kgdb.c

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/*
 * arch/arm/kernel/kgdb.c
 *
 * ARM KGDB support
 *
 * Copyright (c) 2002-2004 MontaVista Software, Inc
 * Copyright (c) 2008 Wind River Systems, Inc.
 *
 * Authors:  George Davis <[email protected]>
 *           Deepak Saxena <[email protected]>
 */
#include <linux/irq.h>
#include <linux/kdebug.h>
#include <linux/kgdb.h>
#include <asm/traps.h>

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
    { "r0", 4, offsetof(struct pt_regs, ARM_r0)},
    { "r1", 4, offsetof(struct pt_regs, ARM_r1)},
    { "r2", 4, offsetof(struct pt_regs, ARM_r2)},
    { "r3", 4, offsetof(struct pt_regs, ARM_r3)},
    { "r4", 4, offsetof(struct pt_regs, ARM_r4)},
    { "r5", 4, offsetof(struct pt_regs, ARM_r5)},
    { "r6", 4, offsetof(struct pt_regs, ARM_r6)},
    { "r7", 4, offsetof(struct pt_regs, ARM_r7)},
    { "r8", 4, offsetof(struct pt_regs, ARM_r8)},
    { "r9", 4, offsetof(struct pt_regs, ARM_r9)},
    { "r10", 4, offsetof(struct pt_regs, ARM_r10)},
    { "fp", 4, offsetof(struct pt_regs, ARM_fp)},
    { "ip", 4, offsetof(struct pt_regs, ARM_ip)},
    { "sp", 4, offsetof(struct pt_regs, ARM_sp)},
    { "lr", 4, offsetof(struct pt_regs, ARM_lr)},
    { "pc", 4, offsetof(struct pt_regs, ARM_pc)},
    { "f0", 12, -1 },
    { "f1", 12, -1 },
    { "f2", 12, -1 },
    { "f3", 12, -1 },
    { "f4", 12, -1 },
    { "f5", 12, -1 },
    { "f6", 12, -1 },
    { "f7", 12, -1 },
    { "fps", 4, -1 },
    { "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
};

char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
    if (regno >= DBG_MAX_REG_NUM || regno < 0)
        return NULL;

    if (dbg_reg_def[regno].offset != -1)
        memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
               dbg_reg_def[regno].size);
    else
        memset(mem, 0, dbg_reg_def[regno].size);
    return dbg_reg_def[regno].name;
}

int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
    if (regno >= DBG_MAX_REG_NUM || regno < 0)
        return -EINVAL;

    if (dbg_reg_def[regno].offset != -1)
        memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
               dbg_reg_def[regno].size);
    return 0;
}

void
sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
{
    struct pt_regs *thread_regs;
    int regno;

    /* Just making sure... */
    if (task == NULL)
        return;

    /* Initialize to zero */
    for (regno = 0; regno < GDB_MAX_REGS; regno++)
        gdb_regs[regno] = 0;

    /* Otherwise, we have only some registers from switch_to() */
    thread_regs     = task_pt_regs(task);
    gdb_regs[_R0]       = thread_regs->ARM_r0;
    gdb_regs[_R1]       = thread_regs->ARM_r1;
    gdb_regs[_R2]       = thread_regs->ARM_r2;
    gdb_regs[_R3]       = thread_regs->ARM_r3;
    gdb_regs[_R4]       = thread_regs->ARM_r4;
    gdb_regs[_R5]       = thread_regs->ARM_r5;
    gdb_regs[_R6]       = thread_regs->ARM_r6;
    gdb_regs[_R7]       = thread_regs->ARM_r7;
    gdb_regs[_R8]       = thread_regs->ARM_r8;
    gdb_regs[_R9]       = thread_regs->ARM_r9;
    gdb_regs[_R10]      = thread_regs->ARM_r10;
    gdb_regs[_FP]       = thread_regs->ARM_fp;
    gdb_regs[_IP]       = thread_regs->ARM_ip;
    gdb_regs[_SPT]      = thread_regs->ARM_sp;
    gdb_regs[_LR]       = thread_regs->ARM_lr;
    gdb_regs[_PC]       = thread_regs->ARM_pc;
    gdb_regs[_CPSR]     = thread_regs->ARM_cpsr;
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
    regs->ARM_pc = pc;
}

