arch/powerpc/mm/mmu_context_book3s64.c

   1 /*
   2  *  MMU context allocation for 64-bit kernels.
   3  *
   4  *  Copyright (C) 2004 Anton Blanchard, IBM Corp. <anton@samba.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/errno.h>
  16 #include <linux/string.h>
  17 #include <linux/types.h>
  18 #include <linux/mm.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/idr.h>
  21 #include <linux/export.h>
  22 #include <linux/gfp.h>
  23 #include <linux/slab.h>
  24
  25 #include <asm/mmu_context.h>
  26 #include <asm/pgalloc.h>
  27
  28 #include "icswx.h"
  29
  30 static DEFINE_SPINLOCK(mmu_context_lock);
  31 static DEFINE_IDA(mmu_context_ida);
  32
  33 int __init_new_context(void)
  34 {
  35         int index;
  36         int err;
  37
  38 again:
  39         if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
  40                 return -ENOMEM;
  41
  42         spin_lock(&mmu_context_lock);
  43         err = ida_get_new_above(&mmu_context_ida, 1, &index);
  44         spin_unlock(&mmu_context_lock);
  45
  46         if (err == -EAGAIN)
  47                 goto again;
  48         else if (err)
  49                 return err;
  50
  51         if (index > MAX_USER_CONTEXT) {
  52                 spin_lock(&mmu_context_lock);
  53                 ida_remove(&mmu_context_ida, index);
  54                 spin_unlock(&mmu_context_lock);
  55                 return -ENOMEM;
  56         }
  57
  58         return index;
  59 }
  60 EXPORT_SYMBOL_GPL(__init_new_context);
  61 static int radix__init_new_context(struct mm_struct *mm, int index)
  62 {
  63         unsigned long rts_field;
  64
  65         /*
  66          * set the process table entry,
  67          */
  68         rts_field = radix__get_tree_size();
  69         process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
  70         return 0;
  71 }
  72
  73 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
  74 {
  75         int index;
  76
  77         index = __init_new_context();
  78         if (index < 0)
  79                 return index;
  80
  81         if (radix_enabled()) {
  82                 radix__init_new_context(mm, index);
  83         } else {
  84
  85                 /* The old code would re-promote on fork, we don't do that
  86                  * when using slices as it could cause problem promoting slices
  87                  * that have been forced down to 4K
  88                  *
  89                  * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
  90                  * explicitly against context.id == 0. This ensures that we
  91                  * properly initialize context slice details for newly allocated
  92                  * mm's (which will have id == 0) and don't alter context slice
  93                  * inherited via fork (which will have id != 0).
  94                  *
  95                  * We should not be calling init_new_context() on init_mm. Hence a
  96                  * check against 0 is ok.
  97                  */
  98                 if (mm->context.id == 0)
  99                         slice_set_user_psize(mm, mmu_virtual_psize);
 100                 subpage_prot_init_new_context(mm);
 101         }
 102         mm->context.id = index;
 103 #ifdef CONFIG_PPC_ICSWX
 104         mm->context.cop_lockp = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
 105         if (!mm->context.cop_lockp) {
 106                 __destroy_context(index);
 107                 subpage_prot_free(mm);
 108                 mm->context.id = MMU_NO_CONTEXT;
 109                 return -ENOMEM;
 110         }
 111         spin_lock_init(mm->context.cop_lockp);
 112 #endif /* CONFIG_PPC_ICSWX */
 113
 114 #ifdef CONFIG_PPC_64K_PAGES
 115         mm->context.pte_frag = NULL;
 116 #endif
 117 #ifdef CONFIG_SPAPR_TCE_IOMMU
 118         mm_iommu_init(mm);
 119 #endif
 120         return 0;
 121 }
 122
 123 void __destroy_context(int context_id)
 124 {
 125         spin_lock(&mmu_context_lock);
 126         ida_remove(&mmu_context_ida, context_id);
 127         spin_unlock(&mmu_context_lock);
 128 }
 129 EXPORT_SYMBOL_GPL(__destroy_context);
 130
 131 #ifdef CONFIG_PPC_64K_PAGES
 132 static void destroy_pagetable_page(struct mm_struct *mm)
 133 {
 134         int count;
 135         void *pte_frag;
 136         struct page *page;
 137
 138         pte_frag = mm->context.pte_frag;
 139         if (!pte_frag)
 140                 return;
 141
 142         page = virt_to_page(pte_frag);
 143         /* drop all the pending references */
 144         count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
 145         /* We allow PTE_FRAG_NR fragments from a PTE page */
 146         if (page_ref_sub_and_test(page, PTE_FRAG_NR - count)) {
 147                 pgtable_page_dtor(page);
 148                 free_hot_cold_page(page, 0);
 149         }
 150 }
 151
 152 #else
 153 static inline void destroy_pagetable_page(struct mm_struct *mm)
 154 {
 155         return;
 156 }
 157 #endif
 158
 159 void destroy_context(struct mm_struct *mm)
 160 {
 161 #ifdef CONFIG_SPAPR_TCE_IOMMU
 162         WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
 163 #endif
 164 #ifdef CONFIG_PPC_ICSWX
 165         drop_cop(mm->context.acop, mm);
 166         kfree(mm->context.cop_lockp);
 167         mm->context.cop_lockp = NULL;
 168 #endif /* CONFIG_PPC_ICSWX */
 169
 170         if (radix_enabled())
 171                 process_tb[mm->context.id].prtb1 = 0;
 172         else
 173                 subpage_prot_free(mm);
 174         destroy_pagetable_page(mm);
 175         __destroy_context(mm->context.id);
 176         mm->context.id = MMU_NO_CONTEXT;
 177 }
 178
 179 #ifdef CONFIG_PPC_RADIX_MMU
 180 void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
 181 {
 182         asm volatile("isync": : :"memory");
 183         mtspr(SPRN_PID, next->context.id);
 184         asm volatile("isync \n"
 185                      PPC_SLBIA(0x7)
 186                      : : :"memory");
 187 }
 188 #endif