arch/sparc/mm/tsb.c

   1 /* arch/sparc64/mm/tsb.c
   2  *
   3  * Copyright (C) 2006, 2008 David S. Miller <davem@davemloft.net>
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/preempt.h>
   8 #include <linux/slab.h>
   9 #include <asm/page.h>
  10 #include <asm/tlbflush.h>
  11 #include <asm/tlb.h>
  12 #include <asm/mmu_context.h>
  13 #include <asm/pgtable.h>
  14 #include <asm/tsb.h>
  15 #include <asm/oplib.h>
  16
  17 extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];
  18
  19 static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_shift, unsigned long nentries)
  20 {
  21         vaddr >>= hash_shift;
  22         return vaddr & (nentries - 1);
  23 }
  24
  25 static inline int tag_compare(unsigned long tag, unsigned long vaddr)
  26 {
  27         return (tag == (vaddr >> 22));
  28 }
  29
  30 /* TSB flushes need only occur on the processor initiating the address
  31  * space modification, not on each cpu the address space has run on.
  32  * Only the TLB flush needs that treatment.
  33  */
  34
  35 void flush_tsb_kernel_range(unsigned long start, unsigned long end)
  36 {
  37         unsigned long v;
  38
  39         for (v = start; v < end; v += PAGE_SIZE) {
  40                 unsigned long hash = tsb_hash(v, PAGE_SHIFT,
  41                                               KERNEL_TSB_NENTRIES);
  42                 struct tsb *ent = &swapper_tsb[hash];
  43
  44                 if (tag_compare(ent->tag, v))
  45                         ent->tag = (1UL << TSB_TAG_INVALID_BIT);
  46         }
  47 }
  48
  49 static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
  50                             unsigned long tsb, unsigned long nentries)
  51 {
  52         unsigned long i;
  53
  54         for (i = 0; i < tb->tlb_nr; i++) {
  55                 unsigned long v = tb->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 tlb_batch *tb)
  69 {
  70         struct mm_struct *mm = tb->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(tb, PAGE_SHIFT, base, nentries);
  80
  81 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
  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(tb, HPAGE_SHIFT, base, nentries);
  88         }
  89 #endif
  90         spin_unlock_irqrestore(&mm->context.lock, flags);
  91 }
  92
  93 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_8K
  94 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_8K
  95
  96 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
  97 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_4MB
  98 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_4MB
  99 #endif
 100
 101 static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
 102 {
 103         unsigned long tsb_reg, base, tsb_paddr;
 104         unsigned long page_sz, tte;
 105
 106         mm->context.tsb_block[tsb_idx].tsb_nentries =
 107                 tsb_bytes / sizeof(struct tsb);
 108
 109         base = TSBMAP_BASE;
 110         tte = pgprot_val(PAGE_KERNEL_LOCKED);
 111         tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
 112         BUG_ON(tsb_paddr & (tsb_bytes - 1UL));
 113
 114         /* Use the smallest page size that can map the whole TSB
 115          * in one TLB entry.
 116          */
 117         switch (tsb_bytes) {
 118         case 8192 << 0:
 119                 tsb_reg = 0x0UL;
 120 #ifdef DCACHE_ALIASING_POSSIBLE
 121                 base += (tsb_paddr & 8192);
 122 #endif
 123                 page_sz = 8192;
 124                 break;
 125
 126         case 8192 << 1:
 127                 tsb_reg = 0x1UL;
 128                 page_sz = 64 * 1024;
 129                 break;
 130
 131         case 8192 << 2:
 132                 tsb_reg = 0x2UL;
 133                 page_sz = 64 * 1024;
 134                 break;
 135
 136         case 8192 << 3:
 137                 tsb_reg = 0x3UL;
 138                 page_sz = 64 * 1024;
 139                 break;
 140
 141         case 8192 << 4:
 142                 tsb_reg = 0x4UL;
 143                 page_sz = 512 * 1024;
 144                 break;
 145
 146         case 8192 << 5:
 147                 tsb_reg = 0x5UL;
 148                 page_sz = 512 * 1024;
 149                 break;
 150
 151         case 8192 << 6:
 152                 tsb_reg = 0x6UL;
 153                 page_sz = 512 * 1024;
 154                 break;
 155
 156         case 8192 << 7:
 157                 tsb_reg = 0x7UL;
 158                 page_sz = 4 * 1024 * 1024;
 159                 break;
 160
 161         default:
 162                 printk(KERN_ERR "TSB[%s:%d]: Impossible TSB size %lu, killing process.\n",
 163                        current->comm, current->pid, tsb_bytes);
 164                 do_exit(SIGSEGV);
 165         }
 166         tte |= pte_sz_bits(page_sz);
 167
 168         if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 169                 /* Physical mapping, no locked TLB entry for TSB.  */
 170                 tsb_reg |= tsb_paddr;
 171
 172                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 173                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
 174                 mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
