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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>

00036 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 */
};

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 */
}

void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
      int reg;

#if (KGDB_GDB_REG_SIZE == 32)
      u32 *ptr = (u32 *)gdb_regs;
#else
      u64 *ptr = (u64 *)gdb_regs;
#endif

      for (reg = 0; 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;

      /* FP REGS */
      if (!(current && (regs->cp0_status & ST0_CU1)))
            return;

      save_fp(current);
      for (reg = 0; reg < 32; reg++)
            *(ptr++) = current->thread.fpu.fpr[reg];
}

void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
      int reg;

#if (KGDB_GDB_REG_SIZE == 32)
      const u32 *ptr = (u32 *)gdb_regs;
#else
      const u64 *ptr = (u64 *)gdb_regs;
#endif

      for (reg = 0; reg < 32; reg++)
            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 = *(ptr++);

      /* FP REGS from current */
      if (!(current && (regs->cp0_status & ST0_CU1)))
            return;

      for (reg = 0; reg < 32; reg++)
            current->thread.fpu.fpr[reg] = *(ptr++);
      restore_fp(current);
}

/*
 * 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;
}

/*
 * 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;

      /* Userpace 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), 0, 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;
}

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

/*
 * Handle the 's' and 'c' commands
 */
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;
      int cpu = smp_processor_id();

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

            atomic_set(&kgdb_cpu_doing_single_step, -1);
            if (remcom_in_buffer[0] == 's')
                  atomic_set(&kgdb_cpu_doing_single_step, cpu);

            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);
}

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