C++ clear_tsk_thread_flag函数代码示例

//.........这里部分代码省略.........
		ret = -EIO;
		if (is_user_addr_valid(child, addr, sizeof(tmp)) < 0)
			break;
		if (access_process_vm(child, addr, &data, sizeof(data), 1) != sizeof(data))
			break;
		ret = 0;
		break;

	case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
		ret = -EIO;
		if ((addr & 3) || addr < 0)
			break;

		ret = 0;
		switch (addr >> 2) {
		case 0 ... PT__END-1:
			ret = put_reg(child, addr >> 2, data);
			break;

		default:
			ret = -EIO;
			break;
		}
		break;

	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
	case PTRACE_CONT: /* restart after signal. */
		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;
		ptrace_disable(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->exit_state == EXIT_ZOMBIE)	/* already dead */
			break;
		child->exit_code = SIGKILL;
		clear_tsk_thread_flag(child, TIF_SINGLESTEP);
		ptrace_disable(child);
		wake_up_process(child);
		break;

	case PTRACE_SINGLESTEP:  /* set the trap flag. */
		ret = -EIO;
		if (!valid_signal(data))
			break;
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		ptrace_enable(child);
		child->exit_code = data;
		wake_up_process(child);
		ret = 0;
		break;

	case PTRACE_DETACH:	/* detach a process that was attached. */

//.........这里部分代码省略.........
		retval = -ENOMEM;
		pid = alloc_pid(p->nsproxy->pid_ns_for_children);
		if (!pid)
			goto bad_fork_cleanup_io;
	}

	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
	/*
	 * Clear TID on mm_release()?
	 */
	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
#ifdef CONFIG_BLOCK
	p->plug = NULL;
#endif
#ifdef CONFIG_FUTEX
	p->robust_list = NULL;
#ifdef CONFIG_COMPAT
	p->compat_robust_list = NULL;
#endif
	INIT_LIST_HEAD(&p->pi_state_list);
	p->pi_state_cache = NULL;
#endif
	/*
	 * sigaltstack should be cleared when sharing the same VM
	 */
	if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
		p->sas_ss_sp = p->sas_ss_size = 0;

	/*
	 * Syscall tracing and stepping should be turned off in the
	 * child regardless of CLONE_PTRACE.
	 */
	user_disable_single_step(p);
	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
	clear_all_latency_tracing(p);

	/* ok, now we should be set up.. */
	p->pid = pid_nr(pid);
	if (clone_flags & CLONE_THREAD) {
		p->exit_signal = -1;
		p->group_leader = current->group_leader;
		p->tgid = current->tgid;
	} else {
		if (clone_flags & CLONE_PARENT)
			p->exit_signal = current->group_leader->exit_signal;
		else
			p->exit_signal = (clone_flags & CSIGNAL);
		p->group_leader = p;
		p->tgid = p->pid;
	}

	p->nr_dirtied = 0;
	p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
	p->dirty_paused_when = 0;

	p->pdeath_signal = 0;
	INIT_LIST_HEAD(&p->thread_group);
	p->task_works = NULL;

	/*
	 * Make it visible to the rest of the system, but dont wake it up yet.
	 * Need tasklist lock for parent etc handling!
	 */

//.........这里部分代码省略.........
				/* Zero the top 32 bits */
				*(unsigned int *) ((char *) task_regs(child) + addr - 4) = 0;
				*(unsigned int *) ((char *) task_regs(child) + addr) = data;
				ret = 0;
			}
			goto out_tsk;
		}
		else
#endif
		{
			if ((addr & (sizeof(long)-1)) || (unsigned long) addr >= sizeof(struct pt_regs))
				goto out_tsk;
			if ((addr >= PT_GR1 && addr <= PT_GR31) ||
					addr == PT_IAOQ0 || addr == PT_IAOQ1 ||
					(addr >= PT_FR0 && addr <= PT_FR31 + 4) ||
					addr == PT_SAR) {
				*(unsigned long *) ((char *) task_regs(child) + addr) = data;
				ret = 0;
			}
			goto out_tsk;
		}

