/*      $NetBSD: db_run.c,v 1.34 2026/03/14 20:11:01 andvar Exp $       */

/*
 * Mach Operating System
 * Copyright (c) 1993-1990 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 *
 *      Author: David B. Golub, Carnegie Mellon University
 *      Date:   7/90
 */

/*
 * Commands to run process.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: db_run.c,v 1.34 2026/03/14 20:11:01 andvar Exp $");

#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/proc.h>

#include <machine/db_machdep.h>

#include <ddb/db_run.h>
#include <ddb/db_access.h>
#include <ddb/db_break.h>

int     db_inst_count;
int     db_load_count;
int     db_store_count;

#ifdef  SOFTWARE_SSTEP
static void     db_set_temp_breakpoint(db_breakpoint_t, db_addr_t);
static void     db_delete_temp_breakpoint(db_breakpoint_t);
static struct   db_breakpoint   db_not_taken_bkpt;
static struct   db_breakpoint   db_taken_bkpt;
#endif

#if defined(DDB)
#include <ddb/db_lex.h>
#include <ddb/db_watch.h>
#include <ddb/db_output.h>
#include <ddb/db_sym.h>
#include <ddb/db_extern.h>

static int      db_run_mode;
#define STEP_NONE       0
#define STEP_ONCE       1
#define STEP_RETURN     2
#define STEP_CALLT      3
#define STEP_CONTINUE   4
#define STEP_INVISIBLE  5
#define STEP_COUNT      6

static bool             db_sstep_print;
static int              db_loop_count;
static int              db_call_depth;

bool
db_stop_at_pc(db_regs_t *regs, bool *is_breakpoint)
{
        db_addr_t       pc;
        db_breakpoint_t bkpt;

        pc = PC_REGS(regs);

#ifdef  FIXUP_PC_AFTER_BREAK
        if (*is_breakpoint) {
                /*
                 * Breakpoint trap.  Regardless if we treat this as a
                 * real breakpoint (e.g. software single-step), fix up the PC.
                 */
                FIXUP_PC_AFTER_BREAK(regs);
                pc = PC_REGS(regs);
        }
#endif

#ifdef  SOFTWARE_SSTEP
        /*
         * If we stopped at one of the single-step breakpoints, say it's not
         * really a breakpoint so that we don't skip over the real instruction.
         */
        if (db_taken_bkpt.address == pc || db_not_taken_bkpt.address == pc)
                *is_breakpoint = false;
#endif  /* SOFTWARE_SSTEP */

        db_clear_single_step(regs);
        db_clear_breakpoints();
        db_clear_watchpoints();

        /*
         * Now check for a breakpoint at this address.
         */
        bkpt = db_find_breakpoint_here(pc);
        if (bkpt) {
                if (--bkpt->count == 0) {
                        bkpt->count = bkpt->init_count;
                        *is_breakpoint = true;
                        return (true);  /* stop here */
                }
        } else if (*is_breakpoint) {
#ifdef PC_ADVANCE
                PC_ADVANCE(regs);
#else
                PC_REGS(regs) += BKPT_SIZE;
#endif
        }

        *is_breakpoint = false;

        if (db_run_mode == STEP_INVISIBLE) {
                db_run_mode = STEP_CONTINUE;
                return (false); /* continue */
        }
        if (db_run_mode == STEP_COUNT) {
                return (false); /* continue */
        }
        if (db_run_mode == STEP_ONCE) {
                if (--db_loop_count > 0) {
                        if (db_sstep_print) {
                                db_printf("\t\t");
                                db_print_loc_and_inst(pc);
                                db_printf("\n");
                        }
                        return (false); /* continue */
                }
        }
        if (db_run_mode == STEP_RETURN) {
                db_expr_t ins = db_get_value(pc, sizeof(int), false);

                /* continue until matching return */

                if (!inst_trap_return(ins) &&
                    (!inst_return(ins) || --db_call_depth != 0)) {
                        if (db_sstep_print) {
                                if (inst_call(ins) || inst_return(ins)) {
                                        int i;

