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Date: Mon, 9 Nov 2020 20:48:01 -0800
From: Sami Tolvanen <>
To: Josh Poimboeuf <>
Cc: Peter Zijlstra <>, Jann Horn <>, 
	"the arch/x86 maintainers" <>, Masahiro Yamada <>, 
	Steven Rostedt <>, Will Deacon <>, 
	Greg Kroah-Hartman <>, "Paul E. McKenney" <>, 
	Kees Cook <>, Nick Desaulniers <>, 
	clang-built-linux <>, 
	Kernel Hardening <>, 
	linux-arch <>, 
	Linux ARM <>, 
	linux-kbuild <>, kernel list <>,
Subject: Re: [PATCH v6 22/25] x86/asm: annotate indirect jumps

On Mon, Nov 9, 2020 at 6:29 PM Josh Poimboeuf <> 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:

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

Thanks, I'll give it a try.


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