tracefs splats in lockdown=confidentiality mode

[Steven Rostedt]

On Fri, 1 Nov 2019 15:08:03 -0600
dann frazier <dann.frazier at canonical.com> wrote:

> hey,
>   fyi, I'm seeing a bunch of errors from tracefs when booting 5.4-rc5 in
> lockdown=confidentiality mode:
> 
> [    1.763630] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
> [    1.772332] Could not create tracefs 'available_events' entry
> [    1.778633] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
> [    1.787095] Could not create tracefs 'set_event' entry
> [    1.792412] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
> (...)
> [    2.899481] Could not create tracefs 'set_graph_notrace' entry
> [    2.905671] Lockdown: swapper/0: use of tracefs is restricted; see man kernel_lockdown.7
> [    2.913934] ------------[ cut here ]------------
> [    2.918435] Could not register function stat for cpu 0
> [    2.923717] WARNING: CPU: 1 PID: 1 at kernel/trace/ftrace.c:987 ftrace_init_tracefs_toplevel+0x168/0x1bc
> [    2.933939] Modules linked in:
> [    2.937290] CPU: 1 PID: 1 Comm: 

Looks to me that it's working as designed ;-)

I'm guessing we could quiet these warnings for boot up though. :-/

But there should be at least one message that states that the tracefs
files are not being created due to lockdown.

-- Steve