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 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
;
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");
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
,
48 ring_buffer_read_start(iter
.buffer_iter
[cpu
]);
49 tracing_iter_reset(&iter
, cpu
);
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
)) {
62 kdb_printf("---------------------------------\n");
66 print_trace_line(&iter
);
67 trace_printk_seq(&iter
.seq
);
72 if (KDB_FLAG(CMD_INTERRUPT
))
77 kdb_printf(" (ftrace buffer empty)\n");
79 kdb_printf("---------------------------------\n");
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
)
107 skip_entries
= simple_strtol(argv
[1], &cp
, 0);
113 cpu_file
= simple_strtol(argv
[2], &cp
, 0);
114 if (*cp
|| cpu_file
>= NR_CPUS
|| cpu_file
< 0 ||
115 !cpu_online(cpu_file
))
118 cpu_file
= RING_BUFFER_ALL_CPUS
;
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
);
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
);
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
);
158 late_initcall(kdb_ftrace_register
);