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ptrace.c

/*
 *  linux/arch/m68knommu/kernel/ptrace.c
 *
 *  Copyright (C) 1994 by Hamish Macdonald
 *  Taken from linux/kernel/ptrace.c and modified for M680x0.
 *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of
 * this archive for more details.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/signal.h>

#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>

/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/* determines which bits in the SR the user has access to. */
/* 1 = access 0 = no access */
#define SR_MASK 0x001f

/* sets the trace bits. */
#define TRACE_BITS 0x8000

/* Find the stack offset for a register, relative to thread.esp0. */
#define PT_REG(reg)     ((long)&((struct pt_regs *)0)->reg)
#define SW_REG(reg)     ((long)&((struct switch_stack *)0)->reg \
                   - sizeof(struct switch_stack))
/* Mapping from PT_xxx to the stack offset at which the register is
   saved.  Notice that usp has no stack-slot and needs to be treated
   specially (see get_reg/put_reg below). */
static int regoff[] = {
      PT_REG(d1), PT_REG(d2), PT_REG(d3), PT_REG(d4),
      PT_REG(d5), SW_REG(d6), SW_REG(d7), PT_REG(a0),
      PT_REG(a1), PT_REG(a2), SW_REG(a3), SW_REG(a4),
      SW_REG(a5), SW_REG(a6), PT_REG(d0), -1,
      PT_REG(orig_d0), PT_REG(sr), PT_REG(pc),
};

/*
 * Get contents of register REGNO in task TASK.
 */
static inline long get_reg(struct task_struct *task, int regno)
{
      unsigned long *addr;

      if (regno == PT_USP)
            addr = &task->thread.usp;
      else if (regno < ARRAY_SIZE(regoff))
            addr = (unsigned long *)(task->thread.esp0 + regoff[regno]);
      else
            return 0;
      return *addr;
}

/*
 * Write contents of register REGNO in task TASK.
 */
static inline int put_reg(struct task_struct *task, int regno,
                    unsigned long data)
{
      unsigned long *addr;

      if (regno == PT_USP)
            addr = &task->thread.usp;
      else if (regno < ARRAY_SIZE(regoff))
            addr = (unsigned long *) (task->thread.esp0 + regoff[regno]);
      else
            return -1;
      *addr = data;
      return 0;
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure the single step bit is not set.
 */
void ptrace_disable(struct task_struct *child)
{
      unsigned long tmp;
      /* make sure the single step bit is not set. */
      tmp = get_reg(child, PT_SR) & ~(TRACE_BITS << 16);
      put_reg(child, PT_SR, tmp);
}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
      int ret;

      switch (request) {
            /* when I and D space are separate, these will need to be fixed. */
            case PTRACE_PEEKTEXT: /* read word at location addr. */ 
            case PTRACE_PEEKDATA:
                  ret = generic_ptrace_peekdata(child, addr, data);
                  break;

            /* read the word at location addr in the USER area. */
            case PTRACE_PEEKUSR: {
                  unsigned long tmp;
                  
                  ret = -EIO;
                  if ((addr & 3) || addr < 0 ||
                      addr > sizeof(struct user) - 3)
                        break;
                  
                  tmp = 0;  /* Default return condition */
                  addr = addr >> 2; /* temporary hack. */
                  ret = -EIO;
                  if (addr < 19) {
                        tmp = get_reg(child, addr);
                        if (addr == PT_SR)
                              tmp >>= 16;
                  } else if (addr >= 21 && addr < 49) {
                        tmp = child->thread.fp[addr - 21];
#ifdef CONFIG_M68KFPU_EMU
                        /* Convert internal fpu reg representation
                         * into long double format
                         */
                        if (FPU_IS_EMU && (addr < 45) && !(addr % 3))
                              tmp = ((tmp & 0xffff0000) << 15) |
                                    ((tmp & 0x0000ffff) << 16);
#endif
                  } else if (addr == 49) {
                        tmp = child->mm->start_code;
                  } else if (addr == 50) {
                        tmp = child->mm->start_data;
                  } else if (addr == 51) {
                        tmp = child->mm->end_code;
                  } else
                        break;
                  ret = put_user(tmp,(unsigned long *) data);
                  break;
            }

