From: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
To: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Mark Rutland <Mark.Rutland-5wv7dgnIgG8@public.gmane.org>,
"msalter-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<msalter-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org"
<matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Catalin Marinas <Catalin.Marinas-5wv7dgnIgG8@public.gmane.org>,
"leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org"
<leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Subject: Re: [RFC PATCH] arm64/efi: isolate EFI stub from the kernel proper
Date: Tue, 15 Sep 2015 15:46:29 +0100 [thread overview]
Message-ID: <20150915144629.GG31157@arm.com> (raw)
In-Reply-To: <1442311903-19213-1-git-send-email-ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
On Tue, Sep 15, 2015 at 11:11:43AM +0100, Ard Biesheuvel wrote:
> Since arm64 does not use a builtin decompressor, the EFI stub is built
> into the kernel proper. So far, this has been working fine, but actually,
> since the stub is in fact a PE/COFF relocatable binary that is executed
> at an unknown offset in the 1:1 mapping provided by the UEFI firmware, we
> should not be seamlessly sharing code with the kernel proper, which is a
> position dependent executable linked at a high virtual offset.
>
> So instead, separate the contents of libstub and its dependencies, by
> putting them into their own namespace by prefixing all of its symbols
> with __efistub. This way, we have tight control over what parts of the
> kernel proper are referenced by the stub.
Could we add an __efistub annotation to spit out warnings if the stub
calls into unexpected kernel code, like we do for __init/__ref?
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH] arm64/efi: isolate EFI stub from the kernel proper
Date: Tue, 15 Sep 2015 15:46:29 +0100 [thread overview]
Message-ID: <20150915144629.GG31157@arm.com> (raw)
In-Reply-To: <1442311903-19213-1-git-send-email-ard.biesheuvel@linaro.org>
On Tue, Sep 15, 2015 at 11:11:43AM +0100, Ard Biesheuvel wrote:
> Since arm64 does not use a builtin decompressor, the EFI stub is built
> into the kernel proper. So far, this has been working fine, but actually,
> since the stub is in fact a PE/COFF relocatable binary that is executed
> at an unknown offset in the 1:1 mapping provided by the UEFI firmware, we
> should not be seamlessly sharing code with the kernel proper, which is a
> position dependent executable linked at a high virtual offset.
>
> So instead, separate the contents of libstub and its dependencies, by
> putting them into their own namespace by prefixing all of its symbols
> with __efistub. This way, we have tight control over what parts of the
> kernel proper are referenced by the stub.
Could we add an __efistub annotation to spit out warnings if the stub
calls into unexpected kernel code, like we do for __init/__ref?
Will
next prev parent reply other threads:[~2015-09-15 14:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-15 10:11 [RFC PATCH] arm64/efi: isolate EFI stub from the kernel proper Ard Biesheuvel
2015-09-15 10:11 ` Ard Biesheuvel
[not found] ` <1442311903-19213-1-git-send-email-ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2015-09-15 14:46 ` Will Deacon [this message]
2015-09-15 14:46 ` Will Deacon
[not found] ` <20150915144629.GG31157-5wv7dgnIgG8@public.gmane.org>
2015-09-15 15:24 ` Ard Biesheuvel
2015-09-15 15:24 ` Ard Biesheuvel
[not found] ` <CAKv+Gu8j1APZkGnFhZArNAtoyYOokP2bgemYH5n7Pn8jQ1b1XA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-09-17 10:51 ` Ard Biesheuvel
2015-09-17 10:51 ` Ard Biesheuvel
[not found] ` <CAKv+Gu_KuOxA+EMSV0YcQR9rmO+R=-y9tivweNym3o+E4DrnHQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-09-17 16:09 ` Will Deacon
2015-09-17 16:09 ` Will Deacon
[not found] ` <20150917160925.GP25634-5wv7dgnIgG8@public.gmane.org>
2015-09-23 16:44 ` Ard Biesheuvel
2015-09-23 16:44 ` Ard Biesheuvel
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