kgdb.c

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/*
 *  Originally written by Glenn Engel, Lake Stevens Instrument Division
 *
 *  Contributed by HP Systems
 *
 *  Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
 *  Send complaints, suggestions etc. to <[email protected]>
 *
 *  Copyright (C) 1995 Andreas Busse
 *
 *  Copyright (C) 2003 MontaVista Software Inc.
 *  Author: Jun Sun, [email protected] or [email protected]
 *
 *  Copyright (C) 2004-2005 MontaVista Software Inc.
 *  Author: Manish Lachwani, [email protected] or [email protected]
 *
 *  Copyright (C) 2007-2008 Wind River Systems, Inc.
 *  Author/Maintainer: Jason Wessel, [email protected]
 *
 *  This file is licensed under the terms of the GNU General Public License
 *  version 2. This program is licensed "as is" without any warranty of any
 *  kind, whether express or implied.
 */

#include <linux/ptrace.h>       /* for linux pt_regs struct */
#include <linux/kgdb.h>
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <asm/inst.h>
#include <asm/fpu.h>
#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/sigcontext.h>

static struct hard_trap_info {
    unsigned char tt;   /* Trap type code for MIPS R3xxx and R4xxx */
    unsigned char signo;    /* Signal that we map this trap into */
} hard_trap_info[] = {
    { 6, SIGBUS },      /* instruction bus error */
    { 7, SIGBUS },      /* data bus error */
    { 9, SIGTRAP },     /* break */
/*  { 11, SIGILL }, */  /* CPU unusable */
    { 12, SIGFPE },     /* overflow */
    { 13, SIGTRAP },    /* trap */
    { 14, SIGSEGV },    /* virtual instruction cache coherency */
    { 15, SIGFPE },     /* floating point exception */
    { 23, SIGSEGV },    /* watch */
    { 31, SIGSEGV },    /* virtual data cache coherency */
    { 0, 0}         /* Must be last */
};

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
    { "zero", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
    { "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
    { "v0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
    { "v1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
    { "a0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
    { "a1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
    { "a2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
    { "a3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
    { "t0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
    { "t1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
    { "t2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
    { "t3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
    { "t4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
    { "t5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
    { "t6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
    { "t7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
    { "s0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16]) },
    { "s1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17]) },
    { "s2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18]) },
    { "s3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19]) },
    { "s4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20]) },
    { "s5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21]) },
    { "s6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22]) },
    { "s7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23]) },
    { "t8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24]) },
    { "t9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25]) },
    { "k0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26]) },
    { "k1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27]) },
    { "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28]) },
    { "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29]) },
    { "s8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30]) },
    { "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31]) },
    { "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_status) },
    { "lo", GDB_SIZEOF_REG, offsetof(struct pt_regs, lo) },
    { "hi", GDB_SIZEOF_REG, offsetof(struct pt_regs, hi) },
    { "bad", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_badvaddr) },
    { "cause", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_cause) },
    { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_epc) },
    { "f0", GDB_SIZEOF_REG, 0 },
    { "f1", GDB_SIZEOF_REG, 1 },
    { "f2", GDB_SIZEOF_REG, 2 },
    { "f3", GDB_SIZEOF_REG, 3 },
    { "f4", GDB_SIZEOF_REG, 4 },
    { "f5", GDB_SIZEOF_REG, 5 },
    { "f6", GDB_SIZEOF_REG, 6 },
    { "f7", GDB_SIZEOF_REG, 7 },
    { "f8", GDB_SIZEOF_REG, 8 },
    { "f9", GDB_SIZEOF_REG, 9 },
    { "f10", GDB_SIZEOF_REG, 10 },
    { "f11", GDB_SIZEOF_REG, 11 },
    { "f12", GDB_SIZEOF_REG, 12 },
    { "f13", GDB_SIZEOF_REG, 13 },
    { "f14", GDB_SIZEOF_REG, 14 },
    { "f15", GDB_SIZEOF_REG, 15 },
    { "f16", GDB_SIZEOF_REG, 16 },
    { "f17", GDB_SIZEOF_REG, 17 },
    { "f18", GDB_SIZEOF_REG, 18 },
    { "f19", GDB_SIZEOF_REG, 19 },
    { "f20", GDB_SIZEOF_REG, 20 },
    { "f21", GDB_SIZEOF_REG, 21 },
    { "f22", GDB_SIZEOF_REG, 22 },
    { "f23", GDB_SIZEOF_REG, 23 },
    { "f24", GDB_SIZEOF_REG, 24 },
    { "f25", GDB_SIZEOF_REG, 25 },
    { "f26", GDB_SIZEOF_REG, 26 },
    { "f27", GDB_SIZEOF_REG, 27 },
    { "f28", GDB_SIZEOF_REG, 28 },
    { "f29", GDB_SIZEOF_REG, 29 },
    { "f30", GDB_SIZEOF_REG, 30 },
    { "f31", GDB_SIZEOF_REG, 31 },
    { "fsr", GDB_SIZEOF_REG, 0 },
    { "fir", GDB_SIZEOF_REG, 0 },
};

