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 #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(tb, 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 #else
 100 #error Broken base page size setting...
 101 #endif
 102
 103 #ifdef CONFIG_HUGETLB_PAGE
 104 #if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
 105 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_64K
 106 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_64K
 107 #elif defined(CONFIG_HUGETLB_PAGE_SIZE_512K)
 108 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_512K
 109 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_512K
 110 #elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
 111 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_4MB
 112 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_4MB
 113 #else
 114 #error Broken huge page size setting...
 115 #endif
 116 #endif
 117
 118 static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
 119 {
 120         unsigned long tsb_reg, base, tsb_paddr;
 121         unsigned long page_sz, tte;
 122
 123         mm->context.tsb_block[tsb_idx].tsb_nentries =
 124                 tsb_bytes / sizeof(struct tsb);
 125
 126         base = TSBMAP_BASE;
 127         tte = pgprot_val(PAGE_KERNEL_LOCKED);
 128         tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
 129         BUG_ON(tsb_paddr & (tsb_bytes - 1UL));
 130
 131         /* Use the smallest page size that can map the whole TSB
 132          * in one TLB entry.
 133          */
 134         switch (tsb_bytes) {
 135         case 8192 << 0:
 136                 tsb_reg = 0x0UL;
 137 #ifdef DCACHE_ALIASING_POSSIBLE
 138                 base += (tsb_paddr & 8192);
 139 #endif
 140                 page_sz = 8192;
 141                 break;
 142
 143         case 8192 << 1:
 144                 tsb_reg = 0x1UL;
 145                 page_sz = 64 * 1024;
 146                 break;
 147
 148         case 8192 << 2:
 149                 tsb_reg = 0x2UL;
 150                 page_sz = 64 * 1024;
 151                 break;
 152
 153         case 8192 << 3:
 154                 tsb_reg = 0x3UL;
 155                 page_sz = 64 * 1024;
 156                 break;
 157
 158         case 8192 << 4:
 159                 tsb_reg = 0x4UL;
 160                 page_sz = 512 * 1024;
 161                 break;
 162
 163         case 8192 << 5:
 164                 tsb_reg = 0x5UL;
 165                 page_sz = 512 * 1024;
 166                 break;
 167
 168         case 8192 << 6:
 169                 tsb_reg = 0x6UL;
 170                 page_sz = 512 * 1024;
 171                 break;
 172
 173         case 8192 << 7:
 174                 tsb_reg = 0x7UL;
 175                 page_sz = 4 * 1024 * 1024;
 176                 break;
 177
 178         default:
 179                 printk(KERN_ERR "TSB[%s:%d]: Impossible TSB size %lu, killing process.\n",
 180                        current->comm, current->pid, tsb_bytes);
 181                 do_exit(SIGSEGV);
 182         }
 183         tte |= pte_sz_bits(page_sz);
 184
 185         if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 186                 /* Physical mapping, no locked TLB entry for TSB.  */
 187                 tsb_reg |= tsb_paddr;
 188
 189                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 190                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
 191                 mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
 192         } else {
 193                 tsb_reg |= base;
 194                 tsb_reg |= (tsb_paddr & (page_sz - 1UL));
 195                 tte |= (tsb_paddr & ~(page_sz - 1UL));
 196
 197                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 198                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
 199                 mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
 200         }
 201
 202         /* Setup the Hypervisor TSB descriptor.  */
 203         if (tlb_type == hypervisor) {
 204                 struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];
 205
 206                 switch (tsb_idx) {
 207                 case MM_TSB_BASE:
 208                         hp->pgsz_idx = HV_PGSZ_IDX_BASE;
 209                         break;
 210 #ifdef CONFIG_HUGETLB_PAGE
 211                 case MM_TSB_HUGE:
 212                         hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
 213                         break;
 214 #endif
 215                 default:
 216                         BUG();
 217                 }
 218                 hp->assoc = 1;
 219                 hp->num_ttes = tsb_bytes / 16;
 220                 hp->ctx_idx = 0;
 221                 switch (tsb_idx) {
 222                 case MM_TSB_BASE:
 223                         hp->pgsz_mask = HV_PGSZ_MASK_BASE;
 224                         break;
 225 #ifdef CONFIG_HUGETLB_PAGE
 226                 case MM_TSB_HUGE:
 227                         hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
 228                         break;
 229 #endif
 230                 default:
 231                         BUG();
 232                 }
 233                 hp->tsb_base = tsb_paddr;
 234                 hp->resv = 0;
 235         }
 236 }
 237
 238 struct kmem_cache *pgtable_cache __read_mostly;
 239
 240 static struct kmem_cache *tsb_caches[8] __read_mostly;
 241
 242 static const char *tsb_cache_names[8] = {
 243         "tsb_8KB",
 244         "tsb_16KB",
 245         "tsb_32KB",
 246         "tsb_64KB",
 247         "tsb_128KB",
 248         "tsb_256KB",
 249         "tsb_512KB",
 250         "tsb_1MB",
 251 };
 252
 253 void __init pgtable_cache_init(void)
