr = iter.tr; |
30 | |
31 | old_userobj = tr->trace_flags; |
32 | |
33 | /* don't look at user memory in panic mode */ |
34 | tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; |
35 | |
36 | kdb_printf("Dumping ftrace buffer:\n" ); |
37 | if (skip_entries) |
38 | kdb_printf("(skipping %d entries)\n" , skip_entries); |
39 | |
40 | trace_iterator_reset(iter: &iter); |
41 | iter.iter_flags |= TRACE_FILE_LAT_FMT; |
42 | |
43 | if (cpu_file == RING_BUFFER_ALL_CPUS) { |
44 | for_each_tracing_cpu(cpu) { |
45 | iter.buffer_iter[cpu] = |
46 | ring_buffer_read_prepare(buffer: iter.array_buffer->buffer, |
47 | cpu, GFP_ATOMIC); |
48 | ring_buffer_read_start(iter: iter.buffer_iter[cpu]); |
49 | tracing_iter_reset(iter: &iter, cpu); |
50 | } |
51 | } else { |
52 | iter.cpu_file = cpu_file; |
53 | iter.buffer_iter[cpu_file] = |
54 | ring_buffer_read_prepare(buffer: iter.array_buffer->buffer, |
55 | cpu: cpu_file, GFP_ATOMIC); |
56 | ring_buffer_read_start(iter: iter.buffer_iter[cpu_file]); |
57 | tracing_iter_reset(iter: &iter, cpu: cpu_file); |
58 | } |
59 | |
60 | while (trace_find_next_entry_inc(iter: &iter)) { |
61 | if (!cnt) |
62 | kdb_printf("---------------------------------\n" ); |
63 | cnt++; |
64 | |
65 | if (!skip_entries) { |
66 | print_trace_line(iter: &iter); |
67 | trace_printk_seq(s: &iter.seq); |
68 | } else { |
69 | skip_entries--; |
70 | } |
71 | |
72 | if (KDB_FLAG(CMD_INTERRUPT)) |
73 | goto out; |
74 | } |
75 | |
76 | if (!cnt) |
77 | kdb_printf(" (ftrace buffer empty)\n" ); |
78 | else |
79 | kdb_printf("---------------------------------\n" ); |
80 | |
81 | out: |
82 | tr->trace_flags = old_userobj; |
83 | |
84 | for_each_tracing_cpu(cpu) { |
85 | if (iter.buffer_iter[cpu]) { |
86 | ring_buffer_read_finish(iter: iter.buffer_iter[cpu]); |
87 | iter.buffer_iter[cpu] = NULL; |
88 | } |
89 | } |
90 | } |
91 | |
92 | /* |
93 | * kdb_ftdump - Dump the ftrace log buffer |
94 | */ |
95 | static int kdb_ftdump(int argc, const char **argv) |
96 | { |
97 | int skip_entries = 0; |
98 | long cpu_file; |
99 | char *cp; |
100 | int cnt; |
101 | int cpu; |
102 | |
103 | if (argc > 2) |
104 | return KDB_ARGCOUNT; |
105 | |
106 | if (argc) { |
107 | skip_entries = simple_strtol(argv[1], &cp, 0); |
108 | if (*cp) |
109 | skip_entries = 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: cpu_file)) |
116 | return KDB_BADINT; |
117 | } else { |
118 | cpu_file = RING_BUFFER_ALL_CPUS; |
119 | } |
120 | |
121 | kdb_trap_printk++; |
122 | |
123 | trace_init_global_iter(iter: &iter); |
124 | iter.buffer_iter = buffer_iter; |
125 | |
126 | for_each_tracing_cpu(cpu) { |
127 | atomic_inc(v: &per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); |
128 | } |
129 | |
130 | /* A negative skip_entries means skip all but the last entries */ |
131 | if (skip_entries < 0) { |
132 | if (cpu_file == RING_BUFFER_ALL_CPUS) |
133 | cnt = trace_total_entries(NULL); |
134 | else |
135 | cnt = trace_total_entries_cpu(NULL, cpu: cpu_file); |
136 | skip_entries = max(cnt + skip_entries, 0); |
137 | } |
138 | |
139 | ftrace_dump_buf(skip_entries, cpu_file); |
140 | |
141 | for_each_tracing_cpu(cpu) { |
142 | atomic_dec(v: &per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); |
143 | } |
144 | |
145 | kdb_trap_printk--; |
146 | |
147 | return 0; |
148 | } |
149 | |
150 | static kdbtab_t ftdump_cmd = { |
151 | .name = "ftdump" , |
152 | .func = kdb_ftdump, |
153 | .usage = "[skip_#entries] [cpu]" , |
154 | .help = "Dump ftrace log; -skip dumps last #entries" , |
155 | .flags = KDB_ENABLE_ALWAYS_SAFE, |
156 | }; |
157 | |
158 | static __init int kdb_ftrace_register(void) |
159 | { |
160 | kdb_register(cmd: &ftdump_cmd); |
161 | return 0; |
162 | } |
163 | |
164 | late_initcall(kdb_ftrace_register); |
165 | |