/*      $OpenBSD: undefined.c,v 1.18 2026/03/08 17:07:31 deraadt Exp $  */
/*      $NetBSD: undefined.c,v 1.22 2003/11/29 22:21:29 bjh21 Exp $     */

/*
 * Copyright (c) 2001 Ben Harris.
 * Copyright (c) 1995 Mark Brinicombe.
 * Copyright (c) 1995 Brini.
 * All rights reserved.
 *
 * This code is derived from software written for Brini by Mark Brinicombe
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Brini.
 * 4. The name of the company nor the name of the author may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * RiscBSD kernel project
 *
 * undefined.c
 *
 * Fault handler
 *
 * Created      : 06/01/95
 */

#include <sys/param.h>

#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/signal.h>
#include <sys/signalvar.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/user.h>

#include <uvm/uvm_extern.h>

#include <machine/cpu.h>
#include <machine/frame.h>
#include <arm/undefined.h>
#include <arm/vfp.h>
#include <machine/trap.h>


static int gdb_trapper(u_int, u_int, struct trapframe *, int, uint32_t);

LIST_HEAD(, undefined_handler) undefined_handlers[MAX_COPROCS];


void *
install_coproc_handler(int coproc, undef_handler_t handler)
{
        struct undefined_handler *uh;

        KASSERT(coproc >= 0 && coproc < MAX_COPROCS);
        KASSERT(handler != NULL); /* Used to be legal. */

        /* XXX: M_TEMP??? */
        uh = (struct undefined_handler *)malloc(sizeof(*uh), M_TEMP, M_WAITOK);
        uh->uh_handler = handler;
        install_coproc_handler_static(coproc, uh);
        return uh;
}

void
install_coproc_handler_static(int coproc, struct undefined_handler *uh)
{

        LIST_INSERT_HEAD(&undefined_handlers[coproc], uh, uh_link);
}

void
remove_coproc_handler(void *cookie)
{
        struct undefined_handler *uh = cookie;

        LIST_REMOVE(uh, uh_link);
        free(uh, M_TEMP, 0);
}


static int
gdb_trapper(u_int addr, u_int insn, struct trapframe *frame, int code, uint32_t fpexc)
{
        union sigval sv;
        struct proc *p;
        p = (curproc == NULL) ? &proc0 : curproc;

        if (insn == GDB_BREAKPOINT || insn == GDB5_BREAKPOINT) {
                if (code == FAULT_USER) {
                        sv.sival_int = addr;
                        trapsignal(p, SIGTRAP, 0, TRAP_BRKPT, sv);
                        return 0;
                }
        }
        return 1;
}

static struct undefined_handler gdb_uh;

void
undefined_init(void)
{
        int loop;

        /* Not actually necessary -- the initialiser is just NULL */
        for (loop = 0; loop < MAX_COPROCS; ++loop)
                LIST_INIT(&undefined_handlers[loop]);

        /* Install handler for GDB breakpoints */
        gdb_uh.uh_handler = gdb_trapper;
        install_coproc_handler_static(0, &gdb_uh);
}


void
undefinedinstruction(trapframe_t *frame)
{
        struct proc *p;
        u_int fault_pc;
        int fault_instruction;
        int fault_code;
        int coprocessor;
        struct undefined_handler *uh;
        uint32_t fpexc;
#ifdef VERBOSE_ARM32
        int s;
#endif
        union sigval sv;

        /* Before enabling interrupts, save FPU state */
        fpexc = vfp_save();

        /* Enable interrupts if they were enabled before the exception. */
        if (!(frame->tf_spsr & PSR_I))
                enable_interrupts(PSR_I);

        frame->tf_pc -= INSN_SIZE;
        fault_pc = frame->tf_pc;

        /* Get the current proc structure or proc0 if there is none. */
        p = (curproc == NULL) ? &proc0 : curproc;

        /*
         * Fetch the opcode and Make sure the program counter is correctly
         * aligned.
         */
        if (copyin32((void *)fault_pc, &fault_instruction) != 0) {
                /* Give the user an illegal instruction signal. */
                sv.sival_int = (u_int32_t) fault_pc;
                trapsignal(p, SIGILL, 0, ILL_ILLOPC, sv);
                userret(p);
                return;
        }

        /* Update vmmeter statistics */
        atomic_inc_int(&uvmexp.traps);

        /* Check for coprocessor instruction */

        /*
         * According to the datasheets you only need to look at bit 27 of the
         * instruction to tell the difference between an undefined
         * instruction and a coprocessor instruction following an undefined
         * instruction trap.
         */

        coprocessor = 0;
        if ((fault_instruction & (1 << 27)) != 0)
                coprocessor = (fault_instruction >> 8) & 0x0f;
        else {          /* check for special instructions */
                if (((fault_instruction & 0xfe000000) == 0xf2000000) ||
                    ((fault_instruction & 0xff100000) == 0xf4000000))
                        coprocessor = 10;       /* vfp / simd */
        }

        if ((frame->tf_spsr & PSR_MODE) == PSR_USR32_MODE) {
                /*
                 * Modify the fault_code to reflect the USR/SVC state at
                 * time of fault.
                 */
                fault_code = FAULT_USER;
                p->p_addr->u_pcb.pcb_tf = frame;
        } else
                fault_code = 0;

        /* OK this is were we do something about the instruction. */
        LIST_FOREACH(uh, &undefined_handlers[coprocessor], uh_link)
            if (uh->uh_handler(fault_pc, fault_instruction, frame,
                               fault_code, fpexc) == 0)
                    break;

        if (uh == NULL) {
                /* Fault has not been handled */
                
#ifdef VERBOSE_ARM32
                s = spltty();

                if ((fault_instruction & 0x0f000010) == 0x0e000000) {
                        printf("CDP\n");
                        disassemble(fault_pc);
                } else if ((fault_instruction & 0x0e000000) == 0x0c000000) {
                        printf("LDC/STC\n");
                        disassemble(fault_pc);
                } else if ((fault_instruction & 0x0f000010) == 0x0e000010) {
                        printf("MRC/MCR\n");
                        disassemble(fault_pc);
                } else if ((fault_instruction & ~INSN_COND_MASK)
                         != (KERNEL_BREAKPOINT & ~INSN_COND_MASK)) {
                        printf("Undefined instruction\n");
                        disassemble(fault_pc);
                }

                splx(s);
#endif
        
                if ((fault_code & FAULT_USER) == 0) {
                        printf("Undefined instruction in kernel\n");
#ifdef DDB
                        db_enter();
#endif
                }

                sv.sival_int = frame->tf_pc;
                trapsignal(p, SIGILL, 0, ILL_ILLOPC, sv);
        }

        if ((fault_code & FAULT_USER) == 0)
                return;

        userret(p);
}