Re: [PATCH v3 10/21] objtool: Ignore jumps to the end of the function for checksum runs

On Wed, May 13, 2026 at 09:36:17AM +0200, Peter Zijlstra wrote:

On Tue, May 12, 2026 at 08:33:44PM -0700, Josh Poimboeuf wrote:

quoted

Sometimes Clang arm64 code jumps to the end of the function for UB.
No need to make that an error for checksum runs.

I'm not sure I understand the rationale. If the compiler trips UB, we
want to be complaining about that no?

Same as when clang just stops code-gen, also something we commonly see
when it hits UB.

Right, but I guess the question is, should we always warn about that, or
should we only warn about it when doing stack validation or ORC or some
other CFG-traversing thing?

The checksum thing is only used when manually enabled by klp-build
(never for normal kernel builds), so it would be a weird spot to report
the Clang "jumping to the end of the function" UB.

If we care about that for arm64 then the UB check probably belongs in a
new standalone objtool command that would get used during a regular
kernel build.

-- 
Josh