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