[PATCHv2 14/18] arm64: mm: use fixmap when creating page tables
Laura Abbott
labbott at redhat.com
Mon Jan 4 14:38:42 PST 2016
On 01/04/2016 09:56 AM, Mark Rutland wrote:
> As a prepratory step to allow us to allocate early page tables form
"page tables from"
> unmapped memory using memblock_alloc, modify the __create_mapping
> callees to map and unmap the tables they modify using fixmap entries.
>
> All but the top-level pgd initialisation is performed via the fixmap.
> Subsequent patches will inject the pgd physical address, and migrate to
> using the FIX_PGD slot.
>
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Jeremy Linton <jeremy.linton at arm.com>
> Cc: Laura Abbott <labbott at fedoraproject.org>
> Cc: Will Deacon <will.deacon at arm.com>
> ---
> arch/arm64/include/asm/pgtable.h | 2 +-
> arch/arm64/mm/mmu.c | 63 ++++++++++++++++++++++++++--------------
> 2 files changed, 42 insertions(+), 23 deletions(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 824e7f0..6fbf9fa 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -534,7 +534,7 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd)
> #define pud_offset(dir, addr) ((pud_t *)__va(pud_offset_phys((dir), (addr))))
>
> #define pud_fixmap(addr) ((pud_t *)set_fixmap_offset(FIX_PUD, addr))
> -#define pud_fixmap_offset(pgd, addr) pud_fixmap(pmd_offset_phys(pgd, addr))
> +#define pud_fixmap_offset(pgd, addr) pud_fixmap(pud_offset_phys(pgd, addr))
Was this supposed to be folded into a previous patch?
> #define pud_fixmap_unmap() clear_fixmap(FIX_PUD)
>
> #define pgd_page(pgd) pfn_to_page(__phys_to_pfn(pgd_val(pgd) & PHYS_MASK))
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 8879aed..bf09d44 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -63,19 +63,30 @@ pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> }
> EXPORT_SYMBOL(phys_mem_access_prot);
>
> -static void __init *early_pgtable_alloc(void)
> +static phys_addr_t __init early_pgtable_alloc(void)
> {
> phys_addr_t phys;
> void *ptr;
>
> phys = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> BUG_ON(!phys);
> - ptr = __va(phys);
> +
> + /*
> + * The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE
> + * slot will be free, so we can (ab)use the FIX_PTE slot to initialise
> + * any level of table.
> + */
> + ptr = pte_fixmap(phys);
> +
> memset(ptr, 0, PAGE_SIZE);
>
> - /* Ensure the zeroed page is visible to the page table walker */
> - dsb(ishst);
> - return ptr;
> + /*
> + * Implicit barriers also ensure the zeroed page is visible to the page
> + * table walker
> + */
> + pte_fixmap_unmap();
> +
> + return phys;
> }
>
> /*
> @@ -99,24 +110,28 @@ static void split_pmd(pmd_t *pmd, pte_t *pte)
> static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
> unsigned long end, unsigned long pfn,
> pgprot_t prot,
> - void *(*pgtable_alloc)(void))
> + phys_addr_t (*pgtable_alloc)(void))
> {
> pte_t *pte;
>
> if (pmd_none(*pmd) || pmd_sect(*pmd)) {
> - pte = pgtable_alloc();
> + phys_addr_t pte_phys = pgtable_alloc();
> + pte = pte_fixmap(pte_phys);
> if (pmd_sect(*pmd))
> split_pmd(pmd, pte);
> - __pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE);
> + __pmd_populate(pmd, pte_phys, PMD_TYPE_TABLE);
> flush_tlb_all();
> + pte_fixmap_unmap();
> }
> BUG_ON(pmd_bad(*pmd));
>
> - pte = pte_offset_kernel(pmd, addr);
> + pte = pte_fixmap_offset(pmd, addr);
> do {
> set_pte(pte, pfn_pte(pfn, prot));
> pfn++;
> } while (pte++, addr += PAGE_SIZE, addr != end);
> +
> + pte_fixmap_unmap();
> }
>
> static void split_pud(pud_t *old_pud, pmd_t *pmd)
> @@ -134,7 +149,7 @@ static void split_pud(pud_t *old_pud, pmd_t *pmd)
> static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
> unsigned long addr, unsigned long end,
> phys_addr_t phys, pgprot_t prot,
> - void *(*pgtable_alloc)(void))
> + phys_addr_t (*pgtable_alloc)(void))
> {
> pmd_t *pmd;
> unsigned long next;
> @@ -143,7 +158,8 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
> * Check for initial section mappings in the pgd/pud and remove them.