                                        db_printf("[after %6d]     ",
                                            db_inst_count);
                                        for (i = db_call_depth; --i > 0; )
                                                db_printf("  ");
                                        db_print_loc_and_inst(pc);
                                        db_printf("\n");
                                }
                        }
                        if (inst_call(ins))
                                db_call_depth++;
                        return (false); /* continue */
                }
        }
        if (db_run_mode == STEP_CALLT) {
                db_expr_t ins = db_get_value(pc, sizeof(int), false);

                /* continue until call or return */

                if (!inst_call(ins) &&
                    !inst_return(ins) &&
                    !inst_trap_return(ins)) {
                        return (false); /* continue */
                }
        }
        db_run_mode = STEP_NONE;
        return (true);
}

void
db_restart_at_pc(db_regs_t *regs, bool watchpt)
{
        db_addr_t pc = PC_REGS(regs);
#ifdef SOFTWARE_SSTEP
        db_addr_t brpc;
#endif

        if ((db_run_mode == STEP_COUNT) ||
            (db_run_mode == STEP_RETURN) ||
            (db_run_mode == STEP_CALLT)) {
                db_expr_t               ins __unused;

                /*
                 * We are about to execute this instruction,
                 * so count it now.
                 */
                ins = db_get_value(pc, sizeof(int), false);
                db_inst_count++;
                db_load_count += inst_load(ins);
                db_store_count += inst_store(ins);

#ifdef SOFTWARE_SSTEP
                /*
                 * Account for instructions in delay slots.
                 */
                brpc = next_instr_address(pc, true);
                if ((brpc != pc) &&
                    (inst_branch(ins) || inst_call(ins) || inst_return(ins))) {
                        ins = db_get_value(brpc, sizeof(int), false);
                        db_inst_count++;
                        db_load_count += inst_load(ins);
                        db_store_count += inst_store(ins);
                }
#endif
        }

        if (db_run_mode == STEP_CONTINUE) {
                if (watchpt || db_find_breakpoint_here(pc)) {
                        /*
                         * Step over breakpoint/watchpoint.
                         */
                        db_run_mode = STEP_INVISIBLE;
                        db_set_single_step(regs);
                } else {
                        db_set_breakpoints();
                        db_set_watchpoints();
                }
        } else {
                db_set_single_step(regs);
        }
}

void
db_single_step(db_regs_t *regs)
{

        if (db_run_mode == STEP_CONTINUE) {
                db_run_mode = STEP_INVISIBLE;
                db_set_single_step(regs);
        }
}

/* single-step */
/*ARGSUSED*/
void
db_single_step_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
        bool print = false;

        if (count == -1)
                count = 1;

        if (modif[0] == 'p')
                print = true;

        db_run_mode = STEP_ONCE;
        db_loop_count = count;
        db_sstep_print = print;
        db_inst_count = 0;
        db_load_count = 0;
        db_store_count = 0;

        db_cmd_loop_done = true;
}

/* trace and print until call/return */
/*ARGSUSED*/
void
db_trace_until_call_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
        bool print = false;

        if (modif[0] == 'p')
                print = true;

        db_run_mode = STEP_CALLT;
        db_sstep_print = print;
        db_inst_count = 0;
        db_load_count = 0;
        db_store_count = 0;

        db_cmd_loop_done = true;
}

/*ARGSUSED*/
void
db_trace_until_matching_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{
        bool print = false;

        if (modif[0] == 'p')
                print = true;

        db_run_mode = STEP_RETURN;
        db_call_depth = 1;
        db_sstep_print = print;
        db_inst_count = 0;
        db_load_count = 0;
        db_store_count = 0;

        db_cmd_loop_done = true;
}

/* continue */
/*ARGSUSED*/
void
db_continue_cmd(db_expr_t addr, bool have_addr,
    db_expr_t count, const char *modif)
{

        if (modif[0] == 'c')
                db_run_mode = STEP_COUNT;
        else
                db_run_mode = STEP_CONTINUE;
        db_inst_count = 0;
        db_load_count = 0;
        db_store_count = 0;

