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    Subject[PATCH 3/5] arm64: kdump: Remove some redundant checks in map_mem()
    Date
    arm64_memblock_init()
    if (!IS_ENABLED(CONFIG_ZONE_DMA/DMA32))
    reserve_crashkernel()
    //initialize crashk_res when
    //"crashkernel=" is correctly specified
    paging_init()
    map_mem()

    As shown in the above pseudo code, the crashk_res.end can only be
    initialized to non-zero when both "!IS_ENABLED(CONFIG_ZONE_DMA/DMA32)"
    and crash_mem_map are true. So some checks in map_mem() can be adjusted
    or optimized.

    Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
    ---
    arch/arm64/mm/mmu.c | 25 +++++++++++--------------
    1 file changed, 11 insertions(+), 14 deletions(-)

    diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
    index 626ec32873c6c36..6028a5757e4eae2 100644
    --- a/arch/arm64/mm/mmu.c
    +++ b/arch/arm64/mm/mmu.c
    @@ -529,12 +529,12 @@ static void __init map_mem(pgd_t *pgdp)

    #ifdef CONFIG_KEXEC_CORE
    if (crash_mem_map) {
    - if (IS_ENABLED(CONFIG_ZONE_DMA) ||
    - IS_ENABLED(CONFIG_ZONE_DMA32))
    - flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
    - else if (crashk_res.end)
    + if (crashk_res.end)
    memblock_mark_nomap(crashk_res.start,
    resource_size(&crashk_res));
    + else if (IS_ENABLED(CONFIG_ZONE_DMA) ||
    + IS_ENABLED(CONFIG_ZONE_DMA32))
    + flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
    }
    #endif

    @@ -571,16 +571,13 @@ static void __init map_mem(pgd_t *pgdp)
    * through /sys/kernel/kexec_crash_size interface.
    */
    #ifdef CONFIG_KEXEC_CORE
    - if (crash_mem_map &&
    - !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) {
    - if (crashk_res.end) {
    - __map_memblock(pgdp, crashk_res.start,
    - crashk_res.end + 1,
    - PAGE_KERNEL,
    - NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
    - memblock_clear_nomap(crashk_res.start,
    - resource_size(&crashk_res));
    - }
    + if (crashk_res.end) {
    + __map_memblock(pgdp, crashk_res.start,
    + crashk_res.end + 1,
    + PAGE_KERNEL,
    + NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
    + memblock_clear_nomap(crashk_res.start,
    + resource_size(&crashk_res));
    }
    #endif
    }
    --
    2.25.1
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