/* * Copyright 2005, Paul Mackerras, IBM Corporation. * Copyright 2009, Benjamin Herrenschmidt, IBM Corporation. * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #define CREATE_TRACE_POINTS #include #if H_PGTABLE_RANGE > (USER_VSID_RANGE * (TASK_SIZE_USER64 / TASK_CONTEXT_SIZE)) #warning Limited user VSID range means pagetable space is wasted #endif #ifdef CONFIG_SPARSEMEM_VMEMMAP /* * vmemmap is the starting address of the virtual address space where * struct pages are allocated for all possible PFNs present on the system * including holes and bad memory (hence sparse). These virtual struct * pages are stored in sequence in this virtual address space irrespective * of the fact whether the corresponding PFN is valid or not. This achieves * constant relationship between address of struct page and its PFN. * * During boot or memory hotplug operation when a new memory section is * added, physical memory allocation (including hash table bolting) will * be performed for the set of struct pages which are part of the memory * section. This saves memory by not allocating struct pages for PFNs * which are not valid. * * ---------------------------------------------- * | PHYSICAL ALLOCATION OF VIRTUAL STRUCT PAGES| * ---------------------------------------------- * * f000000000000000 c000000000000000 * vmemmap +--------------+ +--------------+ * + | page struct | +--------------> | page struct | * | +--------------+ +--------------+ * | | page struct | +--------------> | page struct | * | +--------------+ | +--------------+ * | | page struct | + +------> | page struct | * | +--------------+ | +--------------+ * | | page struct | | +--> | page struct | * | +--------------+ | | +--------------+ * | | page struct | | | * | +--------------+ | | * | | page struct | | | * | +--------------+ | | * | | page struct | | | * | +--------------+ | | * | | page struct | | | * | +--------------+ | | * | | page struct | +-------+ | * | +--------------+ | * | | page struct | +-----------+ * | +--------------+ * | | page struct | No mapping * | +--------------+ * | | page struct | No mapping * v +--------------+ * * ----------------------------------------- * | RELATION BETWEEN STRUCT PAGES AND PFNS| * ----------------------------------------- * * vmemmap +--------------+ +---------------+ * + | page struct | +-------------> | PFN | * | +--------------+ +---------------+ * | | page struct | +-------------> | PFN | * | +--------------+ +---------------+ * | | page struct | +-------------> | PFN | * | +--------------+ +---------------+ * | | page struct | +-------------> | PFN | * | +--------------+ +---------------+ * | | | * | +--------------+ * | | | * | +--------------+ * | | | * | +--------------+ +---------------+ * | | page struct | +-------------> | PFN | * | +--------------+ +---------------+ * | | | * | +--------------+ * | | | * | +--------------+ +---------------+ * | | page struct | +-------------> | PFN | * | +--------------+ +---------------+ * | | page struct | +-------------> | PFN | * v +--------------+ +---------------+ */ /* * On hash-based CPUs, the vmemmap is bolted in the hash table. * */ int __meminit hash__vmemmap_create_mapping(unsigned long start, unsigned long page_size, unsigned long phys) { int rc; if ((start + page_size) >= H_VMEMMAP_END) { pr_warn("Outside the supported range\n"); return -1; } rc = htab_bolt_mapping(start, start + page_size, phys, pgprot_val(PAGE_KERNEL), mmu_vmemmap_psize, mmu_kernel_ssize); if (rc < 0) { int rc2 = htab_remove_mapping(start, start + page_size, mmu_vmemmap_psize, mmu_kernel_ssize); BUG_ON(rc2 && (rc2 != -ENOENT)); } return rc; } #ifdef CONFIG_MEMORY_HOTPLUG void hash__vmemmap_remove_mapping(unsigned long start, unsigned long page_size) { int rc = htab_remove_mapping(start, start + page_size, mmu_vmemmap_psize, mmu_kernel_ssize); BUG_ON((rc < 0) && (rc != -ENOENT)); WARN_ON(rc == -ENOENT); } #endif #endif /* CONFIG_SPARSEMEM_VMEMMAP */ /* * map_kernel_page