arch/powerpc/mm/tlb_64.c

   1 /*
   2  * This file contains the routines for flushing entries from the
   3  * TLB and MMU hash table.
   4  *
   5  *  Derived from arch/ppc64/mm/init.c:
   6  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   7  *
   8  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   9  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  10  *    Copyright (C) 1996 Paul Mackerras
  11  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
  12  *
  13  *  Derived from "arch/i386/mm/init.c"
  14  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  15  *
  16  *  Dave Engebretsen <engebret@us.ibm.com>
  17  *      Rework for PPC64 port.
  18  *
  19  *  This program is free software; you can redistribute it and/or
  20  *  modify it under the terms of the GNU General Public License
  21  *  as published by the Free Software Foundation; either version
  22  *  2 of the License, or (at your option) any later version.
  23  */
  24
  25 #include <linux/config.h>
  26 #include <linux/kernel.h>
  27 #include <linux/mm.h>
  28 #include <linux/init.h>
  29 #include <linux/percpu.h>
  30 #include <linux/hardirq.h>
  31 #include <asm/pgalloc.h>
  32 #include <asm/tlbflush.h>
  33 #include <asm/tlb.h>
  34 #include <asm/bug.h>
  35
  36 DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);
  37
  38 /* This is declared as we are using the more or less generic
  39  * include/asm-ppc64/tlb.h file -- tgall
  40  */
  41 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  42 DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
  43 unsigned long pte_freelist_forced_free;
  44
  45 struct pte_freelist_batch
  46 {
  47         struct rcu_head rcu;
  48         unsigned int    index;
  49         pgtable_free_t  tables[0];
  50 };
  51
  52 DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
  53 unsigned long pte_freelist_forced_free;
  54
  55 #define PTE_FREELIST_SIZE \
  56         ((PAGE_SIZE - sizeof(struct pte_freelist_batch)) \
  57           / sizeof(pgtable_free_t))
  58
  59 #ifdef CONFIG_SMP
  60 static void pte_free_smp_sync(void *arg)
  61 {
  62         /* Do nothing, just ensure we sync with all CPUs */
  63 }
  64 #endif
  65
  66 /* This is only called when we are critically out of memory
  67  * (and fail to get a page in pte_free_tlb).
  68  */
  69 static void pgtable_free_now(pgtable_free_t pgf)
  70 {
  71         pte_freelist_forced_free++;
  72
  73         smp_call_function(pte_free_smp_sync, NULL, 0, 1);
  74
  75         pgtable_free(pgf);
  76 }
  77
  78 static void pte_free_rcu_callback(struct rcu_head *head)
  79 {
  80         struct pte_freelist_batch *batch =
  81                 container_of(head, struct pte_freelist_batch, rcu);
  82         unsigned int i;
  83
  84         for (i = 0; i < batch->index; i++)
  85                 pgtable_free(batch->tables[i]);
  86
  87         free_page((unsigned long)batch);
  88 }
  89
  90 static void pte_free_submit(struct pte_freelist_batch *batch)
  91 {
  92         INIT_RCU_HEAD(&batch->rcu);
  93         call_rcu(&batch->rcu, pte_free_rcu_callback);
  94 }
  95
  96 void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf)
  97 {
  98         /* This is safe as we are holding page_table_lock */
  99         cpumask_t local_cpumask = cpumask_of_cpu(smp_processor_id());
 100         struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
 101
 102         if (atomic_read(&tlb->mm->mm_users) < 2 ||
 103             cpus_equal(tlb->mm->cpu_vm_mask, local_cpumask)) {
 104                 pgtable_free(pgf);
 105                 return;
 106         }
 107
 108         if (*batchp == NULL) {
 109                 *batchp = (struct pte_freelist_batch *)__get_free_page(GFP_ATOMIC);
 110                 if (*batchp == NULL) {
 111                         pgtable_free_now(pgf);
 112                         return;
 113                 }
 114                 (*batchp)->index = 0;
 115         }
 116         (*batchp)->tables[(*batchp)->index++] = pgf;
 117         if ((*batchp)->index == PTE_FREELIST_SIZE) {
 118                 pte_free_submit(*batchp);
 119                 *batchp = NULL;
 120         }
 121 }
 122
 123 /*
 124  * Update the MMU hash table to correspond with a change to
 125  * a Linux PTE.  If wrprot is true, it is permissible to
 126  * change the existing HPTE to read-only rather than removing it
 127  * (if we remove it we should clear the _PTE_HPTEFLAGS bits).
 128  */
 129 void hpte_update(struct mm_struct *mm, unsigned long addr,
 130                  pte_t *ptep, unsigned long pte, int huge)
 131 {
 132         struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
 133         unsigned long vsid;
 134         unsigned int psize = mmu_virtual_psize;
 135         int i;
 136
 137         i = batch->index;
 138
 139         /* We mask the address for the base page size. Huge pages will
 140          * have applied their own masking already
 141          */
 142         addr &= PAGE_MASK;
 143
 144         /* Get page size (maybe move back to caller) */
 145         if (huge) {
 146 #ifdef CONFIG_HUGETLB_PAGE
 147                 psize = mmu_huge_psize;
 148 #else
 149                 BUG();
 150 #endif
 151         }
 152
 153         /*
 154          * This can happen when we are in the middle of a TLB batch and
 155          * we encounter memory pressure (eg copy_page_range when it tries
 156          * to allocate a new pte). If we have to reclaim memory and end
 157          * up scanning and resetting referenced bits then our batch context
 158          * will change mid stream.
 159          *
 160          * We also need to ensure only one page size is present in a given
 161          * batch
 162          */
 163         if (i != 0 && (mm != batch->mm || batch->psize != psize)) {
 164                 flush_tlb_pending();
 165                 i = 0;
 166         }
 167         if (i == 0) {
 168                 batch->mm = mm;
 169                 batch->psize = psize;
 170         }
 171         if (addr < KERNELBASE) {
 172                 vsid = get_vsid(mm->context.id, addr);
 173                 WARN_ON(vsid == 0);
 174         } else
 175                 vsid = get_kernel_vsid(addr);
 176         batch->vaddr[i] = (vsid << 28 ) | (addr & 0x0fffffff);
 177         batch->pte[i] = __real_pte(__pte(pte), ptep);
 178         batch->index = ++i;
 179         if (i >= PPC64_TLB_BATCH_NR)
 180                 flush_tlb_pending();
 181 }
 182
 183 void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
 184 {
 185         int i;
 186         int cpu;
 187         cpumask_t tmp;
 188         int local = 0;
 189
 190         BUG_ON(in_interrupt());
 191
 192         cpu = get_cpu();
 193         i = batch->index;
 194         tmp = cpumask_of_cpu(cpu);
 195         if (cpus_equal(batch->mm->cpu_vm_mask, tmp))
 196                 local = 1;
 197
 198         if (i == 1)
 199                 flush_hash_page(batch->vaddr[0], batch->pte[0],
 200                                 batch->psize, local);
 201         else
 202                 flush_hash_range(i, local);
 203         batch->index = 0;
 204         put_cpu();
 205 }
 206
 207 void pte_free_finish(void)
 208 {
 209         /* This is safe as we are holding page_table_lock */
 210         struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
 211
 212         if (*batchp == NULL)
 213                 return;
 214         pte_free_submit(*batchp);
 215         *batchp = NULL;
 216 }