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// SPDX-License-Identifier: GPL-2.0
/*
* kdb helper for dumping the ftrace buffer
*
* Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
*
* ftrace_dump_buf based on ftrace_dump:
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
*
*/
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/kdb.h>
#include <linux/ftrace.h>
#include "trace.h"
#include "trace_output.h"
static struct trace_iterator iter;
static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS];
static void ftrace_dump_buf(int skip_entries, long cpu_file)
{
struct trace_array *tr;
unsigned int old_userobj;
int cnt = 0, cpu;
tr = iter.tr;
old_userobj = tr->trace_flags;
/* don't look at user memory in panic mode */
tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
kdb_printf("Dumping ftrace buffer:\n");
if (skip_entries)
kdb_printf("(skipping %d entries)\n", skip_entries);
/* reset all but tr, trace, and overruns */
memset(&iter.seq, 0,
sizeof(struct trace_iterator) -
offsetof(struct trace_iterator, seq));
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;
if (cpu_file == RING_BUFFER_ALL_CPUS) {
for_each_tracing_cpu(cpu) {
iter.buffer_iter[cpu] =
ring_buffer_read_prepare(iter.trace_buffer->buffer,
cpu, GFP_ATOMIC);
ring_buffer_read_start(iter.buffer_iter[cpu]);
tracing_iter_reset(&iter, cpu);
}
} else {
iter.cpu_file = cpu_file;
iter.buffer_iter[cpu_file] =
ring_buffer_read_prepare(iter.trace_buffer->buffer,
cpu_file, GFP_ATOMIC);
ring_buffer_read_start(iter.buffer_iter[cpu_file]);
tracing_iter_reset(&iter, cpu_file);
}
while (trace_find_next_entry_inc(&iter)) {
if (!cnt)
kdb_printf("---------------------------------\n");
cnt++;
if (!skip_entries) {
print_trace_line(&iter);
trace_printk_seq(&iter.seq);
} else {
skip_entries--;
}
if (KDB_FLAG(CMD_INTERRUPT))
goto out;
}
if (!cnt)
kdb_printf(" (ftrace buffer empty)\n");
else
kdb_printf("---------------------------------\n");
out:
tr->trace_flags = old_userobj;
for_each_tracing_cpu(cpu) {
if (iter.buffer_iter[cpu]) {
ring_buffer_read_finish(iter.buffer_iter[cpu]);
iter.buffer_iter[cpu] = NULL;
}
}
}
/*
* kdb_ftdump - Dump the ftrace log buffer
*/
static int kdb_ftdump(int argc, const char **argv)
{
int skip_entries = 0;
long cpu_file;
char *cp;
int cnt;
int cpu;
if (argc > 2)
return KDB_ARGCOUNT;
if (argc) {
skip_entries = simple_strtol(argv[1], &cp, 0);
if (*cp)
skip_entries = 0;
}
if (argc == 2) {
cpu_file = simple_strtol(argv[2], &cp, 0);
if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
!cpu_online(cpu_file))
return KDB_BADINT;
} else {
cpu_file = RING_BUFFER_ALL_CPUS;
}
kdb_trap_printk++;
trace_init_global_iter(&iter);
iter.buffer_iter = buffer_iter;
for_each_tracing_cpu(cpu) {
atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
}
/* A negative skip_entries means skip all but the last entries */
if (skip_entries < 0) {
if (cpu_file == RING_BUFFER_ALL_CPUS)
cnt = trace_total_entries(NULL);
else
cnt = trace_total_entries_cpu(NULL, cpu_file);
skip_entries = max(cnt + skip_entries, 0);
}
ftrace_dump_buf(skip_entries, cpu_file);
for_each_tracing_cpu(cpu) {
atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
}
kdb_trap_printk--;
return 0;
}
static __init int kdb_ftrace_register(void)
{
kdb_register_flags("ftdump", kdb_ftdump, "[skip_#entries] [cpu]",
"Dump ftrace log; -skip dumps last #entries", 0,
KDB_ENABLE_ALWAYS_SAFE);
return 0;
}
late_initcall(kdb_ftrace_register);
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