linux-kernel - Re: [PATCH] NOMMU: use copy_*_user_page() in access_process

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Message-ID: <4B0DBC48.7000208@snapgear.com>
Date:	Thu, 26 Nov 2009 09:22:48 +1000
From:	Greg Ungerer <gerg@...pgear.com>
To:	Mike Frysinger <vapier@...too.org>
CC:	uclinux-dev@...inux.org, David Howells <dhowells@...hat.com>,
	David McCullough <davidm@...pgear.com>,
	Greg Ungerer <gerg@...inux.org>,
	Paul Mundt <lethal@...ux-sh.org>, linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org,
	Jie Zhang <jie.zhang@...log.com>
Subject: Re: [PATCH] NOMMU: use copy_*_user_page() in access_process_vm()

Mike Frysinger wrote:
> From: Jie Zhang <jie.zhang@...log.com>
> 
> The mmu code uses the copy_*_user_page() variants in access_process_vm()
> rather than copy_*_user() as the former includes an icache flush.  This is
> important when doing things like setting software breakpoints with gdb.
> So switch the nommu code over to do the same.
> 
> Signed-off-by: Jie Zhang <jie.zhang@...log.com>
> Signed-off-by: Mike Frysinger <vapier@...too.org>

Acked-by: Greg Ungerer <gerg@...inux.org>


>  mm/nommu.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 9876fa0..51ae9be 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -1889,9 +1889,11 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in
>  
>  		/* only read or write mappings where it is permitted */
>  		if (write && vma->vm_flags & VM_MAYWRITE)
> -			len -= copy_to_user((void *) addr, buf, len);
> +			copy_to_user_page(vma, NULL, NULL,
> +					  (void *) addr, buf, len);
>  		else if (!write && vma->vm_flags & VM_MAYREAD)
> -			len -= copy_from_user(buf, (void *) addr, len);
> +			copy_from_user_page(vma, NULL, NULL,
> +					    buf, (void *) addr, len);
>  		else
>  			len = 0;
>  	} else {


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Greg Ungerer  --  Principal Engineer        EMAIL:     gerg@...pgear.com
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