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[linux/fpc-iii.git] / kernel / trace / trace_kdb.c
blob9da76104f7a28ba1cc8e5ad06a00dc46d7826a29
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * kdb helper for dumping the ftrace buffer
5 * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
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>
12 #include <linux/init.h>
13 #include <linux/kgdb.h>
14 #include <linux/kdb.h>
15 #include <linux/ftrace.h>
17 #include "trace.h"
18 #include "trace_output.h"
20 static struct trace_iterator iter;
21 static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS];
23 static void ftrace_dump_buf(int skip_entries, long cpu_file)
25 struct trace_array *tr;
26 unsigned int old_userobj;
27 int cnt = 0, cpu;
29 tr = iter.tr;
31 old_userobj = tr->trace_flags;
33 /* don't look at user memory in panic mode */
34 tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
36 kdb_printf("Dumping ftrace buffer:\n");
37 if (skip_entries)
38 kdb_printf("(skipping %d entries)\n", skip_entries);
40 trace_iterator_reset(&iter);
41 iter.iter_flags |= TRACE_FILE_LAT_FMT;
43 if (cpu_file == RING_BUFFER_ALL_CPUS) {
44 for_each_tracing_cpu(cpu) {
45 iter.buffer_iter[cpu] =
46 ring_buffer_read_prepare(iter.array_buffer->buffer,
47 cpu, GFP_ATOMIC);
48 ring_buffer_read_start(iter.buffer_iter[cpu]);
49 tracing_iter_reset(&iter, cpu);
51 } else {
52 iter.cpu_file = cpu_file;
53 iter.buffer_iter[cpu_file] =
54 ring_buffer_read_prepare(iter.array_buffer->buffer,
55 cpu_file, GFP_ATOMIC);
56 ring_buffer_read_start(iter.buffer_iter[cpu_file]);
57 tracing_iter_reset(&iter, cpu_file);
60 while (trace_find_next_entry_inc(&iter)) {
61 if (!cnt)
62 kdb_printf("---------------------------------\n");
63 cnt++;
65 if (!skip_entries) {
66 print_trace_line(&iter);
67 trace_printk_seq(&iter.seq);
68 } else {
69 skip_entries--;
72 if (KDB_FLAG(CMD_INTERRUPT))
73 goto out;
76 if (!cnt)
77 kdb_printf(" (ftrace buffer empty)\n");
78 else
79 kdb_printf("---------------------------------\n");
81 out:
82 tr->trace_flags = old_userobj;
84 for_each_tracing_cpu(cpu) {
85 if (iter.buffer_iter[cpu]) {
86 ring_buffer_read_finish(iter.buffer_iter[cpu]);
87 iter.buffer_iter[cpu] = NULL;
93 * kdb_ftdump - Dump the ftrace log buffer
95 static int kdb_ftdump(int argc, const char **argv)
97 int skip_entries = 0;
98 long cpu_file;
99 char *cp;
100 int cnt;
101 int cpu;
103 if (argc > 2)
104 return KDB_ARGCOUNT;
106 if (argc) {
107 skip_entries = simple_strtol(argv[1], &cp, 0);
108 if (*cp)
109 skip_entries = 0;
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 = RING_BUFFER_ALL_CPUS;
121 kdb_trap_printk++;
123 trace_init_global_iter(&iter);
124 iter.buffer_iter = buffer_iter;
126 for_each_tracing_cpu(cpu) {
127 atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled);
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_file);
136 skip_entries = max(cnt + skip_entries, 0);
139 ftrace_dump_buf(skip_entries, cpu_file);
141 for_each_tracing_cpu(cpu) {
142 atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled);
145 kdb_trap_printk--;
147 return 0;
150 static __init int kdb_ftrace_register(void)
152 kdb_register_flags("ftdump", kdb_ftdump, "[skip_#entries] [cpu]",
153 "Dump ftrace log; -skip dumps last #entries", 0,
154 KDB_ENABLE_ALWAYS_SAFE);
155 return 0;
158 late_initcall(kdb_ftrace_register);