x86/mm/set_memory: Fix -Wmissing-prototypes warnings

Add missing includes and move prototypes into the header set_memory.h in
order to fix -Wmissing-prototypes warnings.

 [ bp: Add ifdeffery around arch_invalidate_pmem() ]
Signed-off-by: Benjamin Thiel <b.thiel@posteo.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200320145028.6013-1-b.thiel@posteo.de

arch/x86/include/asm/set_memory.h

@@ -46,6 +46,8 @@ int set_memory_4k(unsigned long addr, int numpages);
 int set_memory_encrypted(unsigned long addr, int numpages);
 int set_memory_decrypted(unsigned long addr, int numpages);
 int set_memory_np_noalias(unsigned long addr, int numpages);
+int set_memory_nonglobal(unsigned long addr, int numpages);
+int set_memory_global(unsigned long addr, int numpages);
 
 int set_pages_array_uc(struct page **pages, int addrinarray);
 int set_pages_array_wc(struct page **pages, int addrinarray);

arch/x86/mm/pat/set_memory.c

@@ -15,6 +15,7 @@
 #include <linux/gfp.h>
 #include <linux/pci.h>
 #include <linux/vmalloc.h>
+#include <linux/libnvdimm.h>
 
 #include <asm/e820/api.h>
 #include <asm/processor.h>
@@ -304,11 +305,13 @@ void clflush_cache_range(void *vaddr, unsigned int size)
 }
 EXPORT_SYMBOL_GPL(clflush_cache_range);
 
+#ifdef CONFIG_ARCH_HAS_PMEM_API
 void arch_invalidate_pmem(void *addr, size_t size)
 {
 	clflush_cache_range(addr, size);
 }
 EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
+#endif
 
 static void __cpa_flush_all(void *arg)
 {

arch/x86/mm/pti.c

@@ -39,6 +39,7 @@
 #include <asm/tlbflush.h>
 #include <asm/desc.h>
 #include <asm/sections.h>
+#include <asm/set_memory.h>
 
 #undef pr_fmt
 #define pr_fmt(fmt)     "Kernel/User page tables isolation: " fmt
@@ -554,13 +555,6 @@ static inline bool pti_kernel_image_global_ok(void)
 	return true;
 }
 
-/*
- * This is the only user for these and it is not arch-generic
- * like the other set_memory.h functions.  Just extern them.
- */
-extern int set_memory_nonglobal(unsigned long addr, int numpages);
-extern int set_memory_global(unsigned long addr, int numpages);
-
 /*
  * For some configurations, map all of kernel text into the user page
  * tables.  This reduces TLB misses, especially on non-PCID systems.