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Subject[PATCH] 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@chromium.org>
---
arch/arm/include/asm/pgtable-3level.h | 4 ----
arch/arm/include/asm/pgtable.h | 4 ++++
arch/arm/mm/dump.c | 3 +++
3 files changed, 7 insertions(+), 4 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 1f7b1e13d945..ff1559f9200c 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -264,6 +264,9 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
note_page(st, addr, 3, pmd_val(*pmd));
else
walk_pte(st, pmd, addr);
+
+ if (SECTION_SIZE < PMD_SIZE && pmd_sect(*pmd))
+ note_page(st, addr + SECTION_SIZE, 3, pmd_val(pmd[1]));
}
}

--
1.7.9.5

--
Kees Cook
Chrome OS Security


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