On December 12, 2024 3:49:37 PM EST, Linus Walleij <[email protected]>
wrote:
>On Wed, Dec 11, 2024 at 7:53 PM Steven Rostedt <[email protected]> wrote:
>
>> From: Steven Rostedt <[email protected]>
>>
>> A bug was discovered where the idle shadow stacks were not initialized
>> for offline CPUs when starting function graph tracer, and when they came
>> online they were not traced due to the missing shadow stack. To fix
>> this, the idle task shadow stack initialization was moved to using the
>> CPU hotplug callbacks. But it removed the initialization when the
>> function graph was enabled. The problem here is that the hotplug
>> callbacks are called when the CPUs come online, but the idle shadow
>> stack initialization only happens if function graph is currently
>> active. This caused the online CPUs to not get their shadow stack
>> initialized.
>>
>> The idle shadow stack initialization still needs to be done when the
>> function graph is registered, as they will not be allocated if function
>> graph is not registered.
>>
>> Cc: [email protected]
>> Fixes: 2c02f7375e65 ("fgraph: Use CPU hotplug mechanism to initialize idle
>> shadow stacks")
>> Reported-by: Linus Walleij <[email protected]>
>> Closes:
>> https://lore.kernel.org/all/CACRpkdaTBrHwRbbrphVy-=sedz6mssxhtkypotlrtq+dgga...@mail.gmail.com/
>> Signed-off-by: Steven Rostedt (Google) <[email protected]>
>
>Yep that solves my issue and I can go on debugging my boot!
>Tested-by: Linus Walleij <[email protected]>
>
>Thanks for patching this up so quickly Stephen, you're the best.
>
No problem, but I don't know who this "Stephen" is? ;-)
-- Steve
>Yours,
>Linus Walleij
