[SPARC64]: Non-executable page support.

Based upon the PAX patches.  Credit to PaX Team
<pageexec@freemail.hu>
Signed-off-by: David S. Miller <davem@redhat.com>

arch/sparc64/kernel/itlb_base.S

@@ -41,6 +41,9 @@
 	CREATE_VPTE_OFFSET2(%g4, %g6)			! Create VPTE offset
 	ldxa		[%g3 + %g6] ASI_P, %g5		! Load VPTE
 1:	brgez,pn	%g5, 3f				! Not valid, branch out
+	 sethi		%hi(_PAGE_EXEC), %g4		! Delay-slot
+	andcc		%g5, %g4, %g0			! Executable?
+	be,pn		%xcc, 3f			! Nope, branch.
 	 nop						! Delay-slot
 2:	stxa		%g5, [%g0] ASI_ITLB_DATA_IN	! Load PTE into TLB
 	retry						! Trap return
@@ -69,9 +72,6 @@ winfix_trampoline:
 	done						! Do it to it
 
 /* ITLB ** ICACHE line 4: Unused...	*/
-	nop
-	nop
-	nop
 	nop
 	nop
 	nop

arch/sparc64/mm/fault.c

@@ -257,7 +257,7 @@ static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code,
 	 * in that case.
 	 */
 
-	if (!(fault_code & FAULT_CODE_WRITE) &&
+	if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
 	    (insn & 0xc0800000) == 0xc0800000) {
 		if (insn & 0x2000)
 			asi = (regs->tstate >> 24);
@@ -408,6 +408,16 @@ asmlinkage void do_sparc64_fault(struct pt_regs *regs)
 	 */
 good_area:
 	si_code = SEGV_ACCERR;
+
+	/* If we took a ITLB miss on a non-executable page, catch
+	 * that here.
+	 */
+	if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
+		BUG_ON(address != regs->tpc);
+		BUG_ON(regs->tstate & TSTATE_PRIV);
+		goto bad_area;
+	}
+
 	if (fault_code & FAULT_CODE_WRITE) {
 		if (!(vma->vm_flags & VM_WRITE))
 			goto bad_area;

include/asm-sparc64/pgtable.h

@@ -180,16 +180,27 @@
 
 /* Don't set the TTE _PAGE_W bit here, else the dirty bit never gets set. */
 #define PAGE_SHARED	__pgprot (_PAGE_PRESENT | _PAGE_VALID | _PAGE_CACHE | \
-				  __ACCESS_BITS | _PAGE_WRITE)
+				  __ACCESS_BITS | _PAGE_WRITE | _PAGE_EXEC)
 
 #define PAGE_COPY	__pgprot (_PAGE_PRESENT | _PAGE_VALID | _PAGE_CACHE | \
-				  __ACCESS_BITS)
+				  __ACCESS_BITS | _PAGE_EXEC)
 
 #define PAGE_READONLY	__pgprot (_PAGE_PRESENT | _PAGE_VALID | _PAGE_CACHE | \
-				  __ACCESS_BITS)
+				  __ACCESS_BITS | _PAGE_EXEC)
 
 #define PAGE_KERNEL	__pgprot (_PAGE_PRESENT | _PAGE_VALID | _PAGE_CACHE | \
-				  __PRIV_BITS | __ACCESS_BITS | __DIRTY_BITS)
+				  __PRIV_BITS | \
+				  __ACCESS_BITS | __DIRTY_BITS | _PAGE_EXEC)
+
+#define PAGE_SHARED_NOEXEC	__pgprot (_PAGE_PRESENT | _PAGE_VALID | \
+					  _PAGE_CACHE | \
+					  __ACCESS_BITS | _PAGE_WRITE)
+
+#define PAGE_COPY_NOEXEC	__pgprot (_PAGE_PRESENT | _PAGE_VALID | \
+					  _PAGE_CACHE | __ACCESS_BITS)
+
+#define PAGE_READONLY_NOEXEC	__pgprot (_PAGE_PRESENT | _PAGE_VALID | \
+					  _PAGE_CACHE | __ACCESS_BITS)
 
 #define _PFN_MASK	_PAGE_PADDR
 
@@ -197,18 +208,18 @@
 		   __ACCESS_BITS | _PAGE_E)
 
 #define __P000	PAGE_NONE
-#define __P001	PAGE_READONLY
-#define __P010	PAGE_COPY
-#define __P011	PAGE_COPY
+#define __P001	PAGE_READONLY_NOEXEC
+#define __P010	PAGE_COPY_NOEXEC
+#define __P011	PAGE_COPY_NOEXEC
 #define __P100	PAGE_READONLY
 #define __P101	PAGE_READONLY
 #define __P110	PAGE_COPY
 #define __P111	PAGE_COPY
 
 #define __S000	PAGE_NONE
-#define __S001	PAGE_READONLY
-#define __S010	PAGE_SHARED
-#define __S011	PAGE_SHARED
+#define __S001	PAGE_READONLY_NOEXEC
+#define __S010	PAGE_SHARED_NOEXEC
+#define __S011	PAGE_SHARED_NOEXEC
 #define __S100	PAGE_READONLY
 #define __S101	PAGE_READONLY
 #define __S110	PAGE_SHARED