// 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);

        trace_iterator_reset(&iter);
        iter.iter_flags |= TRACE_FILE_LAT_FMT;

        if (cpu_file == RING_BUFFER_ALL_CPUS) {
                for_each_tracing_cpu(cpu) {
                        iter.buffer_iter[cpu] =
                        ring_buffer_read_start(iter.array_buffer->buffer,
                                               cpu, GFP_ATOMIC);
                        tracing_iter_reset(&iter, cpu);
                }
        } else {
                iter.cpu_file = cpu_file;
                iter.buffer_iter[cpu_file] =
                        ring_buffer_read_start(iter.array_buffer->buffer,
                                                 cpu_file, GFP_ATOMIC);
                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;
        int err;
        int cnt;

        if (argc > 2)
                return KDB_ARGCOUNT;

        if (argc && kstrtoint(argv[1], 0, &skip_entries))
                return KDB_BADINT;

        if (argc == 2) {
                err = kstrtol(argv[2], 0, &cpu_file);
                if (err || 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;

        tracer_tracing_disable(iter.tr);

        /* 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);

        tracer_tracing_enable(iter.tr);

        kdb_trap_printk--;

        return 0;
}

static kdbtab_t ftdump_cmd = {
        .name = "ftdump",
        .func = kdb_ftdump,
        .usage = "[skip_#entries] [cpu]",
        .help = "Dump ftrace log; -skip dumps last #entries",
        .flags = KDB_ENABLE_ALWAYS_SAFE,
};

static __init int kdb_ftrace_register(void)
{
        kdb_register(&ftdump_cmd);
        return 0;
}

late_initcall(kdb_ftrace_register);