linux-kernel - Re: [PATCH 6/6] arm64: compat: Check for AArch32 state

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Message-ID: <56CAF306.1060102@arm.com>
Date:	Mon, 22 Feb 2016 11:37:42 +0000
From:	"Suzuki K. Poulose" <Suzuki.Poulose@....com>
To:	Will Deacon <will.deacon@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, catalin.marinas@....com,
	mark.rutland@....com, ynorov@...iumnetworks.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] arm64: compat: Check for AArch32 state

On 09/02/16 17:36, Will Deacon wrote:
> On Thu, Jan 28, 2016 at 11:32:17AM +0000, Suzuki K Poulose wrote:
>> Make sure we have AArch32 state available for running COMPAT binaries.


>>   		 */
>>   		seq_puts(m, "Features\t:");
>> -		if (personality(current->personality) == PER_LINUX32) {
>> +		if (system_supports_32bit_el0() &&
>> +			personality(current->personality) == PER_LINUX32) {
>
> Wouldn't it be better to prevent tasks changing to the PER_LINUX32
> personality on systems that don't support AArch32 at EL0?

Yes, thats the ideal solution. I took a look at it  and it requires us to
hook in arm64 wrapper for the personality syscall. I will take a look.

Thanks
Suzuki