On Wed, 16 Oct 2019 13:33:12 +0200
Miroslav Benes [off-list ref] wrote:

Livepatch uses ftrace for redirection to new patched functions. It means
that if ftrace is disabled, all live patched functions are disabled as
well. Toggling global 'ftrace_enabled' sysctl thus affect it directly.
It is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.

Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be
disabled by disabling ftrace_enabled. Equally, a callback with the flag
set cannot be registered if ftrace_enabled is disabled.

v2->v3:
- ftrace_enabled explicitly set to true
- selftest from Joe Lawrence (I just split it to two patches)
- typo fix

v1->v2:
- different logic, proposed by Joe Lawrence

Joe Lawrence (2):
  selftests/livepatch: Make dynamic debug setup and restore generic
  selftests/livepatch: Test interaction with ftrace_enabled

Miroslav Benes (1):
  ftrace: Introduce PERMANENT ftrace_ops flag

Would you like me to take all three patches through my tree?

-- Steve