arch/sparc64/mm/tsb.c

   1 /* arch/sparc64/mm/tsb.c
   2  *
   3  * Copyright (C) 2006 David S. Miller <davem@davemloft.net>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <asm/system.h>
   8 #include <asm/page.h>
   9 #include <asm/tlbflush.h>
  10 #include <asm/tlb.h>
  11 #include <asm/mmu_context.h>
  12 #include <asm/pgtable.h>
  13 #include <asm/tsb.h>
  14 #include <asm/oplib.h>
  15
  16 extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];
  17
  18 static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_shift, unsigned long nentries)
  19 {
  20         vaddr >>= hash_shift;
  21         return vaddr & (nentries - 1);
  22 }
  23
  24 static inline int tag_compare(unsigned long tag, unsigned long vaddr)
  25 {
  26         return (tag == (vaddr >> 22));
  27 }
  28
  29 /* TSB flushes need only occur on the processor initiating the address
  30  * space modification, not on each cpu the address space has run on.
  31  * Only the TLB flush needs that treatment.
  32  */
  33
  34 void flush_tsb_kernel_range(unsigned long start, unsigned long end)
  35 {
  36         unsigned long v;
  37
  38         for (v = start; v < end; v += PAGE_SIZE) {
  39                 unsigned long hash = tsb_hash(v, PAGE_SHIFT,
  40                                               KERNEL_TSB_NENTRIES);
  41                 struct tsb *ent = &swapper_tsb[hash];
  42
  43                 if (tag_compare(ent->tag, v)) {
  44                         ent->tag = (1UL << TSB_TAG_INVALID_BIT);
  45                         membar_storeload_storestore();
  46                 }
  47         }
  48 }
  49
  50 static void __flush_tsb_one(struct mmu_gather *mp, unsigned long hash_shift, unsigned long tsb, unsigned long nentries)
  51 {
  52         unsigned long i;
  53
  54         for (i = 0; i < mp->tlb_nr; i++) {
  55                 unsigned long v = mp->vaddrs[i];
  56                 unsigned long tag, ent, hash;
  57
  58                 v &= ~0x1UL;
  59
  60                 hash = tsb_hash(v, hash_shift, nentries);
  61                 ent = tsb + (hash * sizeof(struct tsb));
  62                 tag = (v >> 22UL);
  63
  64                 tsb_flush(ent, tag);
  65         }
  66 }
  67
  68 void flush_tsb_user(struct mmu_gather *mp)
  69 {
  70         struct mm_struct *mm = mp->mm;
  71         unsigned long nentries, base, flags;
  72
  73         spin_lock_irqsave(&mm->context.lock, flags);
  74
  75         base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
  76         nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
  77         if (tlb_type == cheetah_plus || tlb_type == hypervisor)
  78                 base = __pa(base);
  79         __flush_tsb_one(mp, PAGE_SHIFT, base, nentries);
  80
  81 #ifdef CONFIG_HUGETLB_PAGE
  82         if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
  83                 base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
  84                 nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
  85                 if (tlb_type == cheetah_plus || tlb_type == hypervisor)
  86                         base = __pa(base);
  87                 __flush_tsb_one(mp, HPAGE_SHIFT, base, nentries);
  88         }
  89 #endif
  90         spin_unlock_irqrestore(&mm->context.lock, flags);
  91 }
  92
  93 #if defined(CONFIG_SPARC64_PAGE_SIZE_8KB)
  94 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_8K
  95 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_8K
  96 #elif defined(CONFIG_SPARC64_PAGE_SIZE_64KB)
  97 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_64K
  98 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_64K
  99 #elif defined(CONFIG_SPARC64_PAGE_SIZE_512KB)
 100 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_512K
 101 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_512K
 102 #elif defined(CONFIG_SPARC64_PAGE_SIZE_4MB)
 103 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_4MB
 104 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_4MB
 105 #else
 106 #error Broken base page size setting...
 107 #endif
 108
 109 #ifdef CONFIG_HUGETLB_PAGE
 110 #if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
 111 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_64K
 112 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_64K
 113 #elif defined(CONFIG_HUGETLB_PAGE_SIZE_512K)
 114 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_512K
 115 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_512K
 116 #elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
 117 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_4MB
 118 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_4MB
 119 #else
 120 #error Broken huge page size setting...
