Re: [PATCH v6 22/25] x86/asm: annotate indirect jumps

Sami Tolvanen
2020-11-10T04:48:16Z

On Mon, Nov 9, 2020 at 6:29 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> How would I recreate all these warnings?

You can reproduce all of these using a normal gcc build without any of
the LTO patches by running objtool check -arfld vmlinux.o. However,
with gcc you'll see even more warnings due to duplicate symbol names,
as Peter pointed out elsewhere in the thread, so I looked at only the
warnings that objtool also prints with LTO.

Note that the LTO series contains a patch to split noinstr validation
from --vmlinux, as we need to run objtool here even if
CONFIG_VMLINUX_VALIDATION isn't selected, so I have not looked at the
noinstr warnings. The latest LTO tree is available here:

https://github.com/samitolvanen/linux/commits/clang-lto

> Here's the patch for hopefully making the warnings more helpful:

Thanks, I'll give it a try.

Sami