        db_cmd_loop_done = true;
}
#endif /* DDB */

#ifdef SOFTWARE_SSTEP
/*
 *      Software implementation of single-stepping.
 *      If your machine does not have a trace mode
 *      similar to the vax or sun ones you can use
 *      this implementation, done for the mips.
 *      Just define the above conditional and provide
 *      the functions/macros defined below.
 *
 * bool inst_branch(int inst)
 * bool inst_call(int inst)
 *      returns true if the instruction might branch
 *
 * bool inst_return(int inst)
 *      returns true is the instruction will return to its caller
 *
 * bool inst_unconditional_flow_transfer(int inst)
 *      returns true if the instruction is an unconditional
 *      transfer of flow (i.e. unconditional branch)
 *
 * db_addr_t branch_taken(int inst, db_addr_t pc, db_regs_t *regs)
 *      returns the target address of the branch
 *
 * db_addr_t next_instr_address(db_addr_t pc, bool bd)
 *      returns the address of the first instruction following the
 *      one at "pc", which is either in the taken path of the branch
 *      (bd == true) or not.  This is for machines (e.g. mips) with
 *      branch delays.
 *
 *      A single-step may involve at most 2 breakpoints -
 *      one for branch-not-taken and one for branch taken.
 *      If one of these addresses does not already have a breakpoint,
 *      we allocate a breakpoint and save it here.
 *      These breakpoints are deleted on return.
 */

#if !defined(DDB)
/* XXX - don't check for existing breakpoints in KGDB-only case */
#define db_find_breakpoint_here(pc)     (0)
#endif

void
db_set_single_step(db_regs_t *regs)
{
        db_addr_t pc = PC_REGS(regs), brpc = pc;
        bool unconditional;
        unsigned int inst;

        /*
         *      User was stopped at pc, e.g. the instruction
         *      at pc was not executed.
         */
        inst = db_get_value(pc, sizeof(int), false);
        if (inst_branch(inst) || inst_call(inst) || inst_return(inst)) {
                brpc = branch_taken(inst, pc, regs);
                if (brpc != pc) {       /* self-branches are hopeless */
                        db_set_temp_breakpoint(&db_taken_bkpt, brpc);
                } else
                        db_taken_bkpt.address = 0;
                pc = next_instr_address(pc, true);
        }

        /*
         *      Check if this control flow instruction is an
         *      unconditional transfer.
         */
        unconditional = inst_unconditional_flow_transfer(inst);

        pc = next_instr_address(pc, false);

        /*
         *      We only set the sequential breakpoint if previous
         *      instruction was not an unconditional change of flow
         *      control.  If the previous instruction is an
         *      unconditional change of flow control, setting a
         *      breakpoint in the next sequential location may set
         *      a breakpoint in data or in another routine, which
         *      could screw up in either the program or the debugger.
         *      (Consider, for instance, that the next sequential
         *      instruction is the start of a routine needed by the
         *      debugger.)
         *
         *      Also, don't set both the taken and not-taken breakpoints
         *      in the same place even if the MD code would otherwise
         *      have us do so.
         */
        if (unconditional == false &&
            db_find_breakpoint_here(pc) == 0 &&
            pc != brpc)
                db_set_temp_breakpoint(&db_not_taken_bkpt, pc);
        else
                db_not_taken_bkpt.address = 0;
}

void
db_clear_single_step(db_regs_t *regs)
{

        if (db_taken_bkpt.address != 0)
                db_delete_temp_breakpoint(&db_taken_bkpt);

        if (db_not_taken_bkpt.address != 0)
                db_delete_temp_breakpoint(&db_not_taken_bkpt);
}

void
db_set_temp_breakpoint(db_breakpoint_t bkpt, db_addr_t addr)
{

        bkpt->map = NULL;
        bkpt->address = addr;
        /* bkpt->flags = BKPT_TEMP;     - this is not used */
        bkpt->init_count = 1;
        bkpt->count = 1;

        bkpt->bkpt_inst = db_get_value(bkpt->address, BKPT_SIZE, false);
        db_put_value(bkpt->address, BKPT_SIZE,
                BKPT_SET(bkpt->bkpt_inst, bkpt->address));
}

void
db_delete_temp_breakpoint(db_breakpoint_t bkpt)
{

        db_put_value(bkpt->address, BKPT_SIZE, bkpt->bkpt_inst);
        bkpt->address = 0;
}
#endif /* SOFTWARE_SSTEP */