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/system.h>
  10 #include <asm/page.h>
  11 #include <asm/tlbflush.h>
  12 #include <asm/tlb.h>
  13 #include <asm/mmu_context.h>
  14 #include <asm/pgtable.h>
  15 #include <asm/tsb.h>
  16 #include <asm/oplib.h>
  17
  18 extern struct tsb swapper_tsb[KERNEL_TSB_NENTRIES];
  19
  20 static inline unsigned long tsb_hash(unsigned long vaddr, unsigned long hash_shift, unsigned long nentries)
  21 {
  22         vaddr >>= hash_shift;
  23         return vaddr & (nentries - 1);
  24 }
  25
  26 static inline int tag_compare(unsigned long tag, unsigned long vaddr)
  27 {
  28         return (tag == (vaddr >> 22));
  29 }
  30
  31 /* TSB flushes need only occur on the processor initiating the address
  32  * space modification, not on each cpu the address space has run on.
  33  * Only the TLB flush needs that treatment.
  34  */
  35
  36 void flush_tsb_kernel_range(unsigned long start, unsigned long end)
  37 {
  38         unsigned long v;
  39
  40         for (v = start; v < end; v += PAGE_SIZE) {
  41                 unsigned long hash = tsb_hash(v, PAGE_SHIFT,
  42                                               KERNEL_TSB_NENTRIES);
  43                 struct tsb *ent = &swapper_tsb[hash];
  44
  45                 if (tag_compare(ent->tag, v))
  46                         ent->tag = (1UL << TSB_TAG_INVALID_BIT);
  47         }
  48 }
  49
  50 static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
  51                             unsigned long tsb, unsigned long nentries)
  52 {
  53         unsigned long i;
  54
  55         for (i = 0; i < tb->tlb_nr; i++) {
  56                 unsigned long v = tb->vaddrs[i];
  57                 unsigned long tag, ent, hash;
  58
  59                 v &= ~0x1UL;
  60
  61                 hash = tsb_hash(v, hash_shift, nentries);
  62                 ent = tsb + (hash * sizeof(struct tsb));
  63                 tag = (v >> 22UL);
  64
  65                 tsb_flush(ent, tag);
  66         }
  67 }
  68
  69 void flush_tsb_user(struct tlb_batch *tb)
  70 {
  71         struct mm_struct *mm = tb->mm;
  72         unsigned long nentries, base, flags;
  73
  74         spin_lock_irqsave(&mm->context.lock, flags);
  75
  76         base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
  77         nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
  78         if (tlb_type == cheetah_plus || tlb_type == hypervisor)
  79                 base = __pa(base);
  80         __flush_tsb_one(tb, PAGE_SHIFT, base, nentries);
  81
  82 #ifdef CONFIG_HUGETLB_PAGE
  83         if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
  84                 base = (unsigned long) mm->context.tsb_block[MM_TSB_HUGE].tsb;
  85                 nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
  86                 if (tlb_type == cheetah_plus || tlb_type == hypervisor)
  87                         base = __pa(base);
  88                 __flush_tsb_one(tb, HPAGE_SHIFT, base, nentries);
  89         }
  90 #endif
  91         spin_unlock_irqrestore(&mm->context.lock, flags);
  92 }
  93
  94 #if defined(CONFIG_SPARC64_PAGE_SIZE_8KB)
  95 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_8K
  96 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_8K
  97 #elif defined(CONFIG_SPARC64_PAGE_SIZE_64KB)
  98 #define HV_PGSZ_IDX_BASE        HV_PGSZ_IDX_64K
  99 #define HV_PGSZ_MASK_BASE       HV_PGSZ_MASK_64K
 100 #else
 101 #error Broken base page size setting...
 102 #endif
 103
 104 #ifdef CONFIG_HUGETLB_PAGE
 105 #if defined(CONFIG_HUGETLB_PAGE_SIZE_64K)
 106 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_64K
 107 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_64K
 108 #elif defined(CONFIG_HUGETLB_PAGE_SIZE_512K)
 109 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_512K
 110 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_512K
 111 #elif defined(CONFIG_HUGETLB_PAGE_SIZE_4MB)
 112 #define HV_PGSZ_IDX_HUGE        HV_PGSZ_IDX_4MB
 113 #define HV_PGSZ_MASK_HUGE       HV_PGSZ_MASK_4MB
 114 #else
 115 #error Broken huge page size setting...