> */
> if (pud_none(*pud) || pud_sect(*pud)) {
> - pmd = pgtable_alloc();
> + phys_addr_t pmd_phys = pgtable_alloc();
> + pmd = pmd_fixmap(pmd_phys);
> if (pud_sect(*pud)) {
> /*
> * need to have the 1G of mappings continue to be
> @@ -151,12 +167,13 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
> */
> split_pud(pud, pmd);
> }
> - pud_populate(mm, pud, pmd);
> + __pud_populate(pud, pmd_phys, PUD_TYPE_TABLE);
> flush_tlb_all();
> + pmd_fixmap_unmap();
> }
> BUG_ON(pud_bad(*pud));
>
> - pmd = pmd_offset(pud, addr);
> + pmd = pmd_fixmap_offset(pud, addr);
> do {
> next = pmd_addr_end(addr, end);
> /* try section mapping first */
> @@ -182,6 +199,8 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud,
> }
> phys += next - addr;
> } while (pmd++, addr = next, addr != end);
> +
> + pmd_fixmap_unmap();
> }
>
> static inline bool use_1G_block(unsigned long addr, unsigned long next,
> @@ -199,18 +218,18 @@ static inline bool use_1G_block(unsigned long addr, unsigned long next,
> static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
> unsigned long addr, unsigned long end,
> phys_addr_t phys, pgprot_t prot,
> - void *(*pgtable_alloc)(void))
> + phys_addr_t (*pgtable_alloc)(void))
> {
> pud_t *pud;
> unsigned long next;
>
> if (pgd_none(*pgd)) {
> - pud = pgtable_alloc();
> - pgd_populate(mm, pgd, pud);
> + phys_addr_t pud_phys = pgtable_alloc();
> + __pgd_populate(pgd, pud_phys, PUD_TYPE_TABLE);
> }
> BUG_ON(pgd_bad(*pgd));
>
> - pud = pud_offset(pgd, addr);
> + pud = pud_fixmap_offset(pgd, addr);
> do {
> next = pud_addr_end(addr, end);
>
> @@ -243,6 +262,8 @@ static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
> }
> phys += next - addr;
> } while (pud++, addr = next, addr != end);
> +
> + pud_fixmap_unmap();
> }
>
> /*
> @@ -252,7 +273,7 @@ static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd,
> static void __create_mapping(struct mm_struct *mm, pgd_t *pgd,
> phys_addr_t phys, unsigned long virt,
> phys_addr_t size, pgprot_t prot,
> - void *(*pgtable_alloc)(void))
> + phys_addr_t (*pgtable_alloc)(void))
> {
> unsigned long addr, length, end, next;
>
> @@ -275,14 +296,12 @@ static void __create_mapping(struct mm_struct *mm, pgd_t *pgd,
> } while (pgd++, addr = next, addr != end);
> }
>
> -static void *late_pgtable_alloc(void)
> +static phys_addr_t late_pgtable_alloc(void)
> {
> void *ptr = (void *)__get_free_page(PGALLOC_GFP);
> BUG_ON(!ptr);
> -
> - /* Ensure the zeroed page is visible to the page table walker */
> dsb(ishst);
This dropped the comment but not the actual barrier, was that intentional?
> - return ptr;
> + return __pa(ptr);
> }
>
> static void __init create_mapping(phys_addr_t phys, unsigned long virt,
>
Thanks,
Laura
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