diff options
Diffstat (limited to 'arch/powerpc/mm/pgtable-hash64.c')
| -rw-r--r-- | arch/powerpc/mm/pgtable-hash64.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/arch/powerpc/mm/pgtable-hash64.c b/arch/powerpc/mm/pgtable-hash64.c new file mode 100644 index 000000000000..c23e286a6b8f --- /dev/null +++ b/arch/powerpc/mm/pgtable-hash64.c @@ -0,0 +1,342 @@ +/* + * 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 <linux/sched.h> +#include <asm/pgalloc.h> +#include <asm/tlb.h> + +#include "mmu_decl.h" + +#define CREATE_TRACE_POINTS +#include <trace/events/thp.h> + +#ifdef CONFIG_SPARSEMEM_VMEMMAP +/* + * 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 = 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, unsigned long flags) +{ + 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, + __pgprot(flags))); + } 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, flags, + 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(!pmd_trans_huge(*pmdp)); + assert_spin_locked(&mm->page_table_lock); +#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)); + + 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. + */ + kick_all_cpus_sync(); + /* + * 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(&mm->page_table_lock); + /* + * 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(&mm->page_table_lock); + 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; +} + +void hash__pmdp_huge_split_prepare(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmdp) +{ + VM_BUG_ON(address & ~HPAGE_PMD_MASK); + VM_BUG_ON(REGION_ID(address) != USER_REGION_ID); + + /* + * We can't mark the pmd none here, because that will cause a race + * against exit_mmap. We need to continue mark pmd TRANS HUGE, while + * we spilt, but at the same time we wan't rest of the ppc64 code + * not to insert hash pte on this, because we will be modifying + * the deposited pgtable in the caller of this function. Hence + * clear the _PAGE_USER so that we move the fault handling to + * higher level function and that will serialize against ptl. + * We need to flush existing hash pte entries here even though, + * the translation is still valid, because we will withdraw + * pgtable_t after this. + */ + pmd_hugepage_update(vma->vm_mm, address, pmdp, 0, _PAGE_PRIVILEGED); +} + +/* + * 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; + const struct cpumask *tmp; + + /* 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_vsid(mm->context.id, addr, ssize); + WARN_ON(vsid == 0); + } else { + vsid = get_kernel_vsid(addr, mmu_kernel_ssize); + ssize = mmu_kernel_ssize; + } + + tmp = cpumask_of(smp_processor_id()); + if (cpumask_equal(mm_cpumask(mm), tmp)) + 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_linux_pte_or_hugepte 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_linux_pte_or_hugepage to finish. + */ + kick_all_cpus_sync(); + 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 */ |