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authorWill Deacon <will.deacon@arm.com>2012-12-18 14:15:15 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2013-01-10 10:48:48 +0000
commita6fadf7e67d3794aae40244f435d281a62736c93 (patch)
tree2f12828305659a7ae4ec51305f44f1d836aa474b
parent02522463c84748b3b8ad770f9424bcfa70a5b4c4 (diff)
downloadlinux-stericsson-a6fadf7e67d3794aae40244f435d281a62736c93.tar.gz
arm64: mm: introduce present, faulting entries for PAGE_NONE
This is mostly a port of dbf62d50067e ("ARM: mm: introduce L_PTE_VALID for page table entries") and 26ffd0d43b18 ("ARM: mm: introduce present, faulting entries for PAGE_NONE") from ARM, which makes use of present, faulting page table entries for page table entries mapped as PROT_NONE. The main difference with this implementation is that we can make use of the two pte type bits in order to avoid allocating a software bit for identifying PROT_NONE pages, instead reserving the 10b suffix for these types of mappings. This is required to prevent users from accessing such pages via syscalls such as read/write over a pipe. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/include/asm/pgtable.h24
1 files changed, 13 insertions, 11 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7adf4142a85c..e333a243bfcc 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -24,7 +24,8 @@
/*
* Software defined PTE bits definition.
*/
-#define PTE_VALID (_AT(pteval_t, 1) << 0) /* pte_present() check */
+#define PTE_VALID (_AT(pteval_t, 1) << 0)
+#define PTE_PROT_NONE (_AT(pteval_t, 1) << 1) /* only when !PTE_VALID */
#define PTE_FILE (_AT(pteval_t, 1) << 2) /* only when !pte_present() */
#define PTE_DIRTY (_AT(pteval_t, 1) << 55)
#define PTE_SPECIAL (_AT(pteval_t, 1) << 56)
@@ -60,9 +61,12 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
extern pgprot_t pgprot_default;
-#define _MOD_PROT(p, b) __pgprot(pgprot_val(p) | (b))
+#define __pgprot_modify(prot,mask,bits) \
+ __pgprot((pgprot_val(prot) & ~(mask)) | (bits))
+
+#define _MOD_PROT(p, b) __pgprot_modify(p, 0, b)
-#define PAGE_NONE _MOD_PROT(pgprot_default, PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
+#define PAGE_NONE __pgprot_modify(pgprot_default, PTE_TYPE_MASK, PTE_PROT_NONE)
#define PAGE_SHARED _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define PAGE_SHARED_EXEC _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN)
#define PAGE_COPY _MOD_PROT(pgprot_default, PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
@@ -72,7 +76,7 @@ extern pgprot_t pgprot_default;
#define PAGE_KERNEL _MOD_PROT(pgprot_default, PTE_PXN | PTE_UXN | PTE_DIRTY)
#define PAGE_KERNEL_EXEC _MOD_PROT(pgprot_default, PTE_UXN | PTE_DIRTY)
-#define __PAGE_NONE __pgprot(_PAGE_DEFAULT | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
+#define __PAGE_NONE __pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE)
#define __PAGE_SHARED __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define __PAGE_SHARED_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
#define __PAGE_COPY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_RDONLY)
@@ -125,14 +129,14 @@ extern struct page *empty_zero_page;
/*
* The following only work if pte_present(). Undefined behaviour otherwise.
*/
-#define pte_present(pte) (pte_val(pte) & PTE_VALID)
+#define pte_present(pte) (pte_val(pte) & (PTE_VALID | PTE_PROT_NONE))
#define pte_dirty(pte) (pte_val(pte) & PTE_DIRTY)
#define pte_young(pte) (pte_val(pte) & PTE_AF)
#define pte_special(pte) (pte_val(pte) & PTE_SPECIAL)
#define pte_write(pte) (!(pte_val(pte) & PTE_RDONLY))
#define pte_exec(pte) (!(pte_val(pte) & PTE_UXN))
-#define pte_present_user(pte) \
+#define pte_valid_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
#define PTE_BIT_FUNC(fn,op) \
@@ -156,7 +160,7 @@ extern void __sync_icache_dcache(pte_t pteval, unsigned long addr);
static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
- if (pte_present_user(pte)) {
+ if (pte_valid_user(pte)) {
if (pte_exec(pte))
__sync_icache_dcache(pte, addr);
if (!pte_dirty(pte))
@@ -172,9 +176,6 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
#define pte_huge(pte) ((pte_val(pte) & PTE_TYPE_MASK) == PTE_TYPE_HUGEPAGE)
#define pte_mkhuge(pte) (__pte((pte_val(pte) & ~PTE_TYPE_MASK) | PTE_TYPE_HUGEPAGE))
-#define __pgprot_modify(prot,mask,bits) \
- __pgprot((pgprot_val(prot) & ~(mask)) | (bits))
-
#define __HAVE_ARCH_PTE_SPECIAL
/*
@@ -266,7 +267,8 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
- const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY;
+ const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY |
+ PTE_PROT_NONE | PTE_VALID;
pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
return pte;
}