kernel-hardening - Re: [PATCH v9 00/16] Add support for Clang LTO

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Date: Sat, 9 Jan 2021 16:46:21 +0100
From: Sedat Dilek <sedat.dilek@...il.com>
To: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Sami Tolvanen <samitolvanen@...gle.com>, Masahiro Yamada <masahiroy@...nel.org>, 
	Steven Rostedt <rostedt@...dmis.org>, Will Deacon <will@...nel.org>, 
	Peter Zijlstra <peterz@...radead.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Kees Cook <keescook@...omium.org>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, 
	Clang-Built-Linux ML <clang-built-linux@...glegroups.com>, kernel-hardening@...ts.openwall.com, 
	linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pci@...r.kernel.org
Subject: Re: [PATCH v9 00/16] Add support for Clang LTO

On Sat, Jan 9, 2021 at 4:36 PM Josh Poimboeuf <jpoimboe@...hat.com> wrote:
>
> On Sat, Jan 09, 2021 at 03:54:20PM +0100, Sedat Dilek wrote:
> > I am interested in having Clang LTO (Clang-CFI) for x86-64 working and
> > help with testing.
> >
> > I tried the Git tree mentioned in [3] <jpoimboe.git#objtool-vmlinux>
> > (together with changes from <peterz.git#x86/urgent>).
> >
> > I only see in my build-log...
> >
> > drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:
> > eb_relocate_parse_slow()+0x3d0: stack state mismatch: cfa1=7+120
> > cfa2=-1+0
> > drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool:
> > eb_copy_relocations()+0x229: stack state mismatch: cfa1=7+120
> > cfa2=-1+0
> >
> > ...which was reported and worked on in [1].
> >
> > This is with Clang-IAS version 11.0.1.
> >
> > Unfortunately, the recent changes in <samitolvanen.github#clang-cfi>
> > do not cleanly apply with Josh stuff.
> > My intention/wish was to report this combination of patchsets "heals"
> > a lot of objtool-warnings for vmlinux.o I observed with Clang-CFI.
> >
> > Is it possible to have a Git branch where Josh's objtool-vmlinux is
> > working together with Clang-LTO?
> > For testing purposes.
>
> I updated my branch with my most recent work from before the holidays,
> can you try it now?  It still doesn't fix any of the crypto warnings,
> but I'll do that in a separate set after posting these next week.
>

Thanks, Josh.

Did you push it (oh ah push it push it really really really good...)
to your remote Git please :-).

- Sedat -

[1] https://www.youtube.com/watch?v=vCadcBR95oU

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