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arm64: decouple early fixmap init from linear mapping

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Since the early fixmap page tables are populated using pages that are
part of the static footprint of the kernel, they are covered by the
initial kernel mapping, and we can refer to them without using __va/__pa
translations, which are tied to the linear mapping.

Since the fixmap page tables are disjoint from the kernel mapping up
to the top level pgd entry, we can refer to bm_pte[] directly, and there
is no need to walk the page tables and perform __pa()/__va() translations
at each step.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-02-16 13:52:38 +01:00 committed by Catalin Marinas
parent 6533945a32
commit 157962f5a8
1 changed files with 6 additions and 10 deletions
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16
arch/arm64/mm/mmu.c
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@ -616,7 +616,7 @@ static inline pud_t * fixmap_pud(unsigned long addr)
BUG_ON(pgd_none(*pgd) || pgd_bad(*pgd));
return pud_offset(pgd, addr);
return pud_offset_kimg(pgd, addr);
}
static inline pmd_t * fixmap_pmd(unsigned long addr)
@ -625,16 +625,12 @@ static inline pmd_t * fixmap_pmd(unsigned long addr)
BUG_ON(pud_none(*pud) || pud_bad(*pud));
return pmd_offset(pud, addr);
return pmd_offset_kimg(pud, addr);
}
static inline pte_t * fixmap_pte(unsigned long addr)
{
pmd_t *pmd = fixmap_pmd(addr);
BUG_ON(pmd_none(*pmd) || pmd_bad(*pmd));
return pte_offset_kernel(pmd, addr);
return &bm_pte[pte_index(addr)];
}
void __init early_fixmap_init(void)
@ -646,14 +642,14 @@ void __init early_fixmap_init(void)
pgd = pgd_offset_k(addr);
pgd_populate(&init_mm, pgd, bm_pud);
pud = pud_offset(pgd, addr);
pud = fixmap_pud(addr);
pud_populate(&init_mm, pud, bm_pmd);
pmd = pmd_offset(pud, addr);
pmd = fixmap_pmd(addr);
pmd_populate_kernel(&init_mm, pmd, bm_pte);
/*
* The boot-ioremap range spans multiple pmds, for which
* we are not preparted:
* we are not prepared:
*/
BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT)
!= (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT));