// SPDX-License-Identifier: GPL-2.0#include <linux/ptrace.h>#include <linux/sched.h>#include <linux/sched/task_stack.h>#include <linux/export.h>#include <asm/syscall.h> static int collect_syscall(struct task_struct *target, struct syscall_info *info){	struct pt_regs *regs; 	if (!try_get_task_stack(target)) {		/* Task has no stack, so the task isn't in a syscall. */		memset(info, 0, sizeof(*info));		info->data.nr = -1;		return 0;	} 	regs = task_pt_regs(target);	if (unlikely(!regs)) {		put_task_stack(target);		return -EAGAIN;	} 	info->sp = user_stack_pointer(regs);	info->data.instruction_pointer = instruction_pointer(regs); 	info->data.nr = syscall_get_nr(target, regs);	if (info->data.nr != -1L)		syscall_get_arguments(target, regs,				      (unsigned long *)&info->data.args[0]); 	put_task_stack(target);	return 0;} /** * task_current_syscall - Discover what a blocked task is doing. * @target:		thread to examine * @info:		structure with the following fields: *			 .sp        - filled with user stack pointer *			 .data.nr   - filled with system call number or -1 *			 .data.args - filled with @maxargs system call arguments *			 .data.instruction_pointer - filled with user PC * * If @target is blocked in a system call, returns zero with @info.data.nr * set to the the call's number and @info.data.args filled in with its * arguments. Registers not used for system call arguments may not be available * and it is not kosher to use &struct user_regset calls while the system * call is still in progress.  Note we may get this result if @target * has finished its system call but not yet returned to user mode, such * as when it's stopped for signal handling or syscall exit tracing. * * If @target is blocked in the kernel during a fault or exception, * returns zero with *@info.data.nr set to -1 and does not fill in * @info.data.args. If so, it's now safe to examine @target using * &struct user_regset get() calls as long as we're sure @target won't return * to user mode. * * Returns -%EAGAIN if @target does not remain blocked. */int task_current_syscall(struct task_struct *target, struct syscall_info *info){	long state;	unsigned long ncsw; 	if (target == current)		return collect_syscall(target, info); 	state = target->state;	if (unlikely(!state))		return -EAGAIN; 	ncsw = wait_task_inactive(target, state);	if (unlikely(!ncsw) ||	    unlikely(collect_syscall(target, info)) ||	    unlikely(wait_task_inactive(target, state) != ncsw))		return -EAGAIN; 	return 0;}