From: Bjorn Helgaas <bjorn.helgaas@hp.com>
To: Daniel J Blueman <daniel.blueman@quadrics.com>
Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org,
marcelo.tosatti@cyclades.com
Subject: Re: pte_modify fix backport...
Date: Thu, 05 Aug 2004 15:56:39 +0000 [thread overview]
Message-ID: <200408050956.39053.bjorn.helgaas@hp.com> (raw)
In-Reply-To: <1091704431.1829.235.camel@pc107.quadrics.com>
On Thursday 05 August 2004 5:13 am, Daniel J Blueman wrote:
> This patch [1] corrects the behaviour of pte_modify() on ia64 to not
> clear page protection flags it shouldn't touch.
>
> Without this patch, it clears the uncacheable flag on UC memory regions,
> which can cause MCAs with device I/O.
>
> It was taken into 2.6.0 a while ago, but is yet to be included in 2.4 -
> the patch here is rediffed against 2.4.26-rc5.
>
> Is there chance of it being taken in?
I put this in the 2.4 ia64 BK tree a couple days ago. Can you check
here: http://lia64.bkbits.net:8080/linux-ia64-2.4 and make sure that
it works for you?
The plain patch is also available here, if that works better for you:
ftp://ftp.kernel.org/pub/linux/kernel/ports/ia64/v2.4/testing/cset/index.html
> diff -durN linux-2.4.26-rc5-orig/include/asm-ia64/pgtable.h linux-2.4.26-rc5-patched/include/asm-ia64/pgtable.h
> --- linux-2.4.26-rc5-orig/include/asm-ia64/pgtable.h 2004-02-18 13:36:32.000000000 +0000
> +++ linux-2.4.26-rc5-patched/include/asm-ia64/pgtable.h 2004-08-05 11:46:03.000000000 +0100
> @@ -60,7 +60,8 @@
> #define _PAGE_PROTNONE (__IA64_UL(1) << 63)
>
> #define _PFN_MASK _PAGE_PPN_MASK
> -#define _PAGE_CHG_MASK (_PFN_MASK | _PAGE_A | _PAGE_D)
> +/* Mask of bits which may be changed by pte_modify(); the odd bits are there for _PAGE_PROTNONE */
> +#define _PAGE_CHG_MASK (_PAGE_P | _PAGE_PROTNONE | _PAGE_PL_MASK | _PAGE_AR_MASK | _PAGE_ED)
>
> #define _PAGE_SIZE_4K 12
> #define _PAGE_SIZE_8K 13
> @@ -216,7 +217,7 @@
> ({ pte_t __pte; pte_val(__pte) = physpage + pgprot_val(pgprot); __pte; })
>
> #define pte_modify(_pte, newprot) \
> - (__pte((pte_val(_pte) & _PAGE_CHG_MASK) | pgprot_val(newprot)))
> + (__pte((pte_val(_pte) & ~_PAGE_CHG_MASK) | (pgprot_val(newprot) & _PAGE_CHG_MASK)))
>
> #define page_pte_prot(page,prot) mk_pte(page, prot)
> #define page_pte(page) page_pte_prot(page, __pgprot(0))
>
> --
> Daniel J Blueman
> Software Engineer, Quadrics Ltd
next prev parent reply other threads:[~2004-08-05 15:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-05 11:13 pte_modify fix backport Daniel J Blueman
2004-08-05 15:56 ` Bjorn Helgaas [this message]
2004-08-05 16:21 ` Daniel J Blueman
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