text: /*
   * Copyright 2003 PathScale, Inc.
   * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   *
   * Licensed under the GPL
   */
  
  #define __FRAME_OFFSETS
  #include <asm/ptrace.h>
  #include <linux/sched.h>
  #include <linux/errno.h>
  #include <linux/mm.h>
  #include <asm/uaccess.h>
  #include <asm/elf.h>
  
  /*
   * determines which flags the user has access to.
   * 1 = access 0 = no access
   */
  #define FLAG_MASK 0x44dd5UL
  
  int putreg(struct task_struct *child, int regno, unsigned long value)
  {
  	unsigned long tmp;
  
  #ifdef TIF_IA32
  	/* Some code in the 64bit emulation may not be 64bit clean.
  	   Don't take any chances. */
  	if (test_tsk_thread_flag(child, TIF_IA32))
  		value &= 0xffffffff;
  #endif
  	switch (regno){
  	case FS:
  	case GS:
  	case DS:
  	case ES:
  	case SS:
  	case CS:
  		if (value && (value & 3) != 3)
  			return -EIO;
  		value &= 0xffff;
  		break;
  
  	case FS_BASE:
  	case GS_BASE:
  		if (!((value >> 48) == 0 || (value >> 48) == 0xffff))
  			return -EIO;
  		break;
  
  	case EFLAGS:
  		value &= FLAG_MASK;
  		tmp = PT_REGS_EFLAGS(&child->thread.regs) & ~FLAG_MASK;
  		value |= tmp;
  		break;
  	}
  
  	PT_REGS_SET(&child->thread.regs, regno, value);
  	return 0;
  }
  
  int poke_user(struct task_struct *child, long addr, long data)
  {
  	if ((addr & 3) || addr < 0)
  		return -EIO;
  
  	if (addr < MAX_REG_OFFSET)
  		return putreg(child, addr, data);
  	else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
  		(addr <= offsetof(struct user, u_debugreg[7]))){
  		addr -= offsetof(struct user, u_debugreg[0]);
  		addr = addr >> 2;
  		if ((addr == 4) || (addr == 5))
  			return -EIO;
  		child->thread.arch.debugregs[addr] = data;
  		return 0;
  	}
  	return -EIO;
  }
  
  unsigned long getreg(struct task_struct *child, int regno)
  {
  	unsigned long retval = ~0UL;
  	switch (regno) {
  	case FS:
  	case GS:
  	case DS:
  	case ES:
  	case SS:
  	case CS:
  		retval = 0xffff;
  		/* fall through */
  	default:
  		retval &= PT_REG(&child->thread.regs, regno);
  #ifdef TIF_IA32
  		if (test_tsk_thread_flag(child, TIF_IA32))
  			retval &= 0xffffffff;
  #endif
  	}
  	return retval;
  }
  
  int peek_user(struct task_struct *child, long addr, long data)
  {
  	/* read the word at location addr in the USER area. */
  	unsigned long tmp;
  
  	if ((addr & 3) || addr < 0)
  		return -EIO;
  
  	tmp = 0;  /* Default return condition */
  	if (addr < MAX_REG_OFFSET){
  		tmp = getreg(child, addr);
  	}
  	else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
  		(addr <= offsetof(struct user, u_debugreg[7]))){
  		addr -= offsetof(struct user, u_debugreg[0]);
  		addr = addr >> 2;
  		tmp = child->thread.arch.debugregs[addr];
  	}
  	return put_user(tmp, (unsigned long *) data);
  }
  
  /* XXX Mostly copied from sys-i386 */
  int is_syscall(unsigned long addr)
  {
  	unsigned short instr;
  	int n;
  
  	n = copy_from_user(&instr, (void __user *) addr, sizeof(instr));
  	if (n){
  		/* access_process_vm() grants access to vsyscall and stub,
  		 * while copy_from_user doesn't. Maybe access_process_vm is
  		 * slow, but that doesn't matter, since it will be called only
  		 * in case of singlestepping, if copy_from_user failed.
  		 */
  		n = access_process_vm(current, addr, &instr, sizeof(instr), 0);
  		if (n != sizeof(instr)) {
  			printk("is_syscall : failed to read instruction from "
  			       "0x%lx\n", addr);
  			return 1;
  		}
  	}
  	/* sysenter */
  	return instr == 0x050f;
  }
  
  int get_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
  {
  	int err, n, cpu = ((struct thread_info *) child->stack)->cpu;
  	long fpregs[HOST_FP_SIZE];
  
  	BUG_ON(sizeof(*buf) != sizeof(fpregs));
  	err = save_fp_registers(userspace_pid[cpu], fpregs);
  	if (err)
  		return err;
  
  	n = copy_to_user(buf, fpregs, sizeof(fpregs));
  	if(n > 0)
  		return -EFAULT;
  
  	return n;
  }
  
  int set_fpregs(struct user_i387_struct __user *buf, struct task_struct *child)
  {
  	int n, cpu = ((struct thread_info *) child->stack)->cpu;
  	long fpregs[HOST_FP_SIZE];
  
  	BUG_ON(sizeof(*buf) != sizeof(fpregs));
  	n = copy_from_user(fpregs, buf, sizeof(fpregs));
  	if (n > 0)
  		return -EFAULT;
  
  	return restore_fp_registers(userspace_pid[cpu], fpregs);
  }
  
  long subarch_ptrace(struct task_struct *child, long request, long addr,
  		    long data)
  {
  	int ret = -EIO;
  
  	switch (request) {
  	case PTRACE_GETFPXREGS: /* Get the child FPU state. */
  		ret = get_fpregs((struct user_i387_struct __user *) data,
  				 child);
  		break;
  	case PTRACE_SETFPXREGS: /* Set the child FPU state. */
  		ret = set_fpregs((struct user_i387_struct __user *) data,
  				 child);
  		break;
  	}
  
  	return ret;
  }
  