From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Avi Kivity <avi@qumranet.com>
Subject: Re: [git pull] core, x86: make LIST_POISON less deadly
Date: Mon, 14 Jul 2008 08:03:16 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.1.10.0807140758100.3305@woody.linux-foundation.org> (raw)
In-Reply-To: <20080714144828.GA22666@elte.hu>
On Mon, 14 Jul 2008, Ingo Molnar wrote:
>
> +config ILLEGAL_POINTER_VALUE
> + hex
> + default 0 if X86_32
> + default 0xffffc10000000000 if X86_64
This looks like a singularly bad pointer value on x86-64.
Why not pick something that is *guaranteed* to fault? The above looks like
any future setup that supports 41 bits of addressing and has extended the
page tables (yes, it will happen eventually) will find that to be a
perfectly valid address?
It's also visually confusing, since it's visually very close to a real
kernel pointer too.
Grr.
Why not use something sane like 0xdead000000000000, which has the high bit
set but very fundamentally isn't a valid pointer, and never will be? And
which is a *lot* more visually obvious too!
Linus
next prev parent reply other threads:[~2008-07-14 15:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-14 14:48 Ingo Molnar
2008-07-14 15:03 ` Linus Torvalds [this message]
2008-07-14 15:12 ` Ingo Molnar
2008-07-14 15:53 ` Avi Kivity
2008-07-14 15:59 ` Linus Torvalds
2008-07-14 16:07 ` Ingo Molnar
2008-07-14 16:08 ` Avi Kivity
2008-07-14 16:26 ` Linus Torvalds
2008-07-14 16:34 ` Ingo Molnar
2008-07-14 18:33 ` Andi Kleen
2008-07-14 18:42 ` Linus Torvalds
2008-07-14 19:11 ` Andi Kleen
2008-07-14 19:30 ` Linus Torvalds
2008-07-14 19:42 ` Andi Kleen
2008-07-14 18:35 ` Andi Kleen
2008-07-14 18:42 ` Linus Torvalds
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