powerpc/8xx: add support for huge pages on VMAP and VMALLOC

powerpc 8xx has 4 page sizes:
- 4k
- 16k
- 512k
- 8M

At the time being, vmalloc and vmap only support huge pages which are leaf
at PMD level.

Here the PMD level is 4M, it doesn't correspond to any supported page
size.

For now, implement use of 16k and 512k pages which is done at PTE level.

Support of 8M pages will be implemented later, it requires vmalloc to
support hugepd tables.

Link: https://lkml.kernel.org/r/8b972f1c[e-mail]
Signed-off-by: Christophe Leroy <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Uladzislau Rezki <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/powerpc/Kconfig

···
 	select GENERIC_VDSO_TIME_NS
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
-	select HAVE_ARCH_HUGE_VMAP		if PPC_BOOK3S_64 && PPC_RADIX_MMU
+	select HAVE_ARCH_HUGE_VMAP		if PPC_RADIX_MMU || PPC_8xx
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
 	select HAVE_ARCH_KASAN			if PPC32 && PPC_PAGE_SHIFT <= 14

arch/powerpc/include/asm/nohash/32/mmu-8xx.h

···
 #ifndef __ASSEMBLY__
 
 #include <linux/mmdebug.h>
+#include <linux/sizes.h>
 
 void mmu_pin_tlb(unsigned long top, bool readonly);
 
···
 		return mmu_psize_defs[mmu_psize].shift;
 	BUG();
 }
+
+static inline bool arch_vmap_try_size(unsigned long addr, unsigned long end, u64 pfn,
+				      unsigned int max_page_shift, unsigned long size)
+{
+	if (end - addr < size)
+		return false;
+
+	if ((1UL << max_page_shift) < size)
+		return false;
+
+	if (!IS_ALIGNED(addr, size))
+		return false;
+
+	if (!IS_ALIGNED(PFN_PHYS(pfn), size))
+		return false;
+
+	return true;
+}
+
+static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr, unsigned long end,
+							 u64 pfn, unsigned int max_page_shift)
+{
+	if (arch_vmap_try_size(addr, end, pfn, max_page_shift, SZ_512K))
+		return SZ_512K;
+	if (PAGE_SIZE == SZ_16K)
+		return SZ_16K;
+	if (arch_vmap_try_size(addr, end, pfn, max_page_shift, SZ_16K))
+		return SZ_16K;
+	return PAGE_SIZE;
+}
+#define arch_vmap_pte_range_map_size arch_vmap_pte_range_map_size
+
+static inline int arch_vmap_pte_supported_shift(unsigned long size)
+{
+	if (size >= SZ_512K)
+		return 19;
+	else if (size >= SZ_16K)
+		return 14;
+	else
+		return PAGE_SHIFT;
+}
+#define arch_vmap_pte_supported_shift arch_vmap_pte_supported_shift
 
 /* patch sites */
 extern s32 patch__itlbmiss_exit_1, patch__dtlbmiss_exit_1;