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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 5 Mar 2011 12:52:34 -0800
Message-ID: <AANLkTi=mce6tzg=vwf45XUQoADA=YbP2QJ2_tpg=QgQE@mail.gmail.com>
Subject: Re: [PATCH v4 3/4] exec: unify do_execve/compat_do_execve code
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To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, pageexec@freemail.hu, Solar Designer <solar@openwall.com>, Eugene Teo <eteo@redhat.com>, Brad Spengler <spender@grsecurity.net>, Roland McGrath <roland@redhat.com>, Milton Miller <miltonm@bga.com>

Ok, everything looks fine to me.

Except looking at this, I don't think this part:

On Sat, Mar 5, 2011 at 12:31 PM, Oleg Nesterov <oleg@redhat.com> wrote:
>
> =A0struct user_arg_ptr {
> - =A0 =A0 =A0 const char __user *const __user *native;
> +#ifdef CONFIG_COMPAT
> + =A0 =A0 =A0 bool is_compat;
> +#endif
> + =A0 =A0 =A0 union {
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 const char __user *const __user *native;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 compat_uptr_t __user *compat;
> + =A0 =A0 =A0 } ptr;
> =A0};

will necessarily even compile on an architecture that doesn't have any
'compat' support.

Do we even define 'compat_uptr_t' for that case? I don't think so.

So I suspect you need two of those annoying #ifdef's. Or we need to
have some way to guarantee that 'compat_uptr_t' exists.

                           Linus

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