 121 #endif
 122 #endif
 123
 124 static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
 125 {
 126         unsigned long tsb_reg, base, tsb_paddr;
 127         unsigned long page_sz, tte;
 128
 129         mm->context.tsb_block[tsb_idx].tsb_nentries =
 130                 tsb_bytes / sizeof(struct tsb);
 131
 132         base = TSBMAP_BASE;
 133         tte = pgprot_val(PAGE_KERNEL_LOCKED);
 134         tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
 135         BUG_ON(tsb_paddr & (tsb_bytes - 1UL));
 136
 137         /* Use the smallest page size that can map the whole TSB
 138          * in one TLB entry.
 139          */
 140         switch (tsb_bytes) {
 141         case 8192 << 0:
 142                 tsb_reg = 0x0UL;
 143 #ifdef DCACHE_ALIASING_POSSIBLE
 144                 base += (tsb_paddr & 8192);
 145 #endif
 146                 page_sz = 8192;
 147                 break;
 148
 149         case 8192 << 1:
 150                 tsb_reg = 0x1UL;
 151                 page_sz = 64 * 1024;
 152                 break;
 153
 154         case 8192 << 2:
 155                 tsb_reg = 0x2UL;
 156                 page_sz = 64 * 1024;
 157                 break;
 158
 159         case 8192 << 3:
 160                 tsb_reg = 0x3UL;
 161                 page_sz = 64 * 1024;
 162                 break;
 163
 164         case 8192 << 4:
 165                 tsb_reg = 0x4UL;
 166                 page_sz = 512 * 1024;
 167                 break;
 168
 169         case 8192 << 5:
 170                 tsb_reg = 0x5UL;
 171                 page_sz = 512 * 1024;
 172                 break;
 173
 174         case 8192 << 6:
 175                 tsb_reg = 0x6UL;
 176                 page_sz = 512 * 1024;
 177                 break;
 178
 179         case 8192 << 7:
 180                 tsb_reg = 0x7UL;
 181                 page_sz = 4 * 1024 * 1024;
 182                 break;
 183
 184         default:
 185                 BUG();
 186         };
 187         tte |= pte_sz_bits(page_sz);
 188
 189         if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 190                 /* Physical mapping, no locked TLB entry for TSB.  */
 191                 tsb_reg |= tsb_paddr;
 192
 193                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 194                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
 195                 mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
 196         } else {
 197                 tsb_reg |= base;
 198                 tsb_reg |= (tsb_paddr & (page_sz - 1UL));
 199                 tte |= (tsb_paddr & ~(page_sz - 1UL));
 200
 201                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 202                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
 203                 mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
 204         }
 205
 206         /* Setup the Hypervisor TSB descriptor.  */
 207         if (tlb_type == hypervisor) {
 208                 struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];
 209
 210                 switch (tsb_idx) {
 211                 case MM_TSB_BASE:
 212                         hp->pgsz_idx = HV_PGSZ_IDX_BASE;
 213                         break;
 214 #ifdef CONFIG_HUGETLB_PAGE
 215                 case MM_TSB_HUGE:
 216                         hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
 217                         break;
 218 #endif
 219                 default:
 220                         BUG();
 221                 };
 222                 hp->assoc = 1;
 223                 hp->num_ttes = tsb_bytes / 16;
 224                 hp->ctx_idx = 0;
 225                 switch (tsb_idx) {
 226                 case MM_TSB_BASE:
 227                         hp->pgsz_mask = HV_PGSZ_MASK_BASE;
 228                         break;
 229 #ifdef CONFIG_HUGETLB_PAGE
 230                 case MM_TSB_HUGE:
 231                         hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
 232                         break;
 233 #endif
 234                 default:
 235                         BUG();
 236                 };
 237                 hp->tsb_base = tsb_paddr;
 238                 hp->resv = 0;
 239         }
 240 }
 241
 242 static kmem_cache_t *tsb_caches[8] __read_mostly;
 243
 244 static const char *tsb_cache_names[8] = {
 245         "tsb_8KB",
 246         "tsb_16KB",
 247         "tsb_32KB",
 248         "tsb_64KB",
 249         "tsb_128KB",
 250         "tsb_256KB",
 251         "tsb_512KB",
 252         "tsb_1MB",
 253 };
 254
 255 void __init tsb_cache_init(void)
 256 {
 257         unsigned long i;
 258
 259         for (i = 0; i < 8; i++) {
 260                 unsigned long size = 8192 << i;
 261                 const char *name = tsb_cache_names[i];
 262
 263                 tsb_caches[i] = kmem_cache_create(name,
 264                                                   size, size,
 265                                                   SLAB_HWCACHE_ALIGN |
 266                                                   SLAB_MUST_HWCACHE_ALIGN,
 267                                                   NULL, NULL);
 268                 if (!tsb_caches[i]) {
 269                         prom_printf("Could not create %s cache\n", name);
 270                         prom_halt();
 271                 }
 272         }
 273 }
 274
 275 /* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
 276  * do_sparc64_fault() invokes this routine to try and grow it.
