arch/ppc64/mm/tlb.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 #include <linux/config.h>
  25 #include <linux/kernel.h>
  26 #include <linux/mm.h>
  27 #include <linux/init.h>
  28 #include <linux/percpu.h>
  29 #include <linux/hardirq.h>
  30 #include <asm/pgalloc.h>
  31 #include <asm/tlbflush.h>
  32 #include <asm/tlb.h>
  33 #include <linux/highmem.h>
  34
  35 DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);
  36
  37 /* This is declared as we are using the more or less generic
  38  * include/asm-ppc64/tlb.h file -- tgall
  39  */
  40 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  41 DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
  42 unsigned long pte_freelist_forced_free;
  43
  44 struct pte_freelist_batch
  45 {
  46         struct rcu_head rcu;
  47         unsigned int    index;
  48         pgtable_free_t  tables[0];
  49 };
  50
  51 DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
  52 unsigned long pte_freelist_forced_free;
  53
  54 #define PTE_FREELIST_SIZE \
  55         ((PAGE_SIZE - sizeof(struct pte_freelist_batch)) \
  56           / sizeof(pgtable_free_t))
  57
  58 #ifdef CONFIG_SMP
  59 static void pte_free_smp_sync(void *arg)
  60 {
  61         /* Do nothing, just ensure we sync with all CPUs */
  62 }
  63 #endif
  64
  65 /* This is only called when we are critically out of memory
  66  * (and fail to get a page in pte_free_tlb).
  67  */
  68 static void pgtable_free_now(pgtable_free_t pgf)
  69 {
  70         pte_freelist_forced_free++;
  71
  72         smp_call_function(pte_free_smp_sync, NULL, 0, 1);
  73
  74         pgtable_free(pgf);
  75 }
  76
  77 static void pte_free_rcu_callback(struct rcu_head *head)
  78 {
  79         struct pte_freelist_batch *batch =
  80                 container_of(head, struct pte_freelist_batch, rcu);
  81         unsigned int i;
  82
  83         for (i = 0; i < batch->index; i++)
  84                 pgtable_free(batch->tables[i]);
  85
  86         free_page((unsigned long)batch);
  87 }
  88
  89 static void pte_free_submit(struct pte_freelist_batch *batch)
  90 {
  91         INIT_RCU_HEAD(&batch->rcu);
  92         call_rcu(&batch->rcu, pte_free_rcu_callback);
  93 }
  94
  95 void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf)
  96 {
  97         /* This is safe as we are holding page_table_lock */
  98         cpumask_t local_cpumask = cpumask_of_cpu(smp_processor_id());
  99         struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
 100
 101         if (atomic_read(&tlb->mm->mm_users) < 2 ||
 102             cpus_equal(tlb->mm->cpu_vm_mask, local_cpumask)) {
 103                 pgtable_free(pgf);
 104                 return;
 105         }
 106
 107         if (*batchp == NULL) {
 108                 *batchp = (struct pte_freelist_batch *)__get_free_page(GFP_ATOMIC);
 109                 if (*batchp == NULL) {
 110                         pgtable_free_now(pgf);
 111                         return;
 112                 }
 113                 (*batchp)->index = 0;
 114         }
 115         (*batchp)->tables[(*batchp)->index++] = pgf;
 116         if ((*batchp)->index == PTE_FREELIST_SIZE) {
 117                 pte_free_submit(*batchp);
 118                 *batchp = NULL;
 119         }
 120 }
 121
 122 /*
 123  * Update the MMU hash table to correspond with a change to
 124  * a Linux PTE.  If wrprot is true, it is permissible to
 125  * change the existing HPTE to read-only rather than removing it
 126  * (if we remove it we should clear the _PTE_HPTEFLAGS bits).
 127  */
 128 void hpte_update(struct mm_struct *mm, unsigned long addr,
 129                  unsigned long pte, int wrprot)
 130 {
 131         int i;
 132         unsigned long context = 0;
 133         struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
 134
 135         if (REGION_ID(addr) == USER_REGION_ID)
 136                 context = mm->context.id;
 137         i = batch->index;
 138
 139         /*
 140          * This can happen when we are in the middle of a TLB batch and
 141          * we encounter memory pressure (eg copy_page_range when it tries
 142          * to allocate a new pte). If we have to reclaim memory and end
 143          * up scanning and resetting referenced bits then our batch context
 144          * will change mid stream.
 145          */
 146         if (unlikely(i != 0 && context != batch->context)) {
 147                 flush_tlb_pending();
 148                 i = 0;
 149         }
 150
 151         if (i == 0) {
 152                 batch->context = context;
 153                 batch->mm = mm;
 154         }
 155         batch->pte[i] = __pte(pte);
 156         batch->addr[i] = addr;
 157         batch->index = ++i;
 158         if (i >= PPC64_TLB_BATCH_NR)
 159                 flush_tlb_pending();
 160 }
 161
 162 void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
 163 {
 164         int i;
 165         int cpu;
 166         cpumask_t tmp;
 167         int local = 0;
 168
 169         BUG_ON(in_interrupt());
 170
 171         cpu = get_cpu();
 172         i = batch->index;
 173         tmp = cpumask_of_cpu(cpu);
 174         if (cpus_equal(batch->mm->cpu_vm_mask, tmp))
 175                 local = 1;
 176
 177         if (i == 1)
 178                 flush_hash_page(batch->context, batch->addr[0], batch->pte[0],
 179                                 local);
 180         else
 181                 flush_hash_range(batch->context, i, local);
 182         batch->index = 0;
 183         put_cpu();
 184 }
 185
 186 void pte_free_finish(void)
 187 {
 188         /* This is safe as we are holding page_table_lock */
 189         struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
 190
 191         if (*batchp == NULL)
 192                 return;
 193         pte_free_submit(*batchp);
 194         *batchp = NULL;
 195 }