arch/powerpc/mm/tlb_hash64.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  *
  12  *  Derived from "arch/i386/mm/init.c"
  13  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  14  *
  15  *  Dave Engebretsen <engebret@us.ibm.com>
  16  *      Rework for PPC64 port.
  17  *
  18  *  This program is free software; you can redistribute it and/or
  19  *  modify it under the terms of the GNU General Public License
  20  *  as published by the Free Software Foundation; either version
  21  *  2 of the License, or (at your option) any later version.
  22  */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/mm.h>
  26 #include <linux/init.h>
  27 #include <linux/percpu.h>
  28 #include <linux/hardirq.h>
  29 #include <asm/pgalloc.h>
  30 #include <asm/tlbflush.h>
  31 #include <asm/tlb.h>
  32 #include <asm/bug.h>
  33
  34 DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);
  35
  36 /* This is declared as we are using the more or less generic
  37  * arch/powerpc/include/asm/tlb.h file -- tgall
  38  */
  39 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  40
  41 /*
  42  * A linux PTE was changed and the corresponding hash table entry
  43  * neesd to be flushed. This function will either perform the flush
  44  * immediately or will batch it up if the current CPU has an active
  45  * batch on it.
  46  *
  47  * Must be called from within some kind of spinlock/non-preempt region...
  48  */
  49 void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
  50                      pte_t *ptep, unsigned long pte, int huge)
  51 {
  52         struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
  53         unsigned long vsid, vaddr;
  54         unsigned int psize;
  55         int ssize;
  56         real_pte_t rpte;
  57         int i;
  58
  59         i = batch->index;
  60
  61         /* We mask the address for the base page size. Huge pages will
  62          * have applied their own masking already
  63          */
  64         addr &= PAGE_MASK;
  65
  66         /* Get page size (maybe move back to caller).
  67          *
  68          * NOTE: when using special 64K mappings in 4K environment like
  69          * for SPEs, we obtain the page size from the slice, which thus
  70          * must still exist (and thus the VMA not reused) at the time
  71          * of this call
  72          */
  73         if (huge) {
  74 #ifdef CONFIG_HUGETLB_PAGE
  75                 psize = get_slice_psize(mm, addr);
  76 #else
  77                 BUG();
  78                 psize = pte_pagesize_index(mm, addr, pte); /* shutup gcc */
  79 #endif
  80         } else
  81                 psize = pte_pagesize_index(mm, addr, pte);
  82
  83         /* Build full vaddr */
  84         if (!is_kernel_addr(addr)) {
  85                 ssize = user_segment_size(addr);
  86                 vsid = get_vsid(mm->context.id, addr, ssize);
  87                 WARN_ON(vsid == 0);
  88         } else {
  89                 vsid = get_kernel_vsid(addr, mmu_kernel_ssize);
  90                 ssize = mmu_kernel_ssize;
  91         }
  92         vaddr = hpt_va(addr, vsid, ssize);
  93         rpte = __real_pte(__pte(pte), ptep);
  94
  95         /*
  96          * Check if we have an active batch on this CPU. If not, just
  97          * flush now and return. For now, we don global invalidates
  98          * in that case, might be worth testing the mm cpu mask though
  99          * and decide to use local invalidates instead...
 100          */
 101         if (!batch->active) {
 102                 flush_hash_page(vaddr, rpte, psize, ssize, 0);
 103                 return;
 104         }
 105
 106         /*
 107          * This can happen when we are in the middle of a TLB batch and
 108          * we encounter memory pressure (eg copy_page_range when it tries
 109          * to allocate a new pte). If we have to reclaim memory and end
 110          * up scanning and resetting referenced bits then our batch context
 111          * will change mid stream.
 112          *
 113          * We also need to ensure only one page size is present in a given
 114          * batch
 115          */
 116         if (i != 0 && (mm != batch->mm || batch->psize != psize ||
 117                        batch->ssize != ssize)) {
 118                 __flush_tlb_pending(batch);
 119                 i = 0;
 120         }
 121         if (i == 0) {
 122                 batch->mm = mm;
 123                 batch->psize = psize;
 124                 batch->ssize = ssize;
 125         }
 126         batch->pte[i] = rpte;
 127         batch->vaddr[i] = vaddr;
 128         batch->index = ++i;
 129         if (i >= PPC64_TLB_BATCH_NR)
 130                 __flush_tlb_pending(batch);
 131 }
 132
 133 /*
 134  * This function is called when terminating an mmu batch or when a batch
 135  * is full. It will perform the flush of all the entries currently stored
 136  * in a batch.
 137  *
 138  * Must be called from within some kind of spinlock/non-preempt region...
 139  */
 140 void __flush_tlb_pending(struct ppc64_tlb_batch *batch)
 141 {
 142         const struct cpumask *tmp;
 143         int i, local = 0;
 144
 145         i = batch->index;
 146         tmp = cpumask_of(smp_processor_id());
 147         if (cpumask_equal(mm_cpumask(batch->mm), tmp))
 148                 local = 1;
 149         if (i == 1)
 150                 flush_hash_page(batch->vaddr[0], batch->pte[0],
 151                                 batch->psize, batch->ssize, local);
 152         else
 153                 flush_hash_range(i, local);
 154         batch->index = 0;
 155 }
 156
 157 /**
 158  * __flush_hash_table_range - Flush all HPTEs for a given address range
 159  *                            from the hash table (and the TLB). But keeps
 160  *                            the linux PTEs intact.
 161  *
 162  * @mm          : mm_struct of the target address space (generally init_mm)
 163  * @start       : starting address
 164  * @end         : ending address (not included in the flush)
 165  *
 166  * This function is mostly to be used by some IO hotplug code in order
 167  * to remove all hash entries from a given address range used to map IO
 168  * space on a removed PCI-PCI bidge without tearing down the full mapping
 169  * since 64K pages may overlap with other bridges when using 64K pages
 170  * with 4K HW pages on IO space.
 171  *
 172  * Because of that usage pattern, it's only available with CONFIG_HOTPLUG
 173  * and is implemented for small size rather than speed.
 174  */
 175 #ifdef CONFIG_HOTPLUG
 176
 177 void __flush_hash_table_range(struct mm_struct *mm, unsigned long start,
 178                               unsigned long end)
 179 {
 180         unsigned long flags;
 181
 182         start = _ALIGN_DOWN(start, PAGE_SIZE);
 183         end = _ALIGN_UP(end, PAGE_SIZE);
 184
 185         BUG_ON(!mm->pgd);
 186
 187         /* Note: Normally, we should only ever use a batch within a
 188          * PTE locked section. This violates the rule, but will work
 189          * since we don't actually modify the PTEs, we just flush the
 190          * hash while leaving the PTEs intact (including their reference
 191          * to being hashed). This is not the most performance oriented
 192          * way to do things but is fine for our needs here.
 193          */
 194         local_irq_save(flags);
 195         arch_enter_lazy_mmu_mode();
 196         for (; start < end; start += PAGE_SIZE) {
 197                 pte_t *ptep = find_linux_pte(mm->pgd, start);
 198                 unsigned long pte;
 199
 200                 if (ptep == NULL)
 201                         continue;
 202                 pte = pte_val(*ptep);
 203                 if (!(pte & _PAGE_HASHPTE))
 204                         continue;
 205                 hpte_need_flush(mm, start, ptep, pte, 0);
 206         }
 207         arch_leave_lazy_mmu_mode();
 208         local_irq_restore(flags);
 209 }
 210
 211 #endif /* CONFIG_HOTPLUG */