	case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
	case PTRACE_CONT:
		ret = -EIO;
		DBG("sys_ptrace(%s)\n",
			request == PTRACE_SYSCALL ? "SYSCALL" : "CONT");
		if (!valid_signal(data))
			goto out_tsk;
		child->ptrace &= ~(PT_SINGLESTEP|PT_BLOCKSTEP);
		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;
		goto out_wake_notrap;

	case PTRACE_KILL:
		/*
		 * 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.
		 */
		ret = 0;
		DBG("sys_ptrace(KILL)\n");
		if (child->exit_state == EXIT_ZOMBIE)	/* already dead */
			goto out_tsk;
		child->exit_code = SIGKILL;
		goto out_wake_notrap;

	case PTRACE_SINGLEBLOCK:
		DBG("sys_ptrace(SINGLEBLOCK)\n");
		ret = -EIO;
		if (!valid_signal(data))
			goto out_tsk;
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		child->ptrace &= ~PT_SINGLESTEP;
		child->ptrace |= PT_BLOCKSTEP;
		child->exit_code = data;

		/* Enable taken branch trap. */
		pa_psw(child)->r = 0;
		pa_psw(child)->t = 1;
		pa_psw(child)->h = 0;
		pa_psw(child)->l = 0;

//.........这里部分代码省略.........
		case PTRACE_POKETEXT: /* write the word at location addr. */
		case PTRACE_POKEDATA:
			ret = 0;
			if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
				break;
			ret = -EIO;
			break;

		case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
			if ((addr & 3) || addr < 0 || addr >= sizeof(struct user)) {
				ret = -EIO;
				break ;
			}
			addr = addr >> 2; /* temporary hack. */
			    
			if (addr == PT_ORIG_ER0) {
				ret = -EIO;
				break ;
			}
			if (addr < H8300_REGS_NO) {
				ret = h8300_put_reg(child, addr, data);
				break ;
			}
			ret = -EIO;
			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)
				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);
			/* make sure the single step bit is not set. */
			h8300_disable_trace(child);
			ret = 0;
		}

/*
 * 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->exit_state == EXIT_ZOMBIE) /* already dead */
				break;
			child->exit_code = SIGKILL;
			h8300_disable_trace(child);
			wake_up_process(child);
			break;
		}

		case PTRACE_SINGLESTEP: {  /* set the trap flag. */
			ret = -EIO;
			if ((unsigned long) data > _NSIG)
				break;
			clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
			child->exit_code = data;
			h8300_enable_trace(child);
			wake_up_process(child);
			ret = 0;

/*
 * This creates a new process as a copy of the old one,
 * but does not actually start it yet.
 *
 * It copies the registers, and all the appropriate
 * parts of the process environment (as per the clone
 * flags). The actual kick-off is left to the caller.
 */
struct task_struct *copy_process(unsigned long clone_flags,
				 unsigned long stack_start,
				 struct pt_regs *regs,
				 unsigned long stack_size,
				 int __user *parent_tidptr,
				 int __user *child_tidptr)
{
	int retval;
	struct task_struct *p = NULL;

	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
		return ERR_PTR(-EINVAL);

	/*
	 * Thread groups must share signals as well, and detached threads
	 * can only be started up within the thread group.
	 */
	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
		return ERR_PTR(-EINVAL);

	/*
	 * Shared signal handlers imply shared VM. By way of the above,
	 * thread groups also imply shared VM. Blocking this case allows
	 * for various simplifications in other code.
	 */
	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
		return ERR_PTR(-EINVAL);

	retval = security_task_create(clone_flags);
	if (retval)
		goto fork_out;

	retval = -ENOMEM;
	p = dup_task_struct(current);
	if (!p)
		goto fork_out;

	retval = -EAGAIN;
	if (atomic_read(&p->user->processes) >=
			p->rlim[RLIMIT_NPROC].rlim_cur) {
		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
				p->user != &root_user)
			goto bad_fork_free;
	}

	atomic_inc(&p->user->__count);
	atomic_inc(&p->user->processes);
	get_group_info(p->group_info);

