From 59511cfd08f32d0e9d363ffa0fdaaa75afdc52b1 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Wed, 10 Mar 2021 11:49:42 +0100
Subject: [PATCH] arm64: mm: use XN table mapping attributes for user/kernel
mappings
As the kernel and user space page tables are strictly mutually exclusive
when it comes to executable permissions, we can set the UXN table attribute
on all table entries that are created while creating kernel mappings in the
swapper page tables, and the PXN table attribute on all table entries that
are created while creating user space mappings in user space page tables.
While at it, get rid of a redundant comment.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20210310104942.174584-4-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/pgalloc.h | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 27cc643d05095..31fbab3d6f992 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -27,7 +27,10 @@ static inline void __pud_populate(pud_t *pudp, phys_addr_t pmdp, pudval_t prot)
static inline void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmdp)
{
- __pud_populate(pudp, __pa(pmdp), PUD_TYPE_TABLE);
+ pudval_t pudval = PUD_TYPE_TABLE;
+
+ pudval |= (mm == &init_mm) ? PUD_TABLE_UXN : PUD_TABLE_PXN;
+ __pud_populate(pudp, __pa(pmdp), pudval);
}
#else
static inline void __pud_populate(pud_t *pudp, phys_addr_t pmdp, pudval_t prot)
@@ -45,7 +48,10 @@ static inline void __p4d_populate(p4d_t *p4dp, phys_addr_t pudp, p4dval_t prot)
static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4dp, pud_t *pudp)
{
- __p4d_populate(p4dp, __pa(pudp), P4D_TYPE_TABLE);
+ p4dval_t p4dval = P4D_TYPE_TABLE;
+
+ p4dval |= (mm == &init_mm) ? P4D_TABLE_UXN : P4D_TABLE_PXN;
+ __p4d_populate(p4dp, __pa(pudp), p4dval);
}
#else
static inline void __p4d_populate(p4d_t *p4dp, phys_addr_t pudp, p4dval_t prot)
@@ -70,16 +76,15 @@ static inline void __pmd_populate(pmd_t *pmdp, phys_addr_t ptep,
static inline void
pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmdp, pte_t *ptep)
{
- /*
- * The pmd must be loaded with the physical address of the PTE table
- */
- __pmd_populate(pmdp, __pa(ptep), PMD_TYPE_TABLE);
+ VM_BUG_ON(mm != &init_mm);
+ __pmd_populate(pmdp, __pa(ptep), PMD_TYPE_TABLE | PMD_TABLE_UXN);
}
static inline void
pmd_populate(struct mm_struct *mm, pmd_t *pmdp, pgtable_t ptep)
{
- __pmd_populate(pmdp, page_to_phys(ptep), PMD_TYPE_TABLE);
+ VM_BUG_ON(mm == &init_mm);
+ __pmd_populate(pmdp, page_to_phys(ptep), PMD_TYPE_TABLE | PMD_TABLE_PXN);
}
#define pmd_pgtable(pmd) pmd_page(pmd)
--
2.30.2