From f4710445458c0a1bd1c3c014ada2e7d7dc7b882f Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 25 Jan 2016 11:45:08 +0000 Subject: [PATCH] arm64: mm: use fixmap when creating page tables As a preparatory step to allow us to allocate early 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 Reviewed-by: Catalin Marinas Tested-by: Ard Biesheuvel Reviewed-by: Ard Biesheuvel Tested-by: Jeremy Linton Cc: Laura Abbott Cc: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/mm/mmu.c | 61 ++++++++++++++++++++++++++++++--------------- 1 file changed, 41 insertions(+), 20 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 8879aed4b1cb..5248b0218fcb 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_set_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_clear_fixmap(); + + 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_set_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_clear_fixmap(); } BUG_ON(pmd_bad(*pmd)); - pte = pte_offset_kernel(pmd, addr); + pte = pte_set_fixmap_offset(pmd, addr); do { set_pte(pte, pfn_pte(pfn, prot)); pfn++; } while (pte++, addr += PAGE_SIZE, addr != end); + + pte_clear_fixmap(); } 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_set_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_clear_fixmap(); } BUG_ON(pud_bad(*pud)); - pmd = pmd_offset(pud, addr); + pmd = pmd_set_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_clear_fixmap(); } 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_set_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_clear_fixmap(); } /* @@ -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 +296,14 @@ 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); - return ptr; + return __pa(ptr); } static void __init create_mapping(phys_addr_t phys, unsigned long virt,