mm: vmalloc: group declarations depending on CONFIG_MMU together

Patch series "x86/module: use large ROX pages for text allocations", v7.

These patches add support for using large ROX pages for allocations of
executable memory on x86.

They address Andy's comments [1] about having executable mappings for code
that was not completely formed.

The approach taken is to allocate ROX memory along with writable but not
executable memory and use the writable copy to perform relocations and
alternatives patching.  After the module text gets into its final shape,
the contents of the writable memory is copied into the actual ROX location
using text poking.

The allocations of the ROX memory use vmalloc(VMAP_ALLOW_HUGE_MAP) to
allocate PMD aligned memory, fill that memory with invalid instructions
and in the end remap it as ROX.  Portions of these large pages are handed
out to execmem_alloc() callers without any changes to the permissions. 
When the memory is freed with execmem_free() it is invalidated again so
that it won't contain stale instructions.

The module memory allocation, x86 code dealing with relocations and
alternatives patching take into account the existence of the two copies,
the writable memory and the ROX memory at the actual allocated virtual
address.

[1] https://lore.kernel.org/all/[email protected]


This patch (of 8):

There are a couple of declarations that depend on CONFIG_MMU in
include/linux/vmalloc.h spread all over the file.

Group them all together to improve code readability.

No functional changes.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport (Microsoft) <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
Reviewed-by: Luis Chamberlain <[email protected]>
Tested-by: kdevops <[email protected]>
Cc: Andreas Larsson <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Brian Cain <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Guo Ren <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: John Paul Adrian Glaubitz <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Russell King <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

include/linux/vmalloc.h

@@ -134,12 +134,6 @@ extern void vm_unmap_ram(const void *mem, unsigned int count);
 extern void *vm_map_ram(struct page **pages, unsigned int count, int node);
 extern void vm_unmap_aliases(void);
 
-#ifdef CONFIG_MMU
-extern unsigned long vmalloc_nr_pages(void);
-#else
-static inline unsigned long vmalloc_nr_pages(void) { return 0; }
-#endif
-
 extern void *vmalloc_noprof(unsigned long size) __alloc_size(1);
 #define vmalloc(...)		alloc_hooks(vmalloc_noprof(__VA_ARGS__))
 
@@ -266,37 +260,44 @@ static inline bool is_vm_area_hugepages(const void *addr)
 #endif
 }
 
+/* for /proc/kcore */
+long vread_iter(struct iov_iter *iter, const char *addr, size_t count);
+
+/*
+ *	Internals.  Don't use..
+ */
+__init void vm_area_add_early(struct vm_struct *vm);
+__init void vm_area_register_early(struct vm_struct *vm, size_t align);
+
+int register_vmap_purge_notifier(struct notifier_block *nb);
+int unregister_vmap_purge_notifier(struct notifier_block *nb);
+
 #ifdef CONFIG_MMU
+#define VMALLOC_TOTAL (VMALLOC_END - VMALLOC_START)
+
+unsigned long vmalloc_nr_pages(void);
+
 int vm_area_map_pages(struct vm_struct *area, unsigned long start,
 		      unsigned long end, struct page **pages);
 void vm_area_unmap_pages(struct vm_struct *area, unsigned long start,
 			 unsigned long end);
 void vunmap_range(unsigned long addr, unsigned long end);
+
 static inline void set_vm_flush_reset_perms(void *addr)
 {
 	struct vm_struct *vm = find_vm_area(addr);
 
 	if (vm)
 		vm->flags |= VM_FLUSH_RESET_PERMS;
 }
+#else  /* !CONFIG_MMU */
+#define VMALLOC_TOTAL 0UL
 
-#else
-static inline void set_vm_flush_reset_perms(void *addr)
-{
-}
-#endif
-
-/* for /proc/kcore */
-extern long vread_iter(struct iov_iter *iter, const char *addr, size_t count);
-
-/*
- *	Internals.  Don't use..
- */
-extern __init void vm_area_add_early(struct vm_struct *vm);
-extern __init void vm_area_register_early(struct vm_struct *vm, size_t align);
+static inline unsigned long vmalloc_nr_pages(void) { return 0; }
+static inline void set_vm_flush_reset_perms(void *addr) {}
+#endif /* CONFIG_MMU */
 
-#ifdef CONFIG_SMP
-# ifdef CONFIG_MMU
+#if defined(CONFIG_MMU) && defined(CONFIG_SMP)
 struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
 				     const size_t *sizes, int nr_vms,
 				     size_t align);
@@ -311,22 +312,9 @@ pcpu_get_vm_areas(const unsigned long *offsets,
 	return NULL;
 }
 
-static inline void
-pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
-{
-}
-# endif
-#endif
-
-#ifdef CONFIG_MMU
-#define VMALLOC_TOTAL (VMALLOC_END - VMALLOC_START)
-#else
-#define VMALLOC_TOTAL 0UL
+static inline void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) {}
 #endif
 
-int register_vmap_purge_notifier(struct notifier_block *nb);
-int unregister_vmap_purge_notifier(struct notifier_block *nb);
-
 #if defined(CONFIG_MMU) && defined(CONFIG_PRINTK)
 bool vmalloc_dump_obj(void *object);
 #else