 116 #endif
 117 #endif
 118
 119 static void setup_tsb_params(struct mm_struct *mm, unsigned long tsb_idx, unsigned long tsb_bytes)
 120 {
 121         unsigned long tsb_reg, base, tsb_paddr;
 122         unsigned long page_sz, tte;
 123
 124         mm->context.tsb_block[tsb_idx].tsb_nentries =
 125                 tsb_bytes / sizeof(struct tsb);
 126
 127         base = TSBMAP_BASE;
 128         tte = pgprot_val(PAGE_KERNEL_LOCKED);
 129         tsb_paddr = __pa(mm->context.tsb_block[tsb_idx].tsb);
 130         BUG_ON(tsb_paddr & (tsb_bytes - 1UL));
 131
 132         /* Use the smallest page size that can map the whole TSB
 133          * in one TLB entry.
 134          */
 135         switch (tsb_bytes) {
 136         case 8192 << 0:
 137                 tsb_reg = 0x0UL;
 138 #ifdef DCACHE_ALIASING_POSSIBLE
 139                 base += (tsb_paddr & 8192);
 140 #endif
 141                 page_sz = 8192;
 142                 break;
 143
 144         case 8192 << 1:
 145                 tsb_reg = 0x1UL;
 146                 page_sz = 64 * 1024;
 147                 break;
 148
 149         case 8192 << 2:
 150                 tsb_reg = 0x2UL;
 151                 page_sz = 64 * 1024;
 152                 break;
 153
 154         case 8192 << 3:
 155                 tsb_reg = 0x3UL;
 156                 page_sz = 64 * 1024;
 157                 break;
 158
 159         case 8192 << 4:
 160                 tsb_reg = 0x4UL;
 161                 page_sz = 512 * 1024;
 162                 break;
 163
 164         case 8192 << 5:
 165                 tsb_reg = 0x5UL;
 166                 page_sz = 512 * 1024;
 167                 break;
 168
 169         case 8192 << 6:
 170                 tsb_reg = 0x6UL;
 171                 page_sz = 512 * 1024;
 172                 break;
 173
 174         case 8192 << 7:
 175                 tsb_reg = 0x7UL;
 176                 page_sz = 4 * 1024 * 1024;
 177                 break;
 178
 179         default:
 180                 printk(KERN_ERR "TSB[%s:%d]: Impossible TSB size %lu, killing process.\n",
 181                        current->comm, current->pid, tsb_bytes);
 182                 do_exit(SIGSEGV);
 183         }
 184         tte |= pte_sz_bits(page_sz);
 185
 186         if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 187                 /* Physical mapping, no locked TLB entry for TSB.  */
 188                 tsb_reg |= tsb_paddr;
 189
 190                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 191                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = 0;
 192                 mm->context.tsb_block[tsb_idx].tsb_map_pte = 0;
 193         } else {
 194                 tsb_reg |= base;
 195                 tsb_reg |= (tsb_paddr & (page_sz - 1UL));
 196                 tte |= (tsb_paddr & ~(page_sz - 1UL));
 197
 198                 mm->context.tsb_block[tsb_idx].tsb_reg_val = tsb_reg;
 199                 mm->context.tsb_block[tsb_idx].tsb_map_vaddr = base;
 200                 mm->context.tsb_block[tsb_idx].tsb_map_pte = tte;
 201         }
 202
 203         /* Setup the Hypervisor TSB descriptor.  */
 204         if (tlb_type == hypervisor) {
 205                 struct hv_tsb_descr *hp = &mm->context.tsb_descr[tsb_idx];
 206
 207                 switch (tsb_idx) {
 208                 case MM_TSB_BASE:
 209                         hp->pgsz_idx = HV_PGSZ_IDX_BASE;
 210                         break;
 211 #ifdef CONFIG_HUGETLB_PAGE
 212                 case MM_TSB_HUGE:
 213                         hp->pgsz_idx = HV_PGSZ_IDX_HUGE;
 214                         break;
 215 #endif
 216                 default:
 217                         BUG();
 218                 }
 219                 hp->assoc = 1;
 220                 hp->num_ttes = tsb_bytes / 16;
 221                 hp->ctx_idx = 0;
 222                 switch (tsb_idx) {
 223                 case MM_TSB_BASE:
 224                         hp->pgsz_mask = HV_PGSZ_MASK_BASE;
 225                         break;
 226 #ifdef CONFIG_HUGETLB_PAGE
 227                 case MM_TSB_HUGE:
 228                         hp->pgsz_mask = HV_PGSZ_MASK_HUGE;
 229                         break;
 230 #endif
 231                 default:
 232                         BUG();
 233                 }
 234                 hp->tsb_base = tsb_paddr;
 235                 hp->resv = 0;
 236         }
 237 }
 238
 239 struct kmem_cache *pgtable_cache __read_mostly;
 240
 241 static struct kmem_cache *tsb_caches[8] __read_mostly;
 242
 243 static const char *tsb_cache_names[8] = {
 244         "tsb_8KB",
 245         "tsb_16KB",
 246         "tsb_32KB",
 247         "tsb_64KB",
 248         "tsb_128KB",
 249         "tsb_256KB",
 250         "tsb_512KB",
 251         "tsb_1MB",
 252 };
 253
 254 void __init pgtable_cache_init(void)
 255 {
 256         unsigned long i;
 257
 258         pgtable_cache = kmem_cache_create("pgtable_cache",
 259                                           PAGE_SIZE, PAGE_SIZE,
 260                                           0,
 261                                           _clear_page);
 262         if (!pgtable_cache) {
