1 files changed, 130 insertions, 16 deletions

diff --git a/include/asm-s390/pgtable.h b/include/asm-s390/pgtable.h
index 304ee7736413..13c16546eff5 100644
--- a/include/asm-s390/pgtable.h
+++ b/include/asm-s390/pgtable.h
@@ -224,6 +224,8 @@ extern unsigned long vmalloc_end;
 #define _PAGE_TYPE_FILE         0x601   /* bit 0x002 is used for offset !! */
 #define _PAGE_TYPE_RO           0x200
 #define _PAGE_TYPE_RW           0x000
+#define _PAGE_TYPE_EX_RO        0x202
+#define _PAGE_TYPE_EX_RW        0x002
 
 /*
  * PTE type bits are rather complicated. handle_pte_fault uses pte_present,
@@ -244,11 +246,13 @@ extern unsigned long vmalloc_end;
  * _PAGE_TYPE_FILE      11?1   ->   11?1
  * _PAGE_TYPE_RO        0100   ->   1100
  * _PAGE_TYPE_RW        0000   ->   1000
+ * _PAGE_TYPE_EX_RO     0110   ->   1110
+ * _PAGE_TYPE_EX_RW     0010   ->   1010
  *
- * pte_none is true for bits combinations 1000, 1100
+ * pte_none is true for bits combinations 1000, 1010, 1100, 1110
  * pte_present is true for bits combinations 0000, 0010, 0100, 0110, 1001
  * pte_file is true for bits combinations 1101, 1111
- * swap pte is 1011 and 0001, 0011, 0101, 0111, 1010 and 1110 are invalid.
+ * swap pte is 1011 and 0001, 0011, 0101, 0111 are invalid.
  */
 
 #ifndef __s390x__
@@ -313,33 +317,100 @@ extern unsigned long vmalloc_end;
 #define PAGE_NONE       __pgprot(_PAGE_TYPE_NONE)
 #define PAGE_RO         __pgprot(_PAGE_TYPE_RO)
 #define PAGE_RW         __pgprot(_PAGE_TYPE_RW)
+#define PAGE_EX_RO      __pgprot(_PAGE_TYPE_EX_RO)
+#define PAGE_EX_RW      __pgprot(_PAGE_TYPE_EX_RW)
 
 #define PAGE_KERNEL     PAGE_RW
 #define PAGE_COPY       PAGE_RO
 
 /*
- * The S390 can't do page protection for execute, and considers that the
- * same are read. Also, write permissions imply read permissions. This is
- * the closest we can get..
+ * Dependent on the EXEC_PROTECT option s390 can do execute protection.
+ * Write permission always implies read permission. In theory with a
+ * primary/secondary page table execute only can be implemented but
+ * it would cost an additional bit in the pte to distinguish all the
+ * different pte types. To avoid that execute permission currently
+ * implies read permission as well.
  */
          /*xwr*/
 #define __P000  PAGE_NONE
 #define __P001  PAGE_RO
 #define __P010  PAGE_RO
 #define __P011  PAGE_RO
-#define __P100  PAGE_RO
-#define __P101  PAGE_RO
-#define __P110  PAGE_RO
-#define __P111  PAGE_RO
+#define __P100  PAGE_EX_RO
+#define __P101  PAGE_EX_RO
+#define __P110  PAGE_EX_RO
+#define __P111  PAGE_EX_RO
 
 #define __S000  PAGE_NONE
 #define __S001  PAGE_RO
 #define __S010  PAGE_RW
 #define __S011  PAGE_RW
-#define __S100  PAGE_RO
-#define __S101  PAGE_RO
-#define __S110  PAGE_RW
-#define __S111  PAGE_RW
+#define __S100  PAGE_EX_RO
+#define __S101  PAGE_EX_RO
+#define __S110  PAGE_EX_RW
+#define __S111  PAGE_EX_RW
+
+#ifndef __s390x__
+# define PMD_SHADOW_SHIFT       1
+# define PGD_SHADOW_SHIFT       1
+#else /* __s390x__ */
+# define PMD_SHADOW_SHIFT       2
+# define PGD_SHADOW_SHIFT       2
+#endif /* __s390x__ */
+
+static inline struct page *get_shadow_page(struct page *page)
+{
+        if (s390_noexec && !list_empty(&page->lru))
+                return virt_to_page(page->lru.next);
+        return NULL;
+}
+
+static inline pte_t *get_shadow_pte(pte_t *ptep)
+{
+        unsigned long pteptr = (unsigned long) (ptep);
+
+        if (s390_noexec) {
+                unsigned long offset = pteptr & (PAGE_SIZE - 1);
+                void *addr = (void *) (pteptr ^ offset);
+                struct page *page = virt_to_page(addr);
+                if (!list_empty(&page->lru))
+                        return (pte_t *) ((unsigned long) page->lru.next |
+                                                                offset);
+        }
+        return NULL;
+}
+
+static inline pmd_t *get_shadow_pmd(pmd_t *pmdp)
+{
+        unsigned long pmdptr = (unsigned long) (pmdp);
+
+        if (s390_noexec) {
+                unsigned long offset = pmdptr &
+                                ((PAGE_SIZE << PMD_SHADOW_SHIFT) - 1);
+                void *addr = (void *) (pmdptr ^ offset);
+                struct page *page = virt_to_page(addr);
+                if (!list_empty(&page->lru))
+                        return (pmd_t *) ((unsigned long) page->lru.next |
+                                                                offset);
+        }
+        return NULL;
+}
+
+static inline pgd_t *get_shadow_pgd(pgd_t *pgdp)
+{
+        unsigned long pgdptr = (unsigned long) (pgdp);
+
+        if (s390_noexec) {
+                unsigned long offset = pgdptr &
+                                ((PAGE_SIZE << PGD_SHADOW_SHIFT) - 1);
+                void *addr = (void *) (pgdptr ^ offset);
+                struct page *page = virt_to_page(addr);
+                if (!list_empty(&page->lru))
+                        return (pgd_t *) ((unsigned long) page->lru.next |
+                                                                offset);
+        }
+        return NULL;
+}
 
