arm64: Introduce VA_BITS and translation level options

This patch adds virtual address space size and a level of translation
tables to kernel configuration. It facilicates introduction of
different MMU options, such as 4KB + 4 levels, 16KB + 4 levels and
64KB + 3 levels, easily.

The idea is based on the discussion with Catalin Marinas:
http://www.spinics.net/linux/lists/arm-kernel/msg319552.html

Signed-off-by: Jungseok Lee <[e-mail]>
Reviewed-by: Sungjinn Chung <[e-mail]>
Acked-by: Kukjin Kim <[e-mail]>
Reviewed-by: Christoffer Dall <[e-mail]>
Signed-off-by: Catalin Marinas <[e-mail]>
Tested-by: Jungseok Lee <[e-mail]>

arch/arm64/Kconfig

···
 
 menu "Kernel Features"
 
+choice
+	prompt "Page size"
+	default ARM64_4K_PAGES
+	help
+	  Page size (translation granule) configuration.
+
+config ARM64_4K_PAGES
+	bool "4KB"
+	help
+	  This feature enables 4KB pages support.
+
 config ARM64_64K_PAGES
-	bool "Enable 64KB pages support"
+	bool "64KB"
 	help
 	  This feature enables 64KB pages support (4KB by default)
 	  allowing only two levels of page tables and faster TLB
 	  look-up. AArch32 emulation is not available when this feature
 	  is enabled.
+
+endchoice
+
+choice
+	prompt "Virtual address space size"
+	default ARM64_VA_BITS_39 if ARM64_4K_PAGES
+	default ARM64_VA_BITS_42 if ARM64_64K_PAGES
+	help
+	  Allows choosing one of multiple possible virtual address
+	  space sizes. The level of translation table is determined by
+	  a combination of page size and virtual address space size.
+
+config ARM64_VA_BITS_39
+	bool "39-bit"
+	depends on ARM64_4K_PAGES
+
+config ARM64_VA_BITS_42
+	bool "42-bit"
+	depends on ARM64_64K_PAGES
+
+endchoice
+
+config ARM64_VA_BITS
+	int
+	default 39 if ARM64_VA_BITS_39
+	default 42 if ARM64_VA_BITS_42
+
+config ARM64_2_LEVELS
+	def_bool y if ARM64_64K_PAGES && ARM64_VA_BITS_42
+
+config ARM64_3_LEVELS
+	def_bool y if ARM64_4K_PAGES && ARM64_VA_BITS_39
 
 config CPU_BIG_ENDIAN
        bool "Build big-endian kernel"

arch/arm64/include/asm/memory.h

···
  * The module space lives between the addresses given by TASK_SIZE
  * and PAGE_OFFSET - it must be within 128MB of the kernel text.
  */
-#ifdef CONFIG_ARM64_64K_PAGES
-#define VA_BITS			(42)
-#else
-#define VA_BITS			(39)
-#endif
+#define VA_BITS			(CONFIG_ARM64_VA_BITS)
 #define PAGE_OFFSET		(UL(0xffffffffffffffff) << (VA_BITS - 1))
 #define MODULES_END		(PAGE_OFFSET)
 #define MODULES_VADDR		(MODULES_END - SZ_64M)

arch/arm64/include/asm/page.h

···
 
 #ifndef __ASSEMBLY__
 
-#ifdef CONFIG_ARM64_64K_PAGES
+#ifdef CONFIG_ARM64_2_LEVELS
 #include <asm/pgtable-2level-types.h>
 #else
 #include <asm/pgtable-3level-types.h>

arch/arm64/include/asm/pgalloc.h

···
 
 #define check_pgt_cache()		do { } while (0)
 
-#ifndef CONFIG_ARM64_64K_PAGES
+#ifndef CONFIG_ARM64_2_LEVELS
 
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
···
 	set_pud(pud, __pud(__pa(pmd) | PMD_TYPE_TABLE));
 }
 
-#endif	/* CONFIG_ARM64_64K_PAGES */
+#endif	/* CONFIG_ARM64_2_LEVELS */
 
 extern pgd_t *pgd_alloc(struct mm_struct *mm);
 extern void pgd_free(struct mm_struct *mm, pgd_t *pgd);

arch/arm64/include/asm/pgtable-hwdef.h

···
 #ifndef __ASM_PGTABLE_HWDEF_H
 #define __ASM_PGTABLE_HWDEF_H
 
-#ifdef CONFIG_ARM64_64K_PAGES
+#ifdef CONFIG_ARM64_2_LEVELS
 #include <asm/pgtable-2level-hwdef.h>
 #else
 #include <asm/pgtable-3level-hwdef.h>

arch/arm64/include/asm/pgtable.h

···
 extern void __pgd_error(const char *file, int line, unsigned long val);
 
 #define pte_ERROR(pte)		__pte_error(__FILE__, __LINE__, pte_val(pte))
-#ifndef CONFIG_ARM64_64K_PAGES
+#ifndef CONFIG_ARM64_2_LEVELS
 #define pmd_ERROR(pmd)		__pmd_error(__FILE__, __LINE__, pmd_val(pmd))
 #endif
 #define pgd_ERROR(pgd)		__pgd_error(__FILE__, __LINE__, pgd_val(pgd))
···
  */
 #define mk_pte(page,prot)	pfn_pte(page_to_pfn(page),prot)
 
-#ifndef CONFIG_ARM64_64K_PAGES
+#ifndef CONFIG_ARM64_2_LEVELS
 
 #define pud_none(pud)		(!pud_val(pud))
 #define pud_bad(pud)		(!(pud_val(pud) & 2))
···
 	return __va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
 }
 
-#endif	/* CONFIG_ARM64_64K_PAGES */
+#endif	/* CONFIG_ARM64_2_LEVELS */
 
 /* to find an entry in a page-table-directory */
 #define pgd_index(addr)		(((addr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
···
 #define pgd_offset_k(addr)	pgd_offset(&init_mm, addr)
 
 /* Find an entry in the second-level page table.. */
-#ifndef CONFIG_ARM64_64K_PAGES
+#ifndef CONFIG_ARM64_2_LEVELS
 #define pmd_index(addr)		(((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
 {

arch/arm64/include/asm/tlb.h

···
 	tlb_remove_page(tlb, pte);
 }
 
-#ifndef CONFIG_ARM64_64K_PAGES
+#ifndef CONFIG_ARM64_2_LEVELS
 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 				  unsigned long addr)
 {