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ptrace.c

/*
 * linux/arch/sh/kernel/ptrace.c
 *
 * Original x86 implementation:
 *    By Ross Biro 1/23/92
 *    edited by Linus Torvalds
 *
 * SuperH version:   Copyright (C) 1999, 2000  Kaz Kojima & Niibe Yutaka
 *
 */
#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/slab.h>
#include <linux/security.h>
#include <linux/signal.h>
#include <linux/io.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu_context.h>

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

/*
 * This routine will get a word off of the process kernel stack.
 */
static inline int get_stack_long(struct task_struct *task, int offset)
{
      unsigned char *stack;

      stack = (unsigned char *)task_pt_regs(task);
      stack += offset;
      return (*((int *)stack));
}

/*
 * This routine will put a word on the process kernel stack.
 */
static inline int put_stack_long(struct task_struct *task, int offset,
                         unsigned long data)
{
      unsigned char *stack;

      stack = (unsigned char *)task_pt_regs(task);
      stack += offset;
      *(unsigned long *) stack = data;
      return 0;
}

static void ptrace_disable_singlestep(struct task_struct *child)
{
      clear_tsk_thread_flag(child, TIF_SINGLESTEP);

      /*
       * Ensure the UBC is not programmed at the next context switch.
       *
       * Normally this is not needed but there are sequences such as
       * singlestep, signal delivery, and continue that leave the
       * ubc_pc non-zero leading to spurious SIGTRAPs.
       */
      if (child->thread.ubc_pc != 0) {
            ubc_usercnt -= 1;
            child->thread.ubc_pc = 0;
      }
}

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
      ptrace_disable_singlestep(child);
}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
      struct user * dummy = NULL;
      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;

            if (addr < sizeof(struct pt_regs))
                  tmp = get_stack_long(child, addr);
            else if (addr >= (long) &dummy->fpu &&
                   addr < (long) &dummy->u_fpvalid) {
                  if (!tsk_used_math(child)) {
                        if (addr == (long)&dummy->fpu.fpscr)
                              tmp = FPSCR_INIT;
                        else
                              tmp = 0;
                  } else
                        tmp = ((long *)&child->thread.fpu)
                              [(addr - (long)&dummy->fpu) >> 2];
            } else if (addr == (long) &dummy->u_fpvalid)
                  tmp = !!tsk_used_math(child);
            else
                  tmp = 0;
            ret = put_user(tmp, (unsigned long __user *)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;

            if (addr < sizeof(struct pt_regs))
                  ret = put_stack_long(child, addr, data);
            else if (addr >= (long) &dummy->fpu &&
                   addr < (long) &dummy->u_fpvalid) {
                  set_stopped_child_used_math(child);
                  ((long *)&child->thread.fpu)
                        [(addr - (long)&dummy->fpu) >> 2] = data;
                  ret = 0;
            } else if (addr == (long) &dummy->u_fpvalid) {
                  conditional_stopped_child_used_math(data, child);
                  ret = 0;
            }
            break;

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

            ptrace_disable_singlestep(child);

            child->exit_code = data;
            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: {
            ret = 0;
            if (child->exit_state == EXIT_ZOMBIE)     /* already dead */
                  break;
            ptrace_disable_singlestep(child);
            child->exit_code = SIGKILL;
            wake_up_process(child);
            break;
      }

      case PTRACE_SINGLESTEP: {  /* set the trap flag. */
            long pc;
            struct pt_regs *regs = NULL;

            ret = -EIO;
            if (!valid_signal(data))
                  break;
            clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
            if ((child->ptrace & PT_DTRACE) == 0) {
                  /* Spurious delayed TF traps may occur */
                  child->ptrace |= PT_DTRACE;
            }

            pc = get_stack_long(child, (long)&regs->pc);

            /* Next scheduling will set up UBC */
            if (child->thread.ubc_pc == 0)
                  ubc_usercnt += 1;
            child->thread.ubc_pc = pc;

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

#ifdef CONFIG_SH_DSP
      case PTRACE_GETDSPREGS: {
            unsigned long dp;

            ret = -EIO;
            dp = ((unsigned long) child) + THREAD_SIZE -
                   sizeof(struct pt_dspregs);
            if (*((int *) (dp - 4)) == SR_FD) {
                  copy_to_user(addr, (void *) dp,
                        sizeof(struct pt_dspregs));
                  ret = 0;
            }
            break;
      }

      case PTRACE_SETDSPREGS: {
            unsigned long dp;

            ret = -EIO;
            dp = ((unsigned long) child) + THREAD_SIZE -
                   sizeof(struct pt_dspregs);
            if (*((int *) (dp - 4)) == SR_FD) {
                  copy_from_user((void *) dp, addr,
                        sizeof(struct pt_dspregs));
                  ret = 0;
            }
            break;
      }
#endif
      default:
            ret = ptrace_request(child, request, addr, data);
            break;
      }

      return ret;
}

asmlinkage void do_syscall_trace(void)
{
      struct task_struct *tsk = current;

      if (!test_thread_flag(TIF_SYSCALL_TRACE) &&
          !test_thread_flag(TIF_SINGLESTEP))
            return;
      if (!(tsk->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) &&
                         !test_thread_flag(TIF_SINGLESTEP) ? 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 (tsk->exit_code) {
            send_sig(tsk->exit_code, tsk, 1);
            tsk->exit_code = 0;
      }
}

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