Merge branch 'always-allow-sleepable-and-fmod_ret-programs-on-syscalls'

Merge branch 'always-allow-sleepable-and-fmod_ret-programs-on-syscalls'

Viktor Malik says:

====================
Always allow sleepable and fmod_ret programs on syscalls

Both sleepable and fmod_ret programs are only allowed on selected
functions. For convenience, the error injection list was originally
used.

When error injection is disabled, that list is empty and sleepable
tracing programs, as well as fmod_ret programs, are effectively
unavailable.

This patch series addresses the issue by at least enabling sleepable and
fmod_ret programs on syscalls, if error injection is disabled. More
details on why syscalls are used can be found in [1].

[1] https://lore.kernel.org/bpf/CAADnVQK6qP8izg+k9yV0vdcT-+=axtFQ2fKw7D-2Ei-V6WS5Dw@mail.gmail.com/

Changes in v3:
- Handle LoongArch (Leon)
- Add Kumar's and Leon's acks

Changes in v2:
- Check "sys_" prefix instead of "sys" for powerpc syscalls (AI review)
- Add link to the original discussion (Kumar)
- Add explanation why arch syscall prefixes are hard-coded (Leon)
====================

Link: https://patch.msgid.link/cover.1773055375.git.vmalik@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>