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/*

 * Copyright (c) 2008 Jiri Svoboda

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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.

 */

/** @addtogroup debug

 * @{

 */

/** @file

 */

#include <stdio.h>

#include <stdlib.h>

#include <assert.h>

#include <sys/types.h>

#include <errno.h>

#include <udebug.h>

#include "../../../cons.h"

#include "../../../main.h"

#include "../../../breakpoint.h"

#include "../../../include/arch.h"

#define OPCODE_BREAK        0x0000000d

static istate_t istate;

typedef enum {

    OP_J,

    OP_JAL,

    OP_JALR,

    OP_JR

} op_t;

typedef struct {

    uint32_t mask;

    uint32_t value;

    op_t op;

} instr_desc_t;

static instr_desc_t decoding_table[] = {

    { 0xfc000000, 0x08000000, OP_J },

    { 0xfc000000, 0x0c000000, OP_JAL },

    { 0xfc1f07ff, 0x00000009, OP_JALR },

    { 0xfc1fffff, 0x00000008, OP_JR },

    { 0, 0, -1 }

};

int arch_breakpoint_set(breakpoint_t *b)

{

    return bstore_push(&b->arch.bs, b->addr, OPCODE_BREAK);

}

int arch_breakpoint_remove(breakpoint_t *b)

{

    return bstore_pop(&b->arch.bs);

}

static int islot_read(uintptr_t addr, uint32_t *instr)

{

    int rc;

    rc = udebug_mem_read(app_phone, instr, addr, sizeof(uint32_t));

    if (rc != EOK) {

        cons_printf("Error reading memory address 0x%zx\n", addr);

    }

    return rc;

}

static op_t instr_decode(uint32_t instr)

{

    instr_desc_t *idesc;

    idesc = &decoding_table[0];

    while (idesc->op >= 0) {

        if ((instr & idesc->mask) == idesc->value)

            return idesc->op;

        ++idesc;

    }

    return -1;

}

static int get_reg(int reg_no, uint32_t *value)

{

    int rc;

    cons_printf("get_reg...\n");

    if (reg_no == 0) {

        *value = 0;

        return 0;

    }

    /* FIXME: ugly */

    *value = ((uint32_t *)&istate)[reg_no - 1];

    printf("get_reg ok (0x%08x)\n", *value);

    return 0;

}

/** Get address of the instruction that will be executed after the current one.

 *

 * Assumptions: addr == PC, *addr is not covered by a BREAK.

 *

 * @param addr  Address of an instruction.

 * @return  Address of the instruction that will be executed afterwards.

 */

static int get_next_addr(uintptr_t addr, uintptr_t *next_addr)

{

    /* TODO: J[AL]R, branches and delay slots */

    uint32_t instr;

    op_t op;

    int rc;

    rc = islot_read(addr, &instr);

    if (rc != 0) return rc;

    op = instr_decode(instr);

    switch (op) {

    case OP_J:

    case OP_JAL:

        *next_addr =

            ((addr + 4) & 0xf0000000) |

            ((instr & 0x03ffffff) << 2);

        break;

    case OP_JR:

    case OP_JALR:

        rc = get_reg((instr >> 21) & 0x1f, next_addr);

        break;

    default:

        /* Regular instruction */  

        *next_addr = addr + 4;

        break;

    }

    return 0;  

}

static void _ev_breakpoint(thash_t thread_hash)

{

    breakpoint_t *b;

    dthread_t *dt;

    int rc;

    uint32_t epc;

    uintptr_t brk_addr;

    uintptr_t next_addr;

    uint32_t brkp;

    brkp = OPCODE_BREAK;

    cons_printf("arch_event_breakpoint\n");

    rc = udebug_regs_read(app_phone, thread_hash, &istate);

    cons_printf("udebug_regs_read -> %d\n", rc);

    epc = istate_get_pc(&istate);

    cons_printf("EPC was 0x%08x\n", epc);

    brk_addr = epc;

    dt = dthread_get();

    if (active_bkpt != NULL) {

        assert(active_bkpt->arch.bs.address == brk_addr);

        b = active_bkpt;

