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ptrace_32.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
 * Audit support: Yuichi Nakamura <ynakam@hitachisoft.jp>
 */
#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 <linux/audit.h>
#include <linux/seccomp.h>
#include <linux/tracehook.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;
}

void user_enable_single_step(struct task_struct *child)
{
      struct pt_regs *regs = task_pt_regs(child);
      long pc;

      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);
}

void user_disable_single_step(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)
{
      user_disable_single_step(child);
}

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

      switch (request) {
      /* 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;
      }

      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;

#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((void *)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, (void *)addr,
                        sizeof(struct pt_dspregs));
                  ret = 0;
            }
            break;
      }
#endif
#ifdef CONFIG_BINFMT_ELF_FDPIC
      case PTRACE_GETFDPIC: {
            unsigned long tmp = 0;

            switch (addr) {
            case PTRACE_GETFDPIC_EXEC:
                  tmp = child->mm->context.exec_fdpic_loadmap;
                  break;
            case PTRACE_GETFDPIC_INTERP:
                  tmp = child->mm->context.interp_fdpic_loadmap;
                  break;
            default:
                  break;
            }

            ret = 0;
            if (put_user(tmp, (unsigned long *) data)) {
                  ret = -EFAULT;
                  break;
            }
            break;
      }
#endif
      default:
            ret = ptrace_request(child, request, addr, data);
            break;
      }

      return ret;
}

static inline int audit_arch(void)
{
      int arch = EM_SH;

#ifdef CONFIG_CPU_LITTLE_ENDIAN
      arch |= __AUDIT_ARCH_LE;
#endif

      return arch;
}

asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
      long ret = 0;

      secure_computing(regs->regs[0]);

      if (test_thread_flag(TIF_SYSCALL_TRACE) &&
          tracehook_report_syscall_entry(regs))
            /*
             * Tracing decided this syscall should not happen.
             * We'll return a bogus call number to get an ENOSYS
             * error, but leave the original number in regs->regs[0].
             */
            ret = -1L;

      if (unlikely(current->audit_context))
            audit_syscall_entry(audit_arch(), regs->regs[3],
                            regs->regs[4], regs->regs[5],
                            regs->regs[6], regs->regs[7]);

      return ret ?: regs->regs[0];
}

asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
{
      int step;

      if (unlikely(current->audit_context))
            audit_syscall_exit(AUDITSC_RESULT(regs->regs[0]),
                           regs->regs[0]);

      step = test_thread_flag(TIF_SINGLESTEP);
      if (step || test_thread_flag(TIF_SYSCALL_TRACE))
            tracehook_report_syscall_exit(regs, step);
}

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