On 01/14, Andrii Nakryiko wrote:

Should we just fix whoever is blocking kernel-internal special syscall
(sys_uretprobe)?

Well, we can add __NR_uretprobe to mode1_syscalls[] but this won't
really help.

We can't "fix" the existing user-space setups which can nack any
"unnecessary/unknown" syscall.

What would happen if someone blocked that other
special kernel-internal syscall for signal handling (can't remember
the name,

sys_rt_sigreturn().

Yes, the task will crash after return from the signal handler if this
syscall is filtered out.

But, unlike sys_uretprobe(), sys_rt_sigreturn() is old, so the existing
setups must know that sigreturn() should be respected...

Oleg.