	/*
	 * If multiple threads are within copy_process(), then this check
	 * triggers too late. This doesn't hurt, the check is only there
	 * to stop root fork bombs.
	 */
	if (nr_threads >= max_threads)
		goto bad_fork_cleanup_count;

	if (!try_module_get(p->thread_info->exec_domain->module))
		goto bad_fork_cleanup_count;

	if (p->binfmt && !try_module_get(p->binfmt->module))
		goto bad_fork_cleanup_put_domain;

	p->did_exec = 0;
	copy_flags(clone_flags, p);
	if (clone_flags & CLONE_IDLETASK)
		p->pid = 0;
	else {
		p->pid = alloc_pidmap();
		if (p->pid == -1)
			goto bad_fork_cleanup;
	}
	retval = -EFAULT;
	if (clone_flags & CLONE_PARENT_SETTID)
		if (put_user(p->pid, parent_tidptr))
			goto bad_fork_cleanup;

	p->proc_dentry = NULL;

	INIT_LIST_HEAD(&p->children);
	INIT_LIST_HEAD(&p->sibling);
	init_waitqueue_head(&p->wait_chldexit);
	p->vfork_done = NULL;
	spin_lock_init(&p->alloc_lock);
	spin_lock_init(&p->proc_lock);

	clear_tsk_thread_flag(p, TIF_SIGPENDING);
	init_sigpending(&p->pending);

	p->it_real_value = p->it_virt_value = p->it_prof_value = 0;
	p->it_real_incr = p->it_virt_incr = p->it_prof_incr = 0;
	init_timer(&p->real_timer);
//.........这里部分代码省略.........

/*
 * Copy architecture-specific thread state
 */
int copy_thread(unsigned long clone_flags, unsigned long usp,
	unsigned long kthread_arg, struct task_struct *p)
{
	struct thread_info *ti = task_thread_info(p);
	struct pt_regs *childregs, *regs = current_pt_regs();
	unsigned long childksp;
	p->set_child_tid = p->clear_child_tid = NULL;

	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;

	/* set up new TSS. */
	childregs = (struct pt_regs *) childksp - 1;
	/*  Put the stack after the struct pt_regs.  */
	childksp = (unsigned long) childregs;
	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
	if (unlikely(p->flags & PF_KTHREAD)) {
		/* kernel thread */
		unsigned long status = p->thread.cp0_status;
		memset(childregs, 0, sizeof(struct pt_regs));
		ti->addr_limit = KERNEL_DS;
		p->thread.reg16 = usp; /* fn */
		p->thread.reg17 = kthread_arg;
		p->thread.reg29 = childksp;
		p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
		status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
			 ((status & (ST0_KUC | ST0_IEC)) << 2);
#else
		status |= ST0_EXL;
#endif
		childregs->cp0_status = status;
		return 0;
	}

	/* user thread */
	*childregs = *regs;
	childregs->regs[7] = 0; /* Clear error flag */
	childregs->regs[2] = 0; /* Child gets zero as return value */
	if (usp)
		childregs->regs[29] = usp;
	ti->addr_limit = USER_DS;

	p->thread.reg29 = (unsigned long) childregs;
	p->thread.reg31 = (unsigned long) ret_from_fork;

	/*
	 * New tasks lose permission to use the fpu. This accelerates context
	 * switching for most programs since they don't use the fpu.
	 */
	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);

	clear_tsk_thread_flag(p, TIF_USEDFPU);
	clear_tsk_thread_flag(p, TIF_USEDMSA);
	clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);

#ifdef CONFIG_MIPS_MT_FPAFF
	clear_tsk_thread_flag(p, TIF_FPUBOUND);
#endif /* CONFIG_MIPS_MT_FPAFF */

	if (clone_flags & CLONE_SETTLS)
		ti->tp_value = regs->regs[7];

	return 0;
}

long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
	int ret;
	unsigned long __user *datap = (unsigned long __user *)data;

	switch (request) {
		/* Read word at location address. */
		case PTRACE_PEEKTEXT:
		case PTRACE_PEEKDATA: {
			unsigned long tmp;
			int copied;

			ret = -EIO;

