ptrace.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

#ifdef CONFIG_S390_SUPPORT
					skip=8;
#endif
				}
				else
				{
					copymax=PT_PSWMASK+8;
				}
				if(writingtouser)
					mask=PSW_MASK_DEBUGCHANGE;
			}
			else if(useraddr<(PT_PSWADDR+8))
			{
				copymax=PT_PSWADDR+8;
				mask=PSW_ADDR_DEBUGCHANGE;
#ifdef CONFIG_S390_SUPPORT
				if(parent_31bit)
					skip=4;
#endif

			}
			else
			{
#ifdef CONFIG_S390_SUPPORT
				if(parent_31bit && useraddr <= PT_GPR15+4)
				{
					copymax=useraddr+4;
					if(useraddr<PT_GPR15+4)
						skip=4;
				}
				else
#endif
					copymax=PT_FPC;
			}
		}
		else if(useraddr<(PT_FPR15+sizeof(freg_t)))
		{
			copymax=(PT_FPR15+sizeof(freg_t));
			realuseraddr=(addr_t)&(((u8 *)&task->thread.fp_regs)[useraddr-PT_FPC]);
		}
		else if(useraddr<sizeof(struct user_regs_struct))
		{
#ifdef CONFIG_S390_SUPPORT
			if( parent_31bit && useraddr <= PT_IEEE_IP+4)
			{
				switch(useraddr)
				{
				case PT_CR_11+4:
				case U64OFFSETOF(per_info.ending_addr)+4:
				case U64OFFSETOF(per_info.lowcore.words.address)+4:
					copymax=useraddr+4;
					break;
				case  PT_SINGLE_STEP:
				case  U64OFFSETOF(per_info.lowcore.words.perc_atmid):
					/* We copy 2 bytes in excess for the atmid member this also gets around */
					/* alignment for this member in 32 bit */
					skip=8;
					copymax=useraddr+4;
					break;
				default: 
					copymax=useraddr+4;
					skip=4;
				}
			}
			else
#endif
			{
				copymax=sizeof(struct user_regs_struct);
			}
			realuseraddr=(addr_t)&(((u8 *)&task->thread.per_info)[useraddr-PT_CR_9]);
		}
		else 
		{
			copymax=sizeof(struct user);
			realuseraddr=(addr_t)NULL;
		}
		copylen=copymax-useraddr;
		copylen=(copylen>len ? len:copylen);
		if(ptrace_usercopy(realuseraddr,copyaddr,copylen,tofromuser,writingtouser,mask))
			return (-EIO);
		copyaddr+=copylen;
		len-=copylen;
		useraddr+=copylen
#if CONFIG_S390_SUPPORT
			+skip
#endif
			;
	}
	FixPerRegisters(task);
	return(0);
}

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

typedef struct
{
__u32	len;
__u32	kernel_addr;
__u32	process_addr;
} ptrace_area_emu31;


asmlinkage int sys_ptrace(long request, long pid, long addr, long data)
{
	struct task_struct *child;
	int ret = -EPERM;
	int copied;
#ifdef CONFIG_S390_SUPPORT
	int           parent_31bit;
	int           sizeof_parent_long;
	u8            *dataptr;
#else
#define sizeof_parent_long 8
#define dataptr (u8 *)&data
#endif
	lock_kernel();
	if (request == PTRACE_TRACEME) 
	{
		/* are we already being traced? */
		if (current->ptrace & PT_PTRACED)
			goto out;
		/* set the ptrace bit in the process flags. */
		current->ptrace |= PT_PTRACED;
		ret = 0;
		goto out;
	}
	ret = -ESRCH;
	read_lock(&tasklist_lock);
	child = find_task_by_pid(pid);
	if (child)
		get_task_struct(child);
	read_unlock(&tasklist_lock);
	if (!child)
		goto out;
	ret = -EPERM;
	if (pid == 1)		/* you may not mess with init */
		goto out_tsk;
	if (request == PTRACE_ATTACH) 
	{
		ret = ptrace_attach(child);
		goto out_tsk;
	}
	ret = -ESRCH;
	// printk("child=%lX child->flags=%lX",child,child->flags);
	/* I added child!=current line so we can get the */
	/* ieee_instruction_pointer from the user structure DJB */
	if(child!=current)
	{
		if (!(child->ptrace & PT_PTRACED))
			goto out_tsk;
		if (child->state != TASK_STOPPED) 
		{
			if (request != PTRACE_KILL)
				goto out_tsk;
		}
		if (child->p_pptr != current)
			goto out_tsk;
	}
#ifdef CONFIG_S390_SUPPORT
	parent_31bit=(current->thread.flags & S390_FLAG_31BIT);
	sizeof_parent_long=(parent_31bit ? 4:8);
	dataptr=&(((u8 *)&data)[parent_31bit ? 4:0]);
#endif
	switch (request) 
	{
		/* If I and D space are separate, these will need to be fixed. */
	case PTRACE_PEEKTEXT: /* read word at location addr. */ 
	case PTRACE_PEEKDATA: 
	{
		u8 tmp[8];
		copied = access_process_vm(child, addr, tmp, sizeof_parent_long, 0);
		ret = -EIO;
		if (copied != sizeof_parent_long)
			break;
		ret = copy_to_user((void *)data,tmp,sizeof_parent_long);
		ret = ret ? -EFAULT : 0;
		break;
	
