From 36409f6353fc2d7b6516e631415f938eadd92ffa Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 6 Jun 2011 14:14:41 +0200 Subject: [S390] use generic RCU page-table freeing code Replace the s390 specific rcu page-table freeing code with the generic variant. This requires to duplicate the definition for the struct mmu_table_batch as s390 does not use the generic tlb flush code. While we are at it remove the restriction that page table fragments can not be reused after a single fragment has been freed with rcu and split out allocation and freeing of page tables with pgstes. Signed-off-by: Martin Schwidefsky --- arch/s390/mm/pgtable.c | 292 ++++++++++++++++++++----------------------------- 1 file changed, 119 insertions(+), 173 deletions(-) (limited to 'arch/s390/mm') diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index b09763fe5da1..37a23c223705 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -24,94 +24,12 @@ #include #include -struct rcu_table_freelist { - struct rcu_head rcu; - struct mm_struct *mm; - unsigned int pgt_index; - unsigned int crst_index; - unsigned long *table[0]; -}; - -#define RCU_FREELIST_SIZE \ - ((PAGE_SIZE - sizeof(struct rcu_table_freelist)) \ - / sizeof(unsigned long)) - -static DEFINE_PER_CPU(struct rcu_table_freelist *, rcu_table_freelist); - -static void __page_table_free(struct mm_struct *mm, unsigned long *table); - -static struct rcu_table_freelist *rcu_table_freelist_get(struct mm_struct *mm) -{ - struct rcu_table_freelist **batchp = &__get_cpu_var(rcu_table_freelist); - struct rcu_table_freelist *batch = *batchp; - - if (batch) - return batch; - batch = (struct rcu_table_freelist *) __get_free_page(GFP_ATOMIC); - if (batch) { - batch->mm = mm; - batch->pgt_index = 0; - batch->crst_index = RCU_FREELIST_SIZE; - *batchp = batch; - } - return batch; -} - -static void rcu_table_freelist_callback(struct rcu_head *head) -{ - struct rcu_table_freelist *batch = - container_of(head, struct rcu_table_freelist, rcu); - - while (batch->pgt_index > 0) - __page_table_free(batch->mm, batch->table[--batch->pgt_index]); - while (batch->crst_index < RCU_FREELIST_SIZE) - crst_table_free(batch->mm, batch->table[batch->crst_index++]); - free_page((unsigned long) batch); -} - -void rcu_table_freelist_finish(void) -{ - struct rcu_table_freelist **batchp = &get_cpu_var(rcu_table_freelist); - struct rcu_table_freelist *batch = *batchp; - - if (!batch) - goto out; - call_rcu(&batch->rcu, rcu_table_freelist_callback); - *batchp = NULL; -out: - put_cpu_var(rcu_table_freelist); -} - -static void smp_sync(void *arg) -{ -} - #ifndef CONFIG_64BIT #define ALLOC_ORDER 1 -#define TABLES_PER_PAGE 4 -#define FRAG_MASK 15UL -#define SECOND_HALVES 10UL - -void clear_table_pgstes(unsigned long *table) -{ - clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/4); - memset(table + 256, 0, PAGE_SIZE/4); - clear_table(table + 512, _PAGE_TYPE_EMPTY, PAGE_SIZE/4); - memset(table + 768, 0, PAGE_SIZE/4); -} - +#define FRAG_MASK 0x0f #else #define ALLOC_ORDER 2 -#define TABLES_PER_PAGE 2 -#define FRAG_MASK 3UL -#define SECOND_HALVES 2UL - -void clear_table_pgstes(unsigned long *table) -{ - clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2); - memset(table + 256, 0, PAGE_SIZE/2); -} - +#define FRAG_MASK 0x03 #endif unsigned long VMALLOC_START = VMALLOC_END - VMALLOC_SIZE; @@ -140,29 +58,6 @@ void crst_table_free(struct mm_struct *mm, unsigned long *table) free_pages((unsigned long) table, ALLOC_ORDER); } -void crst_table_free_rcu(struct mm_struct *mm, unsigned long *table) -{ - struct rcu_table_freelist *batch; - - preempt_disable(); - if (atomic_read(&mm->mm_users) < 2 && - cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) { - crst_table_free(mm, table); - goto