1SYSCALL_GET_NR(9) Machine State SYSCALL_GET_NR(9)
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6 syscall_get_nr - find what system call a task is executing
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9 int syscall_get_nr(struct task_struct * task, struct pt_regs * regs);
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12 task
13 task of interest, must be blocked
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15 regs
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17 task_pt_regs of task
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20 If task is executing a system call or is at system call tracing about
21 to attempt one, returns the system call number. If task is not
22 executing a system call, i.e. it´s blocked inside the kernel for a
23 fault or signal, returns -1.
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25 Note this returns int even on 64-bit machines. Only 32 bits of system
26 call number can be meaningful. If the actual arch value is 64 bits,
27 this truncates to 32 bits so 0xffffffff means -1.
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29 It´s only valid to call this when task is known to be blocked.
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33Kernel Hackers Manual 2.6. June 2019 SYSCALL_GET_NR(9)