x86: clean up pte_exec

- Rename it to pte_exec() from pte_exec_kernel(). There is nothing
kernel specific in there.
- Move it into the common file because _PAGE_NX is 0 on !PAE and then
pte_exec() will be always evaluate to true.
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/mm/fault_32.c

@@ -615,7 +615,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		if (error_code & PF_INSTR) {
 			pte_t *pte = lookup_address(address);
 
-			if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
+			if (pte && pte_present(*pte) && !pte_exec(*pte))
 				printk(KERN_CRIT "kernel tried to execute "
 					"NX-protected page - exploit attempt? "
 					"(uid: %d)\n", current->uid);

arch/x86/mm/init_32.c

@@ -542,7 +542,7 @@ int __init set_kernel_exec(unsigned long vaddr, int enable)
 	pte = lookup_address(vaddr);
 	BUG_ON(!pte);
 
-	if (!pte_exec_kernel(*pte))
+	if (!pte_exec(*pte))
 		ret = 0;
 
 	if (enable)

include/asm-x86/pgtable-2level.h

@@ -55,14 +55,6 @@ static inline pte_t native_ptep_get_and_clear(pte_t *xp)
 #define pte_none(x)		(!(x).pte_low)
 #define pte_pfn(x)		(pte_val(x) >> PAGE_SHIFT)
 
-/*
- * All present pages are kernel-executable:
- */
-static inline int pte_exec_kernel(pte_t pte)
-{
-	return 1;
-}
-
 /*
  * Bits 0, 6 and 7 are taken, split up the 29 bits of offset
  * into this range:

include/asm-x86/pgtable-3level.h

@@ -19,14 +19,6 @@
 #define pud_bad(pud)				0
 #define pud_present(pud)			1
 
-/*
- * All present pages with !NX bit are kernel-executable:
- */
-static inline int pte_exec_kernel(pte_t pte)
-{
-	return !(pte_val(pte) & _PAGE_NX);
-}
-
 /* Rules for using set_pte: the pte being assigned *must* be
  * either not present or in a state where the hardware will
  * not attempt to update the pte.  In places where this is

include/asm-x86/pgtable.h

@@ -139,6 +139,7 @@ static inline int pte_young(pte_t pte)		{ return pte_val(pte) & _PAGE_ACCESSED;
 static inline int pte_write(pte_t pte)		{ return pte_val(pte) & _PAGE_RW; }
 static inline int pte_file(pte_t pte)		{ return pte_val(pte) & _PAGE_FILE; }
 static inline int pte_huge(pte_t pte)		{ return pte_val(pte) & _PAGE_PSE; }
+static inline int pte_exec(pte_t pte)		{ return !(pte_val(pte) & _PAGE_NX); }
 
 static inline int pmd_large(pmd_t pte) {
 	return (pmd_val(pte) & (_PAGE_PSE|_PAGE_PRESENT)) ==