powerpc/64s: Always define arch unmapped area calls

To avoid any functional changes to radix paths when building with hash
MMU support disabled (and CONFIG_PPC_MM_SLICES=n), always define the
arch get_unmapped_area calls on 64s platforms.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211201144153.2456614-16-npiggin@gmail.com

arch/powerpc/include/asm/book3s/64/hash.h

@@ -99,10 +99,6 @@
  * Defines the address of the vmemap area, in its own region on
  * hash table CPUs.
  */
-#ifdef CONFIG_PPC_MM_SLICES
-#define HAVE_ARCH_UNMAPPED_AREA
-#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
-#endif /* CONFIG_PPC_MM_SLICES */
 
 /* PTEIDX nibble */
 #define _PTEIDX_SECONDARY	0x8

arch/powerpc/include/asm/book3s/64/mmu.h

@@ -4,6 +4,12 @@
 
 #include <asm/page.h>
 
+#ifdef CONFIG_HUGETLB_PAGE
+#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
+#endif
+#define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
+
 #ifndef __ASSEMBLY__
 /*
  * Page size definition

arch/powerpc/mm/hugetlbpage.c

@@ -542,20 +542,26 @@ struct page *follow_huge_pd(struct vm_area_struct *vma,
 	return page;
 }
 
-#ifdef CONFIG_PPC_MM_SLICES
+#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
+static inline int file_to_psize(struct file *file)
+{
+	struct hstate *hstate = hstate_file(file);
+	return shift_to_mmu_psize(huge_page_shift(hstate));
+}
+
 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 					unsigned long len, unsigned long pgoff,
 					unsigned long flags)
 {
-	struct hstate *hstate = hstate_file(file);
-	int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
-
 #ifdef CONFIG_PPC_RADIX_MMU
 	if (radix_enabled())
 		return radix__hugetlb_get_unmapped_area(file, addr, len,
 						       pgoff, flags);
 #endif
-	return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
+#ifdef CONFIG_PPC_MM_SLICES
+	return slice_get_unmapped_area(addr, len, flags, file_to_psize(file), 1);
+#endif
+	BUG();
 }
 #endif
 

arch/powerpc/mm/mmap.c

@@ -80,6 +80,7 @@ static inline unsigned long mmap_base(unsigned long rnd,
 	return PAGE_ALIGN(DEFAULT_MAP_WINDOW - gap - rnd);
 }
 
+#ifdef HAVE_ARCH_UNMAPPED_AREA
 #ifdef CONFIG_PPC_RADIX_MMU
 /*
  * Same function as generic code used only for radix, because we don't need to overload
@@ -181,11 +182,42 @@ radix__arch_get_unmapped_area_topdown(struct file *filp,
 	 */
 	return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 }
+#endif
+
+unsigned long arch_get_unmapped_area(struct file *filp,
+				     unsigned long addr,
+				     unsigned long len,
+				     unsigned long pgoff,
+				     unsigned long flags)
+{
+#ifdef CONFIG_PPC_MM_SLICES
+	return slice_get_unmapped_area(addr, len, flags,
+				       mm_ctx_user_psize(&current->mm->context), 0);
+#else
+	BUG();
+#endif
+}
+
+unsigned long arch_get_unmapped_area_topdown(struct file *filp,
+					     const unsigned long addr0,
+					     const unsigned long len,
+					     const unsigned long pgoff,
+					     const unsigned long flags)
+{
+#ifdef CONFIG_PPC_MM_SLICES
+	return slice_get_unmapped_area(addr0, len, flags,
+				       mm_ctx_user_psize(&current->mm->context), 1);
+#else
+	BUG();
+#endif
+}
+#endif /* HAVE_ARCH_UNMAPPED_AREA */
 
 static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
 					unsigned long random_factor,
 					struct rlimit *rlim_stack)
 {
+#ifdef CONFIG_PPC_RADIX_MMU
 	if (mmap_is_legacy(rlim_stack)) {
 		mm->mmap_base = TASK_UNMAPPED_BASE;
 		mm->get_unmapped_area = radix__arch_get_unmapped_area;
@@ -193,13 +225,9 @@ static void radix__arch_pick_mmap_layout(struct mm_struct *mm,
 		mm->mmap_base = mmap_base(random_factor, rlim_stack);
 		mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown;
 	}
-}
-#else
-/* dummy */
-extern void radix__arch_pick_mmap_layout(struct mm_struct *mm,
-					unsigned long random_factor,
-					struct rlimit *rlim_stack);
 #endif
+}
+
 /*
  * This function, called very early during the creation of a new
  * process VM image, sets up which VM layout function to use:

arch/powerpc/mm/slice.c

@@ -639,26 +639,6 @@ unsigned long slice_get_unmapped_area(unsigned long addr, unsigned long len,
 }
 EXPORT_SYMBOL_GPL(slice_get_unmapped_area);
 
-unsigned long arch_get_unmapped_area(struct file *filp,
-				     unsigned long addr,
-				     unsigned long len,
-				     unsigned long pgoff,
-				     unsigned long flags)
-{
-	return slice_get_unmapped_area(addr, len, flags,
-				       mm_ctx_user_psize(&current->mm->context), 0);
-}
-
-unsigned long arch_get_unmapped_area_topdown(struct file *filp,
-					     const unsigned long addr0,
-					     const unsigned long len,
-					     const unsigned long pgoff,
-					     const unsigned long flags)
-{
-	return slice_get_unmapped_area(addr0, len, flags,
-				       mm_ctx_user_psize(&current->mm->context), 1);
-}
-
 unsigned int notrace get_slice_psize(struct mm_struct *mm, unsigned long addr)
 {
 	unsigned char *psizes;