Re: [PATCH v2] x86/static_call: Fix __static_call_fixup()

Josh Poimboeuf
2023-08-16T21:03:39Z

On Wed, Aug 16, 2023 at 12:44:19PM +0200, Peter Zijlstra wrote:
>
> Christian reported spurious module load crashes after some of Song's
> module memory layout patches.
>
> Turns out that if the very last instruction on the very last page of the
> module is a 'JMP __x86_return_thunk' then __static_call_fixup() will
> trip a fault and die.
>
> And while the module rework made this slightly more likely to happen,
> it's always been possible.
>
> Fixes: ee88d363d156 ("x86,static_call: Use alternative RET encoding")
> Reported-by: Christian Bricart <christian@bricart.de>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>

--
Josh