 277  *
 278  * When we reach the maximum TSB size supported, we stick ~0UL into
 279  * tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
 280  * will not trigger any longer.
 281  *
 282  * The TSB can be anywhere from 8K to 1MB in size, in increasing powers
 283  * of two.  The TSB must be aligned to it's size, so f.e. a 512K TSB
 284  * must be 512K aligned.  It also must be physically contiguous, so we
 285  * cannot use vmalloc().
 286  *
 287  * The idea here is to grow the TSB when the RSS of the process approaches
 288  * the number of entries that the current TSB can hold at once.  Currently,
 289  * we trigger when the RSS hits 3/4 of the TSB capacity.
 290  */
 291 void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
 292 {
 293         unsigned long max_tsb_size = 1 * 1024 * 1024;
 294         unsigned long new_size, old_size, flags;
 295         struct tsb *old_tsb, *new_tsb;
 296         unsigned long new_cache_index, old_cache_index;
 297         unsigned long new_rss_limit;
 298         gfp_t gfp_flags;
 299
 300         if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
 301                 max_tsb_size = (PAGE_SIZE << MAX_ORDER);
 302
 303         new_cache_index = 0;
 304         for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
 305                 unsigned long n_entries = new_size / sizeof(struct tsb);
 306
 307                 n_entries = (n_entries * 3) / 4;
 308                 if (n_entries > rss)
 309                         break;
 310
 311                 new_cache_index++;
 312         }
 313
 314         if (new_size == max_tsb_size)
 315                 new_rss_limit = ~0UL;
 316         else
 317                 new_rss_limit = ((new_size / sizeof(struct tsb)) * 3) / 4;
 318
 319 retry_tsb_alloc:
 320         gfp_flags = GFP_KERNEL;
 321         if (new_size > (PAGE_SIZE * 2))
 322                 gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
 323
 324         new_tsb = kmem_cache_alloc(tsb_caches[new_cache_index], gfp_flags);
 325         if (unlikely(!new_tsb)) {
 326                 /* Not being able to fork due to a high-order TSB
 327                  * allocation failure is very bad behavior.  Just back
 328                  * down to a 0-order allocation and force no TSB
 329                  * growing for this address space.
 330                  */
 331                 if (mm->context.tsb_block[tsb_index].tsb == NULL &&
 332                     new_cache_index > 0) {
 333                         new_cache_index = 0;
 334                         new_size = 8192;
 335                         new_rss_limit = ~0UL;
 336                         goto retry_tsb_alloc;
 337                 }
 338
 339                 /* If we failed on a TSB grow, we are under serious
 340                  * memory pressure so don't try to grow any more.
 341                  */
 342                 if (mm->context.tsb_block[tsb_index].tsb != NULL)
 343                         mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
 344                 return;
 345         }
 346
 347         /* Mark all tags as invalid.  */
 348         tsb_init(new_tsb, new_size);
 349
 350         /* Ok, we are about to commit the changes.  If we are
 351          * growing an existing TSB the locking is very tricky,
 352          * so WATCH OUT!
 353          *
 354          * We have to hold mm->context.lock while committing to the
 355          * new TSB, this synchronizes us with processors in
 356          * flush_tsb_user() and switch_mm() for this address space.
 357          *
 358          * But even with that lock held, processors run asynchronously
 359          * accessing the old TSB via TLB miss handling.  This is OK
 360          * because those actions are just propagating state from the
 361          * Linux page tables into the TSB, page table mappings are not
 362          * being changed.  If a real fault occurs, the processor will
 363          * synchronize with us when it hits flush_tsb_user(), this is
 364          * also true for the case where vmscan is modifying the page
 365          * tables.  The only thing we need to be careful with is to
 366          * skip any locked TSB entries during copy_tsb().
 367          *
 368          * When we finish committing to the new TSB, we have to drop
 369          * the lock and ask all other cpus running this address space
 370          * to run tsb_context_switch() to see the new TSB table.
