summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorCatalin Marinas <catalin.marinas@arm.com>2014-04-03 15:17:32 (GMT)
committerChanho Park <chanho61.park@samsung.com>2014-04-16 12:36:53 (GMT)
commitb1dc2bf6a3a487cac6caf3982be1b7e15b818520 (patch)
treebb76b372fc6e8e7cfc7344c4ac8125610fc12291
parent9fc47e5328125a6b00aa998cb65ae205c9f62649 (diff)
downloadlinux-3.10-b1dc2bf6a3a487cac6caf3982be1b7e15b818520.zip
linux-3.10-b1dc2bf6a3a487cac6caf3982be1b7e15b818520.tar.gz
linux-3.10-b1dc2bf6a3a487cac6caf3982be1b7e15b818520.tar.bz2
arm64: Introduce execute-only page access permissions
The ARMv8 architecture allows execute-only user permissions by clearing the PTE_UXN and PTE_USER bits. The kernel, however, can still access such page. This patch changes the arm64 __P100 and __S100 protection_map[] macros to the new __PAGE_EXECONLY attributes. A side effect is that pte_valid_user() no longer triggers for __PAGE_EXECONLY since PTE_USER isn't set. To work around this, the check is done on the PTE_NG bit via the pte_valid_ng() macro. VM_READ is also checked now for page faults. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/include/asm/pgtable.h11
-rw-r--r--arch/arm64/mm/fault.c5
2 files changed, 8 insertions, 8 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index da92265..64241f0 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -90,6 +90,7 @@ extern pgprot_t pgprot_default;
#define __PAGE_COPY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
#define __PAGE_READONLY __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
#define __PAGE_READONLY_EXEC __pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
+#define __PAGE_EXECONLY __pgprot(_PAGE_DEFAULT | PTE_NG | PTE_PXN)
#endif /* __ASSEMBLY__ */
@@ -97,7 +98,7 @@ extern pgprot_t pgprot_default;
#define __P001 __PAGE_READONLY
#define __P010 __PAGE_COPY
#define __P011 __PAGE_COPY
-#define __P100 __PAGE_READONLY_EXEC
+#define __P100 __PAGE_EXECONLY
#define __P101 __PAGE_READONLY_EXEC
#define __P110 __PAGE_COPY_EXEC
#define __P111 __PAGE_COPY_EXEC
@@ -106,7 +107,7 @@ extern pgprot_t pgprot_default;
#define __S001 __PAGE_READONLY
#define __S010 __PAGE_SHARED
#define __S011 __PAGE_SHARED
-#define __S100 __PAGE_READONLY_EXEC
+#define __S100 __PAGE_EXECONLY
#define __S101 __PAGE_READONLY_EXEC
#define __S110 __PAGE_SHARED_EXEC
#define __S111 __PAGE_SHARED_EXEC
@@ -143,8 +144,8 @@ extern struct page *empty_zero_page;
#define pte_write(pte) (pte_val(pte) & PTE_WRITE)
#define pte_exec(pte) (!(pte_val(pte) & PTE_UXN))
-#define pte_valid_user(pte) \
- ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
+#define pte_valid_ng(pte) \
+ ((pte_val(pte) & (PTE_VALID | PTE_NG)) == (PTE_VALID | PTE_NG))
static inline pte_t pte_wrprotect(pte_t pte)
{
@@ -198,7 +199,7 @@ 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_valid_user(pte)) {
+ if (pte_valid_ng(pte)) {
if (!pte_special(pte) && pte_exec(pte))
__sync_icache_dcache(pte, addr);
if (pte_dirty(pte) && pte_write(pte))
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index bcc965e..89c6763 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -173,8 +173,7 @@ static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
good_area:
/*
* Check that the permissions on the VMA allow for the fault which
- * occurred. If we encountered a write or exec fault, we must have
- * appropriate permissions, otherwise we allow any permission.
+ * occurred.
*/
if (!(vma->vm_flags & vm_flags)) {
fault = VM_FAULT_BADACCESS;
@@ -196,7 +195,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct task_struct *tsk;
struct mm_struct *mm;
int fault, sig, code;
- unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
+ unsigned long vm_flags = VM_READ | VM_WRITE;
unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
tsk = current;