ptrace.c

讲述linux的初始化过程

				goto out;
			}
		pt_succ_return(regs, 0);
#ifdef DEBUG_PTRACE
		printk ("PC=%lx nPC=%lx o7=%lx\n", cregs->tpc, cregs->tnpc, cregs->u_regs [15]);
#endif
		goto out;
	}

	case PTRACE_SETREGS: {
		struct pt_regs32 *pregs = (struct pt_regs32 *) addr;
		struct pt_regs *cregs = child->thread.kregs;
		unsigned int psr, pc, npc, y;
		int i;

		/* Must be careful, tracing process can only set certain
		 * bits in the psr.
		 */
		if (__get_user(psr, (&pregs->psr)) ||
		    __get_user(pc, (&pregs->pc)) ||
		    __get_user(npc, (&pregs->npc)) ||
		    __get_user(y, (&pregs->y))) {
			pt_error_return(regs, EFAULT);
			goto out;
		}
		cregs->tstate &= ~(TSTATE_ICC);
		cregs->tstate |= psr_to_tstate_icc(psr);
               	if(!((pc | npc) & 3)) {
			cregs->tpc = pc;
			cregs->tnpc = npc;
		}
		cregs->y = y;
		for(i = 1; i < 16; i++) {
			if (__get_user(cregs->u_regs[i], (&pregs->u_regs[i-1]))) {
				pt_error_return(regs, EFAULT);
				goto out;
			}
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SETREGS64: {
		struct pt_regs *pregs = (struct pt_regs *) addr;
		struct pt_regs *cregs = child->thread.kregs;
		unsigned long tstate, tpc, tnpc, y;
		int i;

		/* Must be careful, tracing process can only set certain
		 * bits in the psr.
		 */
		if (__get_user(tstate, (&pregs->tstate)) ||
		    __get_user(tpc, (&pregs->tpc)) ||
		    __get_user(tnpc, (&pregs->tnpc)) ||
		    __get_user(y, (&pregs->y))) {
			pt_error_return(regs, EFAULT);
			goto out;
		}
		tstate &= (TSTATE_ICC | TSTATE_XCC);
		cregs->tstate &= ~(TSTATE_ICC | TSTATE_XCC);
		cregs->tstate |= tstate;
		if(!((tpc | tnpc) & 3)) {
			cregs->tpc = tpc;
			cregs->tnpc = tnpc;
		}
		cregs->y = y;
		for(i = 1; i < 16; i++) {
			if (__get_user(cregs->u_regs[i], (&pregs->u_regs[i-1]))) {
				pt_error_return(regs, EFAULT);
				goto out;
			}
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_GETFPREGS: {
		struct fps {
			unsigned int regs[32];
			unsigned int fsr;
			unsigned int flags;
			unsigned int extra;
			unsigned int fpqd;
			struct fq {
				unsigned int insnaddr;
				unsigned int insn;
			} fpq[16];
		} *fps = (struct fps *) addr;
		unsigned long *fpregs = (unsigned long *)(((char *)child) + AOFF_task_fpregs);

		if (copy_to_user(&fps->regs[0], fpregs,
				 (32 * sizeof(unsigned int))) ||
		    __put_user(child->thread.xfsr[0], (&fps->fsr)) ||
		    __put_user(0, (&fps->fpqd)) ||
		    __put_user(0, (&fps->flags)) ||
		    __put_user(0, (&fps->extra)) ||
		    clear_user(&fps->fpq[0], 32 * sizeof(unsigned int))) {
			pt_error_return(regs, EFAULT);
			goto out;
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_GETFPREGS64: {
		struct fps {
			unsigned int regs[64];
			unsigned long fsr;
		} *fps = (struct fps *) addr;
		unsigned long *fpregs = (unsigned long *)(((char *)child) + AOFF_task_fpregs);

		if (copy_to_user(&fps->regs[0], fpregs,
				 (64 * sizeof(unsigned int))) ||
		    __put_user(child->thread.xfsr[0], (&fps->fsr))) {
			pt_error_return(regs, EFAULT);
			goto out;
		}
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SETFPREGS: {
		struct fps {
			unsigned int regs[32];
			unsigned int fsr;
			unsigned int flags;
			unsigned int extra;
			unsigned int fpqd;
			struct fq {
				unsigned int insnaddr;
				unsigned int insn;
			} fpq[16];
		} *fps = (struct fps *) addr;
		unsigned long *fpregs = (unsigned long *)(((char *)child) + AOFF_task_fpregs);
		unsigned fsr;

		if (copy_from_user(fpregs, &fps->regs[0],
				   (32 * sizeof(unsigned int))) ||
		    __get_user(fsr, (&fps->fsr))) {
			pt_error_return(regs, EFAULT);
			goto out;
		}
		child->thread.xfsr[0] &= 0xffffffff00000000UL;
		child->thread.xfsr[0] |= fsr;
		if (!(child->thread.fpsaved[0] & FPRS_FEF))
			child->thread.gsr[0] = 0;
		child->thread.fpsaved[0] |= (FPRS_FEF | FPRS_DL);
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SETFPREGS64: {
		struct fps {
			unsigned int regs[64];
			unsigned long fsr;
		} *fps = (struct fps *) addr;
		unsigned long *fpregs = (unsigned long *)(((char *)child) + AOFF_task_fpregs);

