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    Subject[PATCH 02/15] arm64: Handle section maps for swapper/idmap
    Date
    From: "Suzuki K. Poulose" <suzuki.poulose@arm.com>

    We use section maps with 4K page size to create the swapper/idmaps.
    So far we have used !64K or 4K checks to handle the case where we
    use the section maps.
    This patch adds a new symbol, ARM64_SWAPPER_USES_SECTION_MAPS, to
    handle cases where we use section maps, instead of using the page size
    symbols.

    Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
    ---
    Changes since v1:
    - Use ARM64_SWAPPER_USES_SECTION_MAPS for vmemmap_populate()
    - Fix description
    ---
    arch/arm64/include/asm/kernel-pgtable.h | 31 ++++++++-----
    arch/arm64/mm/mmu.c | 72 ++++++++++++++-----------------
    2 files changed, 52 insertions(+), 51 deletions(-)

    diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
    index 622929d..5876a36 100644
    --- a/arch/arm64/include/asm/kernel-pgtable.h
    +++ b/arch/arm64/include/asm/kernel-pgtable.h
    @@ -19,6 +19,13 @@
    #ifndef __ASM_KERNEL_PGTABLE_H
    #define __ASM_KERNEL_PGTABLE_H

    +/* With 4K pages, we use section maps. */
    +#ifdef CONFIG_ARM64_4K_PAGES
    +#define ARM64_SWAPPER_USES_SECTION_MAPS 1
    +#else
    +#define ARM64_SWAPPER_USES_SECTION_MAPS 0
    +#endif
    +
    /*
    * The idmap and swapper page tables need some space reserved in the kernel
    * image. Both require pgd, pud (4 levels only) and pmd tables to (section)
    @@ -28,26 +35,28 @@
    * could be increased on the fly if system RAM is out of reach for the default
    * VA range, so 3 pages are reserved in all cases.
    */
    -#ifdef CONFIG_ARM64_64K_PAGES
    -#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
    -#else
    +#if ARM64_SWAPPER_USES_SECTION_MAPS
    #define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS - 1)
    +#else
    +#define SWAPPER_PGTABLE_LEVELS (CONFIG_PGTABLE_LEVELS)
    #endif

    #define SWAPPER_DIR_SIZE (SWAPPER_PGTABLE_LEVELS * PAGE_SIZE)
    #define IDMAP_DIR_SIZE (3 * PAGE_SIZE)

    /* Initial memory map size */
    -#ifdef CONFIG_ARM64_64K_PAGES
    -#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT
    -#define SWAPPER_BLOCK_SIZE PAGE_SIZE
    -#define SWAPPER_TABLE_SHIFT PMD_SHIFT
    -#else
    +#if ARM64_SWAPPER_USES_SECTION_MAPS
    #define SWAPPER_BLOCK_SHIFT SECTION_SHIFT
    #define SWAPPER_BLOCK_SIZE SECTION_SIZE
    #define SWAPPER_TABLE_SHIFT PUD_SHIFT
    +#else
    +#define SWAPPER_BLOCK_SHIFT PAGE_SHIFT
    +#define SWAPPER_BLOCK_SIZE PAGE_SIZE
    +#define SWAPPER_TABLE_SHIFT PMD_SHIFT
    #endif

    +/* The size of the initial kernel direct mapping */
    +#define SWAPPER_INIT_MAP_SIZE (_AC(1, UL) << SWAPPER_TABLE_SHIFT)

    /*
    * Initial memory map attributes.
    @@ -55,10 +64,10 @@
    #define SWAPPER_PTE_FLAGS PTE_TYPE_PAGE | PTE_AF | PTE_SHARED
    #define SWAPPER_PMD_FLAGS PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S

    -#ifdef CONFIG_ARM64_64K_PAGES
    -#define SWAPPER_MM_MMUFLAGS PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS
    -#else
    +#if ARM64_SWAPPER_USES_SECTION_MAPS
    #define SWAPPER_MM_MMUFLAGS PMD_ATTRINDX(MT_NORMAL) | SWAPPER_PMD_FLAGS
    +#else
    +#define SWAPPER_MM_MMUFLAGS PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS
    #endif


    diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
    index 9211b85..f533312 100644
    --- a/arch/arm64/mm/mmu.c
    +++ b/arch/arm64/mm/mmu.c
    @@ -32,6 +32,7 @@

