12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788 |
- // 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->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, 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];
- 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 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)
- {
- unsigned long ncsw;
- unsigned int state;
- if (target == current)
- return collect_syscall(target, info);
- state = READ_ONCE(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;
- }
|