			/* The signal trampoline page is outside the normal user-addressable
			 * space but still accessible. This is hack to make it possible to
			 * access the signal handler code in GDB.
			 */
			if ((addr & PAGE_MASK) == cris_signal_return_page) {
				/* The trampoline page is globally mapped, no page table to traverse.*/
				tmp = *(unsigned long*)addr;
			} else {
				copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);

				if (copied != sizeof(tmp))
					break;
			}

			ret = put_user(tmp,datap);
			break;
		}

		/* Read the word at location address in the USER area. */
		case PTRACE_PEEKUSR: {
			unsigned long tmp;

			ret = -EIO;
			if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
				break;

			tmp = get_reg(child, addr >> 2);
			ret = put_user(tmp, datap);
			break;
		}

		/* Write the word at location address. */
		case PTRACE_POKETEXT:
		case PTRACE_POKEDATA:
			ret = 0;

			if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
				break;

			ret = -EIO;
			break;

 		/* Write the word at location address in the USER area. */
		case PTRACE_POKEUSR:
			ret = -EIO;
			if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
				break;

			addr >>= 2;

			if (addr == PT_CCS) {
				/* don't allow the tracing process to change stuff like
				 * interrupt enable, kernel/user bit, dma enables etc.
				 */
				data &= CCS_MASK;
				data |= get_reg(child, PT_CCS) & ~CCS_MASK;
			}
			if (put_reg(child, addr, data))
				break;
			ret = 0;
			break;

		case PTRACE_SYSCALL:
		case PTRACE_CONT:
			ret = -EIO;

			if (!valid_signal(data))
				break;

			/* Continue means no single-step. */
			put_reg(child, PT_SPC, 0);

			if (!get_debugreg(child->pid, PT_BP_CTRL)) {
				unsigned long tmp;
				/* If no h/w bp configured, disable S bit. */
				tmp = get_reg(child, PT_CCS) & ~SBIT_USER;
				put_reg(child, PT_CCS, tmp);
			}

			if (request == PTRACE_SYSCALL) {
				set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
			}
			else {
				clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
			}

//.........这里部分代码省略.........

/*
 * Called by kernel/ptrace.c when detaching..
 *
 * Make sure single step bits etc are not set.
 */
void ptrace_disable(struct task_struct *child)
{
	/* Don't load the watchpoint registers for the ex-child. */
	clear_tsk_thread_flag(child, TIF_LOAD_WATCH);
}

//.........这里部分代码省略.........
	retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
	if (retval)
		goto bad_fork_cleanup_io;

	if (pid != &init_struct_pid) {
		retval = -ENOMEM;
		pid = alloc_pid(p->nsproxy->pid_ns);
		if (!pid)
			goto bad_fork_cleanup_io;
	}

	p->pid = pid_nr(pid);
	p->tgid = p->pid;
	if (clone_flags & CLONE_THREAD)
		p->tgid = current->tgid;

	p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
	p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
#ifdef CONFIG_BLOCK
	p->plug = NULL;
#endif
#ifdef CONFIG_FUTEX
	p->robust_list = NULL;
#ifdef CONFIG_COMPAT
	p->compat_robust_list = NULL;
#endif
	INIT_LIST_HEAD(&p->pi_state_list);
	p->pi_state_cache = NULL;
#endif
	if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
		p->sas_ss_sp = p->sas_ss_size = 0;

	user_disable_single_step(p);
	clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
	clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif
	clear_all_latency_tracing(p);

	
	if (clone_flags & CLONE_THREAD)
		p->exit_signal = -1;
	else if (clone_flags & CLONE_PARENT)
		p->exit_signal = current->group_leader->exit_signal;
	else
		p->exit_signal = (clone_flags & CSIGNAL);

	p->pdeath_signal = 0;
	p->exit_state = 0;

	p->nr_dirtied = 0;
	p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
	p->dirty_paused_when = 0;

	p->group_leader = p;
	INIT_LIST_HEAD(&p->thread_group);

	cgroup_fork_callbacks(p);
	cgroup_callbacks_done = 1;

	
	write_lock_irq(&tasklist_lock);

	
	if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
		p->real_parent = current->real_parent;

