debugger.c

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/*
 * Copyright (C) 2006 Ondrej Palkovsky
 * 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.
 */

#include <arch/debugger.h>
#include <console/kconsole.h>
#include <console/cmd.h>
#include <symtab.h>
#include <print.h>
#include <panic.h>
#include <interrupt.h>
#include <arch/asm.h>
#include <arch/cpu.h>
#include <debug.h>
#include <func.h>
#include <smp/ipi.h>

typedef struct  {
        __address address;      
        int flags;              
        int counter;            
} bpinfo_t;

static bpinfo_t breakpoints[BKPOINTS_MAX];
SPINLOCK_INITIALIZE(bkpoint_lock);

static int cmd_print_breakpoints(cmd_arg_t *argv);
static cmd_info_t bkpts_info = {
        .name = "bkpts",
        .description = "Print breakpoint table.",
        .func = cmd_print_breakpoints,
        .argc = 0,
};

#ifndef CONFIG_DEBUG_AS_WATCHPOINT

static int cmd_del_breakpoint(cmd_arg_t *argv);
static cmd_arg_t del_argv = {
        .type = ARG_TYPE_INT
};
static cmd_info_t delbkpt_info = {
        .name = "delbkpt",
        .description = "delbkpt <number> - Delete breakpoint.",
        .func = cmd_del_breakpoint,
        .argc = 1,
        .argv = &del_argv
};

static int cmd_add_breakpoint(cmd_arg_t *argv);
static cmd_arg_t add_argv = {
        .type = ARG_TYPE_INT
};
static cmd_info_t addbkpt_info = {
        .name = "addbkpt",
        .description = "addbkpt <&symbol> - new breakpoint.",
        .func = cmd_add_breakpoint,
        .argc = 1,
        .argv = &add_argv
};

static cmd_arg_t addw_argv = {
        .type = ARG_TYPE_INT
};
static cmd_info_t addwatchp_info = {
        .name = "addwatchp",
        .description = "addbwatchp <&symbol> - new write watchpoint.",
        .func = cmd_add_breakpoint,
        .argc = 1,
        .argv = &addw_argv
};

#endif

int cmd_print_breakpoints(cmd_arg_t *argv)
{
        int i;
        char *symbol;

        printf("Breakpoint table.\n");
        for (i=0; i < BKPOINTS_MAX; i++)
                if (breakpoints[i].address) {
                        symbol = get_symtab_entry(breakpoints[i].address);
                        printf("%d. %p in %s\n",i,
                               breakpoints[i].address, symbol);
                        printf("     Count(%d) ", breakpoints[i].counter);
                        printf("\n");
                }
        return 1;
}

/* Setup DR register according to table */
static void setup_dr(int curidx)
{
        __native dr7;
        bpinfo_t *cur = &breakpoints[curidx];
        int flags = breakpoints[curidx].flags;

        /* Disable breakpoint in DR7 */
        dr7 = read_dr7();
        dr7 &= ~(0x2 << (curidx*2));

        if (cur->address) { /* Setup DR register */
                /* Set breakpoint to debug registers */
                switch (curidx) {
                case 0:
                        write_dr0(cur->address);
                        break;
                case 1:
                        write_dr1(cur->address);
                        break;
                case 2:
                        write_dr2(cur->address);
                        break;
                case 3:
                        write_dr3(cur->address);
                        break;
                }
                /* Set type to requested breakpoint & length*/
                dr7 &= ~ (0x3 << (16 + 4*curidx));
                dr7 &= ~ (0x3 << (18 + 4*curidx));
                if ((flags & BKPOINT_INSTR)) {
                        ;
                } else {
                        if (sizeof(int) == 4)
                                dr7 |= ((__native) 0x3) << (18 + 4*curidx);
                        else /* 8 */
                                dr7 |= ((__native) 0x2) << (18 + 4*curidx);
                        
                        if ((flags & BKPOINT_WRITE))
                                dr7 |= ((__native) 0x1) << (16 + 4*curidx);
                        else if ((flags & BKPOINT_READ_WRITE))
                                dr7 |= ((__native) 0x3) << (16 + 4*curidx);
                }

                /* Enable global breakpoint */
                dr7 |= 0x2 << (curidx*2);

                write_dr7(dr7);
                
        } 
}
        
int breakpoint_add(void * where, int flags, int curidx)
{
        ipl_t ipl;
        int i;
        bpinfo_t *cur;

        ASSERT( flags & (BKPOINT_INSTR | BKPOINT_WRITE | BKPOINT_READ_WRITE));

        ipl = interrupts_disable();
        spinlock_lock(&bkpoint_lock);
        
        if (curidx == -1) {
                /* Find free space in slots */
                for (i=0; i<BKPOINTS_MAX; i++)
                        if (!breakpoints[i].address) {
                                curidx = i;
                                break;
                        }
                if (curidx == -1) {
                        /* Too many breakpoints */
                        spinlock_unlock(&bkpoint_lock);
                        interrupts_restore(ipl);
                        return -1;
                }
        }
        cur = &breakpoints[curidx];

        cur->address = (__address) where;
        cur->flags = flags;
        cur->counter = 0;

        setup_dr(curidx);

        spinlock_unlock(&bkpoint_lock);
        interrupts_restore(ipl);

