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/pkeys.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/idr.h>
  22 #include <linux/export.h>
  23 #include <linux/gfp.h>
  24 #include <linux/slab.h>
  25
  26 #include <asm/mmu_context.h>
  27 #include <asm/pgalloc.h>
  28
  29 static DEFINE_IDA(mmu_context_ida);
  30
  31 static int alloc_context_id(int min_id, int max_id)
  32 {
  33         return ida_alloc_range(&mmu_context_ida, min_id, max_id, GFP_KERNEL);
  34 }
  35
  36 void hash__reserve_context_id(int id)
  37 {
  38         int result = ida_alloc_range(&mmu_context_ida, id, id, GFP_KERNEL);
  39
  40         WARN(result != id, "mmu: Failed to reserve context id %d (rc %d)\n", id, result);
  41 }
  42
  43 int hash__alloc_context_id(void)
  44 {
  45         unsigned long max;
  46
  47         if (mmu_has_feature(MMU_FTR_68_BIT_VA))
  48                 max = MAX_USER_CONTEXT;
  49         else
  50                 max = MAX_USER_CONTEXT_65BIT_VA;
  51
  52         return alloc_context_id(MIN_USER_CONTEXT, max);
  53 }
  54 EXPORT_SYMBOL_GPL(hash__alloc_context_id);
  55
  56 static int hash__init_new_context(struct mm_struct *mm)
  57 {
  58         int index;
  59
  60         index = hash__alloc_context_id();
  61         if (index < 0)
  62                 return index;
  63
  64         /*
  65          * The old code would re-promote on fork, we don't do that when using
  66          * slices as it could cause problem promoting slices that have been
  67          * forced down to 4K.
  68          *
  69          * For book3s we have MMU_NO_CONTEXT set to be ~0. Hence check
  70          * explicitly against context.id == 0. This ensures that we properly
  71          * initialize context slice details for newly allocated mm's (which will
  72          * have id == 0) and don't alter context slice inherited via fork (which
  73          * will have id != 0).
  74          *
  75          * We should not be calling init_new_context() on init_mm. Hence a
  76          * check against 0 is OK.
  77          */
  78         if (mm->context.id == 0)
  79                 slice_init_new_context_exec(mm);
  80
  81         subpage_prot_init_new_context(mm);
  82
  83         pkey_mm_init(mm);
  84         return index;
  85 }
  86
  87 static int radix__init_new_context(struct mm_struct *mm)
  88 {
  89         unsigned long rts_field;
  90         int index, max_id;
  91
  92         max_id = (1 << mmu_pid_bits) - 1;
  93         index = alloc_context_id(mmu_base_pid, max_id);
  94         if (index < 0)
  95                 return index;
  96
  97         /*
  98          * set the process table entry,
  99          */
 100         rts_field = radix__get_tree_size();
 101         process_tb[index].prtb0 = cpu_to_be64(rts_field | __pa(mm->pgd) | RADIX_PGD_INDEX_SIZE);
 102
 103         /*
 104          * Order the above store with subsequent update of the PID
 105          * register (at which point HW can start loading/caching
 106          * the entry) and the corresponding load by the MMU from
 107          * the L2 cache.
