PTRACE_SYSCALL analysis

[Piotr S. <Pio...@ar...>]

Hello. I'm writing to ask how strace is able to distinguish a syscall entry from a syscall exit with ptrace(PTRACE_SYSCALL...)? On x86_64, it seems you can rely on the -ENOSYS value in RAX. However, for some reason I can't pick up an analogous coherent pattern on ARM. I'd be deeply indebted for sheding some light on the issue.

Best regards
Piotr

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