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    Subject[PATCH v2 40/45] powerpc/8xx: Map linear memory with huge pages
    Date
    Map linear memory space with 512k and 8M pages whenever
    possible.

    Three mappings are performed:
    - One for kernel text
    - One for RO data
    - One for the rest

    Separating the mappings is done to be able to update the
    protection later when using STRICT_KERNEL_RWX.

    The ITLB miss handler now need to also handle huge TLBs
    unless kernel text in pinned.

    Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    ---
    arch/powerpc/kernel/head_8xx.S | 4 +--
    arch/powerpc/mm/nohash/8xx.c | 50 +++++++++++++++++++++++++++++++++-
    2 files changed, 51 insertions(+), 3 deletions(-)

    diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
    index 9a117b9f0998..abb71fad7d6a 100644
    --- a/arch/powerpc/kernel/head_8xx.S
    +++ b/arch/powerpc/kernel/head_8xx.S
    @@ -224,7 +224,7 @@ InstructionTLBMiss:
    3:
    mtcr r11
    #endif
    -#ifdef CONFIG_HUGETLBFS
    +#if defined(CONFIG_HUGETLBFS) || !defined(CONFIG_PIN_TLB_TEXT)
    lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r10) /* Get level 1 entry */
    mtspr SPRN_MD_TWC, r11
    #else
    @@ -234,7 +234,7 @@ InstructionTLBMiss:
    #endif
    mfspr r10, SPRN_MD_TWC
    lwz r10, 0(r10) /* Get the pte */
    -#ifdef CONFIG_HUGETLBFS
    +#if defined(CONFIG_HUGETLBFS) || !defined(CONFIG_PIN_TLB_TEXT)
    rlwimi r11, r10, 32 - 9, _PMD_PAGE_512K
    mtspr SPRN_MI_TWC, r11
    #endif
    diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
    index fb31a0c1c2a4..c62cab996d4d 100644
    --- a/arch/powerpc/mm/nohash/8xx.c
    +++ b/arch/powerpc/mm/nohash/8xx.c
    @@ -126,20 +126,68 @@ void __init mmu_mapin_immr(void)
    PAGE_KERNEL_NCG, MMU_PAGE_512K, true);
    }

    +static void __init mmu_mapin_ram_chunk(unsigned long offset, unsigned long top,
    + pgprot_t prot, bool new)
    +{
    + unsigned long v = PAGE_OFFSET + offset;
    + unsigned long p = offset;
    +
    + WARN_ON(!IS_ALIGNED(offset, SZ_512K) || !IS_ALIGNED(top, SZ_512K));
    +
    + for (; p < ALIGN(p, SZ_8M) && p < top; p += SZ_512K, v += SZ_512K)
    + __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);
    + for (; p < ALIGN_DOWN(top, SZ_8M) && p < top; p += SZ_8M, v += SZ_8M)
    + __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_8M, new);
    + for (; p < ALIGN_DOWN(top, SZ_512K) && p < top; p += SZ_512K, v += SZ_512K)
    + __early_map_kernel_hugepage(v, p, prot, MMU_PAGE_512K, new);
    +
    + if (!new)
    + flush_tlb_kernel_range(PAGE_OFFSET + v, PAGE_OFFSET + top);
    +}
    +
    unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
    {
    + unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
    + unsigned long sinittext = __pa(_sinittext);
    + unsigned long boundary = strict_kernel_rwx_enabled() ? sinittext : etext8;
    + unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);
    +
    + WARN_ON(top < einittext8);
    +
    mmu_mapin_immr();

    - return 0;
    + if (__map_without_ltlbs)
    + return 0;
    +
    + mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, true);
    + mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL_TEXT, true);
    + mmu_mapin_ram_chunk(einittext8, top, PAGE_KERNEL, true);
    +
    + if (top > SZ_32M)
    + memblock_set_current_limit(top);
    +
    + block_mapped_ram = top;
    +
    + return top;
    }

    void mmu_mark_initmem_nx(void)
    {
    + unsigned long etext8 = ALIGN(__pa(_etext), SZ_8M);
    + unsigned long sinittext = __pa(_sinittext);
    + unsigned long boundary = strict_kernel_rwx_enabled() ? sinittext : etext8;
    + unsigned long einittext8 = ALIGN(__pa(_einittext), SZ_8M);
    +
    + mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
    + mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
    }

    #ifdef CONFIG_STRICT_KERNEL_RWX
    void mmu_mark_rodata_ro(void)
    {
    + unsigned long sinittext = __pa(_sinittext);
    +
    + mmu_mapin_ram_chunk(0, sinittext, PAGE_KERNEL_ROX, false);
    }
    #endif

    --
    2.25.0
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