	}
		/* read the word at location addr in the USER area. */
	case PTRACE_PEEKUSR:
		ret=copy_user(child,addr,data,sizeof_parent_long,1,0);
		break;

		/* If 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 = 0;
		if (access_process_vm(child, addr,dataptr, sizeof_parent_long, 1) == sizeof_parent_long)
			break;
		ret = -EIO;
		break;

	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
		ret=copy_user(child,addr,(addr_t)dataptr,sizeof_parent_long,0,1);
		break;

	case PTRACE_SYSCALL: 	/* continue and stop at next (return from) syscall */
	case PTRACE_CONT: 	 /* restart after signal. */
		ret = -EIO;
		if ((unsigned long) data >= _NSIG)
			break;
		if (request == PTRACE_SYSCALL)
			child->ptrace |= PT_TRACESYS;
		else
			child->ptrace &= ~PT_TRACESYS;
		child->exit_code = data;
		/* make sure the single step bit is not set. */
		clear_single_step(child);
		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->state == TASK_ZOMBIE) /* already dead */
			break;
		child->exit_code = SIGKILL;
		clear_single_step(child);
		wake_up_process(child);
		/* make sure the single step bit is not set. */
		break;

	case PTRACE_SINGLESTEP:  /* set the trap flag. */
		ret = -EIO;
		if ((unsigned long) data >= _NSIG)
			break;
		child->ptrace &= ~PT_TRACESYS;
		child->exit_code = data;
		set_single_step(child);
		/* give it a chance to run. */
		wake_up_process(child);
		ret = 0;
		break;

	case PTRACE_DETACH:  /* detach a process that was attached. */
		ret = ptrace_detach(child, data);
		break;

	case PTRACE_PEEKUSR_AREA:
	case PTRACE_POKEUSR_AREA:
		if(parent_31bit)
		{
			ptrace_area_emu31   parea; 
			if(copy_from_user(&parea,(void *)addr,sizeof(parea))==0)
				ret=copy_user(child,parea.kernel_addr,parea.process_addr,
					      parea.len,1,(request==PTRACE_POKEUSR_AREA));
			else ret = -EFAULT;
		}
		else
		{
			ptrace_area   parea; 
			if(copy_from_user(&parea,(void *)addr,sizeof(parea))==0)
				ret=copy_user(child,parea.kernel_addr,parea.process_addr,
					      parea.len,1,(request==PTRACE_POKEUSR_AREA));
			else ret = -EFAULT;
		}
		break;
	default:
		ret = -EIO;
		break;
	}
 out_tsk:
	free_task_struct(child);
 out:
	unlock_kernel();
	return ret;
}



asmlinkage void syscall_trace(void)
{
	lock_kernel();
	if ((current->ptrace & (PT_PTRACED|PT_TRACESYS))
	    != (PT_PTRACED|PT_TRACESYS))
		goto out;
	current->exit_code = SIGTRAP;
	set_current_state(TASK_STOPPED);
	notify_parent(current, SIGCHLD);
	schedule();
	/*
	 * 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;
	}
 out:
	unlock_kernel();
}