C++ ptrace_notify函数代码示例

asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
{
	unsigned long ip;

	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return scno;
	if (!(current->ptrace & PT_PTRACED))
		return scno;

	/*
	 * Save IP.  IP is used to denote syscall entry/exit:
	 *  IP = 0 -> entry, = 1 -> exit
	 */
	ip = regs->ARM_ip;
	regs->ARM_ip = why;

	current_thread_info()->syscall = scno;

	/* 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;
	}
	regs->ARM_ip = ip;

	return current_thread_info()->syscall;
}

// kernel/fork.c
long do_fork(unsigned long clone_flags,
	      unsigned long stack_start,
	      struct pt_regs *regs,
	      unsigned long stack_size,
	      int __user *parent_tidptr,
	      int __user *child_tidptr)
{
	copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr);
	//...
	{//vfork_done
		struct completion vfork;
		if (clone_flags & CLONE_VFORK) {
			p->vfork_done = &vfork;
			init_completion(&vfork);
		}
	}
	//...
	if (clone_flags & CLONE_VFORK) {
		wait_for_completion(&vfork);
		if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
			ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
	}	
	//...
	return pid;
}

asmlinkage void syscall_trace(void)
{
	pr_debug("syscall_trace called\n");
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;
	if (!(current->ptrace & PT_PTRACED))
		return;

	pr_debug("syscall_trace: notifying parent\n");
	/* 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) {
		pr_debug("syscall_trace: sending signal %d to PID %u\n",
			 current->exit_code, current->pid);
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}

int setup_signal_stack_si(unsigned long stack_top, int sig,
			  struct k_sigaction *ka, struct pt_regs *regs,
			  siginfo_t *info, sigset_t *mask)
{
	struct rt_sigframe __user *frame;
	void __user *restorer;
	unsigned long save_sp = PT_REGS_SP(regs);
	int err = 0;

	stack_top &= -8UL;
	frame = (struct rt_sigframe __user *) stack_top - 1;
	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return 1;

	restorer = frame->retcode;
	if(ka->sa.sa_flags & SA_RESTORER)
		restorer = ka->sa.sa_restorer;

	/* See comment above about why this is here */
	PT_REGS_SP(regs) = (unsigned long) frame;

	err |= __put_user(restorer, &frame->pretcode);
	err |= __put_user(sig, &frame->sig);
	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, info);
	err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
				     save_sp);

	/*
	 * This is movl $,%eax ; int $0x80
	 *
	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
	 * reasons and because gdb uses it as a signature to notice
	 * signal handler stack frames.
	 */
	err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
	err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
	err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));

	if(err)
		goto err;

	PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
	PT_REGS_EAX(regs) = (unsigned long) sig;
	PT_REGS_EDX(regs) = (unsigned long) &frame->info;
	PT_REGS_ECX(regs) = (unsigned long) &frame->uc;

	if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
		ptrace_notify(SIGTRAP);
	return 0;

err:
	PT_REGS_SP(regs) = save_sp;
	return err;
}

asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
{
	unsigned long ip;
	current_thread_info()->syscall = scno;

	if (why)
		audit_syscall_exit(regs);
	else {
		if (secure_computing(scno) == -1)
			return -1;
		audit_syscall_entry(AUDIT_ARCH_ARM, scno, regs->ARM_r0,
				    regs->ARM_r1, regs->ARM_r2, regs->ARM_r3);
	}

	if (why == 0 && test_and_clear_thread_flag(TIF_SYSCALL_RESTARTSYS))
		scno = __NR_restart_syscall - __NR_SYSCALL_BASE;
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return scno;
	if (!(current->ptrace & PT_PTRACED))
		return scno;

	/*
	 * IP is used to denote syscall entry/exit:
	 * IP = 0 -> entry, =1 -> exit
	 */
	ip = regs->ARM_ip;
	regs->ARM_ip = why;

