From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Date: Thu, 05 Aug 2004 15:56:39 +0000 Subject: Re: pte_modify fix backport... Message-Id: <200408050956.39053.bjorn.helgaas@hp.com> List-Id: References: <1091704431.1829.235.camel@pc107.quadrics.com> In-Reply-To: <1091704431.1829.235.camel@pc107.quadrics.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Daniel J Blueman Cc: linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, marcelo.tosatti@cyclades.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