 /*
  * Certain architectures need to do special things when PTEs
@@ -348,7 +419,16 @@ extern unsigned long vmalloc_end;
  */
 static inline void set_pte(pte_t *pteptr, pte_t pteval)
 {
+        pte_t *shadow_pte = get_shadow_pte(pteptr);
+
         *pteptr = pteval;
+        if (shadow_pte) {
+                if (!(pte_val(pteval) & _PAGE_INVALID) &&
+                    (pte_val(pteval) & _PAGE_SWX))
+                        pte_val(*shadow_pte) = pte_val(pteval) | _PAGE_RO;
+                else
+                        pte_val(*shadow_pte) = _PAGE_TYPE_EMPTY;
+        }
 }
 #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval)
 
@@ -466,7 +546,7 @@ static inline int pte_read(pte_t pte)
 
 static inline void pgd_clear(pgd_t * pgdp)      { }
 
-static inline void pmd_clear(pmd_t * pmdp)
+static inline void pmd_clear_kernel(pmd_t * pmdp)
 {
         pmd_val(pmdp[0]) = _PAGE_TABLE_INV;
         pmd_val(pmdp[1]) = _PAGE_TABLE_INV;
@@ -474,24 +554,55 @@ static inline void pmd_clear(pmd_t * pmdp)
         pmd_val(pmdp[3]) = _PAGE_TABLE_INV;
 }
 
+static inline void pmd_clear(pmd_t * pmdp)
+{
+        pmd_t *shadow_pmd = get_shadow_pmd(pmdp);
+
+        pmd_clear_kernel(pmdp);
+        if (shadow_pmd)
+                pmd_clear_kernel(shadow_pmd);
+}
+
 #else /* __s390x__ */
 
-static inline void pgd_clear(pgd_t * pgdp)
+static inline void pgd_clear_kernel(pgd_t * pgdp)
 {
         pgd_val(*pgdp) = _PGD_ENTRY_INV | _PGD_ENTRY;
 }
 
-static inline void pmd_clear(pmd_t * pmdp)
+static inline void pgd_clear(pgd_t * pgdp)
+{
+        pgd_t *shadow_pgd = get_shadow_pgd(pgdp);
+
+        pgd_clear_kernel(pgdp);
+        if (shadow_pgd)
+                pgd_clear_kernel(shadow_pgd);
+}
+
+static inline void pmd_clear_kernel(pmd_t * pmdp)
 {
         pmd_val(*pmdp) = _PMD_ENTRY_INV | _PMD_ENTRY;
         pmd_val1(*pmdp) = _PMD_ENTRY_INV | _PMD_ENTRY;
 }
 
+static inline void pmd_clear(pmd_t * pmdp)
+{
+        pmd_t *shadow_pmd = get_shadow_pmd(pmdp);
+
+        pmd_clear_kernel(pmdp);
+        if (shadow_pmd)
+                pmd_clear_kernel(shadow_pmd);
+}
+
 #endif /* __s390x__ */
 
 static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 {
+        pte_t *shadow_pte = get_shadow_pte(ptep);
+
         pte_val(*ptep) = _PAGE_TYPE_EMPTY;
+        if (shadow_pte)
+                pte_val(*shadow_pte) = _PAGE_TYPE_EMPTY;
 }
 
 /*
@@ -609,8 +720,11 @@ ptep_clear_flush(struct vm_area_struct *vma,
                  unsigned long address, pte_t *ptep)
 {
         pte_t pte = *ptep;
+        pte_t *shadow_pte = get_shadow_pte(ptep);
 
         __ptep_ipte(address, ptep);
+        if (shadow_pte)
+                __ptep_ipte(address, shadow_pte);
         return pte;
 }