 254 {
 255         unsigned long i;
 256
 257         pgtable_cache = kmem_cache_create("pgtable_cache",
 258                                           PAGE_SIZE, PAGE_SIZE,
 259                                           0,
 260                                           _clear_page);
 261         if (!pgtable_cache) {
 262                 prom_printf("pgtable_cache_init(): Could not create!\n");
 263                 prom_halt();
 264         }
 265
 266         for (i = 0; i < 8; i++) {
 267                 unsigned long size = 8192 << i;
 268                 const char *name = tsb_cache_names[i];
 269
 270                 tsb_caches[i] = kmem_cache_create(name,
 271                                                   size, size,
 272                                                   0, NULL);
 273                 if (!tsb_caches[i]) {
 274                         prom_printf("Could not create %s cache\n", name);
 275                         prom_halt();
 276                 }
 277         }
 278 }
 279
 280 int sysctl_tsb_ratio = -2;
 281
 282 static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
 283 {
 284         unsigned long num_ents = (new_size / sizeof(struct tsb));
 285
 286         if (sysctl_tsb_ratio < 0)
 287                 return num_ents - (num_ents >> -sysctl_tsb_ratio);
 288         else
 289                 return num_ents + (num_ents >> sysctl_tsb_ratio);
 290 }
 291
 292 /* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
 293  * do_sparc64_fault() invokes this routine to try and grow it.
 294  *
 295  * When we reach the maximum TSB size supported, we stick ~0UL into
 296  * tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
 297  * will not trigger any longer.
 298  *
 299  * The TSB can be anywhere from 8K to 1MB in size, in increasing powers
 300  * of two.  The TSB must be aligned to it's size, so f.e. a 512K TSB
 301  * must be 512K aligned.  It also must be physically contiguous, so we
 302  * cannot use vmalloc().
 303  *
 304  * The idea here is to grow the TSB when the RSS of the process approaches
 305  * the number of entries that the current TSB can hold at once.  Currently,
 306  * we trigger when the RSS hits 3/4 of the TSB capacity.
 307  */
 308 void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
 309 {
 310         unsigned long max_tsb_size = 1 * 1024 * 1024;
 311         unsigned long new_size, old_size, flags;
 312         struct tsb *old_tsb, *new_tsb;
 313         unsigned long new_cache_index, old_cache_index;
 314         unsigned long new_rss_limit;
 315         gfp_t gfp_flags;
 316
 317         if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
 318                 max_tsb_size = (PAGE_SIZE << MAX_ORDER);
 319
 320         new_cache_index = 0;
 321         for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
 322                 new_rss_limit = tsb_size_to_rss_limit(new_size);
 323                 if (new_rss_limit > rss)
 324                         break;
 325                 new_cache_index++;
 326         }
 327
 328         if (new_size == max_tsb_size)
 329                 new_rss_limit = ~0UL;
 330
 331 retry_tsb_alloc:
 332         gfp_flags = GFP_KERNEL;
 333         if (new_size > (PAGE_SIZE * 2))
 334                 gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
 335
 336         new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
 337                                         gfp_flags, numa_node_id());
 338         if (unlikely(!new_tsb)) {
 339                 /* Not being able to fork due to a high-order TSB
 340                  * allocation failure is very bad behavior.  Just back
 341                  * down to a 0-order allocation and force no TSB
 342                  * growing for this address space.
 343                  */
 344                 if (mm->context.tsb_block[tsb_index].tsb == NULL &&
 345                     new_cache_index > 0) {
 346                         new_cache_index = 0;
 347                         new_size = 8192;
 348                         new_rss_limit = ~0UL;
 349                         goto retry_tsb_alloc;
 350                 }
 351
 352                 /* If we failed on a TSB grow, we are under serious
 353                  * memory pressure so don't try to grow any more.
 354                  */
 355                 if (mm->context.tsb_block[tsb_index].tsb != NULL)
 356                         mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
 357                 return;
 358         }
 359
 360         /* Mark all tags as invalid.  */
 361         tsb_init(new_tsb, new_size);
 362
 363         /* Ok, we are about to commit the changes.  If we are
 364          * growing an existing TSB the locking is very tricky,
 365          * so WATCH OUT!
 366          *
 367          * We have to hold mm->context.lock while committing to the
 368          * new TSB, this synchronizes us with processors in
 369          * flush_tsb_user() and switch_mm() for this address space.
 370          *
 371          * But even with that lock held, processors run asynchronously
 372          * accessing the old TSB via TLB miss handling.  This is OK
 373          * because those actions are just propagating state from the
 374          * Linux page tables into the TSB, page table mappings are not
 375          * being changed.  If a real fault occurs, the processor will
 376          * synchronize with us when it hits flush_tsb_user(), this is
 377          * also true for the case where vmscan is modifying the page
 378          * tables.  The only thing we need to be careful with is to
 379          * skip any locked TSB entries during copy_tsb().
