[PATCH v30 04/11] arm64: mm: allow for unmapping memory region from kernel mapping
AKASHI Takahiro
takahiro.akashi at linaro.org
Tue Jan 24 00:49:58 PST 2017
The current implementation of create_mapping_late() is only allowed
to modify permission attributes (read-only or read-write) against
the existing kernel mapping.
In this patch, PAGE_KERNEL_INVALID protection attribute is introduced.
We will now be able to invalidate (or unmap) some part of the existing
kernel mapping by specifying PAGE_KERNEL_INVALID to create_mapping_late().
This feature will be used in a suceeding kdump patch to protect
the memory reserved for crash dump kernel once after loaded.
Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
arch/arm64/include/asm/mmu.h | 2 ++
arch/arm64/include/asm/pgtable-hwdef.h | 2 ++
arch/arm64/include/asm/pgtable-prot.h | 1 +
arch/arm64/include/asm/pgtable.h | 4 ++++
arch/arm64/mm/mmu.c | 29 ++++++++++++++++++++---------
5 files changed, 29 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 47619411f0ff..a6c1367527bc 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -36,6 +36,8 @@ extern void init_mem_pgprot(void);
extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
unsigned long virt, phys_addr_t size,
pgprot_t prot, bool page_mappings_only);
+extern void create_mapping_late(phys_addr_t phys, unsigned long virt,
+ phys_addr_t size, pgprot_t prot);
extern void *fixmap_remap_fdt(phys_addr_t dt_phys);
#endif
diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
index eb0c2bd90de9..e66efec31ca9 100644
--- a/arch/arm64/include/asm/pgtable-hwdef.h
+++ b/arch/arm64/include/asm/pgtable-hwdef.h
@@ -119,6 +119,7 @@
#define PUD_TABLE_BIT (_AT(pgdval_t, 1) << 1)
#define PUD_TYPE_MASK (_AT(pgdval_t, 3) << 0)
#define PUD_TYPE_SECT (_AT(pgdval_t, 1) << 0)
+#define PUD_VALID PUD_TYPE_SECT
/*
* Level 2 descriptor (PMD).
@@ -128,6 +129,7 @@
#define PMD_TYPE_TABLE (_AT(pmdval_t, 3) << 0)
#define PMD_TYPE_SECT (_AT(pmdval_t, 1) << 0)
#define PMD_TABLE_BIT (_AT(pmdval_t, 1) << 1)
+#define PMD_VALID PMD_TYPE_SECT
/*
* Section
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 2142c7726e76..945d84cd5df7 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -54,6 +54,7 @@
#define PAGE_KERNEL_ROX __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_RDONLY)
#define PAGE_KERNEL_EXEC __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_WRITE)
#define PAGE_KERNEL_EXEC_CONT __pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_WRITE | PTE_CONT)
+#define PAGE_KERNEL_INVALID __pgprot(0)
#define PAGE_HYP __pgprot(_PAGE_DEFAULT | PTE_HYP | PTE_HYP_XN)
#define PAGE_HYP_EXEC __pgprot(_PAGE_DEFAULT | PTE_HYP | PTE_RDONLY)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index ffbb9a520563..1904a7c07018 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -364,6 +364,8 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
#define pmd_bad(pmd) (!(pmd_val(pmd) & PMD_TABLE_BIT))
+#define pmd_valid(pmd) (!!(pmd_val(pmd) & PMD_VALID))
+
#define pmd_table(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \
PMD_TYPE_TABLE)
#define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \
@@ -428,6 +430,7 @@ static inline phys_addr_t pmd_page_paddr(pmd_t pmd)
#define pud_none(pud) (!pud_val(pud))
#define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT))
+#define pud_valid(pud) (!!(pud_val(pud) & PUD_VALID))
#define pud_present(pud) (pud_val(pud))
static inline void set_pud(pud_t *pudp, pud_t pud)
@@ -481,6 +484,7 @@ static inline phys_addr_t pud_page_paddr(pud_t pud)
#define pgd_none(pgd) (!pgd_val(pgd))
#define pgd_bad(pgd) (!(pgd_val(pgd) & 2))
+#define pgd_valid(pgd) (!!(pgd_val(pgd) & 1))
#define pgd_present(pgd) (pgd_val(pgd))
static inline void set_pgd(pgd_t *pgdp, pgd_t pgd)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 17243e43184e..9c7adcce8e4e 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -133,7 +133,8 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
* Set the contiguous bit for the subsequent group of PTEs if
* its size and alignment are appropriate.
