linux-kernel - Re: [PATCHv2] arm64: Fix R/O permissions in mark_rodata

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Message-ID: <564A5DC8.9090307@redhat.com>
Date:	Mon, 16 Nov 2015 14:50:48 -0800
From:	Laura Abbott <labbott@...hat.com>
To:	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Laura Abbott <labbott@...oraproject.org>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] arm64: Fix R/O permissions in mark_rodata_ro

On 11/14/2015 11:38 PM, Ard Biesheuvel wrote:
> On 12 November 2015 at 21:21, Laura Abbott <labbott@...oraproject.org> wrote:
>> The permissions in mark_rodata_ro trigger a build error
>> with STRICT_MM_TYPECHECKS. Fix this by introducing
>> PAGE_KERNEL_ROX for the same reasons as PAGE_KERNEL_RO.
>
> Forgive the bikeshedding but perhaps PAGE_KERNEL_EXEC_RO is more consistent?
>

powerpc was using PAGE_KERNEL_ROX so I went with that. Blame powerpc ;)
  
>>  From Ard:
>>
>> "PAGE_KERNEL_EXEC has PTE_WRITE set as well, making the range
>> writeable under the ARMv8.1 DBM feature, that manages the
>> dirty bit in hardware (writing to a page with the PTE_RDONLY
>> and PTE_WRITE bits both set will clear the PTE_RDONLY bit in that case)"
>>
>> Signed-off-by: Laura Abbott <labbott@...oraproject.org>
>
> Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>

Thanks,
Laura

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