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Date: Fri, 30 Nov 2001 17:36:04 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
Organization: Zytor Communications
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To: Davide Libenzi <davidel@xmailserver.org>
CC: lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] task_struct colouring ...
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Davide Libenzi wrote:

>>
>>This seems to confuddle the idea of colouring the kernel stack.
>>
> 
> It's task_truct colouring not stack, to colour the stack you've to go in
> arch/??/kernel/process.c and jitter the stack pointer.
> The task_struct colouring is done at task_struct creation time :
> 
> +struct task_struct *alloc_task_struct(void)
> +{
> +       unsigned long tskb = __get_free_pages(GFP_KERNEL, 1), tsk;
> +       tsk = tskb | ((tskb >> 13) & 0x00000060) | SMP_CACHE_BYTES;
> +       *(unsigned long *) tskb = tsk;
> +       return (struct task_struct *) tsk;
> +}
> 


I know, but I believe the part of the idea was to color not just the
current, but also the stack.

Your idea would make the obvious way to color the kernel stack -- have the
stacks offset by a non-power-of-two -- no longer work.

	-hpa


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