    #include <asm/cputype.h>
    #include <asm/fixmap.h>
    +#include <asm/kernel-pgtable.h>
    #include <asm/sections.h>
    #include <asm/setup.h>
    #include <asm/sizes.h>
    @@ -353,14 +354,11 @@ static void __init map_mem(void)
    * memory addressable from the initial direct kernel mapping.
    *
    * The initial direct kernel mapping, located at swapper_pg_dir, gives
    - * us PUD_SIZE (4K pages) or PMD_SIZE (64K pages) memory starting from
    - * PHYS_OFFSET (which must be aligned to 2MB as per
    - * Documentation/arm64/booting.txt).
    + * us PUD_SIZE (with SECTION maps, i.e, 4K) or PMD_SIZE (without
    + * SECTION maps, i.e, 64K pages) memory starting from PHYS_OFFSET
    + * (which must be aligned to 2MB as per Documentation/arm64/booting.txt).
    */
    - if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
    - limit = PHYS_OFFSET + PMD_SIZE;
    - else
    - limit = PHYS_OFFSET + PUD_SIZE;
    + limit = PHYS_OFFSET + SWAPPER_INIT_MAP_SIZE;
    memblock_set_current_limit(limit);

    /* map all the memory banks */
    @@ -371,21 +369,24 @@ static void __init map_mem(void)
    if (start >= end)
    break;

    -#ifndef CONFIG_ARM64_64K_PAGES
    - /*
    - * For the first memory bank align the start address and
    - * current memblock limit to prevent create_mapping() from
    - * allocating pte page tables from unmapped memory.
    - * When 64K pages are enabled, the pte page table for the
    - * first PGDIR_SIZE is already present in swapper_pg_dir.
    - */
    - if (start < limit)
    - start = ALIGN(start, PMD_SIZE);
    - if (end < limit) {
    - limit = end & PMD_MASK;
    - memblock_set_current_limit(limit);
    + if (ARM64_SWAPPER_USES_SECTION_MAPS) {
    + /*
    + * For the first memory bank align the start address and
    + * current memblock limit to prevent create_mapping() from
    + * allocating pte page tables from unmapped memory. With
    + * the section maps, if the first block doesn't end on section
    + * size boundary, create_mapping() will try to allocate a pte
    + * page, which may be returned from an unmapped area.
    + * When section maps are not used, the pte page table for the
    + * current limit is already present in swapper_pg_dir.
    + */
    + if (start < limit)
    + start = ALIGN(start, SECTION_SIZE);
    + if (end < limit) {
    + limit = end & SECTION_MASK;
    + memblock_set_current_limit(limit);
    + }
    }
    -#endif
    __map_memblock(start, end);
    }

    @@ -498,7 +499,7 @@ int kern_addr_valid(unsigned long addr)
    return pfn_valid(pte_pfn(*pte));
    }
    #ifdef CONFIG_SPARSEMEM_VMEMMAP
    -#ifdef CONFIG_ARM64_64K_PAGES
    +#if !ARM64_SWAPPER_USES_SECTION_MAPS
    int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
    {
    return vmemmap_populate_basepages(start, end, node);
    @@ -638,7 +639,7 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
    {
    const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
    pgprot_t prot = PAGE_KERNEL | PTE_RDONLY;
    - int granularity, size, offset;
    + int size, offset;
    void *dt_virt;

    /*
    @@ -664,24 +665,15 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
    */
    BUILD_BUG_ON(dt_virt_base % SZ_2M);

    - if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) {
    - BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> PMD_SHIFT !=
    - __fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT);
    -
    - granularity = PAGE_SIZE;
    - } else {
    - BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> PUD_SHIFT !=
    - __fix_to_virt(FIX_BTMAP_BEGIN) >> PUD_SHIFT);
    -
    - granularity = PMD_SIZE;
    - }
    + BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT !=
    + __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT);

    - offset = dt_phys % granularity;
    + offset = dt_phys % SWAPPER_BLOCK_SIZE;
    dt_virt = (void *)dt_virt_base + offset;

    /* map the first chunk so we can read the size from the header */
    - create_mapping(round_down(dt_phys, granularity), dt_virt_base,
    - granularity, prot);
    + create_mapping(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
    + SWAPPER_BLOCK_SIZE, prot);

    if (fdt_check_header(dt_virt) != 0)
    return NULL;
    @@ -690,9 +682,9 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
    if (size > MAX_FDT_SIZE)
    return NULL;

    - if (offset + size > granularity)
    - create_mapping(round_down(dt_phys, granularity), dt_virt_base,
    - round_up(offset + size, granularity), prot);
    + if (offset + size > SWAPPER_BLOCK_SIZE)
    + create_mapping(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
    + round_up(offset + size, SWAPPER_BLOCK_SIZE), prot);

    memblock_reserve(dt_phys, size);

    --
    1.7.9.5


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