/*      $NetBSD: undefined.c,v 1.22 2003/11/29 22:21:29 bjh21 Exp $     */

/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * 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 "opt_ddb.h"

#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/signal.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/syslog.h>
#include <sys/vmmeter.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/signalvar.h>
#include <sys/ptrace.h>
#include <sys/vmmeter.h>
#ifdef KDB
#include <sys/kdb.h>
#endif

#include <vm/vm.h>
#include <vm/vm_extern.h>

#include <machine/armreg.h>
#include <machine/asm.h>
#include <machine/cpu.h>
#include <machine/frame.h>
#include <machine/undefined.h>
#include <machine/trap.h>

#include <machine/disassem.h>

#ifdef DDB
#include <ddb/db_output.h>
#endif

#ifdef KDB
#include <machine/db_machdep.h>
#endif

#define ARM_COPROC_INSN(insn)   (((insn) & (1 << 27)) != 0)
#define ARM_VFP_INSN(insn)      ((((insn) & 0xfe000000) == 0xf2000000) || \
                                 (((insn) & 0xff100000) == 0xf4000000))
#define ARM_COPROC(insn)        (((insn) >> 8) & 0xf)

#define THUMB_32BIT_INSN(insn)  ((((insn) & 0xe000) == 0xe000) && \
                                 (((insn) & 0x1800) != 0))
/*
 * Coprocessor, Advanced SIMD, and
 * Floating-point instructions on page A6-251
 * OP1 == 01 OR 11
 * OP2 == 1xxxxxx
 */
#define THUMB_COPROC_INSN(insn) (((insn) & (3 << 26)) == (3 << 26))
/*
 * Advanced SIMD element or structure
 * load/store instructions on page A7-275
 * OP1 == 11
 * OP2 == 001xxx0
*/
#define THUMB_VFP_INSN(insn)    (((insn) & (0x1F1 << 20)) == (0x190 << 20))
#define THUMB_COPROC(insn)      (((insn) >> 8) & 0xf)

#define COPROC_VFP      10

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

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, ("bad coproc"));
        KASSERT(handler != NULL, ("handler is NULL")); /* Used to be legal. */

        /* XXX: M_TEMP??? */
        uh = 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);
}

static int
gdb_trapper(u_int addr, u_int insn, struct trapframe *frame, int code)
{
        struct thread *td;
        ksiginfo_t ksi;
        int error;

        td = (curthread == NULL) ? &thread0 : curthread;

        if (insn == GDB_BREAKPOINT || insn == GDB5_BREAKPOINT) {
                if (code == FAULT_USER) {
                        ksiginfo_init_trap(&ksi);
                        ksi.ksi_signo = SIGTRAP;
                        ksi.ksi_code = TRAP_BRKPT;
                        ksi.ksi_addr = (u_int32_t *)addr;
                        trapsignal(td, &ksi);
                        return 0;
                }
#if 0
#ifdef KGDB
                return !kgdb_trap(T_BREAKPOINT, frame);
#endif
#endif
        }

        if (code == FAULT_USER) {
                /* TODO: No support for ptrace from Thumb-2 */
                if ((frame->tf_spsr & PSR_T) == 0 &&
                    insn == PTRACE_BREAKPOINT) {
                        PROC_LOCK(td->td_proc);
                        _PHOLD(td->td_proc);
                        error = ptrace_clear_single_step(td);
                        _PRELE(td->td_proc);
                        PROC_UNLOCK(td->td_proc);
                        if (error == 0) {
                                ksiginfo_init_trap(&ksi);
                                ksi.ksi_signo = SIGTRAP;
                                ksi.ksi_code = TRAP_TRACE;
                                ksi.ksi_addr = (u_int32_t *)addr;
                                trapsignal(td, &ksi);
                                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(struct trapframe *frame)
{
        struct thread *td;
        u_int fault_pc;
        int fault_instruction;
        int fault_code;
        int coprocessor;
        struct undefined_handler *uh;
#ifdef VERBOSE_ARM32
        int s;
#endif
        ksiginfo_t ksi;

        /* Enable interrupts if they were enabled before the exception. */
        if (__predict_true(frame->tf_spsr & PSR_I) == 0)
                enable_interrupts(PSR_I);

        VM_CNT_INC(v_trap);

        fault_pc = frame->tf_pc;

        /*
         * Get the current thread/proc structure or thread0/proc0 if there is
         * none.
         */
        td = curthread == NULL ? &thread0 : curthread;

        coprocessor = 0;
        if ((frame->tf_spsr & PSR_T) == 0) {
                /*
                 * Make sure the program counter is correctly aligned so we
                 * don't take an alignment fault trying to read the opcode.
                 */
                if (__predict_false((fault_pc & 3) != 0)) {
                        ksiginfo_init_trap(&ksi);
                        ksi.ksi_signo = SIGILL;
                        ksi.ksi_code = ILL_ILLADR;
                        ksi.ksi_addr = (u_int32_t *)(intptr_t) fault_pc;
                        trapsignal(td, &ksi);
                        userret(td, frame);
                        return;
                }

                /*
                 * Should use fuword() here .. but in the interests of
                 * squeezing every bit of speed we will just use ReadWord().
                 * We know the instruction can be read as was just executed
                 * so this will never fail unless the kernel is screwed up
                 * in which case it does not really matter does it ?
                 */

                fault_instruction = *(u_int32_t *)fault_pc;

                /* Check for coprocessor instruction */

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

                if (ARM_COPROC_INSN(fault_instruction))
                        coprocessor = ARM_COPROC(fault_instruction);
                else {          /* check for special instructions */
                        if (ARM_VFP_INSN(fault_instruction))
                                coprocessor = COPROC_VFP; /* vfp / simd */
                }
        } else {
                fault_instruction = *(uint16_t *)fault_pc;
                if (THUMB_32BIT_INSN(fault_instruction)) {
                        fault_instruction <<= 16;
                        fault_instruction |= *(uint16_t *)(fault_pc + 2);

                        /* Coprocessor, Advanced SIMD and Floating-point */
                        if (THUMB_COPROC_INSN(fault_instruction))
                                coprocessor = THUMB_COPROC(fault_instruction);
                        else {
                                /* Advanced SIMD load/store */
                                if (THUMB_VFP_INSN(fault_instruction))
                                        coprocessor = COPROC_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;
                td->td_frame = 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) == 0)
                    break;

        if (uh == NULL && (fault_code & FAULT_USER)) {
                /* Fault has not been handled */
                ksiginfo_init_trap(&ksi);
                ksi.ksi_signo = SIGILL;
                ksi.ksi_code = ILL_ILLOPC;
                ksi.ksi_addr = (u_int32_t *)(intptr_t) fault_pc;
                trapsignal(td, &ksi);
        }

        if ((fault_code & FAULT_USER) == 0) {
                if (fault_instruction == KERNEL_BREAKPOINT) {
#ifdef KDB
                        kdb_trap(T_BREAKPOINT, 0, frame);
#else
                        printf("No debugger in kernel.\n");
#endif
                } else if (uh == NULL) {
                        panic("Undefined instruction in kernel (0x%08x)",
                            fault_instruction);
                }
                return;
        }

        userret(td, frame);
}