		if (copy_from_user(fpregs, &fps->regs[0],
				   (64 * sizeof(unsigned int))) ||
		    __get_user(child->thread.xfsr[0], (&fps->fsr))) {
			pt_error_return(regs, EFAULT);
			goto out;
		}
		if (!(child->thread.fpsaved[0] & FPRS_FEF))
			child->thread.gsr[0] = 0;
		child->thread.fpsaved[0] |= (FPRS_FEF | FPRS_DL | FPRS_DU);
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_READTEXT:
	case PTRACE_READDATA: {
		int res = ptrace_readdata(child, addr,
					  (void *)addr2, data);
		if (res == data) {
			pt_succ_return(regs, 0);
			goto flush_and_out;
		}
		if (res >= 0)
			res = -EIO;
		pt_error_return(regs, -res);
		goto flush_and_out;
	}

	case PTRACE_WRITETEXT:
	case PTRACE_WRITEDATA: {
		int res = ptrace_writedata(child, (void *) addr2,
					   addr, data);
		if (res == data) {
			pt_succ_return(regs, 0);
			goto flush_and_out;
		}
		if (res >= 0)
			res = -EIO;
		pt_error_return(regs, -res);
		goto flush_and_out;
	}
	case PTRACE_SYSCALL: /* continue and stop at (return from) syscall */
		addr = 1;

	case PTRACE_CONT: { /* restart after signal. */
		if (data > _NSIG) {
			pt_error_return(regs, EIO);
			goto out;
		}
		if (addr != 1) {
			if (addr & 3) {
				pt_error_return(regs, EINVAL);
				goto out;
			}
#ifdef DEBUG_PTRACE
			printk ("Original: %016lx %016lx\n", child->thread.kregs->tpc, child->thread.kregs->tnpc);
			printk ("Continuing with %016lx %016lx\n", addr, addr+4);
#endif
			child->thread.kregs->tpc = addr;
			child->thread.kregs->tnpc = addr + 4;
		}

		if (request == PTRACE_SYSCALL)
			child->ptrace |= PT_TRACESYS;
		else
			child->ptrace &= ~PT_TRACESYS;

		child->exit_code = data;
#ifdef DEBUG_PTRACE
		printk("CONT: %s [%d]: set exit_code = %x %lx %lx\n", child->comm,
			child->pid, child->exit_code,
			child->thread.kregs->tpc,
			child->thread.kregs->tnpc);
		       
#endif
		wake_up_process(child);
		pt_succ_return(regs, 0);
		goto out;
	}

/*
 * 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: {
		if (child->state == TASK_ZOMBIE) {	/* already dead */
			pt_succ_return(regs, 0);
			goto out;
		}
		child->exit_code = SIGKILL;
		wake_up_process(child);
		pt_succ_return(regs, 0);
		goto out;
	}

	case PTRACE_SUNDETACH: { /* detach a process that was attached. */
		unsigned long flags;

		if ((unsigned long) data > _NSIG) {
			pt_error_return(regs, EIO);
			goto out;
		}
		child->ptrace &= ~(PT_PTRACED|PT_TRACESYS);
		child->exit_code = data;

		write_lock_irqsave(&tasklist_lock, flags);
		REMOVE_LINKS(child);
		child->p_pptr = child->p_opptr;
		SET_LINKS(child);
		write_unlock_irqrestore(&tasklist_lock, flags);

		wake_up_process(child);
		pt_succ_return(regs, 0);
		goto out;
	}

	/* PTRACE_DUMPCORE unsupported... */

	default:
		pt_error_return(regs, EIO);
		goto out;
	}
flush_and_out:
	{
		unsigned long va;
		for(va =  0; va < (PAGE_SIZE << 1); va += 32)
			spitfire_put_dcache_tag(va, 0x0);
		if (request == PTRACE_PEEKTEXT ||
		    request == PTRACE_POKETEXT ||
		    request == PTRACE_READTEXT ||
		    request == PTRACE_WRITETEXT) {
			for(va =  0; va < (PAGE_SIZE << 1); va += 32)
				spitfire_put_icache_tag(va, 0x0);
			__asm__ __volatile__("flush %g6");
		}
	}
out:
	unlock_kernel();
}

asmlinkage void syscall_trace(void)
{
#ifdef DEBUG_PTRACE
	printk("%s [%d]: syscall_trace\n", current->comm, current->pid);
#endif
	if ((current->ptrace & (PT_PTRACED|PT_TRACESYS))
	    != (PT_PTRACED|PT_TRACESYS))
		return;
	current->exit_code = SIGTRAP;
	current->state = TASK_STOPPED;
	current->thread.flags ^= MAGIC_CONSTANT;
	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
	 */
#ifdef DEBUG_PTRACE
	printk("%s [%d]: syscall_trace exit= %x\n", current->comm,
		current->pid, current->exit_code);
#endif
	if (current->exit_code) {
		send_sig (current->exit_code, current, 1);
		current->exit_code = 0;
	}
}