Commit 316b39db authored Jan 25, 2016 by Mark Rutland Committed by Catalin Marinas Feb 16, 2016

arm64: mm: avoid redundant pa(va(x))



When we "upgrade" to a section mapping, we free any table we made
redundant by giving it back to memblock. To get the PA, we acquire the
physical address and convert this to a VA, then subsequently convert
this back to a PA.

This works currently, but will not work if the tables are not accessed
via linear map VAs (e.g. is we use fixmap slots).

This patch uses {pmd,pud}_page_paddr to acquire the PA. This avoids the
__pa(__va()) round trip, saving some work and avoiding reliance on the
linear mapping.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Jeremy Linton <jeremy.linton@arm.com>
Cc: Laura Abbott <labbott@fedoraproject.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent dca56dca

arch/arm64/mm/mmu.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -171,7 +171,7 @@ static void alloc_init_pmd(struct mm_struct mm, pud_t pud,
		if (!pmd_none(old_pmd)) {
		flush_tlb_all();
		if (pmd_table(old_pmd)) {
		phys_addr_t table = __pa(pte_offset_map(&old_pmd, 0));
		phys_addr_t table = pmd_page_paddr(old_pmd);
		if (!WARN_ON_ONCE(slab_is_available()))
		memblock_free(table, PAGE_SIZE);
		}
		@@ -232,7 +232,7 @@ static void alloc_init_pud(struct mm_struct mm, pgd_t pgd,
		if (!pud_none(old_pud)) {
		flush_tlb_all();
		if (pud_table(old_pud)) {
		phys_addr_t table = __pa(pmd_offset(&old_pud, 0));
		phys_addr_t table = pud_page_paddr(old_pud);
		if (!WARN_ON_ONCE(slab_is_available()))
		memblock_free(table, PAGE_SIZE);
		}