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Date: Mon, 25 Jun 2018 19:39:21 +0800
From: Jun Yao <yaojun8558363@...il.com>
To: linux-arm-kernel@...ts.infradead.org
Cc: catalin.marinas@....com,
will.deacon@....com,
ard.biesheuvel@...aro.org,
james.morse@....com,
linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH v2 2/2] arm64/mm: Move {tramp_pg_dir, swapper_pg_dir} to .rodata section
When CONFIG_ARM64_VA_BITS_36/CONFIG_ARM64_VA_BITS_39/
CONFIG_ARM64_VA_BITS_42 are selected, a block-mapping can be
written to swapper_pg_dir. To defend 'KSMA', we move swapper_pg_dir
to .rodata section when these configurations are selected. At the
same time, we update swapper_pg_dir by fixmap.
Signed-off-by: Jun Yao <yaojun8558363@...il.com>
---
arch/arm64/include/asm/fixmap.h | 1 +
arch/arm64/include/asm/pgalloc.h | 33 ++++++++++++++++++++++++++++++++
arch/arm64/include/asm/pgtable.h | 5 +++++
arch/arm64/kernel/head.S | 6 +++---
arch/arm64/kernel/vmlinux.lds.S | 23 ++++++++++++++++++++++
arch/arm64/mm/mmu.c | 6 ++++++
6 files changed, 71 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/fixmap.h b/arch/arm64/include/asm/fixmap.h
index 62908eeedcdc..881784b43965 100644
--- a/arch/arm64/include/asm/fixmap.h
+++ b/arch/arm64/include/asm/fixmap.h
@@ -83,6 +83,7 @@ enum fixed_addresses {
FIX_PTE,
FIX_PMD,
FIX_PUD,
+ FIX_SWAPPER,
__end_of_fixed_addresses
};
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 2e05bcd944c8..62512ad9c310 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -49,6 +49,22 @@ 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)
{
+#ifdef CONFIG_ARM64_VA_BITS_39
+ if (mm == &init_mm) {
+ pud_t *pud;
+ unsigned long offset;
+ extern spinlock_t pgdir_lock;
+
+ spin_lock(&pgdir_lock);
+ pud = (pud_t *)swapper_set_fixmap();
+ offset = (unsigned long)pudp - (unsigned long)swapper_pg_dir;
+ pud = (pud_t *)((unsigned long)pud + offset);
+ __pud_populate(pud, __pa(pmdp), PMD_TYPE_TABLE);
+ swapper_clear_fixmap();
+ spin_unlock(&pgdir_lock);
+ return;
+ }
+#endif
__pud_populate(pudp, __pa(pmdp), PMD_TYPE_TABLE);
}
#else
@@ -142,6 +158,23 @@ 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
*/
+#if defined(CONFIG_ARM64_VA_BITS_42) || \
+ defined(CONFIG_ARM64_VA_BITS_36)
+ if (mm == &init_mm) {
+ pmd_t *pmd;
+ unsigned long offset;
+ extern spinlock_t pgdir_lock;
+
+ spin_lock(&pgdir_lock);
+ pmd = (pmd_t *)swapper_set_fixmap();
+ offset = (unsigned long)pmdp - (unsigned long)swapper_pg_dir;
+ pmd = (pmd_t *)((unsigned long)pmd + offset);
+ __pmd_populate(pmd, __pa(ptep), PMD_TYPE_TABLE);
+ swapper_clear_fixmap();
+ spin_unlock(&pgdir_lock);
+ return;
+ }
+#endif
__pmd_populate(pmdp, __pa(ptep), PMD_TYPE_TABLE);
}
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index b2435e8b975b..85743ea0709b 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -592,6 +592,11 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd)
/* to find an entry in a kernel page-table-directory */
#define pgd_offset_k(addr) pgd_offset(&init_mm, addr)
+#define swapper_set_fixmap() \
+ set_fixmap_offset(FIX_SWAPPER, __pa_symbol(swapper_pg_dir))
+
+#define swapper_clear_fixmap() clear_fixmap(FIX_SWAPPER)
+
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY |
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 9677deb7b6c7..9db187024b44 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -300,7 +300,7 @@ __create_page_tables:
* dirty cache lines being evicted.
*/
adrp x0, idmap_pg_dir
- adrp x1, swapper_pg_end
+ adrp x1, idmap_pg_end
sub x1, x1, x0
bl __inval_dcache_area
@@ -313,7 +313,7 @@ __create_page_tables:
* Clear the idmap and init page tables.
*/
adrp x0, idmap_pg_dir
- adrp x1, swapper_pg_end
+ adrp x1, idmap_pg_end
sub x1, x1, x0
clear_pages x0, x1
@@ -404,7 +404,7 @@ __create_page_tables:
* tables again to remove any speculatively loaded cache lines.
*/
adrp x0, idmap_pg_dir
- adrp x1, swapper_pg_end
+ adrp x1, idmap_pg_end
sub x1, x1, x0
dmb sy
bl __inval_dcache_area
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index b0e4255fcba4..db72c4680f1d 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -219,6 +219,28 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
+ idmap_pg_end = .;
+
+#if defined(CONFIG_ARM64_VA_BITS_39) || \
+ defined(CONFIG_ARM64_VA_BITS_36) || \
+ defined(CONFIG_ARM64_VA_BITS_42)
+ .rodata : {
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+ . = ALIGN(PAGE_SIZE);
+ tramp_pg_dir = .;
+ . += PAGE_SIZE;
+#endif
+
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+ reserved_ttbr0 = .;
+ . += RESERVED_TTBR0_SIZE;
+#endif
+ swapper_pg_dir = .;
+ . += PAGE_SIZE;
+ swapper_pg_end = .;
+ }
+
+#else
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
tramp_pg_dir = .;
@@ -232,6 +254,7 @@ SECTIONS
swapper_pg_dir = .;
. += PAGE_SIZE;
swapper_pg_end = .;
+#endif
__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
_end = .;
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a3b5f1dffb84..fbaf3e9b4a43 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -66,6 +66,12 @@ static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss;
static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss __maybe_unused;
static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss __maybe_unused;
+#if defined(CONFIG_ARM64_VA_BITS_39) || \
+ defined(CONFIG_ARM64_VA_BITS_36) || \
+ defined(CONFIG_ARM64_VA_BITS_42)
+DEFINE_SPINLOCK(pgdir_lock);
+#endif
+
pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
unsigned long size, pgprot_t vma_prot)
{
--
2.17.1
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