Re: [PATCH v5 2/6] arm64: Introduce VA_BITS and translation level options

From: Christoffer Dall
Date: Thu May 01 2014 - 06:06:39 EST

On Thu, May 01, 2014 at 11:33:56AM +0900, Jungseok Lee wrote:
> 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
>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Steve Capper <steve.capper@xxxxxxxxxx>
> Signed-off-by: Jungseok Lee <jays.lee@xxxxxxxxxxx>
> Reviewed-by: Sungjinn Chung <sungjinn.chung@xxxxxxxxxxx>
> ---
> arch/arm64/Kconfig | 45 +++++++++++++++++++++++++++++++-
> arch/arm64/include/asm/memory.h | 6 +----
> arch/arm64/include/asm/page.h | 2 +-
> arch/arm64/include/asm/pgalloc.h | 4 +--
> arch/arm64/include/asm/pgtable-hwdef.h | 2 +-
> arch/arm64/include/asm/pgtable.h | 8 +++---
> arch/arm64/include/asm/tlb.h | 2 +-
> 7 files changed, 54 insertions(+), 15 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index e759af5..b438540 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -144,14 +144,57 @@ endmenu
>
> menu "Kernel Features"
>
> +choice
> + prompt "Page size"
> + default ARM64_4K_PAGES
> + help
> + Allows page size.
> +
> +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 virtual address space size. A level of translation tables

What does "Allows virtual address space size" mean exactly?

s/A level/The level/

> + 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"
> help
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index e94f945..f6e7480 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -41,11 +41,7 @@
> * 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)
> diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
> index 46bf666..268e53d 100644
> --- a/arch/arm64/include/asm/page.h
> +++ b/arch/arm64/include/asm/page.h
> @@ -33,7 +33,7 @@
>
> #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>
> diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
> index 9bea6e7..4829837 100644
> --- a/arch/arm64/include/asm/pgalloc.h
> +++ b/arch/arm64/include/asm/pgalloc.h
> @@ -26,7 +26,7 @@
>
> #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)
> {
> @@ -44,7 +44,7 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
> 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);
> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> index 5fc8a66..9cd86c6 100644
> --- a/arch/arm64/include/asm/pgtable-hwdef.h
> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> @@ -16,7 +16,7 @@
> #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>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 90c811f..a64ce5e 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -47,7 +47,7 @@ extern void __pmd_error(const char *file, int line, unsigned long val);
> 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))
> @@ -320,7 +320,7 @@ static inline pte_t *pmd_page_vaddr(pmd_t pmd)
> */
> #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))
> @@ -342,7 +342,7 @@ static inline pmd_t *pud_page_vaddr(pud_t pud)
> 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))
> @@ -353,7 +353,7 @@ static inline pmd_t *pud_page_vaddr(pud_t pud)
> #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)
> {
> diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
> index 80e2c08..bc19101 100644
> --- a/arch/arm64/include/asm/tlb.h
> +++ b/arch/arm64/include/asm/tlb.h
> @@ -91,7 +91,7 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
> 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)
> {
> --
> 1.7.10.4
>
>
Otherwise looks good,

Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
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