From 667c27597ca823f20c524bbd486c6709f905673b Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Thu, 26 Nov 2015 15:42:41 +0000 Subject: [PATCH] Revert "arm64: Mark kernel page ranges contiguous" This reverts commit 348a65cdcbbf243073ee39d1f7d4413081ad7eab. Incorrect page table manipulation that does not respect the ARM ARM recommended break-before-make sequence may lead to TLB conflicts. The contiguous PTE patch makes the system even more susceptible to such errors by changing the mapping from a single page to a contiguous range of pages. An additional TLB invalidation would reduce the risk window, however, the correct fix is to switch to a temporary swapper_pg_dir. Once the correct workaround is done, the reverted commit will be re-applied. Signed-off-by: Catalin Marinas Reported-by: Jeremy Linton --- arch/arm64/mm/mmu.c | 69 +++++++---------------------------------------------- 1 file changed, 8 insertions(+), 61 deletions(-) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 78d91b1..873e363 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -85,55 +85,19 @@ static void split_pmd(pmd_t *pmd, pte_t *pte) do { /* * Need to have the least restrictive permissions available - * permissions will be fixed up later. Default the new page - * range as contiguous ptes. + * permissions will be fixed up later */ - set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT)); + set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC)); pfn++; } while (pte++, i++, i < PTRS_PER_PTE); } -/* - * Given a PTE with the CONT bit set, determine where the CONT range - * starts, and clear the entire range of PTE CONT bits. - */ -static void clear_cont_pte_range(pte_t *pte, unsigned long addr) -{ - int i; - - pte -= CONT_RANGE_OFFSET(addr); - for (i = 0; i < CONT_PTES; i++) { - set_pte(pte, pte_mknoncont(*pte)); - pte++; - } - flush_tlb_all(); -} - -/* - * Given a range of PTEs set the pfn and provided page protection flags - */ -static void __populate_init_pte(pte_t *pte, unsigned long addr, - unsigned long end, phys_addr_t phys, - pgprot_t prot) -{ - unsigned long pfn = __phys_to_pfn(phys); - - do { - /* clear all the bits except the pfn, then apply the prot */ - set_pte(pte, pfn_pte(pfn, prot)); - pte++; - pfn++; - addr += PAGE_SIZE; - } while (addr != end); -} - static void alloc_init_pte(pmd_t *pmd, unsigned long addr, - unsigned long end, phys_addr_t phys, + unsigned long end, unsigned long pfn, pgprot_t prot, void *(*alloc)(unsigned long size)) { pte_t *pte; - unsigned long next; if (pmd_none(*pmd) || pmd_sect(*pmd)) { pte = alloc(PTRS_PER_PTE * sizeof(pte_t)); @@ -146,27 +110,9 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr, pte = pte_offset_kernel(pmd, addr); do { - next = min(end, (addr + CONT_SIZE) & CONT_MASK); - if (((addr | next | phys) & ~CONT_MASK) == 0) { - /* a block of CONT_PTES */ - __populate_init_pte(pte, addr, next, phys, - __pgprot(pgprot_val(prot) | PTE_CONT)); - } else { - /* - * If the range being split is already inside of a - * contiguous range but this PTE isn't going to be - * contiguous, then we want to unmark the adjacent - * ranges, then update the portion of the range we - * are interrested in. - */ - clear_cont_pte_range(pte, addr); - __populate_init_pte(pte, addr, next, phys, prot); - } - - pte += (next - addr) >> PAGE_SHIFT; - phys += next - addr; - addr = next; - } while (addr != end); + set_pte(pte, pfn_pte(pfn, prot)); + pfn++; + } while (pte++, addr += PAGE_SIZE, addr != end); } static void split_pud(pud_t *old_pud, pmd_t *pmd) @@ -227,7 +173,8 @@ static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud, } } } else { - alloc_init_pte(pmd, addr, next, phys, prot, alloc); + alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys), + prot, alloc); } phys += next - addr; } while (pmd++, addr = next, addr != end); -- 2.7.4