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ptrace.c

/*
 * File:         arch/blackfin/kernel/ptrace.c
 * Based on:     Taken from linux/kernel/ptrace.c
 * Author:       linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
 *
 * Created:      1/23/92
 * Description:
 *
 * Modified:
 *               Copyright 2004-2006 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

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

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/asm-offsets.h>
#include <asm/dma.h>
#include <asm/fixed_code.h>

#define MAX_SHARED_LIBS 3
#define TEXT_OFFSET 0
/*
 * does not yet catch signals sent when the child dies.
 * in exit.c or in signal.c.
 */

/* determines which bits in the SYSCFG reg the user has access to. */
/* 1 = access 0 = no access */
#define SYSCFG_MASK 0x0007    /* SYSCFG reg */
/* sets the trace bits. */
#define TRACE_BITS 0x0001

/* Find the stack offset for a register, relative to thread.esp0. */
#define PT_REG(reg)     ((long)&((struct pt_regs *)0)->reg)

/*
 * Get the address of the live pt_regs for the specified task.
 * These are saved onto the top kernel stack when the process
 * is not running.
 *
 * Note: if a user thread is execve'd from kernel space, the
 * kernel stack will not be empty on entry to the kernel, so
 * ptracing these tasks will fail.
 */
static inline struct pt_regs *get_user_regs(struct task_struct *task)
{
      return (struct pt_regs *)
          ((unsigned long)task_stack_page(task) +
           (THREAD_SIZE - sizeof(struct pt_regs)));
}

/*
 * Get all user integer registers.
 */
static inline int ptrace_getregs(struct task_struct *tsk, void __user * uregs)
{
      struct pt_regs *regs = get_user_regs(tsk);
      return copy_to_user(uregs, regs, sizeof(struct pt_regs)) ? -EFAULT : 0;
}

/* 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).
 */

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

      struct pt_regs *regs =
          (struct pt_regs *)((unsigned long)task_stack_page(task) +
                         (THREAD_SIZE - sizeof(struct pt_regs)));
      reg_ptr = (char *)regs;

      switch (regno) {
      case PT_USP:
            return task->thread.usp;
      default:
            if (regno <= 216)
                  return *(long *)(reg_ptr + regno);
      }
      /* slight mystery ... never seems to come here but kernel misbehaves without this code! */

      printk(KERN_WARNING "Request to get for unknown register %d\n", regno);
      return 0;
}

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

      struct pt_regs *regs =
          (struct pt_regs *)((unsigned long)task_stack_page(task) +
                         (THREAD_SIZE - sizeof(struct pt_regs)));
      reg_ptr = (char *)regs;

      switch (regno) {
      case PT_PC:
            /*********************************************************************/
            /* At this point the kernel is most likely in exception.             */
            /* The RETX register will be used to populate the pc of the process. */
            /*********************************************************************/
            regs->retx = data;
            regs->pc = data;
            break;
      case PT_RETX:
            break;            /* regs->retx = data; break; */
      case PT_USP:
            regs->usp = data;
            task->thread.usp = data;
            break;
      default:
            if (regno <= 216)
                  *(long *)(reg_ptr + regno) = data;
      }
      return 0;
}

/*
 * check that an address falls within the bounds of the target process's memory mappings
 */
static inline int is_user_addr_valid(struct task_struct *child,
                             unsigned long start, unsigned long len)
{
      struct vm_list_struct *vml;
      struct sram_list_struct *sraml;

      for (vml = child->mm->context.vmlist; vml; vml = vml->next)
            if (start >= vml->vma->vm_start && start + len <= vml->vma->vm_end)
                  return 0;

      for (sraml = child->mm->context.sram_list; sraml; sraml = sraml->next)
            if (start >= (unsigned long)sraml->addr
                && start + len <= (unsigned long)sraml->addr + sraml->length)
                  return 0;

      if (start >= FIXED_CODE_START && start + len <= FIXED_CODE_END)
            return 0;

      return -EIO;
}

/*
 * 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_SYSCFG) & ~TRACE_BITS;
      put_reg(child, PT_SYSCFG, tmp);
}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
      int ret;
      int add = 0;
      unsigned long __user *datap = (unsigned long __user *)data;