*/
- if (((addr | PFN_PHYS(pfn)) & ~CONT_PTE_MASK) == 0) {
+ if ((pgprot_val(prot) & PTE_VALID) &&
+ (((addr | PFN_PHYS(pfn)) & ~CONT_PTE_MASK) == 0)) {
if (end - addr >= CONT_PTE_SIZE && !page_mappings_only)
__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
else
@@ -147,7 +148,8 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
* After the PTE entry has been populated once, we
* only allow updates to the permission attributes.
*/
- BUG_ON(!pgattr_change_is_safe(pte_val(old_pte), pte_val(*pte)));
+ BUG_ON(pte_valid(old_pte) && pte_valid(*pte) &&
+ !pgattr_change_is_safe(pte_val(old_pte), pte_val(*pte)));
} while (pte++, addr += PAGE_SIZE, addr != end);
@@ -190,7 +192,8 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
* Set the contiguous bit for the subsequent group of
* PMDs if its size and alignment are appropriate.
*/
- if (((addr | phys) & ~CONT_PMD_MASK) == 0) {
+ if ((pgprot_val(prot) | PMD_VALID) &&
+ ((addr | phys) & ~CONT_PMD_MASK) == 0) {
if (end - addr >= CONT_PMD_SIZE)
__prot = __pgprot(pgprot_val(prot) |
PTE_CONT);
@@ -203,7 +206,8 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
* After the PMD entry has been populated once, we
* only allow updates to the permission attributes.
*/
- BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd),
+ BUG_ON(pmd_valid(old_pmd) && pmd_valid(*pmd) &&
+ !pgattr_change_is_safe(pmd_val(old_pmd),
pmd_val(*pmd)));
} else {
alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
@@ -263,7 +267,8 @@ static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
* After the PUD entry has been populated once, we
* only allow updates to the permission attributes.
*/
- BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
+ BUG_ON(pud_valid(old_pud) && pud_valid(*pud) &&
+ !pgattr_change_is_safe(pud_val(old_pud),
pud_val(*pud)));
} else {
alloc_init_pmd(pud, addr, next, phys, prot,
@@ -344,8 +349,8 @@ void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
pgd_pgtable_alloc, page_mappings_only);
}
-static void create_mapping_late(phys_addr_t phys, unsigned long virt,
- phys_addr_t size, pgprot_t prot)
+void create_mapping_late(phys_addr_t phys, unsigned long virt,
+ phys_addr_t size, pgprot_t prot)
{
if (virt < VMALLOC_START) {
pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n",
@@ -791,14 +796,20 @@ int __init arch_ioremap_pmd_supported(void)
int pud_set_huge(pud_t *pud, phys_addr_t phys, pgprot_t prot)
{
BUG_ON(phys & ~PUD_MASK);
- set_pud(pud, __pud(phys | PUD_TYPE_SECT | pgprot_val(mk_sect_prot(prot))));
+ set_pud(pud, __pud(phys |
+ ((pgprot_val(prot) & PUD_VALID) ?
+ PUD_TYPE_SECT : 0) |
+ pgprot_val(mk_sect_prot(prot))));
return 1;
}
int pmd_set_huge(pmd_t *pmd, phys_addr_t phys, pgprot_t prot)
{
BUG_ON(phys & ~PMD_MASK);
- set_pmd(pmd, __pmd(phys | PMD_TYPE_SECT | pgprot_val(mk_sect_prot(prot))));
+ set_pmd(pmd, __pmd(phys |
+ ((pgprot_val(prot) & PMD_VALID) ?
+ PMD_TYPE_SECT : 0) |
+ pgprot_val(mk_sect_prot(prot))));
return 1;
}
--
2.11.0
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