linux-kernel - [PATCH v2] ARM: mm: report both sections from PMD

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Date:	Wed, 12 Feb 2014 14:46:38 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Russell King <linux@....linux.org.uk>
Cc:	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Steven Capper <steve.capper@...aro.org>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Kees Cook <keescook@...omium.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Laura Abbott <lauraa@...eaurora.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] ARM: mm: report both sections from PMD

On 2-level page table systems, the PMD has 2 section entries. Report
these, otherwise ARM_PTDUMP will miss reporting permission changes on
odd section boundaries.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
v2:
 - reorganize, suggested by Catalin Marinas.
---
 arch/arm/include/asm/pgtable-3level.h |    4 ----
 arch/arm/include/asm/pgtable.h        |    4 ++++
 arch/arm/mm/dump.c                    |    8 +++++++-
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h
index 03243f7eeddf..fb3de59ee811 100644
--- a/arch/arm/include/asm/pgtable-3level.h
+++ b/arch/arm/include/asm/pgtable-3level.h
@@ -138,10 +138,6 @@
 #define pud_none(pud)		(!pud_val(pud))
 #define pud_bad(pud)		(!(pud_val(pud) & 2))
 #define pud_present(pud)	(pud_val(pud))
-#define pmd_table(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
-						 PMD_TYPE_TABLE)
-#define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
-						 PMD_TYPE_SECT)
 #define pmd_large(pmd)		pmd_sect(pmd)
 
 #define pud_clear(pudp)			\
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 7d59b524f2af..934aa5b60c7c 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -183,6 +183,10 @@ extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
 
 #define pmd_none(pmd)		(!pmd_val(pmd))
 #define pmd_present(pmd)	(pmd_val(pmd))
+#define pmd_table(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
+						 PMD_TYPE_TABLE)
+#define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
+						 PMD_TYPE_SECT)
 
 static inline pte_t *pmd_page_vaddr(pmd_t pmd)
 {
diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index 2b342177f5de..32635b474832 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -260,8 +260,14 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 
 	for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 		addr = start + i * PMD_SIZE;
-		if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd))
+		if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd)) {
 			note_page(st, addr, 3, pmd_val(*pmd));
+			if (SECTION_SIZE < PMD_SIZE &&
+			    pmd_sect(*pmd) && pmd_sect(pmd[1])) {
+				note_page(st, addr + SECTION_SIZE, 3,
+					  pmd_val(pmd[1]));
+			}
+		}
 		else
 			walk_pte(st, pmd, addr);
 	}
-- 
1.7.9.5


-- 
Kees Cook
Chrome OS Security
--
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