static int compiled_break;

int kgdb_arch_handle_exception(int exception_vector, int signo,
                   int err_code, char *remcom_in_buffer,
                   char *remcom_out_buffer,
                   struct pt_regs *linux_regs)
{
    unsigned long addr;
    char *ptr;

    switch (remcom_in_buffer[0]) {
    case 'D':
    case 'k':
    case 'c':
        /*
         * Try to read optional parameter, pc unchanged if no parm.
         * If this was a compiled breakpoint, we need to move
         * to the next instruction or we will just breakpoint
         * over and over again.
         */
        ptr = &remcom_in_buffer[1];
        if (kgdb_hex2long(&ptr, &addr))
            linux_regs->ARM_pc = addr;
        else if (compiled_break == 1)
            linux_regs->ARM_pc += 4;

        compiled_break = 0;

        return 0;
    }

    return -1;
}

static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
{
    kgdb_handle_exception(1, SIGTRAP, 0, regs);

    return 0;
}

static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
{
    compiled_break = 1;
    kgdb_handle_exception(1, SIGTRAP, 0, regs);

    return 0;
}

static struct undef_hook kgdb_brkpt_hook = {
    .instr_mask     = 0xffffffff,
    .instr_val      = KGDB_BREAKINST,
    .fn         = kgdb_brk_fn
};

static struct undef_hook kgdb_compiled_brkpt_hook = {
    .instr_mask     = 0xffffffff,
    .instr_val      = KGDB_COMPILED_BREAK,
    .fn         = kgdb_compiled_brk_fn
};

static void kgdb_call_nmi_hook(void *ignored)
{
       kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
}

void kgdb_roundup_cpus(unsigned long flags)
{
       local_irq_enable();
       smp_call_function(kgdb_call_nmi_hook, NULL, 0);
       local_irq_disable();
}

static int __kgdb_notify(struct die_args *args, unsigned long cmd)
{
    struct pt_regs *regs = args->regs;

    if (kgdb_handle_exception(1, args->signr, cmd, regs))
        return NOTIFY_DONE;
    return NOTIFY_STOP;
}
static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
{
    unsigned long flags;
    int ret;

    local_irq_save(flags);
    ret = __kgdb_notify(ptr, cmd);
    local_irq_restore(flags);

    return ret;
}

static struct notifier_block kgdb_notifier = {
    .notifier_call  = kgdb_notify,
    .priority   = -INT_MAX,
};


int kgdb_arch_init(void)
{
    int ret = register_die_notifier(&kgdb_notifier);

    if (ret != 0)
        return ret;

    register_undef_hook(&kgdb_brkpt_hook);
    register_undef_hook(&kgdb_compiled_brkpt_hook);

    return 0;
}

void kgdb_arch_exit(void)
{
    unregister_undef_hook(&kgdb_brkpt_hook);
    unregister_undef_hook(&kgdb_compiled_brkpt_hook);
    unregister_die_notifier(&kgdb_notifier);
}

/*
 * Register our undef instruction hooks with ARM undef core.
 * We regsiter a hook specifically looking for the KGB break inst
 * and we handle the normal undef case within the do_undefinstr
 * handler.
 */
struct kgdb_arch arch_kgdb_ops = {
#ifndef __ARMEB__
    .gdb_bpt_instr      = {0xfe, 0xde, 0xff, 0xe7}
#else /* ! __ARMEB__ */
    .gdb_bpt_instr      = {0xe7, 0xff, 0xde, 0xfe}
#endif
};