        /* Send IPI */
#ifdef CONFIG_SMP
//      ipi_broadcast(VECTOR_DEBUG_IPI);        
#endif  

        return curidx;
}

#ifdef amd64
# define getip(x)  ((x)->rip)
#else
# define getip(x)  ((x)->eip)
#endif

static void handle_exception(int slot, istate_t *istate)
{
        ASSERT(breakpoints[slot].address);

        /* Handle zero checker */
        if (! (breakpoints[slot].flags & BKPOINT_INSTR)) {
                if ((breakpoints[slot].flags & BKPOINT_CHECK_ZERO)) {
                        if (*((__native *) breakpoints[slot].address) != 0)
                                return;
                        printf("**** Found ZERO on address %p ****\n",
                               slot, breakpoints[slot].address);
                } else {
                        printf("Data watchpoint - new data: %p\n",
                               *((__native *) breakpoints[slot].address));
                }
        }
        printf("Reached breakpoint %d:%p(%s)\n", slot, getip(istate),
               get_symtab_entry(getip(istate)));
        printf("***Type 'exit' to exit kconsole.\n");
        atomic_set(&haltstate,1);
        kconsole("debug");
        atomic_set(&haltstate,0);
}

void breakpoint_del(int slot)
{
        bpinfo_t *cur;
        ipl_t ipl;

        ipl = interrupts_disable();
        spinlock_lock(&bkpoint_lock);

        cur = &breakpoints[slot];
        if (!cur->address) {
                spinlock_unlock(&bkpoint_lock);
                interrupts_restore(ipl);
                return;
        }

        cur->address = NULL;

        setup_dr(slot);

        spinlock_unlock(&bkpoint_lock);
        interrupts_restore(ipl);
#ifdef CONFIG_SMP
//      ipi_broadcast(VECTOR_DEBUG_IPI);        
#endif
}

#ifndef CONFIG_DEBUG_AS_WATCHPOINT

int cmd_del_breakpoint(cmd_arg_t *argv)
{
        if (argv->intval < 0 || argv->intval > BKPOINTS_MAX) {
                printf("Invalid breakpoint number.\n");
                return 0;
        }
        breakpoint_del(argv->intval);
        return 1;
}

static int cmd_add_breakpoint(cmd_arg_t *argv)
{
        int flags;
        int id;

        if (argv == &add_argv) {
                flags = BKPOINT_INSTR;
        } else { /* addwatchp */
                flags = BKPOINT_WRITE;
        }
        printf("Adding breakpoint on address: %p\n", argv->intval);
        id = breakpoint_add((void *)argv->intval, flags, -1);
        if (id < 0)
                printf("Add breakpoint failed.\n");
        else
                printf("Added breakpoint %d.\n", id);
        
        return 1;
}
#endif

static void debug_exception(int n, istate_t *istate)
{
        __native dr6;
        int i;
        
        /* Set RF to restart the instruction  */
#ifdef amd64       
        istate->rflags |= RFLAGS_RF;
#else
        istate->eflags |= EFLAGS_RF;
#endif

        dr6 = read_dr6();
        for (i=0; i < BKPOINTS_MAX; i++) {
                if (dr6 & (1 << i)) {
                        dr6 &= ~ (1 << i);
                        write_dr6(dr6);
                        
                        handle_exception(i, istate);
                }
        }
}

#ifdef CONFIG_SMP
static void debug_ipi(int n, istate_t *istate)
{
        int i;

        spinlock_lock(&bkpoint_lock);
        for (i=0; i < BKPOINTS_MAX; i++)
                setup_dr(i);
        spinlock_unlock(&bkpoint_lock);
}
#endif

void debugger_init()
{
        int i;

        for (i=0; i<BKPOINTS_MAX; i++)
                breakpoints[i].address = NULL;
        
        cmd_initialize(&bkpts_info);
        if (!cmd_register(&bkpts_info))
                panic("could not register command %s\n", bkpts_info.name);

#ifndef CONFIG_DEBUG_AS_WATCHPOINT
        cmd_initialize(&delbkpt_info);
        if (!cmd_register(&delbkpt_info))
                panic("could not register command %s\n", delbkpt_info.name);

        cmd_initialize(&addbkpt_info);
        if (!cmd_register(&addbkpt_info))
                panic("could not register command %s\n", addbkpt_info.name);

        cmd_initialize(&addwatchp_info);
        if (!cmd_register(&addwatchp_info))
                panic("could not register command %s\n", addwatchp_info.name);
#endif
        
        exc_register(VECTOR_DEBUG, "debugger",
                     debug_exception);
#ifdef CONFIG_SMP
        exc_register(VECTOR_DEBUG_IPI, "debugger_smp",
                     debug_ipi);
#endif
}

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