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Subject[PATCH v3 06/20] ARM: LPAE: Introduce L_PTE_NOEXEC and L_PTE_NOWRITE
Date
The LPAE page table format needs to explicitly disable execution or
write permissions on a page by setting the corresponding bits (similar
to the classic page table format with Access Flag enabled). This patch
introduces null definitions for the 2-level format and the actual noexec
and nowrite bits for the LPAE format. It also changes several PTE
maintenance macros and masks.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm/include/asm/pgtable-2level.h | 2 +
arch/arm/include/asm/pgtable.h | 44 +++++++++++++++++++++------------
arch/arm/mm/mmu.c | 6 ++--
3 files changed, 33 insertions(+), 19 deletions(-)
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index 36bdef7..4e21166 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -128,6 +128,8 @@
#define L_PTE_USER (1 << 8)
#define L_PTE_EXEC (1 << 9)
#define L_PTE_SHARED (1 << 10) /* shared(v6), coherent(xsc3) */
+#define L_PTE_NOEXEC (0)
+#define L_PTE_NOWRITE (0)

/*
* These are the memory types, defined to be compatible with
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 1124b98..2ff176c 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -66,23 +66,23 @@ extern pgprot_t pgprot_kernel;

#define _MOD_PROT(p, b) __pgprot(pgprot_val(p) | (b))

-#define PAGE_NONE pgprot_user
-#define PAGE_SHARED _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_WRITE)
+#define PAGE_NONE _MOD_PROT(pgprot_user, L_PTE_NOEXEC | L_PTE_NOWRITE)
+#define PAGE_SHARED _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_WRITE | L_PTE_NOEXEC)
#define PAGE_SHARED_EXEC _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_WRITE | L_PTE_EXEC)
-#define PAGE_COPY _MOD_PROT(pgprot_user, L_PTE_USER)
-#define PAGE_COPY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_EXEC)
-#define PAGE_READONLY _MOD_PROT(pgprot_user, L_PTE_USER)
-#define PAGE_READONLY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_EXEC)
-#define PAGE_KERNEL pgprot_kernel
+#define PAGE_COPY _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_NOEXEC | L_PTE_NOWRITE)
+#define PAGE_COPY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_EXEC | L_PTE_NOWRITE)
+#define PAGE_READONLY _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_NOEXEC | L_PTE_NOWRITE)
+#define PAGE_READONLY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_EXEC | L_PTE_NOWRITE)
+#define PAGE_KERNEL _MOD_PROT(pgprot_kernel, L_PTE_NOEXEC)
#define PAGE_KERNEL_EXEC _MOD_PROT(pgprot_kernel, L_PTE_EXEC)

-#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT)
-#define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_WRITE)
+#define __PAGE_NONE __pgprot(_L_PTE_DEFAULT | L_PTE_NOEXEC | L_PTE_NOWRITE)
+#define __PAGE_SHARED __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_WRITE | L_PTE_NOEXEC)
#define __PAGE_SHARED_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_WRITE | L_PTE_EXEC)
-#define __PAGE_COPY __pgprot(_L_PTE_DEFAULT | L_PTE_USER)
-#define __PAGE_COPY_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_EXEC)
-#define __PAGE_READONLY __pgprot(_L_PTE_DEFAULT | L_PTE_USER)
-#define __PAGE_READONLY_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_EXEC)
+#define __PAGE_COPY __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_NOEXEC | L_PTE_NOWRITE)
+#define __PAGE_COPY_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_EXEC | L_PTE_NOWRITE)
+#define __PAGE_READONLY __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_NOEXEC | L_PTE_NOWRITE)
+#define __PAGE_READONLY_EXEC __pgprot(_L_PTE_DEFAULT | L_PTE_USER | L_PTE_EXEC | L_PTE_NOWRITE)

#endif /* __ASSEMBLY__ */

@@ -165,12 +165,18 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
* Undefined behaviour if not..
*/
#define pte_present(pte) (pte_val(pte) & L_PTE_PRESENT)
-#define pte_write(pte) (pte_val(pte) & L_PTE_WRITE)
#define pte_dirty(pte) (pte_val(pte) & L_PTE_DIRTY)
#define pte_young(pte) (pte_val(pte) & L_PTE_YOUNG)
-#define pte_exec(pte) (pte_val(pte) & L_PTE_EXEC)
#define pte_special(pte) (0)

+#ifdef CONFIG_ARM_LPAE
+#define pte_write(pte) (!(pte_val(pte) & L_PTE_NOWRITE))
+#define pte_exec(pte) (!(pte_val(pte) & L_PTE_NOEXEC))
+#else
+#define pte_write(pte) (pte_val(pte) & L_PTE_WRITE)
+#define pte_exec(pte) (pte_val(pte) & L_PTE_EXEC)
+#endif
+
#define pte_present_user(pte) \
((pte_val(pte) & (L_PTE_PRESENT | L_PTE_USER)) == \
(L_PTE_PRESENT | L_PTE_USER))
@@ -178,8 +184,13 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
#define PTE_BIT_FUNC(fn,op) \
static inline pte_t pte_##fn(pte_t pte) { pte_val(pte) op; return pte; }

+#ifdef CONFIG_ARM_LPAE
+PTE_BIT_FUNC(wrprotect, |= L_PTE_NOWRITE);
+PTE_BIT_FUNC(mkwrite, &= ~L_PTE_NOWRITE);
+#else
PTE_BIT_FUNC(wrprotect, &= ~L_PTE_WRITE);
PTE_BIT_FUNC(mkwrite, |= L_PTE_WRITE);
+#endif
PTE_BIT_FUNC(mkclean, &= ~L_PTE_DIRTY);
PTE_BIT_FUNC(mkdirty, |= L_PTE_DIRTY);
PTE_BIT_FUNC(mkold, &= ~L_PTE_YOUNG);
@@ -272,7 +283,8 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)

static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
- const unsigned long mask = L_PTE_EXEC | L_PTE_WRITE | L_PTE_USER;
+ const unsigned long mask = L_PTE_EXEC | L_PTE_WRITE | L_PTE_USER |
+ L_PTE_NOEXEC | L_PTE_NOWRITE;
pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
return pte;
}
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 2bcf29c..45fe44c 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -191,7 +191,7 @@ void adjust_cr(unsigned long mask, unsigned long set)
}
#endif

-#define PROT_PTE_DEVICE L_PTE_PRESENT|L_PTE_YOUNG|L_PTE_DIRTY|L_PTE_WRITE
+#define PROT_PTE_DEVICE L_PTE_PRESENT|L_PTE_YOUNG|L_PTE_DIRTY|L_PTE_WRITE|L_PTE_NOEXEC
#define PROT_SECT_DEVICE PMD_TYPE_SECT|PMD_SECT_AP_WRITE

static struct mem_type mem_types[] = {
@@ -236,13 +236,13 @@ static struct mem_type mem_types[] = {
},
[MT_LOW_VECTORS] = {
.prot_pte = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
- L_PTE_EXEC,
+ L_PTE_EXEC | L_PTE_NOWRITE,
.prot_l1 = PMD_TYPE_TABLE,
.domain = DOMAIN_USER,
},
[MT_HIGH_VECTORS] = {
.prot_pte = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
- L_PTE_USER | L_PTE_EXEC,
+ L_PTE_USER | L_PTE_EXEC | L_PTE_NOWRITE,
.prot_l1 = PMD_TYPE_TABLE,
.domain = DOMAIN_USER,
},

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