	/*
	 * IP is used to denote syscall entry/exit:
	 * IP = 0 -> entry, =1 -> exit
	 */
	ip = regs->ARM_ip;
	regs->ARM_ip = why;

	/* 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;
	}
	regs->ARM_ip = ip;

	return current_thread_info()->syscall;
}

/*
 * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
 * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
 */
void syscall_trace(struct uml_pt_regs *regs, int entryexit)
{
	int is_singlestep = (current->ptrace & PT_DTRACE) && entryexit;
	int tracesysgood;

	if (unlikely(current->audit_context)) {
		if (!entryexit)
			audit_syscall_entry(HOST_AUDIT_ARCH,
					    UPT_SYSCALL_NR(regs),
					    UPT_SYSCALL_ARG1(regs),
					    UPT_SYSCALL_ARG2(regs),
					    UPT_SYSCALL_ARG3(regs),
					    UPT_SYSCALL_ARG4(regs));
		else audit_syscall_exit(AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
					UPT_SYSCALL_RET(regs));
	}

	/* Fake a debug trap */
	if (is_singlestep)
		send_sigtrap(current, regs, 0);

	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
	 */
	tracesysgood = (current->ptrace & PT_TRACESYSGOOD);
	ptrace_notify(SIGTRAP | (tracesysgood ? 0x80 : 0));

	if (entryexit) /* force do_signal() --> is_syscall() */
		set_thread_flag(TIF_SIGPENDING);

	/*
	 * 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;
	}
}

static void do_syscall_trace(void)
{
	/* 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;
	}
}

asmlinkage void syscall_trace(void)
{
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;
	if (!(current->ptrace & PT_PTRACED))
		return;
	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;
	}
}

static asmlinkage void 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;
	}
}

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.
	 */
	if (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}

/*
 * Notification of system call entry/exit
 * - triggered by current->work.syscall_trace
 */
asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
{
	/* do the secure computing check first */
	if (!entryexit)
		secure_computing(regs->regs[0]);

	if (unlikely(current->audit_context) && entryexit)
		audit_syscall_exit(AUDITSC_RESULT(regs->regs[2]),
		                   regs->regs[2]);

	if (!(current->ptrace & PT_PTRACED))
		goto out;

	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		goto out;

	/* 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;
	}

out:
	if (unlikely(current->audit_context) && !entryexit)
		audit_syscall_entry(audit_arch(), regs->regs[0],
				    regs->regs[4], regs->regs[5],
				    regs->regs[6], regs->regs[7]);
}

asmlinkage int syscall_trace(int why, struct pt_regs *regs, int scno)
{
	unsigned long ip;

	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return scno;
	if (!(current->ptrace & PT_PTRACED))
		return scno;

	ip = regs->UCreg_ip;
	regs->UCreg_ip = why;

	current_thread_info()->syscall = scno;

	ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
				 ? 0x80 : 0));
	if (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
	regs->UCreg_ip = ip;

	return current_thread_info()->syscall;
}

void do_syscall_trace(void)
{
	if (!test_thread_flag(TIF_SYSCALL_TRACE))
		return;

	if (!(current->ptrace & PT_PTRACED))
		return;

	/*
                                                                 
                                               
  */
	ptrace_notify(SIGTRAP|((current->ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));

	/*
                                                                   
                                                               
                                         
  */
	if (current->exit_code) {
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
	}
}

static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
			   sigset_t *set, struct pt_regs * regs)
{
	void __user *restorer;
	struct rt_sigframe __user *frame;
	int err = 0;
	int usig;

	frame = get_sigframe(ka, regs, sizeof(*frame));

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto give_sigsegv;

	usig = current_thread_info()->exec_domain
		&& current_thread_info()->exec_domain->signal_invmap
		&& sig < 32
		? current_thread_info()->exec_domain->signal_invmap[sig]
		: sig;

	err |= __put_user(usig, &frame->sig);
	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, info);
	if (err)
		goto give_sigsegv;

