On Thu, Mar 16, 2023 at 10:20:59PM +0000, Usama Arif wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
> Instead of relying purely on the special-case wrapper in bringup_cpu()
> to pass the idle thread to __cpu_up(), expose idle_thread_get() so that
> the architecture code can obtain it directly when necessary.
>
> This will be useful when the existing __cpu_up() is split into multiple
> phases, only *one* of which will actually need the idle thread.
>
> If the architecture code is to register its new pre-bringup states with
> the cpuhp core, having a special-case wrapper to pass extra arguments is
> non-trivial and it's easier just to let the arch register its function
> pointer to be invoked with the standard API.
>
> To reduce duplication, move the shadow stack reset and kasan unpoisoning
I was wondering what "shadow stack" as that set is not upstream yet. You mean
"shadow call stack" which is apparently something else,
compiler-generated, purely software thing.
> into idle_thread_get() too.
Frankly, I don't think resetting shadow call stack and kasan state
belongs in a function which returns the idle thread. Even more so if you
have to add an @unpoison param which is false sometimes and sometimes
true, depending on where you call the function.
I think you should have a helper
tsk_reset_stacks(struct task_struct *tsk);
or so which is called where @unpoison == true instead of having a getter
function do something unrelated too.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
