Hi Andreas, On 26/07/20 11:05 PM, Andreas Schwab wrote:
On Jul 26 2020, Michael Schmitz wrote:OK, that's -EPERM. Reading the comment in asm/errno.h, -ENOSYS is not a legitimate return code for syscalls to use.ENOSYS is the correct error number for unimplemented syscalls.
Yes, but that wasn't my point. -ENOSYS is returned by the syscall dispatcher in entry.S for unimplemented syscalls, but should never be returned by syscalls that are implemented to avoid messing up syscall detection by user code.
What I attempt to do is support syscall filtering. Returning -ENOSYS in that case would run the risk of masking existing syscalls to user probe code just because the user process happens to have insufficient privileges.
Please correct me if that is actually the expected behaviour here. Cheers, Michael
Andreas.