 380          *
 381          * When we finish committing to the new TSB, we have to drop
 382          * the lock and ask all other cpus running this address space
 383          * to run tsb_context_switch() to see the new TSB table.
 384          */
 385         spin_lock_irqsave(&mm->context.lock, flags);
 386
 387         old_tsb = mm->context.tsb_block[tsb_index].tsb;
 388         old_cache_index =
 389                 (mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
 390         old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
 391                     sizeof(struct tsb));
 392
 393
 394         /* Handle multiple threads trying to grow the TSB at the same time.
 395          * One will get in here first, and bump the size and the RSS limit.
 396          * The others will get in here next and hit this check.
 397          */
 398         if (unlikely(old_tsb &&
 399                      (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
 400                 spin_unlock_irqrestore(&mm->context.lock, flags);
 401
 402                 kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
 403                 return;
 404         }
 405
 406         mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;
 407
 408         if (old_tsb) {
 409                 extern void copy_tsb(unsigned long old_tsb_base,
 410                                      unsigned long old_tsb_size,
 411                                      unsigned long new_tsb_base,
 412                                      unsigned long new_tsb_size);
 413                 unsigned long old_tsb_base = (unsigned long) old_tsb;
 414                 unsigned long new_tsb_base = (unsigned long) new_tsb;
 415
 416                 if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 417                         old_tsb_base = __pa(old_tsb_base);
 418                         new_tsb_base = __pa(new_tsb_base);
 419                 }
 420                 copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
 421         }
 422
 423         mm->context.tsb_block[tsb_index].tsb = new_tsb;
 424         setup_tsb_params(mm, tsb_index, new_size);
 425
 426         spin_unlock_irqrestore(&mm->context.lock, flags);
 427
 428         /* If old_tsb is NULL, we're being invoked for the first time
 429          * from init_new_context().
 430          */
 431         if (old_tsb) {
 432                 /* Reload it on the local cpu.  */
 433                 tsb_context_switch(mm);
 434
 435                 /* Now force other processors to do the same.  */
 436                 preempt_disable();
 437                 smp_tsb_sync(mm);
 438                 preempt_enable();
 439
 440                 /* Now it is safe to free the old tsb.  */
 441                 kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
 442         }
 443 }
 444
 445 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 446 {
 447 #ifdef CONFIG_HUGETLB_PAGE
 448         unsigned long huge_pte_count;
 449 #endif
 450         unsigned int i;
 451
 452         spin_lock_init(&mm->context.lock);
 453
 454         mm->context.sparc64_ctx_val = 0UL;
 455
 456 #ifdef CONFIG_HUGETLB_PAGE
 457         /* We reset it to zero because the fork() page copying
 458          * will re-increment the counters as the parent PTEs are
 459          * copied into the child address space.
 460          */
 461         huge_pte_count = mm->context.huge_pte_count;
 462         mm->context.huge_pte_count = 0;
 463 #endif
 464
 465         /* copy_mm() copies over the parent's mm_struct before calling
 466          * us, so we need to zero out the TSB pointer or else tsb_grow()
 467          * will be confused and think there is an older TSB to free up.
 468          */
 469         for (i = 0; i < MM_NUM_TSBS; i++)
 470                 mm->context.tsb_block[i].tsb = NULL;
 471
 472         /* If this is fork, inherit the parent's TSB size.  We would
 473          * grow it to that size on the first page fault anyways.
 474          */
 475         tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));
 476
 477 #ifdef CONFIG_HUGETLB_PAGE
 478         if (unlikely(huge_pte_count))
 479                 tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
 480 #endif
 481
 482         if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
 483                 return -ENOMEM;
 484
 485         return 0;
 486 }
 487
 488 static void tsb_destroy_one(struct tsb_config *tp)
 489 {
 490         unsigned long cache_index;
 491
 492         if (!tp->tsb)
 493                 return;
 494         cache_index = tp->tsb_reg_val & 0x7UL;
 495         kmem_cache_free(tsb_caches[cache_index], tp->tsb);
 496         tp->tsb = NULL;
 497         tp->tsb_reg_val = 0UL;
 498 }
 499
 500 void destroy_context(struct mm_struct *mm)
 501 {
 502         unsigned long flags, i;
 503
 504         for (i = 0; i < MM_NUM_TSBS; i++)
 505                 tsb_destroy_one(&mm->context.tsb_block[i]);
 506
 507         spin_lock_irqsave(&ctx_alloc_lock, flags);
 508
 509         if (CTX_VALID(mm->context)) {
 510                 unsigned long nr = CTX_NRBITS(mm->context);
 511                 mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
 512         }
 513
 514         spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 515 }