ptrace.c

linux-2.6.15.6

		case 0x1: /* BNE */
		case 0x8: /* BEQZ */
		case 0x9: /* BNEZ */
		case 0xa: /* BLTZ */
		case 0xb: /* BGEZ */
		case 0xc: /* BLEZ */
		case 0xd: /* BGTZ */
			regno1 = ((insn >> 24) & 0xf);
			regno2 = ((insn >> 16) & 0xf);
			if (check_condition_src(op2, regno1, regno2, child)) {
				disp = (long)(insn << 16) >> 14;
				*next_pc = (pc & ~0x3) + disp;
				return;
			}
			break;
		}
	}
	*next_pc = pc + 4;
}

static inline void
compute_next_pc(unsigned long insn, unsigned long pc,
		unsigned long *next_pc, struct task_struct *child)
{
	if (insn & 0x80000000)
		compute_next_pc_for_32bit_insn(insn, pc, next_pc, child);
	else
		compute_next_pc_for_16bit_insn(insn, pc, next_pc, child);
}

static int
register_debug_trap(struct task_struct *child, unsigned long next_pc,
	unsigned long next_insn, unsigned long *code)
{
	struct debug_trap *p = &child->thread.debug_trap;
	unsigned long addr = next_pc & ~3;

	if (p->nr_trap == MAX_TRAPS) {
		printk("kernel BUG at %s %d: p->nr_trap = %d\n",
					__FILE__, __LINE__, p->nr_trap);
		return -1;
	}
	p->addr[p->nr_trap] = addr;
	p->insn[p->nr_trap] = next_insn;
	p->nr_trap++;
	if (next_pc & 3) {
		*code = (next_insn & 0xffff0000) | 0x10f1;
		/* xxx --> TRAP1 */
	} else {
		if ((next_insn & 0x80000000) || (next_insn & 0x8000)) {
			*code = 0x10f17000;
			/* TRAP1 --> NOP */
		} else {
			*code = (next_insn & 0xffff) | 0x10f10000;
			/* TRAP1 --> xxx */
		}
	}
	return 0;
}

static int
unregister_debug_trap(struct task_struct *child, unsigned long addr,
		      unsigned long *code)
{
	struct debug_trap *p = &child->thread.debug_trap;
        int i;

	/* Search debug trap entry. */
	for (i = 0; i < p->nr_trap; i++) {
		if (p->addr[i] == addr)
			break;
	}
	if (i >= p->nr_trap) {
		/* The trap may be requested from debugger.
		 * ptrace should do nothing in this case.
		 */
		return 0;
	}

	/* Recover orignal instruction code. */
	*code = p->insn[i];

	/* Shift debug trap entries. */
	while (i < p->nr_trap - 1) {
		p->insn[i] = p->insn[i + 1];
		p->addr[i] = p->addr[i + 1];
		i++;
	}
	p->nr_trap--;
	return 1;
}

static void
unregister_all_debug_traps(struct task_struct *child)
{
	struct debug_trap *p = &child->thread.debug_trap;
	int i;

	for (i = 0; i < p->nr_trap; i++)
		access_process_vm(child, p->addr[i], &p->insn[i], sizeof(p->insn[i]), 1);
	p->nr_trap = 0;
}

static inline void
invalidate_cache(void)
{
#if defined(CONFIG_CHIP_M32700) || defined(CONFIG_CHIP_OPSP)

	_flush_cache_copyback_all();

#else	/* ! CONFIG_CHIP_M32700 */

	/* Invalidate cache */
	__asm__ __volatile__ (
                "ldi    r0, #-1					\n\t"
                "ldi    r1, #0					\n\t"
                "stb    r1, @r0		; cache off		\n\t"
                ";						\n\t"
                "ldi    r0, #-2					\n\t"
                "ldi    r1, #1					\n\t"
                "stb    r1, @r0		; cache invalidate	\n\t"
                ".fillinsn					\n"
                "0:						\n\t"
                "ldb    r1, @r0		; invalidate check	\n\t"
                "bnez   r1, 0b					\n\t"
                ";						\n\t"
                "ldi    r0, #-1					\n\t"
                "ldi    r1, #1					\n\t"
                "stb    r1, @r0		; cache on		\n\t"
		: : : "r0", "r1", "memory"
	);
	/* FIXME: copying-back d-cache and invalidating i-cache are needed.
	 */
#endif	/* CONFIG_CHIP_M32700 */
}

/* Embed a debug trap (TRAP1) code */
static int
embed_debug_trap(struct task_struct *child, unsigned long next_pc)
{
	unsigned long next_insn, code;
	unsigned long addr = next_pc & ~3;

	if (access_process_vm(child, addr, &next_insn, sizeof(next_insn), 0)
	    != sizeof(next_insn)) {
		return -1; /* error */
	}