      switch (request) {
            /* when I and D space are separate, these will need to be fixed. */
      case PTRACE_PEEKDATA:
            pr_debug("ptrace: PEEKDATA\n");
            add = MAX_SHARED_LIBS * 4;    /* space between text and data */
            /* fall through */
      case PTRACE_PEEKTEXT:   /* read word at location addr. */
            {
                  unsigned long tmp = 0;
                  int copied;

                  ret = -EIO;
                  pr_debug("ptrace: PEEKTEXT at addr 0x%08lx + add %d %ld\n", addr, add,
                           sizeof(data));
                  if (is_user_addr_valid(child, addr + add, sizeof(tmp)) < 0)
                        break;
                  pr_debug("ptrace: user address is valid\n");

#if L1_CODE_LENGTH != 0
                  if (addr + add >= L1_CODE_START
                      && addr + add + sizeof(tmp) <= L1_CODE_START + L1_CODE_LENGTH) {
                        safe_dma_memcpy (&tmp, (const void *)(addr + add), sizeof(tmp));
                        copied = sizeof(tmp);
                  } else
#endif
#if L1_DATA_A_LENGTH != 0
                  if (addr + add >= L1_DATA_A_START
                      && addr + add + sizeof(tmp) <= L1_DATA_A_START + L1_DATA_A_LENGTH) {
                        memcpy(&tmp, (const void *)(addr + add), sizeof(tmp));
                        copied = sizeof(tmp);
                  } else
#endif
#if L1_DATA_B_LENGTH != 0
                  if (addr + add >= L1_DATA_B_START
                      && addr + add + sizeof(tmp) <= L1_DATA_B_START + L1_DATA_B_LENGTH) {
                        memcpy(&tmp, (const void *)(addr + add), sizeof(tmp));
                        copied = sizeof(tmp);
                  } else
#endif
                  if (addr + add >= FIXED_CODE_START
                      && addr + add + sizeof(tmp) <= FIXED_CODE_END) {
                        memcpy(&tmp, (const void *)(addr + add), sizeof(tmp));
                        copied = sizeof(tmp);
                  } else
                        copied = access_process_vm(child, addr + add, &tmp,
                                             sizeof(tmp), 0);
                  pr_debug("ptrace: copied size %d [0x%08lx]\n", copied, tmp);
                  if (copied != sizeof(tmp))
                        break;
                  ret = put_user(tmp, datap);
                  break;
            }

            /* read the word at location addr in the USER area. */
      case PTRACE_PEEKUSR:
            {
                  unsigned long tmp;
                  ret = -EIO;
                  tmp = 0;
                  if ((addr & 3) || (addr > (sizeof(struct pt_regs) + 16))) {
                        printk(KERN_WARNING "ptrace error : PEEKUSR : temporarily returning "
                                            "0 - %x sizeof(pt_regs) is %lx\n",
                             (int)addr, sizeof(struct pt_regs));
                        break;
                  }
                  if (addr == sizeof(struct pt_regs)) {
                        /* PT_TEXT_ADDR */
                        tmp = child->mm->start_code + TEXT_OFFSET;
                  } else if (addr == (sizeof(struct pt_regs) + 4)) {
                        /* PT_TEXT_END_ADDR */
                        tmp = child->mm->end_code;
                  } else if (addr == (sizeof(struct pt_regs) + 8)) {
                        /* PT_DATA_ADDR */
                        tmp = child->mm->start_data;
#ifdef CONFIG_BINFMT_ELF_FDPIC
                  } else if (addr == (sizeof(struct pt_regs) + 12)) {
                        tmp = child->mm->context.exec_fdpic_loadmap;
                  } else if (addr == (sizeof(struct pt_regs) + 16)) {
                        tmp = child->mm->context.interp_fdpic_loadmap;
#endif
                  } else {
                        tmp = get_reg(child, addr);
                  }
                  ret = put_user(tmp, datap);
                  break;
            }

