| /* |
| * Page table allocation functions |
| * |
| * Copyright IBM Corp. 2016 |
| * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/sysctl.h> |
| #include <asm/mmu_context.h> |
| #include <asm/pgalloc.h> |
| #include <asm/gmap.h> |
| #include <asm/tlb.h> |
| #include <asm/tlbflush.h> |
| |
| #ifdef CONFIG_PGSTE |
| |
| static int page_table_allocate_pgste_min = 0; |
| static int page_table_allocate_pgste_max = 1; |
| int page_table_allocate_pgste = 0; |
| EXPORT_SYMBOL(page_table_allocate_pgste); |
| |
| static struct ctl_table page_table_sysctl[] = { |
| { |
| .procname = "allocate_pgste", |
| .data = &page_table_allocate_pgste, |
| .maxlen = sizeof(int), |
| .mode = S_IRUGO | S_IWUSR, |
| .proc_handler = proc_dointvec, |
| .extra1 = &page_table_allocate_pgste_min, |
| .extra2 = &page_table_allocate_pgste_max, |
| }, |
| { } |
| }; |
| |
| static struct ctl_table page_table_sysctl_dir[] = { |
| { |
| .procname = "vm", |
| .maxlen = 0, |
| .mode = 0555, |
| .child = page_table_sysctl, |
| }, |
| { } |
| }; |
| |
| static int __init page_table_register_sysctl(void) |
| { |
| return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM; |
| } |
| __initcall(page_table_register_sysctl); |
| |
| #endif /* CONFIG_PGSTE */ |
| |
| unsigned long *crst_table_alloc(struct mm_struct *mm) |
| { |
| struct page *page = alloc_pages(GFP_KERNEL, 2); |
| |
| if (!page) |
| return NULL; |
| arch_set_page_dat(page, 2); |
| return (unsigned long *) page_to_phys(page); |
| } |
| |
| void crst_table_free(struct mm_struct *mm, unsigned long *table) |
| { |
| free_pages((unsigned long) table, 2); |
| } |
| |
| static void __crst_table_upgrade(void *arg) |
| { |
| struct mm_struct *mm = arg; |
| |
| if (current->active_mm == mm) { |
| clear_user_asce(); |
| set_user_asce(mm); |
| } |
| __tlb_flush_local(); |
| } |
| |
| int crst_table_upgrade(struct mm_struct *mm, unsigned long end) |
| { |
| unsigned long *table, *pgd; |
| int rc, notify; |
| |
| /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ |
| BUG_ON(mm->context.asce_limit < (1UL << 42)); |
| if (end >= TASK_SIZE_MAX) |
| return -ENOMEM; |
| rc = 0; |
| notify = 0; |
| while (mm->context.asce_limit < end) { |
| table = crst_table_alloc(mm); |
| if (!table) { |
| rc = -ENOMEM; |
| break; |
| } |
| spin_lock_bh(&mm->page_table_lock); |
| pgd = (unsigned long *) mm->pgd; |
| if (mm->context.asce_limit == (1UL << 42)) { |
| crst_table_init(table, _REGION2_ENTRY_EMPTY); |
| p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd); |
| mm->pgd = (pgd_t *) table; |
| mm->context.asce_limit = 1UL << 53; |
| mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | |
| _ASCE_USER_BITS | _ASCE_TYPE_REGION2; |
| } else { |
| crst_table_init(table, _REGION1_ENTRY_EMPTY); |
| pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd); |
| mm->pgd = (pgd_t *) table; |
| mm->context.asce_limit = -PAGE_SIZE; |
| mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | |
| _ASCE_USER_BITS | _ASCE_TYPE_REGION1; |
| } |
| notify = 1; |
| spin_unlock_bh(&mm->page_table_lock); |
| } |
| if (notify) |
| on_each_cpu(__crst_table_upgrade, mm, 0); |
| return rc; |
| } |
| |
| void crst_table_downgrade(struct mm_struct *mm) |
| { |
| pgd_t *pgd; |
| |
| /* downgrade should only happen from 3 to 2 levels (compat only) */ |
| BUG_ON(mm->context.asce_limit != (1UL << 42)); |
| |
| if (current->active_mm == mm) { |