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(regs->esp),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
			        regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
	if (err)
		goto give_sigsegv;

	/* Set up to return from userspace.  */
	restorer = (void *)VDSO_SYM(&__kernel_rt_sigreturn);
	if (ka->sa.sa_flags & SA_RESTORER)
		restorer = ka->sa.sa_restorer;
	err |= __put_user(restorer, &frame->pretcode);
	 
	/*
	 * This is movl $,%eax ; int $0x80
	 *
	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
	 * reasons and because gdb uses it as a signature to notice
	 * signal handler stack frames.
	 */
	err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
	err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
	err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));

	if (err)
		goto give_sigsegv;

	/* Set up registers for signal handler */
	regs->esp = (unsigned long) frame;
	regs->eip = (unsigned long) ka->sa.sa_handler;
	regs->eax = (unsigned long) usig;
	regs->edx = (unsigned long) &frame->info;
	regs->ecx = (unsigned long) &frame->uc;

	set_fs(USER_DS);
	regs->xds = __USER_DS;
	regs->xes = __USER_DS;
	regs->xss = __USER_DS;
	regs->xcs = __USER_CS;

	/*
	 * Clear TF when entering the signal handler, but
	 * notify any tracer that was single-stepping it.
	 * The tracer may want to single-step inside the
	 * handler too.
	 */
	regs->eflags &= ~TF_MASK;
	if (test_thread_flag(TIF_SINGLESTEP))
		ptrace_notify(SIGTRAP);

#if DEBUG_SIG
	printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
		current->comm, current->pid, frame, regs->eip, frame->pretcode);
#endif

	return 0;

give_sigsegv:
	force_sigsegv(sig, current);
	return -EFAULT;
}

static int
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
          sigset_t *oldset, struct pt_regs *regs)
{
    int ret;

    /* Are we from a system call? */
    if (current_syscall(regs) >= 0) {
        /* If so, check system call restarting.. */
        switch (current_syscall_ret(regs)) {
        case -ERESTART_RESTARTBLOCK:
        case -ERESTARTNOHAND:
            regs->ax = -EINTR;
            break;

        case -ERESTARTSYS:
            if (!(ka->sa.sa_flags & SA_RESTART)) {
                regs->ax = -EINTR;
                break;
            }
        /* fallthrough */
        case -ERESTARTNOINTR:
            regs->ax = regs->orig_ax;
            regs->ip -= 2;
            break;
        }
    }

    /*
     * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
     * flag so that register information in the sigcontext is correct.
     */
    if (unlikely(regs->flags & X86_EFLAGS_TF) &&
        likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
        regs->flags &= ~X86_EFLAGS_TF;

#ifdef CONFIG_IA32_EMULATION
    if (test_thread_flag(TIF_IA32)) {
        if (ka->sa.sa_flags & SA_SIGINFO)
            ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
        else
            ret = ia32_setup_frame(sig, ka, oldset, regs);
    } else 
#endif
    ret = setup_rt_frame(sig, ka, info, oldset, regs);

    if (ret == 0) {
        /*
         * This has nothing to do with segment registers,
         * despite the name.  This magic affects uaccess.h
         * macros' behavior.  Reset it to the normal setting.
         */
        set_fs(USER_DS);

        /*
         * Clear the direction flag as per the ABI for function entry.
         */
        regs->flags &= ~X86_EFLAGS_DF;

        /*
         * Clear TF when entering the signal handler, but
         * notify any tracer that was single-stepping it.
         * The tracer may want to single-step inside the
         * handler too.
         */
        regs->flags &= ~X86_EFLAGS_TF;
        if (test_thread_flag(TIF_SINGLESTEP))
            ptrace_notify(SIGTRAP);

        spin_lock_irq(&current->sighand->siglock);
        sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
        if (!(ka->sa.sa_flags & SA_NODEFER))
            sigaddset(&current->blocked,sig);
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);
    }

    return ret;
}