// SPDX-License-Identifier: GPL-2.0
/*
 * Created by: Jason Wessel <jason.wessel@windriver.com>
 *
 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kgdb.h>
#include <linux/kdb.h>
#include <linux/kdebug.h>
#include <linux/export.h>
#include <linux/hardirq.h>
#include "kdb_private.h"
#include "../debug_core.h"

/*
 * KDB interface to KGDB internals
 */
get_char_func kdb_poll_funcs[] = {
        dbg_io_get_char,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
};
EXPORT_SYMBOL_GPL(kdb_poll_funcs);

int kdb_poll_idx = 1;
EXPORT_SYMBOL_GPL(kdb_poll_idx);

static struct kgdb_state *kdb_ks;

int kdb_common_init_state(struct kgdb_state *ks)
{
        kdb_initial_cpu = atomic_read(&kgdb_active);
        kdb_current_task = kgdb_info[ks->cpu].task;
        kdb_current_regs = kgdb_info[ks->cpu].debuggerinfo;
        return 0;
}

int kdb_common_deinit_state(void)
{
        kdb_initial_cpu = -1;
        kdb_current_task = NULL;
        kdb_current_regs = NULL;
        return 0;
}

int kdb_stub(struct kgdb_state *ks)
{
        int error = 0;
        kdb_bp_t *bp;
        unsigned long addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs);
        kdb_reason_t reason = KDB_REASON_OOPS;
        kdb_dbtrap_t db_result = KDB_DB_NOBPT;
        int i;

        kdb_ks = ks;
        if (KDB_STATE(REENTRY)) {
                reason = KDB_REASON_SWITCH;
                KDB_STATE_CLEAR(REENTRY);
                addr = instruction_pointer(ks->linux_regs);
        }
        ks->pass_exception = 0;
        if (atomic_read(&kgdb_setting_breakpoint))
                reason = KDB_REASON_KEYBOARD;

        if (ks->err_code == KDB_REASON_SYSTEM_NMI && ks->signo == SIGTRAP)
                reason = KDB_REASON_SYSTEM_NMI;

        else if (in_nmi())
                reason = KDB_REASON_NMI;

        for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
                if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
                        reason = KDB_REASON_BREAK;
                        db_result = KDB_DB_BPT;
                        if (addr != instruction_pointer(ks->linux_regs))
                                kgdb_arch_set_pc(ks->linux_regs, addr);
                        break;
                }
        }
        if (reason == KDB_REASON_BREAK || reason == KDB_REASON_SWITCH) {
                for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
                        if (bp->bp_free)
                                continue;
                        if (bp->bp_addr == addr) {
                                bp->bp_delay = 1;
                                bp->bp_delayed = 1;
        /*
         * SSBPT is set when the kernel debugger must single step a
         * task in order to re-establish an instruction breakpoint
         * which uses the instruction replacement mechanism.  It is
         * cleared by any action that removes the need to single-step
         * the breakpoint.
         */
                                reason = KDB_REASON_BREAK;
                                db_result = KDB_DB_BPT;
                                KDB_STATE_SET(SSBPT);
                                break;
                        }
                }
        }

        if (reason != KDB_REASON_BREAK && ks->ex_vector == 0 &&
                ks->signo == SIGTRAP) {
                reason = KDB_REASON_SSTEP;
                db_result = KDB_DB_BPT;
        }
        /* Set initial kdb state variables */
        KDB_STATE_CLEAR(KGDB_TRANS);
        kdb_common_init_state(ks);
        /* Remove any breakpoints as needed by kdb and clear single step */
        kdb_bp_remove();
        KDB_STATE_CLEAR(DOING_SS);
        KDB_STATE_SET(PAGER);
        if (ks->err_code == DIE_OOPS || reason == KDB_REASON_OOPS) {
                ks->pass_exception = 1;
                KDB_FLAG_SET(CATASTROPHIC);
        }
        /* set CATASTROPHIC if the system contains unresponsive processors */
        for_each_online_cpu(i)
                if (!kgdb_info[i].enter_kgdb)
                        KDB_FLAG_SET(CATASTROPHIC);
        if (KDB_STATE(SSBPT) && reason == KDB_REASON_SSTEP) {
                KDB_STATE_CLEAR(SSBPT);
                KDB_STATE_CLEAR(DOING_SS);
        } else {
                /* Start kdb main loop */
                error = kdb_main_loop(KDB_REASON_ENTER, reason,
                                      ks->err_code, db_result, ks->linux_regs);
        }
        /*
         * Upon exit from the kdb main loop setup break points and restart
         * the system based on the requested continue state
         */
        kdb_common_deinit_state();
        KDB_STATE_CLEAR(PAGER);
        if (error == KDB_CMD_KGDB) {
                if (KDB_STATE(DOING_KGDB))
                        KDB_STATE_CLEAR(DOING_KGDB);
                return DBG_PASS_EVENT;
        }
        kdb_bp_install(ks->linux_regs);
        /* Set the exit state to a single step or a continue */
        if (KDB_STATE(DOING_SS))
                gdbstub_state(ks, "s");
        else
                gdbstub_state(ks, "c");

        KDB_FLAG_CLEAR(CATASTROPHIC);

        /* Invoke arch specific exception handling prior to system resume */
        kgdb_info[ks->cpu].ret_state = gdbstub_state(ks, "e");
        if (ks->pass_exception)
                kgdb_info[ks->cpu].ret_state = 1;
        if (error == KDB_CMD_CPU) {
                KDB_STATE_SET(REENTRY);
                /*
                 * Force clear the single step bit because kdb emulates this
                 * differently vs the gdbstub
                 */
                kgdb_single_step = 0;
                return DBG_SWITCH_CPU_EVENT;
        }
        return kgdb_info[ks->cpu].ret_state;
}

void kdb_gdb_state_pass(char *buf)
{
        gdbstub_state(kdb_ks, buf);
}