linux-kernel - Re: [PATCH 11/27] [AARCH64] Syscalls for ILP32 are passed always via 64bit values.

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Message-ID: <20160623063232.GE13449@yury-N73SV>
Date:	Thu, 23 Jun 2016 09:32:32 +0300
From:	Yury Norov <ynorov@...iumnetworks.com>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	<libc-alpha@...rceware.org>, <linux-kernel@...r.kernel.org>,
	<arnd@...db.de>, <marcus.shawcroft@....com>, <philb@....org>,
	<davem@...emloft.net>, <szabolcs.nagy@....com>,
	<maxim.kuvyrkov@...aro.org>, <joseph@...esourcery.com>,
	<pinskia@...il.com>, Andrew Pinski <apinski@...ium.com>
Subject: Re: [PATCH 11/27] [AARCH64] Syscalls for ILP32 are passed always via
 64bit values.

On Wed, Jun 22, 2016 at 04:49:52PM +0100, Catalin Marinas wrote:
> On Tue, Jun 21, 2016 at 08:06:55AM +0300, Yury Norov wrote:
> > This patch adds support for ILP32 syscalls, sign and zero extending
> > where needed.  Unlike LP64, pointers are 32bit and need to be zero
> > extended rather than the standard sign extend that the code would do.
> > We take advatage of ssize_t being long rather than int for ILP32,
> > to get this correct.
> 
> Unless I misunderstand what this patch does, I thought we agreed that
> 32-bit arguments are passed as 32-bit values and it is the kernel's
> responsibility to zero or sign-extend the upper half (IOW, assume
> garbage just like the PCS ABI).
> 
> We are still debating whether 64-bit values are passed in one or two
> registers but this doesn't change the situation of 32-bit values like
> pointers.
> 
> -- 
> Catalin

Hi Catalin,

I dropped this patch with no regressions. It might be needed it we
choose s390-like wrappers, but this series is not about it anyway.

BTW, what about 64-bit values passing? Any new comments?

Yury.