out; - } - batch = rcu_table_freelist_get(mm); - if (!batch) { - smp_call_function(smp_sync, NULL, 1); - crst_table_free(mm, table); - goto out; - } - batch->table[--batch->crst_index] = table; - if (batch->pgt_index >= batch->crst_index) - rcu_table_freelist_finish(); -out: - preempt_enable(); -} - #ifdef CONFIG_64BIT int crst_table_upgrade(struct mm_struct *mm, unsigned long limit) { @@ -238,124 +133,175 @@ void crst_table_downgrade(struct mm_struct *mm, unsigned long limit) } #endif +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; +} + /* * page table entry allocation/free routines. */ +#ifdef CONFIG_PGSTE +static inline unsigned long *page_table_alloc_pgste(struct mm_struct *mm) +{ + struct page *page; + unsigned long *table; + + page = alloc_page(GFP_KERNEL|__GFP_REPEAT); + if (!page) + return NULL; + pgtable_page_ctor(page); + atomic_set(&page->_mapcount, 3); + table = (unsigned long *) page_to_phys(page); + clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2); + clear_table(table + PTRS_PER_PTE, 0, PAGE_SIZE/2); + return table; +} + +static inline void page_table_free_pgste(unsigned long *table) +{ + struct page *page; + + page = pfn_to_page(__pa(table) >> PAGE_SHIFT); + pgtable_page_ctor(page); + atomic_set(&page->_mapcount, -1); + __free_page(page); +} +#endif + unsigned long *page_table_alloc(struct mm_struct *mm) { struct page *page; unsigned long *table; - unsigned long bits; + unsigned int mask, bit; - bits = (mm->context.has_pgste) ? 3UL : 1UL; +#ifdef CONFIG_PGSTE + if (mm_has_pgste(mm)) + return page_table_alloc_pgste(mm); +#endif + /* Allocate fragments of a 4K page as 1K/2K page table */ spin_lock_bh(&mm->context.list_lock); - page = NULL; + mask = FRAG_MASK; if (!list_empty(&mm->context.pgtable_list)) { page = list_first_entry(&mm->context.pgtable_list, struct page, lru); - if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1)) - page = NULL; + table = (unsigned long *) page_to_phys(page); + mask = atomic_read(&page->_mapcount); + mask = mask | (mask >> 4); } - if (!page) { + if ((mask & FRAG_MASK) == FRAG_MASK) { spin_unlock_bh(&mm->context.list_lock); page = alloc_page(GFP_KERNEL|__GFP_REPEAT); if (!page) return NULL; pgtable_page_ctor(page); - page->flags &= ~FRAG_MASK; + atomic_set(&page->_mapcount, 1); table = (unsigned long *) page_to_phys(page); - if (mm->context.has_pgste) - clear_table_pgstes(table); - else - clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE); + clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE); spin_lock_bh(&mm->context.list_lock); list_add(&page->lru, &mm->context.pgtable_list); + } else { + for (bit = 1; mask & bit; bit <<= 1) + table += PTRS_PER_PTE; + mask = atomic_xor_bits(&page->_mapcount, bit); + if ((mask & FRAG_MASK) == FRAG_MASK) + list_del(&page->lru); } - table = (unsigned long *) page_to_phys(page); - while (page->flags & bits) { - table += 256; - bits <<= 1; - } - page->flags |= bits; - if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1)) - list_move_tail(&page->lru, &mm->context.pgtable_list); spin_unlock_bh(&mm->context.list_lock); return table; } -static void __page_table_free(struct mm_struct *mm, unsigned long *table) +void page_table_free(struct mm_struct *mm, unsigned long *table) { struct page *page; - unsigned long bits; + unsigned int bit, mask; - bits = ((unsigned long) table) & 15; - table = (unsigned long *)(((unsigned long) table) ^ bits); +#ifdef CONFIG_PGSTE + if (mm_has_pgste(mm)) + return page_table_free_pgste(table); +#endif + /* Free 1K/2K page table fragment of a 4K page */ page = pfn_to_page(__pa(table) >> PAGE_SHIFT); - page->flags ^= bits; - if (!