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From: Matt Fleming <matt@codeblueprint.co.uk>
To: Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>
Cc: Toshi Kani <toshi.kani@hp.com>,
	Matt Fleming <matt@codeblueprint.co.uk>,
	linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org,
	Borislav Petkov <bp@alien8.de>,
	Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Subject: [PATCH 2/6] x86/mm/pageattr: Do not strip pte flags from cpa->pfn
Date: Thu, 12 Nov 2015 15:40:19 +0000	[thread overview]
Message-ID: <1447342823-3612-3-git-send-email-matt@codeblueprint.co.uk> (raw)
In-Reply-To: <1447342823-3612-1-git-send-email-matt@codeblueprint.co.uk>

Removing the PAGE_NX bit from cpa->pfn will corrupt the page frame
number address rather than removing PAGE_NX as the code intends. This
is unlikley to be a problem in practice because _PAGE_BIT_NX is bit 63
and most machines do not have page frame numbers that reach that high.

Still, pte flags are never stored in cpa->pfn so we can safely delete
the code.

Cc: Borislav Petkov <bp@alien8.de>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
 arch/x86/mm/pageattr.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 893921b12272..d5240be55915 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -885,11 +885,6 @@ static void populate_pte(struct cpa_data *cpa,
 	pte = pte_offset_kernel(pmd, start);
 
 	while (num_pages-- && start < end) {
-
-		/* deal with the NX bit */
-		if (!(pgprot_val(pgprot) & _PAGE_NX))
-			cpa->pfn &= ~_PAGE_NX;
-
 		set_pte(pte, pfn_pte(cpa->pfn, pgprot));
 
 		start	 += PAGE_SIZE;
-- 
2.6.2

  parent reply	other threads:[~2015-11-12 15:40 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-12 15:40 [GIT PULL 0/6] EFI page table isolation Matt Fleming
2015-11-12 15:40 ` [PATCH 1/6] x86/mm/pageattr: Ensure cpa->pfn only contains page frame numbers Matt Fleming
2015-11-12 18:47   ` Borislav Petkov
2015-11-12 15:40 ` Matt Fleming [this message]
     [not found]   ` <1447342823-3612-3-git-send-email-matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-12 18:47     ` [PATCH 2/6] x86/mm/pageattr: Do not strip pte flags from cpa->pfn Borislav Petkov
2015-11-12 19:28       ` Matt Fleming
2015-11-12 15:40 ` [PATCH 3/6] x86/efi: Map RAM into the identity page table for mixed mode Matt Fleming
2015-11-12 18:01   ` Borislav Petkov
2015-11-12 19:45     ` Matt Fleming
2015-11-12 15:40 ` [PATCH 4/6] x86/efi: Hoist page table switching code into efi_call_virt() Matt Fleming
     [not found]   ` <1447342823-3612-5-git-send-email-matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-12 18:44     ` Borislav Petkov
2015-11-12 20:01       ` Matt Fleming
     [not found]         ` <20151112200108.GF2681-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-13  7:59           ` Borislav Petkov
     [not found]             ` <20151113075943.GB23605-fF5Pk5pvG8Y@public.gmane.org>
2015-11-13 16:19               ` Matt Fleming
2015-11-12 18:47     ` Borislav Petkov
2015-11-12 20:15       ` Matt Fleming
     [not found] ` <1447342823-3612-1-git-send-email-matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-12 15:40   ` [PATCH 5/6] x86/efi: Build our own page table structures Matt Fleming
     [not found]     ` <1447342823-3612-6-git-send-email-matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-12 18:38       ` Borislav Petkov
     [not found]         ` <20151112183813.GF3838-fF5Pk5pvG8Y@public.gmane.org>
2015-11-12 21:38           ` Matt Fleming
2015-11-12 15:40 ` [PATCH 6/6] Documentation/x86: Update EFI memory region description Matt Fleming
2015-11-12 18:37   ` Borislav Petkov
     [not found]   ` <1447342823-3612-7-git-send-email-matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-13  9:22     ` Ingo Molnar
2015-11-13  9:29       ` Matt Fleming
     [not found]         ` <20151113092906.GD2716-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-11-13 16:42           ` Linus Torvalds
     [not found]             ` <CA+55aFxeyspaa_VCv9fRqTpuamFD95siSx9oXp57aO3Fi=EwXw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-11-13 22:22               ` Matt Fleming
2015-11-18  8:18           ` Ingo Molnar
2015-11-19 11:22             ` Matt Fleming

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