currently only called by __ioremap * map_kernel_page adds an entry to the ioremap page table * and adds an entry to the HPT, possibly bolting it */ int hash__map_kernel_page(unsigned long ea, unsigned long pa, pgprot_t prot) { pgd_t *pgdp; pud_t *pudp; pmd_t *pmdp; pte_t *ptep; BUILD_BUG_ON(TASK_SIZE_USER64 > H_PGTABLE_RANGE); if (slab_is_available()) { pgdp = pgd_offset_k(ea); pudp = pud_alloc(&init_mm, pgdp, ea); if (!pudp) return -ENOMEM; pmdp = pmd_alloc(&init_mm, pudp, ea); if (!pmdp) return -ENOMEM; ptep = pte_alloc_kernel(pmdp, ea); if (!ptep) return -ENOMEM; set_pte_at(&init_mm, ea, ptep, pfn_pte(pa >> PAGE_SHIFT, prot)); } else { /* * If the mm subsystem is not fully up, we cannot create a * linux page table entry for this mapping. Simply bolt an * entry in the hardware page table. * */ if (htab_bolt_mapping(ea, ea + PAGE_SIZE, pa, pgprot_val(prot), mmu_io_psize, mmu_kernel_ssize)) { printk(KERN_ERR "Failed to do bolted mapping IO " "memory at %016lx !\n", pa); return -ENOMEM; } } smp_wmb(); return 0; } #ifdef CONFIG_TRANSPARENT_HUGEPAGE unsigned long hash__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, unsigned long clr, unsigned long set) { __be64 old_be, tmp; unsigned long old; #ifdef CONFIG_DEBUG_VM WARN_ON(!hash__pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp)); assert_spin_locked(pmd_lockptr(mm, pmdp)); #endif __asm__ __volatile__( "1: ldarx %0,0,%3\n\ and. %1,%0,%6\n\ bne- 1b \n\ andc %1,%0,%4 \n\ or %1,%1,%7\n\ stdcx. %1,0,%3 \n\ bne- 1b" : "=&r" (old_be), "=&r" (tmp), "=m" (*pmdp) : "r" (pmdp), "r" (cpu_to_be64(clr)), "m" (*pmdp), "r" (cpu_to_be64(H_PAGE_BUSY)), "r" (cpu_to_be64(set)) : "cc" ); old = be64_to_cpu(old_be); trace_hugepage_update(addr, old, clr, set); if (old & H_PAGE_HASHPTE) hpte_do_hugepage_flush(mm, addr, pmdp, old); return old; } pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp) { pmd_t pmd; VM_BUG_ON(address & ~HPAGE_PMD_MASK); VM_BUG_ON(pmd_trans_huge(*pmdp)); VM_BUG_ON(pmd_devmap(*pmdp)); pmd = *pmdp; pmd_clear(pmdp); /* * Wait for all pending hash_page to finish. This is needed * in case of subpage collapse. When we collapse normal pages * to hugepage, we first clear the pmd, then invalidate all * the PTE entries. The assumption here is that any low level * page fault will see a none pmd and take the slow path that * will wait on mmap_sem. But we could very well be in a * hash_page with local ptep pointer value. Such a hash page * can result in adding new HPTE entries for normal subpages. * That means we could be modifying the page content as we * copy them to a huge page. So wait for parallel hash_page * to finish before invalidating HPTE entries. We can do this * by sending an IPI to all the cpus and executing a dummy * function there. */ serialize_against_pte_lookup(vma->vm_mm); /* * Now invalidate the hpte entries in the range * covered by pmd. This make sure we take a * fault and will find the pmd as none, which will * result in a major fault which takes mmap_sem and * hence wait for collapse to complete. Without this * the __collapse_huge_page_copy can result in copying * the old content. */ flush_tlb_pmd_range(vma->vm_mm, &pmd, address); return pmd; } /* * We want to put the pgtable in pmd and use pgtable for tracking * the base page size hptes */ void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, pgtable_t pgtable) { pgtable_t *pgtable_slot; assert_spin_locked(pmd_lockptr(mm, pmdp)); /* * we store the pgtable in the second half of PMD */ pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD; *pgtable_slot = pgtable; /* * expose the deposited pgtable to other cpus. * before we set the hugepage PTE at pmd level * hash fault code looks at the deposted pgtable * to store hash index values. */ smp_wmb(); } pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp) { pgtable_t pgtable; pgtable_t *pgtable_slot; assert_spin_locked(pmd_lockptr(mm, pmdp)); pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD; pgtable = *pgtable_slot; /* * Once we withdraw, mark the entry NULL. */ *pgtable_slot = NULL; /* * We store HPTE information in the deposited PTE fragment. * zero out the content on withdraw. */ memset(pgtable, 0, PTE_FRAG_SIZE); return pgtable; } /* * A linux hugepage PMD was changed and the corresponding hash table entries * neesd to be flushed. */ void hpte_do_hugepage_flush(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, unsigned long old_pmd) { int ssize; unsigned int psize; unsigned long vsid; unsigned long flags = 0; /* get the base page size,vsid and segment size */ #ifdef CONFIG_DEBUG_VM psize = get_slice_psize(mm, addr); BUG_ON(psize == MMU_PAGE_16M); #endif if (old_pmd & H_PAGE_COMBO) psize = MMU_PAGE_4K; else psize = MMU_PAGE_64K; if (!is_kernel_addr(addr)) { ssize = user_segment_size(addr); vsid = get_user_vsid(&mm->context, addr, ssize); WARN_ON(vsid == 0); } else { vsid = get_kernel_vsid(addr, mmu_kernel_ssize); ssize = mmu_kernel_ssize; } if (mm_is_thread_local(mm)) flags |= HPTE_LOCAL_UPDATE; return flush_hash_hugepage(vsid, addr, pmdp, psize, ssize, flags); } pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp) { pmd_t old_pmd; pgtable_t pgtable; unsigned long old; pgtable_t *pgtable_slot; old = pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0); old_pmd = __pmd(old); /* * We have pmd == none and we are holding page_table_lock. * So we can safely go and clear the pgtable hash * index info. */ pgtable_slot = (pgtable_t *)pmdp + PTRS_PER_PMD; pgtable = *pgtable_slot; /* * Let's zero out old valid and hash index details * hash fault look at them. */ memset(pgtable, 0, PTE_FRAG_SIZE); /* * Serialize against find_current_mm_pte variants which does lock-less * lookup in page tables with local interrupts disabled. For huge pages * it casts pmd_t to pte_t. Since format of pte_t is different from * pmd_t we want to prevent transit from pmd pointing to page table * to pmd pointing to huge page (and back) while interrupts are disabled. * We clear pmd to possibly replace it with page table pointer in * different code paths. So make sure we wait for the parallel * find_curren_mm_pte to finish. */ serialize_against_pte_lookup(mm); return old_pmd; } int hash__has_transparent_hugepage(void) { if (!mmu_has_feature(MMU_FTR_16M_PAGE)) return 0; /* * We support THP only if PMD_SIZE is 16MB. */ if (mmu_psize_defs[MMU_PAGE_16M].shift != PMD_SHIFT) return 0; /* * We need to make sure that we support 16MB hugepage in a segement * with base page size 64K or 4K. We only enable THP with a PAGE_SIZE * of 64K. */ /* * If we have 64K HPTE, we will be using that by default */ if (mmu_psize_defs[MMU_PAGE_64K].shift && (mmu_psize_defs[MMU_PAGE_64K].penc[MMU_PAGE_16M] == -1)) return 0; /* * Ok we only have 4K HPTE */ if (mmu_psize_defs[MMU_PAGE_4K].penc[MMU_PAGE_16M] == -1) return 0; return 1; } #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #ifdef CONFIG_STRICT_KERNEL_RWX static bool hash__change_memory_range(unsigned long start, unsigned long end, unsigned long newpp) { unsigned long idx; unsigned int step, shift; shift = mmu_psize_defs[mmu_linear_psize].shift; step = 1 << shift; start = ALIGN_DOWN(start, step); end = ALIGN(end, step); // aligns up if (start >= end) return false; pr_debug("Changing page protection on range 0x%lx-0x%lx, to 0x%lx, step 0x%x\n", start, end, newpp, step); for (idx = start; idx < end; idx += step) /* Not sure if we can do much with the return value */ mmu_hash_ops.hpte_updateboltedpp(newpp, idx, mmu_linear_psize, mmu_kernel_ssize); return true; } void hash__mark_rodata_ro(void) { unsigned long start, end; start = (unsigned long)_stext; end = (unsigned long)__init_begin; WARN_ON(!hash__change_memory_range(start, end, PP_RXXX)); } void hash__mark_initmem_nx(void) { unsigned long start, end, pp; start = (unsigned long)__init_begin; end = (unsigned long)__init_end; pp = htab_convert_pte_flags(pgprot_val(PAGE_KERNEL)); WARN_ON(!hash__change_memory_range(start, end, pp)); } #endif