(page->flags & FRAG_MASK)) { + bit = 1 << ((__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t))); + spin_lock_bh(&mm->context.list_lock); + if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK) + list_del(&page->lru); + mask = atomic_xor_bits(&page->_mapcount, bit); + if (mask & FRAG_MASK) + list_add(&page->lru, &mm->context.pgtable_list); + spin_unlock_bh(&mm->context.list_lock); + if (mask == 0) { pgtable_page_dtor(page); + atomic_set(&page->_mapcount, -1); __free_page(page); } } -void page_table_free(struct mm_struct *mm, unsigned long *table) +#ifdef CONFIG_HAVE_RCU_TABLE_FREE + +static void __page_table_free_rcu(void *table, unsigned bit) { struct page *page; - unsigned long bits; - bits = (mm->context.has_pgste) ? 3UL : 1UL; - bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long); +#ifdef CONFIG_PGSTE + if (bit == FRAG_MASK) + return page_table_free_pgste(table); +#endif + /* Free 1K/2K page table fragment of a 4K page */ page = pfn_to_page(__pa(table) >> PAGE_SHIFT); - spin_lock_bh(&mm->context.list_lock); - page->flags ^= bits; - if (page->flags & FRAG_MASK) { - /* Page now has some free pgtable fragments. */ - if (!list_empty(&page->lru)) - list_move(&page->lru, &mm->context.pgtable_list); - page = NULL; - } else - /* All fragments of the 4K page have been freed. */ - list_del(&page->lru); - spin_unlock_bh(&mm->context.list_lock); - if (page) { + if (atomic_xor_bits(&page->_mapcount, bit) == 0) { pgtable_page_dtor(page); + atomic_set(&page->_mapcount, -1); __free_page(page); } } -void page_table_free_rcu(struct mm_struct *mm, unsigned long *table) +void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table) { - struct rcu_table_freelist *batch; + struct mm_struct *mm; struct page *page; - unsigned long bits; + unsigned int bit, mask; - preempt_disable(); - if (atomic_read(&mm->mm_users) < 2 && - cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id()))) { - page_table_free(mm, table); - goto out; - } - batch = rcu_table_freelist_get(mm); - if (!batch) { - smp_call_function(smp_sync, NULL, 1); - page_table_free(mm, table); - goto out; + mm = tlb->mm; +#ifdef CONFIG_PGSTE + if (mm_has_pgste(mm)) { + table = (unsigned long *) (__pa(table) | FRAG_MASK); + tlb_remove_table(tlb, table); + return; } - bits = (mm->context.has_pgste) ? 3UL : 1UL; - bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long); +#endif + bit = 1 << ((__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t))); page = pfn_to_page(__pa(table) >> PAGE_SHIFT); spin_lock_bh(&mm->context.list_lock); - /* Delayed freeing with rcu prevents reuse of pgtable fragments */ - list_del_init(&page->lru); + if ((atomic_read(&page->_mapcount) & FRAG_MASK) != FRAG_MASK) + list_del(&page->lru); + mask = atomic_xor_bits(&page->_mapcount, bit | (bit << 4)); + if (mask & FRAG_MASK) + list_add_tail(&page->lru, &mm->context.pgtable_list); spin_unlock_bh(&mm->context.list_lock); - table = (unsigned long *)(((unsigned long) table) | bits); - batch->table[batch->pgt_index++] = table; - if (batch->pgt_index >= batch->crst_index) - rcu_table_freelist_finish(); -out: - preempt_enable(); + table = (unsigned long *) (__pa(table) | (bit << 4)); + tlb_remove_table(tlb, table); } +void __tlb_remove_table(void *_table) +{ + void *table = (void *)((unsigned long) _table & PAGE_MASK); + unsigned type = (unsigned long) _table & ~PAGE_MASK; + + if (type) + __page_table_free_rcu(table, type); + else + free_pages((unsigned long) table, ALLOC_ORDER); +} + +#endif + /* * switch on pgstes for its userspace process (for kvm) */ @@ -369,7 +315,7 @@ int s390_enable_sie(void) return -EINVAL; /* Do we have pgstes? if yes, we are done */ - if (tsk->mm->context.has_pgste) + if (mm_has_pgste(tsk->mm)) return 0; /* lets check if we are allowed to replace the mm */ -- cgit v1.2.1