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
	unsigned long unused, struct task_struct *p, struct pt_regs *regs)
{
	struct thread_info *ti = task_thread_info(p);
	struct pt_regs *childregs;
	long childksp;
	p->set_child_tid = p->clear_child_tid = NULL;

	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;

	preempt_disable();

	if (is_fpu_owner())
		save_fp(p);

	if (cpu_has_dsp)
		save_dsp(p);

	preempt_enable();

	/* set up new TSS. */
	childregs = (struct pt_regs *) childksp - 1;
	*childregs = *regs;
	childregs->regs[7] = 0;	/* Clear error flag */

#if defined(CONFIG_BINFMT_IRIX)
	if (current->personality != PER_LINUX) {
		/* Under IRIX things are a little different. */
		childregs->regs[3] = 1;
		regs->regs[3] = 0;
	}
#endif
	childregs->regs[2] = 0;	/* Child gets zero as return value */
	regs->regs[2] = p->pid;

	if (childregs->cp0_status & ST0_CU0) {
		childregs->regs[28] = (unsigned long) ti;
		childregs->regs[29] = childksp;
		ti->addr_limit = KERNEL_DS;
	} else {
		childregs->regs[29] = usp;
		ti->addr_limit = USER_DS;
	}
	p->thread.reg29 = (unsigned long) childregs;
	p->thread.reg31 = (unsigned long) ret_from_fork;

	/*
	 * New tasks lose permission to use the fpu. This accelerates context
	 * switching for most programs since they don't use the fpu.
	 */
	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
	clear_tsk_thread_flag(p, TIF_USEDFPU);

#ifdef CONFIG_MIPS_MT_FPAFF
	/*
	 * FPU affinity support is cleaner if we track the
	 * user-visible CPU affinity from the very beginning.
	 * The generic cpus_allowed mask will already have
	 * been copied from the parent before copy_thread
	 * is invoked.
	 */
	p->thread.user_cpus_allowed = p->cpus_allowed;
#endif /* CONFIG_MIPS_MT_FPAFF */

	if (clone_flags & CLONE_SETTLS)
		ti->tp_value = regs->regs[7];

	return 0;
}

int copy_thread(unsigned long clone_flags, unsigned long stack_start,
		unsigned long stk_sz, struct task_struct *p)
{
	struct pt_regs *childregs = task_pt_regs(p);

	memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));

	/*
	 * Unalias p->thread.sve_state (if any) from the parent task
	 * and disable discard SVE state for p:
	 */
	clear_tsk_thread_flag(p, TIF_SVE);
	p->thread.sve_state = NULL;

	/*
	 * In case p was allocated the same task_struct pointer as some
	 * other recently-exited task, make sure p is disassociated from
	 * any cpu that may have run that now-exited task recently.
	 * Otherwise we could erroneously skip reloading the FPSIMD
	 * registers for p.
	 */
	fpsimd_flush_task_state(p);

	if (likely(!(p->flags & PF_KTHREAD))) {
		*childregs = *current_pt_regs();
		childregs->regs[0] = 0;

		/*
		 * Read the current TLS pointer from tpidr_el0 as it may be
		 * out-of-sync with the saved value.
		 */
		*task_user_tls(p) = read_sysreg(tpidr_el0);

		if (stack_start) {
			if (is_compat_thread(task_thread_info(p)))
				childregs->compat_sp = stack_start;
			else
				childregs->sp = stack_start;
		}

		/*
		 * If a TLS pointer was passed to clone (4th argument), use it
		 * for the new thread.
		 */
		if (clone_flags & CLONE_SETTLS)
			p->thread.uw.tp_value = childregs->regs[3];
	} else {
		memset(childregs, 0, sizeof(struct pt_regs));
		childregs->pstate = PSR_MODE_EL1h;
		if (IS_ENABLED(CONFIG_ARM64_UAO) &&
		    cpus_have_const_cap(ARM64_HAS_UAO))
			childregs->pstate |= PSR_UAO_BIT;

		if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE)
			childregs->pstate |= PSR_SSBS_BIT;

		if (system_uses_irq_prio_masking())
			childregs->pmr_save = GIC_PRIO_IRQON;

		p->thread.cpu_context.x19 = stack_start;
		p->thread.cpu_context.x20 = stk_sz;
	}
	p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
	p->thread.cpu_context.sp = (unsigned long)childregs;