            /* when I and D space are separate, this will have to be fixed. */
            case PTRACE_POKETEXT: /* write the word at location addr. */
            case PTRACE_POKEDATA:
                  ret = generic_ptrace_pokedata(child, addr, data);
                  break;

            case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
                  ret = -EIO;
                  if ((addr & 3) || addr < 0 ||
                      addr > sizeof(struct user) - 3)
                        break;

                  addr = addr >> 2; /* temporary hack. */
                      
                  if (addr == PT_SR) {
                        data &= SR_MASK;
                        data <<= 16;
                        data |= get_reg(child, PT_SR) & ~(SR_MASK << 16);
                  }
                  if (addr < 19) {
                        if (put_reg(child, addr, data))
                              break;
                        ret = 0;
                        break;
                  }
                  if (addr >= 21 && addr < 48)
                  {
#ifdef CONFIG_M68KFPU_EMU
                        /* Convert long double format
                         * into internal fpu reg representation
                         */
                        if (FPU_IS_EMU && (addr < 45) && !(addr % 3)) {
                              data = (unsigned long)data << 15;
                              data = (data & 0xffff0000) |
                                     ((data & 0x0000ffff) >> 1);
                        }
#endif
                        child->thread.fp[addr - 21] = data;
                        ret = 0;
                  }
                  break;

            case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
            case PTRACE_CONT: { /* restart after signal. */
                  long tmp;

                  ret = -EIO;
                  if (!valid_signal(data))
                        break;
                  if (request == PTRACE_SYSCALL)
                        set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                  else
                        clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                  child->exit_code = data;
                  /* make sure the single step bit is not set. */
                  tmp = get_reg(child, PT_SR) & ~(TRACE_BITS << 16);
                  put_reg(child, PT_SR, tmp);
                  wake_up_process(child);
                  ret = 0;
                  break;
            }

            /*
             * make the child exit.  Best I can do is send it a sigkill. 
             * perhaps it should be put in the status that it wants to 
             * exit.
             */
            case PTRACE_KILL: {
                  long tmp;

                  ret = 0;
                  if (child->exit_state == EXIT_ZOMBIE) /* already dead */
                        break;
                  child->exit_code = SIGKILL;
                  /* make sure the single step bit is not set. */
                  tmp = get_reg(child, PT_SR) & ~(TRACE_BITS << 16);
                  put_reg(child, PT_SR, tmp);
                  wake_up_process(child);
                  break;
            }

            case PTRACE_SINGLESTEP: {  /* set the trap flag. */
                  long tmp;

                  ret = -EIO;
                  if (!valid_signal(data))
                        break;
                  clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
                  tmp = get_reg(child, PT_SR) | (TRACE_BITS << 16);
                  put_reg(child, PT_SR, tmp);

                  child->exit_code = data;
                  /* give it a chance to run. */
                  wake_up_process(child);
                  ret = 0;
                  break;
            }

            case PTRACE_DETACH:     /* detach a process that was attached. */
                  ret = ptrace_detach(child, data);
                  break;

            case PTRACE_GETREGS: { /* Get all gp regs from the child. */
                  int i;
                  unsigned long tmp;
                  for (i = 0; i < 19; i++) {
                      tmp = get_reg(child, i);
                      if (i == PT_SR)
                        tmp >>= 16;
                      if (put_user(tmp, (unsigned long *) data)) {
                        ret = -EFAULT;
                        break;
                      }
                      data += sizeof(long);
                  }
                  ret = 0;
                  break;
            }

            case PTRACE_SETREGS: { /* Set all gp regs in the child. */
                  int i;
                  unsigned long tmp;
                  for (i = 0; i < 19; i++) {
                      if (get_user(tmp, (unsigned long *) data)) {
                        ret = -EFAULT;
                        break;
                      }
                      if (i == PT_SR) {
                        tmp &= SR_MASK;
                        tmp <<= 16;
                        tmp |= get_reg(child, PT_SR) & ~(SR_MASK << 16);
                      }
                      put_reg(child, i, tmp);
                      data += sizeof(long);
                  }
                  ret = 0;
                  break;
            }

#ifdef PTRACE_GETFPREGS
            case PTRACE_GETFPREGS: { /* Get the child FPU state. */
                  ret = 0;
                  if (copy_to_user((void *)data, &child->thread.fp,
                               sizeof(struct user_m68kfp_struct)))
                        ret = -EFAULT;
                  break;
            }
#endif

#ifdef PTRACE_SETFPREGS
            case PTRACE_SETFPREGS: { /* Set the child FPU state. */
                  ret = 0;
                  if (copy_from_user(&child->thread.fp, (void *)data,
                                 sizeof(struct user_m68kfp_struct)))
                        ret = -EFAULT;
                  break;
            }
#endif

            default:
                  ret = -EIO;
                  break;
      }
      return ret;
}

asmlinkage void syscall_trace(void)
{
      if (!test_thread_flag(TIF_SYSCALL_TRACE))
            return;
      if (!(current->ptrace & PT_PTRACED))
            return;
      ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
                         ? 0x80 : 0));
      /*
       * this isn't the same as continuing with a signal, but it will do
       * for normal use.  strace only continues with a signal if the
       * stopping signal is not SIGTRAP.  -brl
       */
      if (current->exit_code) {
            send_sig(current->exit_code, current, 1);
            current->exit_code = 0;
      }
}

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