1 // SPDX-License-Identifier: GPL-2.0
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>
18 #include "trace_output.h"
20 static void ftrace_dump_buf(int skip_lines, long cpu_file)
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;
29 trace_init_global_iter(&iter);
30 iter.buffer_iter = buffer_iter;
33 for_each_tracing_cpu(cpu) {
34 atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
37 old_userobj = tr->trace_flags;
39 /* don't look at user memory in panic mode */
40 tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
42 kdb_printf("Dumping ftrace buffer:\n");
44 /* reset all but tr, trace, and overruns */
46 sizeof(struct trace_iterator) -
47 offsetof(struct trace_iterator, seq));
48 iter.iter_flags |= TRACE_FILE_LAT_FMT;
51 if (cpu_file == RING_BUFFER_ALL_CPUS) {
52 for_each_tracing_cpu(cpu) {
53 iter.buffer_iter[cpu] =
54 ring_buffer_read_prepare(iter.trace_buffer->buffer,
56 ring_buffer_read_start(iter.buffer_iter[cpu]);
57 tracing_iter_reset(&iter, cpu);
60 iter.cpu_file = cpu_file;
61 iter.buffer_iter[cpu_file] =
62 ring_buffer_read_prepare(iter.trace_buffer->buffer,
63 cpu_file, GFP_ATOMIC);
64 ring_buffer_read_start(iter.buffer_iter[cpu_file]);
65 tracing_iter_reset(&iter, cpu_file);
68 while (trace_find_next_entry_inc(&iter)) {
70 kdb_printf("---------------------------------\n");
74 print_trace_line(&iter);
75 trace_printk_seq(&iter.seq);
80 if (KDB_FLAG(CMD_INTERRUPT))
85 kdb_printf(" (ftrace buffer empty)\n");
87 kdb_printf("---------------------------------\n");
90 tr->trace_flags = old_userobj;
92 for_each_tracing_cpu(cpu) {
93 atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
96 for_each_tracing_cpu(cpu) {
97 if (iter.buffer_iter[cpu]) {
98 ring_buffer_read_finish(iter.buffer_iter[cpu]);
99 iter.buffer_iter[cpu] = NULL;
105 * kdb_ftdump - Dump the ftrace log buffer
107 static int kdb_ftdump(int argc, const char **argv)
117 skip_lines = simple_strtol(argv[1], &cp, 0);
123 cpu_file = simple_strtol(argv[2], &cp, 0);
124 if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
125 !cpu_online(cpu_file))
128 cpu_file = RING_BUFFER_ALL_CPUS;
132 ftrace_dump_buf(skip_lines, cpu_file);
138 static __init int kdb_ftrace_register(void)
140 kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
141 "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE);
145 late_initcall(kdb_ftrace_register);