 371          */
 372         spin_lock_irqsave(&mm->context.lock, flags);
 373
 374         old_tsb = mm->context.tsb_block[tsb_index].tsb;
 375         old_cache_index =
 376                 (mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
 377         old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
 378                     sizeof(struct tsb));
 379
 380
 381         /* Handle multiple threads trying to grow the TSB at the same time.
 382          * One will get in here first, and bump the size and the RSS limit.
 383          * The others will get in here next and hit this check.
 384          */
 385         if (unlikely(old_tsb &&
 386                      (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
 387                 spin_unlock_irqrestore(&mm->context.lock, flags);
 388
 389                 kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
 390                 return;
 391         }
 392
 393         mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;
 394
 395         if (old_tsb) {
 396                 extern void copy_tsb(unsigned long old_tsb_base,
 397                                      unsigned long old_tsb_size,
 398                                      unsigned long new_tsb_base,
 399                                      unsigned long new_tsb_size);
 400                 unsigned long old_tsb_base = (unsigned long) old_tsb;
 401                 unsigned long new_tsb_base = (unsigned long) new_tsb;
 402
 403                 if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 404                         old_tsb_base = __pa(old_tsb_base);
 405                         new_tsb_base = __pa(new_tsb_base);
 406                 }
 407                 copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
 408         }
 409
 410         mm->context.tsb_block[tsb_index].tsb = new_tsb;
 411         setup_tsb_params(mm, tsb_index, new_size);
 412
 413         spin_unlock_irqrestore(&mm->context.lock, flags);
 414
 415         /* If old_tsb is NULL, we're being invoked for the first time
 416          * from init_new_context().
 417          */
 418         if (old_tsb) {
 419                 /* Reload it on the local cpu.  */
 420                 tsb_context_switch(mm);
 421
 422                 /* Now force other processors to do the same.  */
 423                 smp_tsb_sync(mm);
 424
 425                 /* Now it is safe to free the old tsb.  */
 426                 kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
 427         }
 428 }
 429
 430 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 431 {
 432 #ifdef CONFIG_HUGETLB_PAGE
 433         unsigned long huge_pte_count;
 434 #endif
 435         unsigned int i;
 436
 437         spin_lock_init(&mm->context.lock);
 438
 439         mm->context.sparc64_ctx_val = 0UL;
 440
 441 #ifdef CONFIG_HUGETLB_PAGE
 442         /* We reset it to zero because the fork() page copying
 443          * will re-increment the counters as the parent PTEs are
 444          * copied into the child address space.
 445          */
 446         huge_pte_count = mm->context.huge_pte_count;
 447         mm->context.huge_pte_count = 0;
 448 #endif
 449
 450         /* copy_mm() copies over the parent's mm_struct before calling
 451          * us, so we need to zero out the TSB pointer or else tsb_grow()
 452          * will be confused and think there is an older TSB to free up.
 453          */
 454         for (i = 0; i < MM_NUM_TSBS; i++)
 455                 mm->context.tsb_block[i].tsb = NULL;
 456
 457         /* If this is fork, inherit the parent's TSB size.  We would
 458          * grow it to that size on the first page fault anyways.
 459          */
 460         tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));
 461
 462 #ifdef CONFIG_HUGETLB_PAGE
 463         if (unlikely(huge_pte_count))
 464                 tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
 465 #endif
 466
 467         if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
 468                 return -ENOMEM;
 469
 470         return 0;
 471 }
 472
 473 static void tsb_destroy_one(struct tsb_config *tp)
 474 {
 475         unsigned long cache_index;
 476
 477         if (!tp->tsb)
 478                 return;
 479         cache_index = tp->tsb_reg_val & 0x7UL;
 480         kmem_cache_free(tsb_caches[cache_index], tp->tsb);
 481         tp->tsb = NULL;
 482         tp->tsb_reg_val = 0UL;
 483 }
 484
 485 void destroy_context(struct mm_struct *mm)
 486 {
 487         unsigned long flags, i;
 488
 489         for (i = 0; i < MM_NUM_TSBS; i++)
 490                 tsb_destroy_one(&mm->context.tsb_block[i]);
 491
 492         spin_lock_irqsave(&ctx_alloc_lock, flags);
 493
 494         if (CTX_VALID(mm->context)) {
 495                 unsigned long nr = CTX_NRBITS(mm->context);
 496                 mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
 497         }
 498
 499         spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 500 }