arch/mips/kernel/kgdb.c

root/arch/mips/kernel/kgdb.c
/*
 *  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 <andy@waldorf-gmbh.de>
 *
 *  Copyright (C) 1995 Andreas Busse
 *
 *  Copyright (C) 2003 MontaVista Software Inc.
 *  Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
 *
 *  Copyright (C) 2004-2005 MontaVista Software Inc.
 *  Author: Manish Lachwani, mlachwani@mvista.com or manish@koffee-break.com
 *
 *  Copyright (C) 2007-2008 Wind River Systems, Inc.
 *  Author/Maintainer: Jason Wessel, jason.wessel@windriver.com
 *
 *  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>
#include <asm/irq_regs.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 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;
#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++) = 0;

        /* S0 - S7 */
        *(ptr++) = p->thread.reg16;
        *(ptr++) = p->thread.reg17;
        *(ptr++) = p->thread.reg18;
        *(ptr++) = p->thread.reg19;
        *(ptr++) = p->thread.reg20;
        *(ptr++) = p->thread.reg21;
        *(ptr++) = p->thread.reg22;
        *(ptr++) = p->thread.reg23;

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

        /* GP, SP, FP, RA */
        *(ptr++) = (long)p;
        *(ptr++) = p->thread.reg29;
        *(ptr++) = p->thread.reg30;
        *(ptr++) = p->thread.reg31;

        *(ptr++) = p->thread.cp0_status;

        /* lo, hi */
        *(ptr++) = 0;
        *(ptr++) = 0;

        /*
         * BadVAddr, Cause
         * Ideally these would come from the last exception frame up the stack
         * but that requires unwinding, otherwise we can't know much for sure.
         */
        *(ptr++) = 0;
        *(ptr++) = 0;

        /*
         * PC
         * use return address (RA), i.e. the moment after return from resume()
         */
        *(ptr++) = p->thread.reg31;
}

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;
}

const struct kgdb_arch arch_kgdb_ops = {
#ifdef CONFIG_CPU_BIG_ENDIAN
        .gdb_bpt_instr = { spec_op << 2, 0x00, 0x00, break_op },
#else
        .gdb_bpt_instr = { break_op, 0x00, 0x00, spec_op << 2 },
#endif
};

int kgdb_arch_init(void)
{
        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);
}