changing include/asm-generic/pgtable.h for non-mmu

There are some parts of include/asm-generic/pgtable.h that are relevant to
the non-mmu architectures. To make it easier to include this from them I
would like to ifdef the relevant parts.

Without this there is a handful of functions that are referenced in here
that are not defined on many non-mmu architectures. They could be defined
out of course, as an alternative approach.

Cc: David Howells <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/asm-generic/pgtable.h

···
 #define _ASM_GENERIC_PGTABLE_H
 
 #ifndef __ASSEMBLY__
+#ifdef CONFIG_MMU
 
 #ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
 /*
···
 #endif
 
 /*
- * A facility to provide lazy MMU batching.  This allows PTE updates and
- * page invalidations to be delayed until a call to leave lazy MMU mode
- * is issued.  Some architectures may benefit from doing this, and it is
- * beneficial for both shadow and direct mode hypervisors, which may batch
- * the PTE updates which happen during this window.  Note that using this
- * interface requires that read hazards be removed from the code.  A read
- * hazard could result in the direct mode hypervisor case, since the actual
- * write to the page tables may not yet have taken place, so reads though
- * a raw PTE pointer after it has been modified are not guaranteed to be
- * up to date.  This mode can only be entered and left under the protection of
- * the page table locks for all page tables which may be modified.  In the UP
- * case, this is required so that preemption is disabled, and in the SMP case,
- * it must synchronize the delayed page table writes properly on other CPUs.
- */
-#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
-#define arch_enter_lazy_mmu_mode()	do {} while (0)
-#define arch_leave_lazy_mmu_mode()	do {} while (0)
-#define arch_flush_lazy_mmu_mode()	do {} while (0)
-#endif
-
-/*
- * A facility to provide batching of the reload of page tables with the
- * actual context switch code for paravirtualized guests.  By convention,
- * only one of the lazy modes (CPU, MMU) should be active at any given
- * time, entry should never be nested, and entry and exits should always
- * be paired.  This is for sanity of maintaining and reasoning about the
- * kernel code.
- */
-#ifndef __HAVE_ARCH_ENTER_LAZY_CPU_MODE
-#define arch_enter_lazy_cpu_mode()	do {} while (0)
-#define arch_leave_lazy_cpu_mode()	do {} while (0)
-#define arch_flush_lazy_cpu_mode()	do {} while (0)
-#endif
-
-/*
  * When walking page tables, get the address of the next boundary,
  * or the end address of the range if that comes earlier.  Although no
  * vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.
···
 	}
 	return 0;
 }
+#endif /* CONFIG_MMU */
+
+/*
+ * A facility to provide lazy MMU batching.  This allows PTE updates and
+ * page invalidations to be delayed until a call to leave lazy MMU mode
+ * is issued.  Some architectures may benefit from doing this, and it is
+ * beneficial for both shadow and direct mode hypervisors, which may batch
+ * the PTE updates which happen during this window.  Note that using this
+ * interface requires that read hazards be removed from the code.  A read
+ * hazard could result in the direct mode hypervisor case, since the actual
+ * write to the page tables may not yet have taken place, so reads though
+ * a raw PTE pointer after it has been modified are not guaranteed to be
+ * up to date.  This mode can only be entered and left under the protection of
+ * the page table locks for all page tables which may be modified.  In the UP
+ * case, this is required so that preemption is disabled, and in the SMP case,
+ * it must synchronize the delayed page table writes properly on other CPUs.
+ */
+#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
+#define arch_enter_lazy_mmu_mode()	do {} while (0)
+#define arch_leave_lazy_mmu_mode()	do {} while (0)
+#define arch_flush_lazy_mmu_mode()	do {} while (0)
+#endif
+
+/*
+ * A facility to provide batching of the reload of page tables with the
+ * actual context switch code for paravirtualized guests.  By convention,
+ * only one of the lazy modes (CPU, MMU) should be active at any given
+ * time, entry should never be nested, and entry and exits should always
+ * be paired.  This is for sanity of maintaining and reasoning about the
+ * kernel code.
+ */
+#ifndef __HAVE_ARCH_ENTER_LAZY_CPU_MODE
+#define arch_enter_lazy_cpu_mode()	do {} while (0)
+#define arch_leave_lazy_cpu_mode()	do {} while (0)
+#define arch_flush_lazy_cpu_mode()	do {} while (0)
+#endif
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_GENERIC_PGTABLE_H */