x86/pgtable: Move two more functions from pgtable_64.h to pgtable.h

These two functions are required for PTI on 32 bit:

	* pgdp_maps_userspace()
	* pgd_large()

Also re-implement pgdp_maps_userspace() so that it will work on 64 and 32
bit kernels.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-21-git-send-email-joro@8bytes.org

arch/x86/include/asm/pgtable-2level_types.h

@@ -35,4 +35,7 @@ typedef union {
 
 #define PTRS_PER_PTE	1024
 
+/* This covers all VMSPLIT_* and VMSPLIT_*_OPT variants */
+#define PGD_KERNEL_START	(CONFIG_PAGE_OFFSET >> PGDIR_SHIFT)
+
 #endif /* _ASM_X86_PGTABLE_2LEVEL_DEFS_H */

arch/x86/include/asm/pgtable-3level_types.h

@@ -46,5 +46,6 @@ typedef union {
 #define PTRS_PER_PTE	512
 
 #define MAX_POSSIBLE_PHYSMEM_BITS	36
+#define PGD_KERNEL_START	(CONFIG_PAGE_OFFSET >> PGDIR_SHIFT)
 
 #endif /* _ASM_X86_PGTABLE_3LEVEL_DEFS_H */

arch/x86/include/asm/pgtable.h

@@ -1177,6 +1177,21 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 	}
 }
 #endif
+/*
+ * Page table pages are page-aligned.  The lower half of the top
+ * level is used for userspace and the top half for the kernel.
+ *
+ * Returns true for parts of the PGD that map userspace and
+ * false for the parts that map the kernel.
+ */
+static inline bool pgdp_maps_userspace(void *__ptr)
+{
+	unsigned long ptr = (unsigned long)__ptr;
+
+	return (((ptr & ~PAGE_MASK) / sizeof(pgd_t)) < PGD_KERNEL_START);
+}
+
+static inline int pgd_large(pgd_t pgd) { return 0; }
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 /*

arch/x86/include/asm/pgtable_32.h

@@ -34,8 +34,6 @@ static inline void check_pgt_cache(void) { }
 void paging_init(void);
 void sync_initial_page_table(void);
 
-static inline int pgd_large(pgd_t pgd) { return 0; }
-
 /*
  * Define this if things work differently on an i386 and an i486:
  * it will (on an i486) warn about kernel memory accesses that are

arch/x86/include/asm/pgtable_64.h

@@ -132,41 +132,6 @@ static inline pud_t native_pudp_get_and_clear(pud_t *xp)
 #endif
 }
 
-/*
- * Page table pages are page-aligned.  The lower half of the top
- * level is used for userspace and the top half for the kernel.
- *
- * Returns true for parts of the PGD that map userspace and
- * false for the parts that map the kernel.
- */
-static inline bool pgdp_maps_userspace(void *__ptr)
-{
-	unsigned long ptr = (unsigned long)__ptr;
-
-	return (ptr & ~PAGE_MASK) < (PAGE_SIZE / 2);
-}
-
-#ifdef CONFIG_PAGE_TABLE_ISOLATION
-pgd_t __pti_set_user_pgtbl(pgd_t *pgdp, pgd_t pgd);
-
-/*
- * Take a PGD location (pgdp) and a pgd value that needs to be set there.
- * Populates the user and returns the resulting PGD that must be set in
- * the kernel copy of the page tables.
- */
-static inline pgd_t pti_set_user_pgtbl(pgd_t *pgdp, pgd_t pgd)
-{
-	if (!static_cpu_has(X86_FEATURE_PTI))
-		return pgd;
-	return __pti_set_user_pgtbl(pgdp, pgd);
-}
-#else
-static inline pgd_t pti_set_user_pgtbl(pgd_t *pgdp, pgd_t pgd)
-{
-	return pgd;
-}
-#endif
-
 static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
 {
 	pgd_t pgd;
@@ -206,7 +171,6 @@ extern void sync_global_pgds(unsigned long start, unsigned long end);
 /*
  * Level 4 access.
  */
-static inline int pgd_large(pgd_t pgd) { return 0; }
 #define mk_kernel_pgd(address) __pgd((address) | _KERNPG_TABLE)
 
 /* PUD - Level3 access */

arch/x86/include/asm/pgtable_64_types.h

@@ -153,4 +153,6 @@ extern unsigned int ptrs_per_p4d;
 
 #define EARLY_DYNAMIC_PAGE_TABLES	64
 
+#define PGD_KERNEL_START	((PAGE_SIZE / 2) / sizeof(pgd_t))
+
 #endif /* _ASM_X86_PGTABLE_64_DEFS_H */