From: Denis Vlasenko <vda@ilport.com.ua>
To: "linux-os \(Dick Johnson\)" <linux-os@analogic.com>
Cc: "Linux kernel" <linux-kernel@vger.kernel.org>
Subject: Re: 4k stacks
Date: Wed, 28 Dec 2005 17:16:42 +0200 [thread overview]
Message-ID: <200512281716.43089.vda@ilport.com.ua> (raw)
In-Reply-To: <Pine.LNX.4.61.0512280808290.25369@chaos.analogic.com>
On Wednesday 28 December 2005 15:14, linux-os (Dick Johnson) wrote:
> >> Anyway, getting down to 20 bytes of stack-space available
> >> seems to be pretty scary.
> >
> > + movl %esp, %edi
> > + movl %edi, %ecx
> > + andl $~0x1000, %edi
> > + subl %edi, %ecx
> >
> > ecx will be equal to ?
>
> Whatever the stack was minus that value ANDed with NOT 0x1000,
> i.e. 0x1000 minus the stack already in use. The code assumes
> that the stack starts and ends on a 0x1000 (page) boundary.
> If that's not true, then all bets are off.
Hmm. I must be thick today. (esp - (esp & 0xffffefff))
is always equal to (esp & 0x00001000). Which is either 0 or 0x1000.
--
vda
next prev parent reply other threads:[~2005-12-28 15:16 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-22 21:53 linux-os (Dick Johnson)
2005-12-23 1:11 ` Grant Coady
2005-12-23 17:45 ` Alistair John Strachan
2005-12-23 12:56 ` Krzysztof Halasa
2005-12-24 12:03 ` Denis Vlasenko
2005-12-25 2:43 ` Andrew James Wade
2005-12-26 7:42 ` Andrew James Wade
2005-12-26 8:40 ` Andrew James Wade
2005-12-27 21:12 ` Frank Sorenson
2005-12-28 18:05 ` Grant Coady
2005-12-26 14:38 ` Diego Calleja
2005-12-28 13:14 ` linux-os (Dick Johnson)
2005-12-28 15:16 ` Denis Vlasenko [this message]
2005-12-30 14:45 ` linux-os (Dick Johnson)
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