        /* A breakpoint-clearing BRK has been hit */

        cons_printf("restoring breakpoint %d\n", b->id);

        rc = bstore_pop(&b->arch.bs);

        if (rc != 0) return;

        rc = bstore_push(&b->arch.bs, b->addr, OPCODE_BREAK);

        if (rc != 0) return;

        active_bkpt = NULL;

        return;

    }

    b = breakpoint_find_by_addr(brk_addr);

    if (b == NULL) {

        cons_printf("Unrecognized breakpoint at 0x%lx\n", brk_addr);

    }

    /* A breakpoint has been hit */

    cons_printf("breakpoint_hit...\n");

    breakpoint_hit(b);

    /* While in breakpoint_hit(), singlestep was activated */

    if (dt->arch.singlestep) return;

    cons_printf("move breakpoint\b");

    rc = bstore_pop(&b->arch.bs);

    if (rc != 0) return;

    rc = get_next_addr(brk_addr, &next_addr);

    if (rc != 0) return;

    /*

     * There could be another breakpoint at next_addr,

     * but that's okay. We'll pop the active breakpoint bs

     * before doing anything else.

     */

    rc = bstore_push(&b->arch.bs, next_addr, OPCODE_BREAK);

    if (rc != 0) return;

    active_bkpt = b;

    b->active = true;

    cons_printf("end_hit...\n");

}

static void _ev_singlestep(thash_t thread_hash)

{

    dthread_t *dt;

    int rc;

    uint32_t epc;

    int brk_addr;

    uint32_t brkp;

    dt = dthread_get();

    assert(active_bkpt == NULL);

    assert(dt->arch.singlestep);

    brkp = OPCODE_BREAK;

    cons_printf("arch_event_breakpoint\n");

    rc = udebug_regs_read(app_phone, thread_hash, &istate);

    cons_printf("udebug_regs_read -> %d\n", rc);

    epc = istate_get_pc(&istate);

    cons_printf("EPC was 0x%08x\n", epc);

    brk_addr = epc;

    if (dt->arch.cur.valid) {

        cons_printf("restore breakpoint BRK\n");

        rc = bstore_pop(&dt->arch.cur);

    }

    cons_printf("clear singlestep BRK\n");

    rc = bstore_pop(&dt->arch.next);

    dt->arch.singlestep = false;

    singlestep_hit();

}

void arch_event_breakpoint(thash_t thread_hash)

{

    dthread_t *dt;

    dt = dthread_get();

    if (dt->arch.singlestep) {

        _ev_singlestep(thread_hash);

    } else {

        _ev_breakpoint(thread_hash);

    }

}

void arch_event_trap(dthread_t *dt)

{

    /* Unused */

    (void)dt;

}

void arch_dump_regs(thash_t thash)

{

    /* TODO */

}

void arch_singlestep(dthread_t *dt)

{

    int rc;

    uint32_t epc;

    breakpoint_t *b;

    uint32_t old_instr;

    uintptr_t next_addr;

    assert(active_bkpt == NULL);

    assert(dt->arch.singlestep == false);

    cons_printf("arch_singlestep(dt)\n");

    rc = udebug_regs_read(app_phone, dt->hash, &istate);

    cons_printf("udebug_regs_read -> %d\n", rc);

    epc = istate_get_pc(&istate);

    cons_printf("EPC was 0x%08x\n", epc);

    cons_printf("initial set singlestep\n");

    b = breakpoint_find_by_addr(epc);

    if (b != NULL) {

        /* Cover breakpoint with old instruction */

        old_instr = b->arch.bs.value;

        rc = bstore_push(&dt->arch.cur, epc, old_instr);

        if (rc < 0) return;

    }

    rc = get_next_addr(epc, &next_addr);

    if (rc != 0) return;

    /* Cover next instruction with BREAK */

    rc = bstore_push(&dt->arch.next, next_addr, OPCODE_BREAK);

    if (rc != 0) return;

    dt->arch.singlestep = true;

    dthread_resume(dt);

}

/** @}

 */