Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
arm64: Align less than PAGE_SIZE pgds naturally
When the pgd size is smaller than PAGE_SIZE, pgd_alloc() uses kzalloc()
to save space. However, this is not always naturally aligned as required
by the architecture. This patch creates a kmem_cache for pgd allocations
with the correct alignment.
The current kernel configurations with 4K pages + 39-bit VA and 64K
pages + 42-bit VA use a full page for the pgd and are not affected. The
patch is required for 48-bit VA with 64K pages where the pgd is 512
bytes.
Reported-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
+16
-2
arch/arm64/mm/pgd.c
+16
-2
arch/arm64/mm/pgd.c
···
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#define PGD_SIZE (PTRS_PER_PGD * sizeof(pgd_t))
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static struct kmem_cache *pgd_cache;
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+
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pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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if (PGD_SIZE == PAGE_SIZE)
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return (pgd_t *)get_zeroed_page(GFP_KERNEL);
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else
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return kzalloc(PGD_SIZE, GFP_KERNEL);
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return kmem_cache_zalloc(pgd_cache, GFP_KERNEL);
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}
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void pgd_free(struct mm_struct *mm, pgd_t *pgd)
···
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if (PGD_SIZE == PAGE_SIZE)
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free_page((unsigned long)pgd);
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else
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kfree(pgd);
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kmem_cache_free(pgd_cache, pgd);
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}
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static int __init pgd_cache_init(void)
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{
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/*
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* Naturally aligned pgds required by the architecture.
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*/
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if (PGD_SIZE != PAGE_SIZE)
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pgd_cache = kmem_cache_create("pgd_cache", PGD_SIZE, PGD_SIZE,
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SLAB_PANIC, NULL);
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return 0;
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}
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core_initcall(pgd_cache_init);