Date: Wed, 02 Mar 2011 11:40:18 -0800 (PST)
Message-Id: <20110302.114018.104077586.davem@davemloft.net>
To: torvalds@linux-foundation.org
Cc: oleg@redhat.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org, pageexec@freemail.hu,
        solar@openwall.com, eteo@redhat.com, spender@grsecurity.net,
        roland@redhat.com, miltonm@bga.com
Subject: Re: [PATCH v3 0/4] exec: unify native/compat code
From: David Miller <davem@davemloft.net>
In-Reply-To: <AANLkTinzQmprg+XHKjTj7bA+jFf_N4hta3_09M+SEfRt@mail.gmail.com>
References: <20110302162650.GA26810@redhat.com>
	<20110302164428.GF26810@redhat.com>
	<AANLkTinzQmprg+XHKjTj7bA+jFf_N4hta3_09M+SEfRt@mail.gmail.com>
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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 2 Mar 2011 10:00:23 -0800

> No, I think we're ok with passing the structure by value - it's a
> small structure that would generally be passed in registers (at least
> on some architectures, I guess it will depend on the ABI), and we do
> the "struct-by-value" thing for other things too (notably the page
> table entries), so it's not a new thing in the kernel.

We purposely don't do that "page table entry typedef'd to aggregate" stuff
on sparc32 because otherwise such values get passed on the stack.

Architectures can currently avoid this bad code generation for the
page table case, but with this new code they won't be able to avoid
pass-by-value.
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