	/* Set a trap code. */
	if (register_debug_trap(child, next_pc, next_insn, &code)) {
		return -1; /* error */
	}
	if (access_process_vm(child, addr, &code, sizeof(code), 1)
	    != sizeof(code)) {
		return -1; /* error */
	}
	return 0; /* success */
}

void
withdraw_debug_trap(struct pt_regs *regs)
{
	unsigned long addr;
	unsigned long code;

 	addr = (regs->bpc - 2) & ~3;
	regs->bpc -= 2;
	if (unregister_debug_trap(current, addr, &code)) {
	    access_process_vm(current, addr, &code, sizeof(code), 1);
	    invalidate_cache();
	}
}

static void
init_debug_traps(struct task_struct *child)
{
	struct debug_trap *p = &child->thread.debug_trap;
	int i;
	p->nr_trap = 0;
	for (i = 0; i < MAX_TRAPS; i++) {
		p->addr[i] = 0;
		p->insn[i] = 0;
	}
}


/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
	/* nothing to do.. */
}

static int
do_ptrace(long request, struct task_struct *child, long addr, long data)
{
	unsigned long tmp;
	int ret;

	switch (request) {
	/*
	 * read word at location "addr" in the child process.
	 */
	case PTRACE_PEEKTEXT:
	case PTRACE_PEEKDATA:
		ret = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
		if (ret == sizeof(tmp))
			ret = put_user(tmp,(unsigned long __user *) data);
		else
			ret = -EIO;
		break;

	/*
	 * read the word at location addr in the USER area.
	 */
	case PTRACE_PEEKUSR:
		ret = ptrace_read_user(child, addr,
				       (unsigned long __user *)data);
		break;

	/*
	 * write the word at location addr.
	 */
	case PTRACE_POKETEXT:
	case PTRACE_POKEDATA:
		ret = access_process_vm(child, addr, &data, sizeof(data), 1);
		if (ret == sizeof(data)) {
			ret = 0;
			if (request == PTRACE_POKETEXT) {
				invalidate_cache();
			}
		} else {
			ret = -EIO;
		}
		break;

	/*
	 * write the word at location addr in the USER area.
	 */
	case PTRACE_POKEUSR:
		ret = ptrace_write_user(child, addr, data);
		break;

	/*
	 * continue/restart and stop at next (return from) syscall
	 */
	case PTRACE_SYSCALL:
	case PTRACE_CONT:
		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);
		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;
		unregister_all_debug_traps(child);
		invalidate_cache();
		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
			break;
		child->exit_code = SIGKILL;
		wake_up_process(child);
		break;
	}

	/*
	 * execute single instruction.
	 */
	case PTRACE_SINGLESTEP: {
		unsigned long next_pc;
		unsigned long pc, insn;

		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;
		}

		/* Compute next pc.  */
		pc = get_stack_long(child, PT_BPC);

		if (access_process_vm(child, pc&~3, &insn, sizeof(insn), 0)
		    != sizeof(insn))
			break;

		compute_next_pc(insn, pc, &next_pc, child);
		if (next_pc & 0x80000000)
			break;

		if (embed_debug_trap(child, next_pc))
			break;

		invalidate_cache();
		child->exit_code = data;

		/* give it a chance to run. */
		wake_up_process(child);
		ret = 0;
		break;
	}

	/*
	 * detach a process that was attached.
	 */
	case PTRACE_DETACH:
		ret = 0;
		ret = ptrace_detach(child, data);
		break;

	case PTRACE_GETREGS:
		ret = ptrace_getregs(child, (void __user *)data);
		break;

	case PTRACE_SETREGS:
		ret = ptrace_setregs(child, (void __user *)data);
		break;

	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}

	return ret;
}

asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
{
	struct task_struct *child;
	int ret;

	lock_kernel();
	ret = -EPERM;
	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;

	if (request == PTRACE_ATTACH) {
		ret = ptrace_attach(child);
		if (ret == 0)
			init_debug_traps(child);
		goto out_tsk;
	}

	ret = ptrace_check_attach(child, request == PTRACE_KILL);
	if (ret == 0)
		ret = do_ptrace(request, child, addr, data);

out_tsk:
	put_task_struct(child);
out:
	unlock_kernel();

	return ret;
}

/* notification of system call entry/exit
 * - triggered by current->work.syscall_trace
 */
void do_syscall_trace(void)
{
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;
	if (!(current->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)
				 ? 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 (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}