From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC PATCH v3 0/3] arm64/kernel: get rid of GCC large model code
Date: Mon, 5 Mar 2018 17:40:58 +0000 [thread overview]
Message-ID: <20180305174057.GC13385@arm.com> (raw)
In-Reply-To: <20180214113645.16793-1-ard.biesheuvel@linaro.org>
On Wed, Feb 14, 2018 at 11:36:42AM +0000, Ard Biesheuvel wrote:
> I am resending this as an RFC, because I'd like to understand whether
> anyone else shares my concern, or whether I am being overly paranoid.
>
> v2 blurb:
>
> GCC's large model uses literal pools to emit cross object symbol
> references rather than movz/movk sequences, resulting in data items
> mixed in the with executable code in modules' .text segments, reducing
> cache utilization, but also potentially resulting in the creation of
> code gadgets that are exploitable under speculative execution.
>
> We are using GCC's large model for two separate reasons, both of which can
> be worked around rather easily:
> - KASLR uses it to move modules and the kernel very far apart, which is
> not really needed,
> - the Cortex-A53 erratum code uses it to avoid ADRP instruction altogether,
> which can be replaced by selective patching of only the ADRP instructions
> that are affected by the erratum
I think this is a sensible thing to do, cheers.
Will
prev parent reply other threads:[~2018-03-05 17:40 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-14 11:36 [RFC PATCH v3 0/3] arm64/kernel: get rid of GCC large model code Ard Biesheuvel
2018-02-14 11:36 ` [RFC PATCH v3 1/3] arm64/kernel: kaslr: reduce module randomization range to 4 GB Ard Biesheuvel
2018-02-23 17:00 ` Mark Rutland
2018-02-23 17:07 ` Ard Biesheuvel
2018-03-05 12:22 ` Ard Biesheuvel
2018-02-14 11:36 ` [RFC PATCH v3 2/3] arm64/kernel: don't ban ADRP to work around Cortex-A53 erratum #843419 Ard Biesheuvel
2018-02-23 17:15 ` Mark Rutland
2018-02-23 17:17 ` Ard Biesheuvel
2018-02-23 17:25 ` Mark Rutland
2018-02-24 17:54 ` Ard Biesheuvel
2018-02-26 10:53 ` Mark Rutland
2018-03-05 17:18 ` Will Deacon
2018-03-05 17:26 ` Ard Biesheuvel
2018-03-05 17:34 ` Will Deacon
2018-03-05 17:41 ` Ard Biesheuvel
2018-03-05 17:42 ` Will Deacon
2018-02-14 11:36 ` [RFC PATCH v3 3/3] arm64/kernel: enable A53 erratum #8434319 handling at runtime Ard Biesheuvel
2018-02-23 17:23 ` Mark Rutland
2018-03-05 17:22 ` Will Deacon
2018-03-05 17:29 ` Ard Biesheuvel
2018-03-05 17:40 ` Will Deacon
2018-03-05 18:01 ` Ard Biesheuvel
2018-03-06 15:25 ` Will Deacon
2018-03-05 17:40 ` Will Deacon [this message]
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