 108          */
 109         asm volatile("ptesync;isync" : : : "memory");
 110
 111         mm->context.npu_context = NULL;
 112
 113         return index;
 114 }
 115
 116 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 117 {
 118         int index;
 119
 120         if (radix_enabled())
 121                 index = radix__init_new_context(mm);
 122         else
 123                 index = hash__init_new_context(mm);
 124
 125         if (index < 0)
 126                 return index;
 127
 128         mm->context.id = index;
 129
 130         mm->context.pte_frag = NULL;
 131         mm->context.pmd_frag = NULL;
 132 #ifdef CONFIG_SPAPR_TCE_IOMMU
 133         mm_iommu_init(mm);
 134 #endif
 135         atomic_set(&mm->context.active_cpus, 0);
 136         atomic_set(&mm->context.copros, 0);
 137
 138         return 0;
 139 }
 140
 141 void __destroy_context(int context_id)
 142 {
 143         ida_free(&mmu_context_ida, context_id);
 144 }
 145 EXPORT_SYMBOL_GPL(__destroy_context);
 146
 147 static void destroy_contexts(mm_context_t *ctx)
 148 {
 149         int index, context_id;
 150
 151         for (index = 0; index < ARRAY_SIZE(ctx->extended_id); index++) {
 152                 context_id = ctx->extended_id[index];
 153                 if (context_id)
 154                         ida_free(&mmu_context_ida, context_id);
 155         }
 156 }
 157
 158 static void pte_frag_destroy(void *pte_frag)
 159 {
 160         int count;
 161         struct page *page;
 162
 163         page = virt_to_page(pte_frag);
 164         /* drop all the pending references */
 165         count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
 166         /* We allow PTE_FRAG_NR fragments from a PTE page */
 167         if (atomic_sub_and_test(PTE_FRAG_NR - count, &page->pt_frag_refcount)) {
 168                 pgtable_page_dtor(page);
 169                 __free_page(page);
 170         }
 171 }
 172
 173 static void pmd_frag_destroy(void *pmd_frag)
 174 {
 175         int count;
 176         struct page *page;
 177
 178         page = virt_to_page(pmd_frag);
 179         /* drop all the pending references */
 180         count = ((unsigned long)pmd_frag & ~PAGE_MASK) >> PMD_FRAG_SIZE_SHIFT;
 181         /* We allow PTE_FRAG_NR fragments from a PTE page */
 182         if (atomic_sub_and_test(PMD_FRAG_NR - count, &page->pt_frag_refcount)) {
 183                 pgtable_pmd_page_dtor(page);
 184                 __free_page(page);
 185         }
 186 }
 187
 188 static void destroy_pagetable_cache(struct mm_struct *mm)
 189 {
 190         void *frag;
 191
 192         frag = mm->context.pte_frag;
 193         if (frag)
 194                 pte_frag_destroy(frag);
 195
 196         frag = mm->context.pmd_frag;
 197         if (frag)
 198                 pmd_frag_destroy(frag);
 199         return;
 200 }
 201
 202 void destroy_context(struct mm_struct *mm)
 203 {
 204 #ifdef CONFIG_SPAPR_TCE_IOMMU
 205         WARN_ON_ONCE(!list_empty(&mm->context.iommu_group_mem_list));
 206 #endif
 207         if (radix_enabled())
 208                 WARN_ON(process_tb[mm->context.id].prtb0 != 0);
 209         else
 210                 subpage_prot_free(mm);
 211         destroy_contexts(&mm->context);
 212         mm->context.id = MMU_NO_CONTEXT;
 213 }
 214
 215 void arch_exit_mmap(struct mm_struct *mm)
 216 {
 217         destroy_pagetable_cache(mm);
 218
 219         if (radix_enabled()) {
 220                 /*
 221                  * Radix doesn't have a valid bit in the process table
 222                  * entries. However we know that at least P9 implementation
 223                  * will avoid caching an entry with an invalid RTS field,
 224                  * and 0 is invalid. So this will do.
 225                  *
 226                  * This runs before the "fullmm" tlb flush in exit_mmap,
 227                  * which does a RIC=2 tlbie to clear the process table
 228                  * entry. See the "fullmm" comments in tlb-radix.c.
 229                  *
 230                  * No barrier required here after the store because
 231                  * this process will do the invalidate, which starts with
 232                  * ptesync.
 233                  */
 234                 process_tb[mm->context.id].prtb0 = 0;
 235         }
 236 }
 237
 238 #ifdef CONFIG_PPC_RADIX_MMU
 239 void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
 240 {
 241         mtspr(SPRN_PID, next->context.id);
 242         isync();
 243 }
 244 #endif