linux-kernel - Re: [PATCH v2 0/6] ARM64: meson: GXBaby (S905) and Vega S95 enablement

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20160302135216.GB11670@leverpostej>
Date:	Wed, 2 Mar 2016 13:52:16 +0000
From:	Mark Rutland <mark.rutland@....com>
To:	Andreas Färber <afaerber@...e.de>
Cc:	linux-meson@...glegroups.com, Carlo Caione <carlo@...one.org>,
	linux-arm-kernel@...ts.infradead.org,
	Matthias Brugger <mbrugger@...e.com>,
	Nicolas Saenz <nicolassaenzj@...il.com>,
	André Przywara <andre.przywara@....com>,
	Sudeep Holla <sudeep.holla@....com>,
	devicetree@...r.kernel.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/6] ARM64: meson: GXBaby (S905) and Vega S95
 enablement

On Wed, Mar 02, 2016 at 03:34:55AM +0100, Andreas Färber wrote:
> Hello,
> 
> This series adds initial support for the Amlogic S905 based
> Tronsmart Vega S95 Pro, Meta and Telos TV boxes.
> 
> v2:
> * Pick up previously acked "tronsmart" patch instead (Matthias)
> * Drop ARM_GIC selection (Sudeep)
> * Change some compatible strings (Sudeep, André)
> * Squash some node changes/additions
> 
> Note: On the Vega S95 I need to change TEXT_OFFSET as follows,
> in order to avoid the vendor U-Boot overwriting itself (fwiu);
> for the Mini Mx that's reportedly not necessary.
> 
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 354d75402ace..b7cebdb8b1ce 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -62,7 +62,7 @@ head-y                := arch/arm64/kernel/head.o
>  ifeq ($(CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET), y)
>  TEXT_OFFSET := $(shell awk 'BEGIN {srand(); printf "0x%03x000\n", int(512 * rand())}')
>  else
> -TEXT_OFFSET := 0x00080000
> +TEXT_OFFSET := 0x01080000
>  endif
>  
>  # KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - 3)) - (1 << 61)

Absolute NAK to this. TEXT_OFFSET is not open for platform-specific
modification.

Why can you not just load the Image 2MB higher regardless? Does the
U-Boot on this platform actually read TEXT_OFFSET and take it into
account?

> This in turn runs into an apparent regression introduced with the
> text offset randomization:
> 
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index 6ebd204da16a..afdec27c8871 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -48,7 +48,7 @@
>  #elif (PAGE_OFFSET & 0x1fffff) != 0
>  #error PAGE_OFFSET must be at least 2MB aligned
>  #elif TEXT_OFFSET > 0x1fffff
> -#error TEXT_OFFSET must be less than 2MB
> +//#error TEXT_OFFSET must be less than 2MB
>  #endif
>  
>  #define KERNEL_START   _text

This is not a regression. As above, TEXT_OFFSET is not supposed to be
modified in a platform-specific manner.

Mark.