 175         } else {
 176                 tsb_reg |= base;
 177                 tsb_reg |= (tsb_paddr & (page_sz - 1UL));
 178                 tte |= (tsb_paddr & ~(page_sz - 1UL));
 179
 180                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 181                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
 182                 mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
 183         }
 184
 185         /* Setup the Hypervisor TSB descriptor.  */
 186         if (tlb_type == hypervisor) {
 187                 struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];
 188
 189                 switch (tsb_idx) {
 190                 case MM_TSB_BASE:
 191                         hp->pgsz_idx = HV_PGSZ_IDX_BASE;
 192                         break;
 193 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 194                 case MM_TSB_HUGE:
 195                         hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
 196                         break;
 197 #endif
 198                 default:
 199                         BUG();
 200                 }
 201                 hp->assoc = 1;
 202                 hp->num_ttes = tsb_bytes / 16;
 203                 hp->ctx_idx = 0;
 204                 switch (tsb_idx) {
 205                 case MM_TSB_BASE:
 206                         hp->pgsz_mask = HV_PGSZ_MASK_BASE;
 207                         break;
 208 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 209                 case MM_TSB_HUGE:
 210                         hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
 211                         break;
 212 #endif
 213                 default:
 214                         BUG();
 215                 }
 216                 hp->tsb_base = tsb_paddr;
 217                 hp->resv = 0;
 218         }
 219 }
 220
 221 struct kmem_cache *pgtable_cache __read_mostly;
 222
 223 static struct kmem_cache *tsb_caches[8] __read_mostly;
 224
 225 static const char *tsb_cache_names[8] = {
 226         "tsb_8KB",
 227         "tsb_16KB",
 228         "tsb_32KB",
 229         "tsb_64KB",
 230         "tsb_128KB",
 231         "tsb_256KB",
 232         "tsb_512KB",
 233         "tsb_1MB",
 234 };
 235
 236 void __init pgtable_cache_init(void)
 237 {
 238         unsigned long i;
 239
 240         pgtable_cache = kmem_cache_create("pgtable_cache",
 241                                           PAGE_SIZE, PAGE_SIZE,
 242                                           0,
 243                                           _clear_page);
 244         if (!pgtable_cache) {
 245                 prom_printf("pgtable_cache_init(): Could not create!\n");
 246                 prom_halt();
 247         }
 248
 249         for (i = 0; i < 8; i++) {
 250                 unsigned long size = 8192 << i;
 251                 const char *name = tsb_cache_names[i];
 252
 253                 tsb_caches[i] = kmem_cache_create(name,
 254                                                   size, size,
 255                                                   0, NULL);
 256                 if (!tsb_caches[i]) {
 257                         prom_printf("Could not create %s cache\n", name);
 258                         prom_halt();
 259                 }
 260         }
 261 }
 262
 263 int sysctl_tsb_ratio = -2;
 264
 265 static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
 266 {
 267         unsigned long num_ents = (new_size / sizeof(struct tsb));
 268
 269         if (sysctl_tsb_ratio < 0)
 270                 return num_ents - (num_ents >> -sysctl_tsb_ratio);
 271         else
 272                 return num_ents + (num_ents >> sysctl_tsb_ratio);
 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                 new_rss_limit = tsb_size_to_rss_limit(new_size);
 306                 if (new_rss_limit > rss)
 307                         break;
 308                 new_cache_index++;
 309         }
 310
 311         if (new_size == max_tsb_size)
 312                 new_rss_limit = ~0UL;
 313
 314 retry_tsb_alloc:
 315         gfp_flags = GFP_KERNEL;
 316         if (new_size > (PAGE_SIZE * 2))
 317                 gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
 318
 319         new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
 320                                         gfp_flags, numa_node_id());
 321         if (unlikely(!new_tsb)) {
 322                 /* Not being able to fork due to a high-order TSB
 323                  * allocation failure is very bad behavior.  Just back
 324                  * down to a 0-order allocation and force no TSB
 325                  * growing for this address space.
 326                  */
 327                 if (mm->context.tsb_block[tsb_index].tsb == NULL &&
 328                     new_cache_index > 0) {
 329                         new_cache_index = 0;
 330                         new_size = 8192;
 331                         new_rss_limit = ~0UL;
 332                         goto retry_tsb_alloc;
 333                 }
 334
 335                 /* If we failed on a TSB grow, we are under serious
 336                  * memory pressure so don't try to grow any more.
