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ptrace.c

/*
 *  linux/arch/m68k/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 0xC000
#define T1_BIT 0x8000
#define T0_BIT 0x4000

/* 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 const int regoff[] = {
      [0]   = PT_REG(d1),
      [1]   = PT_REG(d2),
      [2]   = PT_REG(d3),
      [3]   = PT_REG(d4),
      [4]   = PT_REG(d5),
      [5]   = SW_REG(d6),
      [6]   = SW_REG(d7),
      [7]   = PT_REG(a0),
      [8]   = PT_REG(a1),
      [9]   = PT_REG(a2),
      [10]  = SW_REG(a3),
      [11]  = SW_REG(a4),
      [12]  = SW_REG(a5),
      [13]  = SW_REG(a6),
      [14]  = PT_REG(d0),
      [15]  = -1,
      [16]  = PT_REG(orig_d0),
      [17]  = PT_REG(sr),
      [18]  = 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;
      /* Need to take stkadj into account. */
      if (regno == PT_SR || regno == PT_PC) {
            long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
            addr = (unsigned long *) ((unsigned long)addr + stkadj);
            /* The sr is actually a 16 bit register.  */
            if (regno == PT_SR)
                  return *(unsigned short *)addr;
      }
      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;
      /* Need to take stkadj into account. */
      if (regno == PT_SR || regno == PT_PC) {
            long stkadj = *(long *)(task->thread.esp0 + PT_REG(stkadj));
            addr = (unsigned long *) ((unsigned long)addr + stkadj);
            /* The sr is actually a 16 bit register.  */
            if (regno == PT_SR) {
                  *(unsigned short *)addr = data;
                  return 0;
            }
      }
      *addr = data;
      return 0;
}

/*
 * Make sure the single step bit is not set.
 */
static inline void singlestep_disable(struct task_struct *child)
{
      unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
      put_reg(child, PT_SR, tmp);
      clear_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

/*
 * Called by kernel/ptrace.c when detaching..
 */
void ptrace_disable(struct task_struct *child)
{
      singlestep_disable(child);
}

void user_enable_single_step(struct task_struct *child)
{
      unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
      put_reg(child, PT_SR, tmp | T1_BIT);
      set_tsk_thread_flag(child, TIF_DELAYED_TRACE);
}

void user_enable_block_step(struct task_struct *child)
{
      unsigned long tmp = get_reg(child, PT_SR) & ~TRACE_BITS;
      put_reg(child, PT_SR, tmp | T0_BIT);
}

void user_disable_single_step(struct task_struct *child)
{
      singlestep_disable(child);
}

long arch_ptrace(struct task_struct *child, long request,
             unsigned long addr, unsigned long data)
{
      unsigned long tmp;
      int i, ret = 0;
      int regno = addr >> 2; /* temporary hack. */
      unsigned long __user *datap = (unsigned long __user *) data;

      switch (request) {
      /* read the word at location addr in the USER area. */
      case PTRACE_PEEKUSR:
            if (addr & 3)
                  goto out_eio;

            if (regno >= 0 && regno < 19) {
                  tmp = get_reg(child, regno);
            } else if (regno >= 21 && regno < 49) {
                  tmp = child->thread.fp[regno - 21];
                  /* Convert internal fpu reg representation
                   * into long double format
                   */
                  if (FPU_IS_EMU && (regno < 45) && !(regno % 3))
                        tmp = ((tmp & 0xffff0000) << 15) |
                              ((tmp & 0x0000ffff) << 16);
            } else
                  goto out_eio;
            ret = put_user(tmp, datap);
            break;

      case PTRACE_POKEUSR:
      /* write the word at location addr in the USER area */
            if (addr & 3)
                  goto out_eio;

            if (regno == PT_SR) {
                  data &= SR_MASK;
                  data |= get_reg(child, PT_SR) & ~SR_MASK;
            }
            if (regno >= 0 && regno < 19) {
                  if (put_reg(child, regno, data))
                        goto out_eio;
            } else if (regno >= 21 && regno < 48) {
                  /* Convert long double format
                   * into internal fpu reg representation
                   */
                  if (FPU_IS_EMU && (regno < 45) && !(regno % 3)) {
                        data <<= 15;
                        data = (data & 0xffff0000) |
                               ((data & 0x0000ffff) >> 1);
                  }
                  child->thread.fp[regno - 21] = data;
            } else
                  goto out_eio;
            break;

      case PTRACE_GETREGS:    /* Get all gp regs from the child. */
            for (i = 0; i < 19; i++) {
                  tmp = get_reg(child, i);
                  ret = put_user(tmp, datap);
                  if (ret)
                        break;
                  datap++;
            }
            break;

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

      case PTRACE_GETFPREGS:  /* Get the child FPU state. */
            if (copy_to_user(datap, &child->thread.fp,
                         sizeof(struct user_m68kfp_struct)))
                  ret = -EFAULT;
            break;

      case PTRACE_SETFPREGS:  /* Set the child FPU state. */
            if (copy_from_user(&child->thread.fp, datap,
                           sizeof(struct user_m68kfp_struct)))
                  ret = -EFAULT;
            break;

      case PTRACE_GET_THREAD_AREA:
            ret = put_user(task_thread_info(child)->tp_value, datap);
            break;

      default:
            ret = ptrace_request(child, request, addr, data);
            break;
      }

      return ret;
out_eio:
      return -EIO;
}

asmlinkage void syscall_trace(void)
{
      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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