| clear_user_asce(); |
| __tlb_flush_mm(mm); |
| } |
| |
| pgd = mm->pgd; |
| mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN); |
| mm->context.asce_limit = 1UL << 31; |
| mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | |
| _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT; |
| crst_table_free(mm, (unsigned long *) pgd); |
| |
| if (current->active_mm == mm) |
| set_user_asce(mm); |
| } |
| |
| static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) |
| { |
| unsigned int old, new; |
| |
| do { |
| old = atomic_read(v); |
| new = old ^ bits; |
| } while (atomic_cmpxchg(v, old, new) != old); |
| return new; |
| } |
| |
| #ifdef CONFIG_PGSTE |
| |
| struct page *page_table_alloc_pgste(struct mm_struct *mm) |
| { |
| struct page *page; |
| unsigned long *table; |
| |
| page = alloc_page(GFP_KERNEL); |
| if (page) { |
| table = (unsigned long *) page_to_phys(page); |
| clear_table(table, _PAGE_INVALID, PAGE_SIZE/2); |
| clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2); |
| } |
| return page; |
| } |
| |
| void page_table_free_pgste(struct page *page) |
| { |
| __free_page(page); |
| } |
| |
| #endif /* CONFIG_PGSTE */ |
| |
| /* |
| * page table entry allocation/free routines. |
| */ |
| unsigned long *page_table_alloc(struct mm_struct *mm) |
| { |
| unsigned long *table; |
| struct page *page; |
| unsigned int mask, bit; |
| |
| /* Try to get a fragment of a 4K page as a 2K page table */ |
| if (!mm_alloc_pgste(mm)) { |
| table = NULL; |
| spin_lock_bh(&mm->context.pgtable_lock); |
| if (!list_empty(&mm->context.pgtable_list)) { |
| page = list_first_entry(&mm->context.pgtable_list, |
| struct page, lru); |
| mask = atomic_read(&page->_mapcount); |
| mask = (mask | (mask >> 4)) & 3; |
| if (mask != 3) { |
| table = (unsigned long *) page_to_phys(page); |
| bit = mask & 1; /* =1 -> second 2K */ |
| if (bit) |
| table += PTRS_PER_PTE; |
| atomic_xor_bits(&page->_mapcount, 1U << bit); |
| list_del(&page->lru); |
| } |
| } |
| spin_unlock_bh(&mm->context.pgtable_lock); |
| if (table) |
| return table; |
| } |
| /* Allocate a fresh page */ |
| page = alloc_page(GFP_KERNEL); |
| if (!page) |
| return NULL; |
| if (!pgtable_page_ctor(page)) { |
| __free_page(page); |
| return NULL; |
| } |
| arch_set_page_dat(page, 0); |
| /* Initialize page table */ |
| table = (unsigned long *) page_to_phys(page); |
| if (mm_alloc_pgste(mm)) { |
| /* Return 4K page table with PGSTEs */ |
| atomic_set(&page->_mapcount, 3); |
| clear_table(table, _PAGE_INVALID, PAGE_SIZE/2); |
| clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2); |
| } else { |
| /* Return the first 2K fragment of the page */ |
| atomic_set(&page->_mapcount, 1); |
| clear_table(table, _PAGE_INVALID, PAGE_SIZE); |
| spin_lock_bh(&mm->context.pgtable_lock); |
| list_add(&page->lru, &mm->context.pgtable_list); |
| spin_unlock_bh(&mm->context.pgtable_lock); |
| } |
| return table; |
| } |
| |
| void page_table_free(struct mm_struct *mm, unsigned long *table) |
| { |
| struct page *page; |
| unsigned int bit, mask; |
| |
| page = pfn_to_page(__pa(table) >> PAGE_SHIFT); |
| if (!mm_alloc_pgste(mm)) { |
| /* Free 2K page table fragment of a 4K page */ |
| bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); |
| spin_lock_bh(&mm->context.pgtable_lock); |
| mask = atomic_xor_bits(&page->_mapcount, 1U << bit); |
| if (mask & 3) |