 337                  */
 338                 if (mm->context.tsb_block[tsb_index].tsb != NULL)
 339                         mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
 340                 return;
 341         }
 342
 343         /* Mark all tags as invalid.  */
 344         tsb_init(new_tsb, new_size);
 345
 346         /* Ok, we are about to commit the changes.  If we are
 347          * growing an existing TSB the locking is very tricky,
 348          * so WATCH OUT!
 349          *
 350          * We have to hold mm->context.lock while committing to the
 351          * new TSB, this synchronizes us with processors in
 352          * flush_tsb_user() and switch_mm() for this address space.
 353          *
 354          * But even with that lock held, processors run asynchronously
 355          * accessing the old TSB via TLB miss handling.  This is OK
 356          * because those actions are just propagating state from the
 357          * Linux page tables into the TSB, page table mappings are not
 358          * being changed.  If a real fault occurs, the processor will
 359          * synchronize with us when it hits flush_tsb_user(), this is
 360          * also true for the case where vmscan is modifying the page
 361          * tables.  The only thing we need to be careful with is to
 362          * skip any locked TSB entries during copy_tsb().
 363          *
 364          * When we finish committing to the new TSB, we have to drop
 365          * the lock and ask all other cpus running this address space
 366          * to run tsb_context_switch() to see the new TSB table.
 367          */
 368         spin_lock_irqsave(&mm->context.lock, flags);
 369
 370         old_tsb = mm->context.tsb_block[tsb_index].tsb;
 371         old_cache_index =
 372                 (mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
 373         old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
 374                     sizeof(struct tsb));
 375
 376
 377         /* Handle multiple threads trying to grow the TSB at the same time.
 378          * One will get in here first, and bump the size and the RSS limit.
 379          * The others will get in here next and hit this check.
 380          */
 381         if (unlikely(old_tsb &&
 382                      (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
 383                 spin_unlock_irqrestore(&mm->context.lock, flags);
 384
 385                 kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
 386                 return;
 387         }
 388
 389         mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;
 390
 391         if (old_tsb) {
 392                 extern void copy_tsb(unsigned long old_tsb_base,
 393                                      unsigned long old_tsb_size,
 394                                      unsigned long new_tsb_base,
 395                                      unsigned long new_tsb_size);
 396                 unsigned long old_tsb_base = (unsigned long) old_tsb;
 397                 unsigned long new_tsb_base = (unsigned long) new_tsb;
 398
 399                 if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 400                         old_tsb_base = __pa(old_tsb_base);
 401                         new_tsb_base = __pa(new_tsb_base);
 402                 }
 403                 copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
 404         }
 405
 406         mm->context.tsb_block[tsb_index].tsb = new_tsb;
 407         setup_tsb_params(mm, tsb_index, new_size);
 408
 409         spin_unlock_irqrestore(&mm->context.lock, flags);
 410
 411         /* If old_tsb is NULL, we're being invoked for the first time
 412          * from init_new_context().
 413          */
 414         if (old_tsb) {
 415                 /* Reload it on the local cpu.  */
 416                 tsb_context_switch(mm);
 417
 418                 /* Now force other processors to do the same.  */
 419                 preempt_disable();
 420                 smp_tsb_sync(mm);
 421                 preempt_enable();
 422
 423                 /* Now it is safe to free the old tsb.  */
 424                 kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
 425         }
 426 }
 427
 428 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 429 {
 430 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 431         unsigned long huge_pte_count;
 432 #endif
 433         unsigned int i;
 434
 435         spin_lock_init(&mm->context.lock);
 436
 437         mm->context.sparc64_ctx_val = 0UL;
 438
 439 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 440         /* We reset it to zero because the fork() page copying
 441          * will re-increment the counters as the parent PTEs are
 442          * copied into the child address space.
 443          */
 444         huge_pte_count = mm->context.huge_pte_count;
 445         mm->context.huge_pte_count = 0;
 446 #endif
 447
 448         mm->context.pgtable_page = NULL;
 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 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 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         struct page *page;
 489
 490         for (i = 0; i < MM_NUM_TSBS; i++)
 491                 tsb_destroy_one(&mm->context.tsb_block[i]);
 492
 493         page = mm->context.pgtable_page;
 494         if (page && put_page_testzero(page)) {
 495                 pgtable_page_dtor(page);
 496                 free_hot_cold_page(page, 0);
 497         }
 498
 499         spin_lock_irqsave(&ctx_alloc_lock, flags);
 500
 501         if (CTX_VALID(mm->context)) {
 502                 unsigned long nr = CTX_NRBITS(mm->context);
 503                 mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
 504         }
 505
 506         spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 507 }