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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
955b61e5 JW |
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 | ||
955b61e5 JW |
17 | #include "trace.h" |
18 | #include "trace_output.h" | |
19 | ||
03197fc0 DA |
20 | static struct trace_iterator iter; |
21 | static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS]; | |
22 | ||
dbfe6733 | 23 | static void ftrace_dump_buf(int skip_entries, long cpu_file) |
955b61e5 | 24 | { |
983f938a | 25 | struct trace_array *tr; |
955b61e5 JW |
26 | unsigned int old_userobj; |
27 | int cnt = 0, cpu; | |
28 | ||
983f938a | 29 | tr = iter.tr; |
955b61e5 | 30 | |
983f938a | 31 | old_userobj = tr->trace_flags; |
955b61e5 JW |
32 | |
33 | /* don't look at user memory in panic mode */ | |
983f938a | 34 | tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; |
955b61e5 JW |
35 | |
36 | kdb_printf("Dumping ftrace buffer:\n"); | |
03197fc0 DA |
37 | if (skip_entries) |
38 | kdb_printf("(skipping %d entries)\n", skip_entries); | |
955b61e5 JW |
39 | |
40 | /* reset all but tr, trace, and overruns */ | |
41 | memset(&iter.seq, 0, | |
42 | sizeof(struct trace_iterator) - | |
43 | offsetof(struct trace_iterator, seq)); | |
44 | iter.iter_flags |= TRACE_FILE_LAT_FMT; | |
45 | iter.pos = -1; | |
46 | ||
ae3b5093 | 47 | if (cpu_file == RING_BUFFER_ALL_CPUS) { |
19063c77 JW |
48 | for_each_tracing_cpu(cpu) { |
49 | iter.buffer_iter[cpu] = | |
31b265b3 DA |
50 | ring_buffer_read_prepare(iter.trace_buffer->buffer, |
51 | cpu, GFP_ATOMIC); | |
19063c77 JW |
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] = | |
31b265b3 DA |
58 | ring_buffer_read_prepare(iter.trace_buffer->buffer, |
59 | cpu_file, GFP_ATOMIC); | |
19063c77 JW |
60 | ring_buffer_read_start(iter.buffer_iter[cpu_file]); |
61 | tracing_iter_reset(&iter, cpu_file); | |
955b61e5 | 62 | } |
8520dedb DT |
63 | |
64 | while (trace_find_next_entry_inc(&iter)) { | |
955b61e5 JW |
65 | if (!cnt) |
66 | kdb_printf("---------------------------------\n"); | |
67 | cnt++; | |
68 | ||
dbfe6733 | 69 | if (!skip_entries) { |
955b61e5 | 70 | print_trace_line(&iter); |
955b61e5 | 71 | trace_printk_seq(&iter.seq); |
8520dedb | 72 | } else { |
dbfe6733 | 73 | skip_entries--; |
8520dedb DT |
74 | } |
75 | ||
955b61e5 JW |
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: | |
983f938a | 86 | tr->trace_flags = old_userobj; |
955b61e5 | 87 | |
c270cc75 DT |
88 | for_each_tracing_cpu(cpu) { |
89 | if (iter.buffer_iter[cpu]) { | |
955b61e5 | 90 | ring_buffer_read_finish(iter.buffer_iter[cpu]); |
c270cc75 DT |
91 | iter.buffer_iter[cpu] = NULL; |
92 | } | |
93 | } | |
955b61e5 JW |
94 | } |
95 | ||
96 | /* | |
97 | * kdb_ftdump - Dump the ftrace log buffer | |
98 | */ | |
99 | static int kdb_ftdump(int argc, const char **argv) | |
100 | { | |
dbfe6733 | 101 | int skip_entries = 0; |
19063c77 | 102 | long cpu_file; |
955b61e5 | 103 | char *cp; |
03197fc0 DA |
104 | int cnt; |
105 | int cpu; | |
955b61e5 | 106 | |
19063c77 | 107 | if (argc > 2) |
955b61e5 JW |
108 | return KDB_ARGCOUNT; |
109 | ||
110 | if (argc) { | |
dbfe6733 | 111 | skip_entries = simple_strtol(argv[1], &cp, 0); |
955b61e5 | 112 | if (*cp) |
dbfe6733 | 113 | skip_entries = 0; |
955b61e5 JW |
114 | } |
115 | ||
19063c77 JW |
116 | if (argc == 2) { |
117 | cpu_file = simple_strtol(argv[2], &cp, 0); | |
118 | if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 || | |
119 | !cpu_online(cpu_file)) | |
120 | return KDB_BADINT; | |
121 | } else { | |
ae3b5093 | 122 | cpu_file = RING_BUFFER_ALL_CPUS; |
19063c77 JW |
123 | } |
124 | ||
955b61e5 | 125 | kdb_trap_printk++; |
03197fc0 DA |
126 | |
127 | trace_init_global_iter(&iter); | |
128 | iter.buffer_iter = buffer_iter; | |
129 | ||
130 | for_each_tracing_cpu(cpu) { | |
131 | atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled); | |
132 | } | |
133 | ||
134 | /* A negative skip_entries means skip all but the last entries */ | |
135 | if (skip_entries < 0) { | |
136 | if (cpu_file == RING_BUFFER_ALL_CPUS) | |
137 | cnt = trace_total_entries(NULL); | |
138 | else | |
139 | cnt = trace_total_entries_cpu(NULL, cpu_file); | |
140 | skip_entries = max(cnt + skip_entries, 0); | |
141 | } | |
142 | ||
dbfe6733 | 143 | ftrace_dump_buf(skip_entries, cpu_file); |
03197fc0 DA |
144 | |
145 | for_each_tracing_cpu(cpu) { | |
146 | atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled); | |
147 | } | |
148 | ||
955b61e5 JW |
149 | kdb_trap_printk--; |
150 | ||
151 | return 0; | |
152 | } | |
153 | ||
154 | static __init int kdb_ftrace_register(void) | |
155 | { | |
dbfe6733 | 156 | kdb_register_flags("ftdump", kdb_ftdump, "[skip_#entries] [cpu]", |
03197fc0 DA |
157 | "Dump ftrace log; -skip dumps last #entries", 0, |
158 | KDB_ENABLE_ALWAYS_SAFE); | |
955b61e5 JW |
159 | return 0; |
160 | } | |
161 | ||
162 | late_initcall(kdb_ftrace_register); |