int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
    int fp_reg;

    if (regno < 0 || regno >= DBG_MAX_REG_NUM)
        return -EINVAL;

    if (dbg_reg_def[regno].offset != -1 && regno < 38) {
        memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
               dbg_reg_def[regno].size);
    } else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
        /* FP registers 38 -> 69 */
        if (!(regs->cp0_status & ST0_CU1))
            return 0;
        if (regno == 70) {
            /* Process the fcr31/fsr (register 70) */
            memcpy((void *)&current->thread.fpu.fcr31, mem,
                   dbg_reg_def[regno].size);
            goto out_save;
        } else if (regno == 71) {
            /* Ignore the fir (register 71) */
            goto out_save;
        }
        fp_reg = dbg_reg_def[regno].offset;
        memcpy((void *)&current->thread.fpu.fpr[fp_reg], mem,
               dbg_reg_def[regno].size);
out_save:
        restore_fp(current);
    }

    return 0;
}

char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
    int fp_reg;

    if (regno >= DBG_MAX_REG_NUM || regno < 0)
        return NULL;

    if (dbg_reg_def[regno].offset != -1 && regno < 38) {
        /* First 38 registers */
        memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
               dbg_reg_def[regno].size);
    } else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
        /* FP registers 38 -> 69 */
        if (!(regs->cp0_status & ST0_CU1))
            goto out;
        save_fp(current);
        if (regno == 70) {
            /* Process the fcr31/fsr (register 70) */
            memcpy(mem, (void *)&current->thread.fpu.fcr31,
                   dbg_reg_def[regno].size);
            goto out;
        } else if (regno == 71) {
            /* Ignore the fir (register 71) */
            memset(mem, 0, dbg_reg_def[regno].size);
            goto out;
        }
        fp_reg = dbg_reg_def[regno].offset;
        memcpy(mem, (void *)&current->thread.fpu.fpr[fp_reg],
               dbg_reg_def[regno].size);
    }

out:
    return dbg_reg_def[regno].name;

}

void arch_kgdb_breakpoint(void)
{
    __asm__ __volatile__(
        ".globl breakinst\n\t"
        ".set\tnoreorder\n\t"
        "nop\n"
        "breakinst:\tbreak\n\t"
        "nop\n\t"
        ".set\treorder");
}

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

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

static int compute_signal(int tt)
{
    struct hard_trap_info *ht;

    for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
        if (ht->tt == tt)
            return ht->signo;

    return SIGHUP;      /* default for things we don't know about */
}

/*
 * Similar to regs_to_gdb_regs() except that process is sleeping and so
 * we may not be able to get all the info.
 */
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
    int reg;
    struct thread_info *ti = task_thread_info(p);
    unsigned long ksp = (unsigned long)ti + THREAD_SIZE - 32;
    struct pt_regs *regs = (struct pt_regs *)ksp - 1;
#if (KGDB_GDB_REG_SIZE == 32)
    u32 *ptr = (u32 *)gdb_regs;
#else
    u64 *ptr = (u64 *)gdb_regs;
#endif

    for (reg = 0; reg < 16; reg++)
        *(ptr++) = regs->regs[reg];