	ptrace_hw_copy_thread(p);

	return 0;
}

/* 
 * Note that this implementation of ptrace behaves differently from vanilla
 * ptrace.  Contrary to what the man page says, in the PTRACE_PEEKTEXT,
 * PTRACE_PEEKDATA, and PTRACE_PEEKUSER requests the data variable is not
 * ignored.  Instead, the data variable is expected to point at a location
 * (in user space) where the result of the ptrace call is written (instead of
 * being returned).
 */
long arch_ptrace(struct task_struct *child, long request, long addr, long data)
{
    int ret;
    unsigned long __user *datap = (unsigned long __user *)data;

    switch (request) {
        /* Read word at location address. */ 
        case PTRACE_PEEKTEXT:
        case PTRACE_PEEKDATA:
            ret = generic_ptrace_peekdata(child, addr, data);
            break;

        /* Read the word at location address in the USER area. */
        case PTRACE_PEEKUSR: {
            unsigned long tmp;

            ret = -EIO;
            if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
                break;

            tmp = get_reg(child, addr >> 2);
            ret = put_user(tmp, datap);
            break;
        }
        
        /* Write the word at location address. */
        case PTRACE_POKETEXT:
        case PTRACE_POKEDATA:
            ret = generic_ptrace_pokedata(child, addr, data);
            break;
 
         /* Write the word at location address in the USER area. */
        case PTRACE_POKEUSR:
            ret = -EIO;
            if ((addr & 3) || addr < 0 || addr > PT_MAX << 2)
                break;

            addr >>= 2;

            if (addr == PT_DCCR) {
                /* don't allow the tracing process to change stuff like
                 * interrupt enable, kernel/user bit, dma enables etc.
                 */
                data &= DCCR_MASK;
                data |= get_reg(child, PT_DCCR) & ~DCCR_MASK;
            }
            if (put_reg(child, addr, data))
                break;
            ret = 0;
            break;

        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;
            
            /* TODO: make sure any pending breakpoint is killed */
            wake_up_process(child);
            ret = 0;
            
            break;
        
         /* Make the child exit by sending it a sigkill. */
        case PTRACE_KILL:
            ret = 0;
            
            if (child->exit_state == EXIT_ZOMBIE)
                break;
            
            child->exit_code = SIGKILL;
            
            /* TODO: make sure any pending breakpoint is killed */
            wake_up_process(child);
            break;

        /* Set the trap flag. */
        case PTRACE_SINGLESTEP:
            ret = -EIO;
            
            if (!valid_signal(data))
                break;
//.........这里部分代码省略.........

/*
 * This creates a new process as a copy of the old one,
 * but does not actually start it yet.
 *
 * It copies the registers, and all the appropriate
 * parts of the process environment (as per the clone
 * flags). The actual kick-off is left to the caller.
 */
static task_t *copy_process(unsigned long clone_flags,
				 unsigned long stack_start,
				 struct pt_regs *regs,
				 unsigned long stack_size,
				 int __user *parent_tidptr,
				 int __user *child_tidptr,
				 int pid)
{
	int retval;
	struct task_struct *p = NULL;

	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
		return ERR_PTR(-EINVAL);

	/*
	 * Thread groups must share signals as well, and detached threads
	 * can only be started up within the thread group.
	 */
	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
		return ERR_PTR(-EINVAL);

	/*
	 * Shared signal handlers imply shared VM. By way of the above,
	 * thread groups also imply shared VM. Blocking this case allows
	 * for various simplifications in other code.
	 */
	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
		return ERR_PTR(-EINVAL);

	retval = security_task_create(clone_flags);
	if (retval)
		goto fork_out;

	retval = -ENOMEM;
	p = dup_task_struct(current);
	if (!p)
		goto fork_out;

	retval = -EAGAIN;
	if (atomic_read(&p->user->processes) >=
			p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
		if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
				p->user != &root_user)
			goto bad_fork_free;
	}

	atomic_inc(&p->user->__count);
	atomic_inc(&p->user->processes);
	get_group_info(p->group_info);

