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From: David Laight <David.Laight@ACULAB.COM>
To: 'Linus Walleij' <linus.walleij@linaro.org>,
	Will Deacon <will@kernel.org>
Cc: "Jian Cai" <jiancai@google.com>,
	"Nick Desaulniers" <ndesaulniers@google.com>,
	"Manoj Gupta" <manojgupta@google.com>,
	"Luis Lozano" <llozano@google.com>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	"Nathan Chancellor" <nathan@kernel.org>,
	"Russell King" <linux@armlinux.org.uk>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"James Morris" <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Masahiro Yamada" <masahiroy@kernel.org>,
	"Kees Cook" <keescook@chromium.org>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"Andreas Färber" <afaerber@suse.de>,
	"Ingo Molnar" <mingo@kernel.org>, "Marc Zyngier" <maz@kernel.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Mike Rapoport" <rppt@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"David Brazdil" <dbrazdil@google.com>,
	"James Morse" <james.morse@arm.com>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"linux-security-module@vger.kernel.org"
	<linux-security-module@vger.kernel.org>
Subject: RE: [PATCH v4] ARM: Implement SLS mitigation
Date: Wed, 3 Mar 2021 15:29:37 +0000	[thread overview]
Message-ID: <49e8725f29ab4ecda6d669e9216bca29@AcuMS.aculab.com> (raw)
In-Reply-To: <CACRpkdYaSEb8bAztR-s_K17K+Zqusiofwa_dSjz-cwM2+N=57A@mail.gmail.com>

From: Linus Walleij
> Sent: 03 March 2021 15:19
> 
> On Tue, Feb 23, 2021 at 11:05 AM Will Deacon <will@kernel.org> wrote:
> > On Mon, Feb 22, 2021 at 01:50:06PM -0800, Jian Cai wrote:
> > > I am not sure if there are any plans to protect assembly code and I
> > > will leave it to the Arm folks since they know a whole lot better. But
> > > even without that part, we should still have better protection,
> > > especially when overhead does not look too bad: I did some preliminary
> > > experiments on ChromeOS, code size of vmlinux increased 3%, and there
> > > were no noticeable changes to run-time performance of the benchmarks I
> > > used.
> >
> > If the mitigation is required, I'm not sure I see a lot of point in only
> > doing a half-baked job of it. It feels a bit like a box-ticking exercise,
> > in which case any overhead is too much.
> 
> I wrote some suggestions on follow-ups in my reply, and I can
> help out doing some of the patches, I think.
> 
> Since ARM32 RET is mov pc, <>
> git grep 'mov.*pc,' | wc -l gives 93 sites in arch/arm.
> I suppose these need to come out:
> 
> mov pc, lr
> dsb(nsh);
> isb();

Won't that go horribly wrong for conditional returns?

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  reply	other threads:[~2021-03-03 18:43 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-12  5:14 [PATCH] ARM: Implement Clang's " Jian Cai
2021-02-12  5:55 ` Nathan Chancellor
2021-02-12 10:41   ` David Laight
2021-02-12 19:52     ` [PATCH v2] " Jian Cai
2021-02-17  9:49       ` Will Deacon
2021-02-17 11:05         ` David Laight
2021-03-25 14:01         ` Linus Walleij
2021-02-17 18:20       ` Nick Desaulniers
2021-02-19 20:18       ` [PATCH v3] ARM: Implement " Jian Cai
2021-02-19 20:30         ` Nathan Chancellor
2021-02-19 23:08         ` [PATCH v4] " Jian Cai
2021-02-21 10:13           ` Russell King - ARM Linux admin
2021-02-22 11:58           ` Will Deacon
2021-02-22 21:50             ` Jian Cai
2021-02-23 10:04               ` Will Deacon
2021-03-03 15:18                 ` Linus Walleij
2021-03-03 15:29                   ` David Laight [this message]
2021-03-03 15:31                     ` Linus Walleij
2021-02-23  2:31           ` [PATCH v5] " Jian Cai
2021-02-23  2:35             ` Jian Cai
2021-03-03 15:04               ` Linus Walleij
2021-03-04 23:22                 ` Jian Cai
2021-03-06 12:25                   ` Linus Walleij
2021-03-10  4:43                     ` Jian Cai
2021-03-22 11:45                       ` Linus Walleij
2021-03-23 22:39                         ` Jian Cai
2021-03-05  0:53               ` [PATCH v6] " Jian Cai
2021-03-05  9:52                 ` Will Deacon
2021-03-06 12:27                   ` Linus Walleij

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