linux-kernel - Re: [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG

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Date:	Wed, 01 Oct 2008 13:06:28 +0200
From:	Jiri Slaby <jirislaby@...il.com>
To:	Vegard Nossum <vegardno@....uio.no>
CC:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y

On 10/01/2008 12:47 PM, Vegard Nossum wrote:
> Hi,
> 
> Fix for tip/x86/mm-debug (commit 59ea746337c69f6a5f1bc4d5e8544b3cbf12f801).
> I'm not sure if choice of names/structure is entirely correct, comments are
> appreciated.


> From 01613a1949de51c7ab9d0acaaa9a5444722a5cfa Mon Sep 17 00:00:00 2001
> From: Vegard Nossum <vegardno@....ifi.uio.no>
> Date: Wed, 1 Oct 2008 12:36:34 +0200
> Subject: [PATCH] x86: fix virt_addr_valid() with CONFIG_DEBUG_VIRTUAL=y
> 
> virt_addr_valid() calls __pa(), which calls __phys_addr(). With
> CONFIG_DEBUG_VIRTUAL=y, __phys_addr() will kill the kernel if the
> address *isn't* valid. That's clearly wrong for virt_addr_valid().
> 
> Cc: Jiri Slaby <jirislaby@...il.com>
> Cc: Andi Kleen <andi@...stfloor.org>
> Signed-off-by: Vegard Nossum <vegardno@....ifi.uio.no>
> ---
> diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c
> index 395acb1..1580e0b 100644
> --- a/arch/x86/kernel/doublefault_32.c
> +++ b/arch/x86/kernel/doublefault_32.c
> @@ -66,6 +66,6 @@ struct tss_struct doublefault_tss __cacheline_aligned = {
>  		.ds		= __USER_DS,
>  		.fs		= __KERNEL_PERCPU,
>  
> -		.__cr3		= __phys_addr_const((unsigned long)swapper_pg_dir)
> +		.__cr3	= __phys_addr_nodebug((unsigned long)swapper_pg_dir)

Now, this may be switched back to __pa: __pa_nodebug(swapper_pg_dir);

>  	}
>  };
[...]
> --- a/include/asm-x86/page_64.h
> +++ b/include/asm-x86/page_64.h
> @@ -69,6 +69,7 @@ extern unsigned long max_pfn;
>  extern unsigned long phys_base;
>  
>  extern unsigned long __phys_addr(unsigned long);
> +#define __phys_addr_nodebug(x) __phys_addr(x)
>  #define __phys_reloc_hide(x)	(x)

x86_64 is screwed in the same way, isn't it?
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