	/*
	 * If multiple threads are within copy_process(), then this check
	 * triggers too late. This doesn't hurt, the check is only there
	 * to stop root fork bombs.
	 */
	if (nr_threads >= max_threads)
		goto bad_fork_cleanup_count;

	if (!try_module_get(p->thread_info->exec_domain->module))
		goto bad_fork_cleanup_count;

	if (p->binfmt && !try_module_get(p->binfmt->module))
		goto bad_fork_cleanup_put_domain;

	p->did_exec = 0;
	copy_flags(clone_flags, p);
	p->pid = pid;
	retval = -EFAULT;
	if (clone_flags & CLONE_PARENT_SETTID)
		if (put_user(p->pid, parent_tidptr))
			goto bad_fork_cleanup;

	p->proc_dentry = NULL;

	INIT_LIST_HEAD(&p->children);
	INIT_LIST_HEAD(&p->sibling);
	p->vfork_done = NULL;
	spin_lock_init(&p->alloc_lock);
	spin_lock_init(&p->proc_lock);

	clear_tsk_thread_flag(p, TIF_SIGPENDING);
	init_sigpending(&p->pending);

	p->utime = cputime_zero;
	p->stime = cputime_zero;
 	p->sched_time = 0;
	p->rchar = 0;		/* I/O counter: bytes read */
	p->wchar = 0;		/* I/O counter: bytes written */
	p->syscr = 0;		/* I/O counter: read syscalls */
	p->syscw = 0;		/* I/O counter: write syscalls */
	acct_clear_integrals(p);

//.........这里部分代码省略.........

void user_disable_single_step(struct task_struct *child)
{
	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
}

//.........这里部分代码省略.........
			    && addr + sizeof(data) <= L1_DATA_B_START + L1_DATA_B_LENGTH) {
				memcpy((void *)(addr), &data, sizeof(data));
				copied = sizeof(data);

			} else if (addr >= FIXED_CODE_START
			    && addr + sizeof(data) <= FIXED_CODE_END) {
				copy_to_user_page(0, 0, 0, (void *)(addr), &data, sizeof(data));
				copied = sizeof(data);

			} else
				copied = access_process_vm(child, addr, &data,
							   sizeof(data), 1);

			pr_debug("ptrace: copied size %d\n", copied);
			if (copied != sizeof(data))
				break;
			ret = 0;
			break;
		}

	case PTRACE_POKEUSR:	/* write the word at location addr in the USER area */
		ret = -EIO;
		if ((addr & 3) || (addr > (sizeof(struct pt_regs) + 16))) {
			printk(KERN_WARNING "ptrace error : POKEUSR: temporarily returning 0\n");
			break;
		}

		if (addr >= (sizeof(struct pt_regs))) {
			ret = 0;
			break;
		}
		if (addr == PT_SYSCFG) {
			data &= SYSCFG_MASK;
			data |= get_reg(child, PT_SYSCFG);
		}
		ret = put_reg(child, addr, data);
		break;

	case PTRACE_SYSCALL:	/* continue and stop at next (return from) syscall */
	case PTRACE_CONT:	/* restart after signal. */
		pr_debug("ptrace: syscall/cont\n");

		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;
		ptrace_disable(child);
		pr_debug("ptrace: before wake_up_process\n");
		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->exit_state == EXIT_ZOMBIE)	/* already dead */
			break;
		child->exit_code = SIGKILL;
		ptrace_disable(child);
		wake_up_process(child);
		break;

	case PTRACE_SINGLESTEP:	/* set the trap flag. */
		pr_debug("ptrace: single step\n");
		ret = -EIO;
		if (!valid_signal(data))
			break;
		clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
		ptrace_enable(child);
		child->exit_code = data;
		wake_up_process(child);
		ret = 0;
		break;

	case PTRACE_GETREGS:
		/* Get all gp regs from the child. */
		ret = ptrace_getregs(child, datap);
		break;

	case PTRACE_SETREGS:
		printk(KERN_WARNING "ptrace: SETREGS: **** NOT IMPLEMENTED ***\n");
		/* Set all gp regs in the child. */
		ret = 0;
		break;

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

	return ret;
}