    /* S0 - S7 */
    for (reg = 16; reg < 24; reg++)
        *(ptr++) = regs->regs[reg];

    for (reg = 24; reg < 28; reg++)
        *(ptr++) = 0;

    /* GP, SP, FP, RA */
    for (reg = 28; reg < 32; reg++)
        *(ptr++) = regs->regs[reg];

    *(ptr++) = regs->cp0_status;
    *(ptr++) = regs->lo;
    *(ptr++) = regs->hi;
    *(ptr++) = regs->cp0_badvaddr;
    *(ptr++) = regs->cp0_cause;
    *(ptr++) = regs->cp0_epc;
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
    regs->cp0_epc = pc;
}

/*
 * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
 * then try to fall into the debugger
 */
static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
                void *ptr)
{
    struct die_args *args = (struct die_args *)ptr;
    struct pt_regs *regs = args->regs;
    int trap = (regs->cp0_cause & 0x7c) >> 2;

#ifdef CONFIG_KPROBES
    /*
     * Return immediately if the kprobes fault notifier has set
     * DIE_PAGE_FAULT.
     */
    if (cmd == DIE_PAGE_FAULT)
        return NOTIFY_DONE;
#endif /* CONFIG_KPROBES */

    /* Userspace events, ignore. */
    if (user_mode(regs))
        return NOTIFY_DONE;

    if (atomic_read(&kgdb_active) != -1)
        kgdb_nmicallback(smp_processor_id(), regs);

    if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs))
        return NOTIFY_DONE;

    if (atomic_read(&kgdb_setting_breakpoint))
        if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
            regs->cp0_epc += 4;

    /* In SMP mode, __flush_cache_all does IPI */
    local_irq_enable();
    __flush_cache_all();

    return NOTIFY_STOP;
}

#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
int kgdb_ll_trap(int cmd, const char *str,
         struct pt_regs *regs, long err, int trap, int sig)
{
    struct die_args args = {
        .regs   = regs,
        .str    = str,
        .err    = err,
        .trapnr = trap,
        .signr  = sig,

    };

    if (!kgdb_io_module_registered)
        return NOTIFY_DONE;

    return kgdb_mips_notify(NULL, cmd, &args);
}
#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */

static struct notifier_block kgdb_notifier = {
    .notifier_call = kgdb_mips_notify,
};

/*
 * Handle the 'c' command
 */
int kgdb_arch_handle_exception(int vector, int signo, int err_code,
                   char *remcom_in_buffer, char *remcom_out_buffer,
                   struct pt_regs *regs)
{
    char *ptr;
    unsigned long address;

    switch (remcom_in_buffer[0]) {
    case 'c':
        /* handle the optional parameter */
        ptr = &remcom_in_buffer[1];
        if (kgdb_hex2long(&ptr, &address))
            regs->cp0_epc = address;

        return 0;
    }

    return -1;
}

struct kgdb_arch arch_kgdb_ops;

/*
 * We use kgdb_early_setup so that functions we need to call now don't
 * cause trouble when called again later.
 */
int kgdb_arch_init(void)
{
    union mips_instruction insn = {
        .r_format = {
            .opcode = spec_op,
            .func   = break_op,
        }
    };
    memcpy(arch_kgdb_ops.gdb_bpt_instr, insn.byte, BREAK_INSTR_SIZE);

    register_die_notifier(&kgdb_notifier);

    return 0;
}

/*
 *  kgdb_arch_exit - Perform any architecture specific uninitalization.
 *
 *  This function will handle the uninitalization of any architecture
 *  specific callbacks, for dynamic registration and unregistration.
 */
void kgdb_arch_exit(void)
{
    unregister_die_notifier(&kgdb_notifier);
}