            /* when I and D space are separate, this will have to be fixed. */
      case PTRACE_POKEDATA:
            printk(KERN_NOTICE "ptrace: PTRACE_PEEKDATA\n");
            /* fall through */
      case PTRACE_POKETEXT:   /* write the word at location addr. */
            {
                  int copied;

                  ret = -EIO;
                  pr_debug("ptrace: POKETEXT at addr 0x%08lx + add %d %ld bytes %lx\n",
                           addr, add, sizeof(data), data);
                  if (is_user_addr_valid(child, addr + add, sizeof(data)) < 0)
                        break;
                  pr_debug("ptrace: user address is valid\n");

#if L1_CODE_LENGTH != 0
                  if (addr + add >= L1_CODE_START
                      && addr + add + sizeof(data) <= L1_CODE_START + L1_CODE_LENGTH) {
                        safe_dma_memcpy ((void *)(addr + add), &data, sizeof(data));
                        copied = sizeof(data);
                  } else
#endif
#if L1_DATA_A_LENGTH != 0
                  if (addr + add >= L1_DATA_A_START
                      && addr + add + sizeof(data) <= L1_DATA_A_START + L1_DATA_A_LENGTH) {
                        memcpy((void *)(addr + add), &data, sizeof(data));
                        copied = sizeof(data);
                  } else
#endif
#if L1_DATA_B_LENGTH != 0
                  if (addr + add >= L1_DATA_B_START
                      && addr + add + sizeof(data) <= L1_DATA_B_START + L1_DATA_B_LENGTH) {
                        memcpy((void *)(addr + add), &data, sizeof(data));
                        copied = sizeof(data);
                  } else
#endif
                  if (addr + add >= FIXED_CODE_START
                      && addr + add + sizeof(data) <= FIXED_CODE_END) {
                        memcpy((void *)(addr + add), &data, sizeof(data));
                        copied = sizeof(data);
                  } else
                        copied = access_process_vm(child, addr + add, &data,
                                             sizeof(data), 1);
                  pr_debug("ptrace: copied size %d\n", copied);
                  if (copied != sizeof(data))
                        break;
                  ret = 0;
                  break;
            }

      case PTRACE_POKEUSR:    /* write the word at location addr in the USER area */
            ret = -EIO;
            if ((addr & 3) || (addr > (sizeof(struct pt_regs) + 16))) {
                  printk(KERN_WARNING "ptrace error : POKEUSR: temporarily returning 0\n");
                  break;
            }

            if (addr >= (sizeof(struct pt_regs))) {
                  ret = 0;
                  break;
            }
            if (addr == PT_SYSCFG) {
                  data &= SYSCFG_MASK;
                  data |= get_reg(child, PT_SYSCFG);
            }
            ret = put_reg(child, addr, data);
            break;

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

                  pr_debug("ptrace_cont\n");

                  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_SYSCFG) & ~(TRACE_BITS);
                  put_reg(child, PT_SYSCFG, tmp);
                  pr_debug("before wake_up_process\n");
                  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_SYSCFG) & ~(TRACE_BITS);
                  put_reg(child, PT_SYSCFG, tmp);
                  wake_up_process(child);
                  break;
            }

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

                  pr_debug("single step\n");
                  ret = -EIO;
                  if (!valid_signal(data))
                        break;
                  clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);

                  tmp = get_reg(child, PT_SYSCFG) | (TRACE_BITS);
                  put_reg(child, PT_SYSCFG, tmp);

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

      case PTRACE_GETREGS:
            {

                  /* Get all gp regs from the child. */
                  ret = ptrace_getregs(child, datap);
                  break;
            }

      case PTRACE_SETREGS:
            {
                  printk(KERN_NOTICE
                         "ptrace: SETREGS: **** NOT IMPLEMENTED ***\n");
                  /* Set all gp regs in the child. */
                  ret = 0;
                  break;
            }
      default:
            ret = ptrace_request(child, request, addr, data);
            break;
      }

      return ret;
}

asmlinkage void syscall_trace(void)
{

      if (!test_thread_flag(TIF_SYSCALL_TRACE))
            return;

      if (!(current->ptrace & PT_PTRACED))
            return;

      /* the 0x80 provides a way for the tracing parent to distinguish
       * between a syscall stop and SIGTRAP delivery
       */
      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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