blob: 71ffcf5aff122a1ee2a80a69befcf37b392d0704 [file] [log] [blame]
// 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)
unsigned long args[6] = { };
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-> = -1;
return 0;
regs = task_pt_regs(target);
if (unlikely(!regs)) {
return -EAGAIN;
info->sp = user_stack_pointer(regs);
info->data.instruction_pointer = instruction_pointer(regs);
info-> = syscall_get_nr(target, regs);
if (info-> != -1L)
syscall_get_arguments(target, regs, args);
info->data.args[0] = args[0];
info->data.args[1] = args[1];
info->data.args[2] = args[2];
info->data.args[3] = args[3];
info->data.args[4] = args[4];
info->data.args[5] = args[5];
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
* - 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
* set to the the call's number and 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 * set to -1 and does not fill in
* 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;