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74 lines
2.4 KiB
74 lines
2.4 KiB
#include <linux/ptrace.h> |
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#include <linux/sched.h> |
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#include <linux/export.h> |
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#include <asm/syscall.h> |
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static int collect_syscall(struct task_struct *target, long *callno, |
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unsigned long args[6], unsigned int maxargs, |
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unsigned long *sp, unsigned long *pc) |
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{ |
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struct pt_regs *regs = task_pt_regs(target); |
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if (unlikely(!regs)) |
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return -EAGAIN; |
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*sp = user_stack_pointer(regs); |
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*pc = instruction_pointer(regs); |
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*callno = syscall_get_nr(target, regs); |
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if (*callno != -1L && maxargs > 0) |
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syscall_get_arguments(target, regs, 0, maxargs, args); |
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return 0; |
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} |
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/** |
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* task_current_syscall - Discover what a blocked task is doing. |
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* @target: thread to examine |
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* @callno: filled with system call number or -1 |
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* @args: filled with @maxargs system call arguments |
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* @maxargs: number of elements in @args to fill |
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* @sp: filled with user stack pointer |
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* @pc: filled with user PC |
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* |
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* If @target is blocked in a system call, returns zero with *@callno |
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* set to the the call's number and @args filled in with its arguments. |
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* Registers not used for system call arguments may not be available and |
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* it is not kosher to use &struct user_regset calls while the system |
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* call is still in progress. Note we may get this result if @target |
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* has finished its system call but not yet returned to user mode, such |
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* as when it's stopped for signal handling or syscall exit tracing. |
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* |
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* If @target is blocked in the kernel during a fault or exception, |
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* returns zero with *@callno set to -1 and does not fill in @args. |
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* If so, it's now safe to examine @target using &struct user_regset |
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* get() calls as long as we're sure @target won't return to user mode. |
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* |
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* Returns -%EAGAIN if @target does not remain blocked. |
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* |
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* Returns -%EINVAL if @maxargs is too large (maximum is six). |
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*/ |
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int task_current_syscall(struct task_struct *target, long *callno, |
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unsigned long args[6], unsigned int maxargs, |
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unsigned long *sp, unsigned long *pc) |
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{ |
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long state; |
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unsigned long ncsw; |
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if (unlikely(maxargs > 6)) |
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return -EINVAL; |
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if (target == current) |
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return collect_syscall(target, callno, args, maxargs, sp, pc); |
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state = target->state; |
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if (unlikely(!state)) |
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return -EAGAIN; |
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ncsw = wait_task_inactive(target, state); |
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if (unlikely(!ncsw) || |
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unlikely(collect_syscall(target, callno, args, maxargs, sp, pc)) || |
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unlikely(wait_task_inactive(target, state) != ncsw)) |
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return -EAGAIN; |
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return 0; |
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}
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