| list_add(&page->lru, &mm->context.pgtable_list); |
| else |
| list_del(&page->lru); |
| spin_unlock_bh(&mm->context.pgtable_lock); |
| if (mask != 0) |
| return; |
| } |
| |
| pgtable_page_dtor(page); |
| atomic_set(&page->_mapcount, -1); |
| __free_page(page); |
| } |
| |
| void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, |
| unsigned long vmaddr) |
| { |
| struct mm_struct *mm; |
| struct page *page; |
| unsigned int bit, mask; |
| |
| mm = tlb->mm; |
| page = pfn_to_page(__pa(table) >> PAGE_SHIFT); |
| if (mm_alloc_pgste(mm)) { |
| gmap_unlink(mm, table, vmaddr); |
| table = (unsigned long *) (__pa(table) | 3); |
| tlb_remove_table(tlb, table); |
| return; |
| } |
| bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); |
| spin_lock_bh(&mm->context.pgtable_lock); |
| mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit); |
| if (mask & 3) |
| list_add_tail(&page->lru, &mm->context.pgtable_list); |
| else |
| list_del(&page->lru); |
| spin_unlock_bh(&mm->context.pgtable_lock); |
| table = (unsigned long *) (__pa(table) | (1U << bit)); |
| tlb_remove_table(tlb, table); |
| } |
| |
| static void __tlb_remove_table(void *_table) |
| { |
| unsigned int mask = (unsigned long) _table & 3; |
| void *table = (void *)((unsigned long) _table ^ mask); |
| struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT); |
| |
| switch (mask) { |
| case 0: /* pmd, pud, or p4d */ |
| free_pages((unsigned long) table, 2); |
| break; |
| case 1: /* lower 2K of a 4K page table */ |
| case 2: /* higher 2K of a 4K page table */ |
| if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0) |
| break; |
| /* fallthrough */ |
| case 3: /* 4K page table with pgstes */ |
| pgtable_page_dtor(page); |
| atomic_set(&page->_mapcount, -1); |
| __free_page(page); |
| break; |
| } |
| } |
| |
| static void tlb_remove_table_smp_sync(void *arg) |
| { |
| /* Simply deliver the interrupt */ |
| } |
| |
| static void tlb_remove_table_one(void *table) |
| { |
| /* |
| * This isn't an RCU grace period and hence the page-tables cannot be |
| * assumed to be actually RCU-freed. |
| * |
| * It is however sufficient for software page-table walkers that rely |
| * on IRQ disabling. See the comment near struct mmu_table_batch. |
| */ |
| smp_call_function(tlb_remove_table_smp_sync, NULL, 1); |
| __tlb_remove_table(table); |
| } |
| |
| static void tlb_remove_table_rcu(struct rcu_head *head) |
| { |
| struct mmu_table_batch *batch; |
| int i; |
| |
| batch = container_of(head, struct mmu_table_batch, rcu); |
| |
| for (i = 0; i < batch->nr; i++) |
| __tlb_remove_table(batch->tables[i]); |
| |
| free_page((unsigned long)batch); |
| } |
| |
| void tlb_table_flush(struct mmu_gather *tlb) |
| { |
| struct mmu_table_batch **batch = &tlb->batch; |
| |
| if (*batch) { |
| call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); |
| *batch = NULL; |
| } |
| } |
| |
| void tlb_remove_table(struct mmu_gather *tlb, void *table) |
| { |
| struct mmu_table_batch **batch = &tlb->batch; |
| |
| tlb->mm->context.flush_mm = 1; |
| if (*batch == NULL) { |
| *batch = (struct mmu_table_batch *) |
| __get_free_page(GFP_NOWAIT | __GFP_NOWARN); |
| if (*batch == NULL) { |
| __tlb_flush_mm_lazy(tlb->mm); |
| tlb_remove_table_one(table); |
| return; |
| } |
| (*batch)->nr = 0; |
| } |
| (*batch)->tables[(*batch)->nr++] = table; |
| if ((*batch)->nr == MAX_TABLE_BATCH) |
| tlb_flush_mmu(tlb); |
| } |