1 #include <linux/ptrace.h>
2 #include <linux/sched.h>
3 #include <linux/module.h>
4 #include <asm/syscall.h>
6 static int collect_syscall(struct task_struct
*target
, long *callno
,
7 unsigned long args
[6], unsigned int maxargs
,
8 unsigned long *sp
, unsigned long *pc
)
10 struct pt_regs
*regs
= task_pt_regs(target
);
14 *sp
= user_stack_pointer(regs
);
15 *pc
= instruction_pointer(regs
);
17 *callno
= syscall_get_nr(target
, regs
);
18 if (*callno
!= -1L && maxargs
> 0)
19 syscall_get_arguments(target
, regs
, 0, maxargs
, args
);
25 * task_current_syscall - Discover what a blocked task is doing.
26 * @target: thread to examine
27 * @callno: filled with system call number or -1
28 * @args: filled with @maxargs system call arguments
29 * @maxargs: number of elements in @args to fill
30 * @sp: filled with user stack pointer
31 * @pc: filled with user PC
33 * If @target is blocked in a system call, returns zero with *@callno
34 * set to the the call's number and @args filled in with its arguments.
35 * Registers not used for system call arguments may not be available and
36 * it is not kosher to use &struct user_regset calls while the system
37 * call is still in progress. Note we may get this result if @target
38 * has finished its system call but not yet returned to user mode, such
39 * as when it's stopped for signal handling or syscall exit tracing.
41 * If @target is blocked in the kernel during a fault or exception,
42 * returns zero with *@callno set to -1 and does not fill in @args.
43 * If so, it's now safe to examine @target using &struct user_regset
44 * get() calls as long as we're sure @target won't return to user mode.
46 * Returns -%EAGAIN if @target does not remain blocked.
48 * Returns -%EINVAL if @maxargs is too large (maximum is six).
50 int task_current_syscall(struct task_struct
*target
, long *callno
,
51 unsigned long args
[6], unsigned int maxargs
,
52 unsigned long *sp
, unsigned long *pc
)
57 if (unlikely(maxargs
> 6))
60 if (target
== current
)
61 return collect_syscall(target
, callno
, args
, maxargs
, sp
, pc
);
63 state
= target
->state
;
67 ncsw
= wait_task_inactive(target
, state
);
68 if (unlikely(!ncsw
) ||
69 unlikely(collect_syscall(target
, callno
, args
, maxargs
, sp
, pc
)) ||
70 unlikely(wait_task_inactive(target
, state
) != ncsw
))
75 EXPORT_SYMBOL_GPL(task_current_syscall
);
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