 263                 prom_printf("pgtable_cache_init(): Could not create!\n");
 264                 prom_halt();
 265         }
 266
 267         for (i = 0; i < 8; i++) {
 268                 unsigned long size = 8192 << i;
 269                 const char *name = tsb_cache_names[i];
 270
 271                 tsb_caches[i] = kmem_cache_create(name,
 272                                                   size, size,
 273                                                   0, NULL);
 274                 if (!tsb_caches[i]) {
 275                         prom_printf("Could not create %s cache\n", name);
 276                         prom_halt();
 277                 }
 278         }
 279 }
 280
 281 int sysctl_tsb_ratio = -2;
 282
 283 static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
 284 {
 285         unsigned long num_ents = (new_size / sizeof(struct tsb));
 286
 287         if (sysctl_tsb_ratio < 0)
 288                 return num_ents - (num_ents >> -sysctl_tsb_ratio);
 289         else
 290                 return num_ents + (num_ents >> sysctl_tsb_ratio);
 291 }
 292
 293 /* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
 294  * do_sparc64_fault() invokes this routine to try and grow it.
 295  *
 296  * When we reach the maximum TSB size supported, we stick ~0UL into
 297  * tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
 298  * will not trigger any longer.
 299  *
 300  * The TSB can be anywhere from 8K to 1MB in size, in increasing powers
 301  * of two.  The TSB must be aligned to it's size, so f.e. a 512K TSB
 302  * must be 512K aligned.  It also must be physically contiguous, so we
 303  * cannot use vmalloc().
 304  *
 305  * The idea here is to grow the TSB when the RSS of the process approaches
 306  * the number of entries that the current TSB can hold at once.  Currently,
 307  * we trigger when the RSS hits 3/4 of the TSB capacity.
 308  */
 309 void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
 310 {
 311         unsigned long max_tsb_size = 1 * 1024 * 1024;
 312         unsigned long new_size, old_size, flags;
 313         struct tsb *old_tsb, *new_tsb;
 314         unsigned long new_cache_index, old_cache_index;
 315         unsigned long new_rss_limit;
 316         gfp_t gfp_flags;
 317
 318         if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
 319                 max_tsb_size = (PAGE_SIZE << MAX_ORDER);
 320
 321         new_cache_index = 0;
 322         for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
 323                 new_rss_limit = tsb_size_to_rss_limit(new_size);
 324                 if (new_rss_limit > rss)
 325                         break;
 326                 new_cache_index++;
 327         }
 328
 329         if (new_size == max_tsb_size)
 330                 new_rss_limit = ~0UL;
 331
 332 retry_tsb_alloc:
 333         gfp_flags = GFP_KERNEL;
 334         if (new_size > (PAGE_SIZE * 2))
 335                 gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
 336
 337         new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
 338                                         gfp_flags, numa_node_id());
 339         if (unlikely(!new_tsb)) {
 340                 /* Not being able to fork due to a high-order TSB
 341                  * allocation failure is very bad behavior.  Just back
 342                  * down to a 0-order allocation and force no TSB
 343                  * growing for this address space.
 344                  */
 345                 if (mm->context.tsb_block[tsb_index].tsb == NULL &&
 346                     new_cache_index > 0) {
 347                         new_cache_index = 0;
 348                         new_size = 8192;
 349                         new_rss_limit = ~0UL;
 350                         goto retry_tsb_alloc;
 351                 }
 352
 353                 /* If we failed on a TSB grow, we are under serious
 354                  * memory pressure so don't try to grow any more.
 355                  */
 356                 if (mm->context.tsb_block[tsb_index].tsb != NULL)
 357                         mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
 358                 return;
 359         }
 360
 361         /* Mark all tags as invalid.  */
 362         tsb_init(new_tsb, new_size);
 363
 364         /* Ok, we are about to commit the changes.  If we are
 365          * growing an existing TSB the locking is very tricky,
 366          * so WATCH OUT!
 367          *
 368          * We have to hold mm->context.lock while committing to the
 369          * new TSB, this synchronizes us with processors in
 370          * flush_tsb_user() and switch_mm() for this address space.
 371          *
 372          * But even with that lock held, processors run asynchronously
 373          * accessing the old TSB via TLB miss handling.  This is OK
 374          * because those actions are just propagating state from the
 375          * Linux page tables into the TSB, page table mappings are not
 376          * being changed.  If a real fault occurs, the processor will
 377          * synchronize with us when it hits flush_tsb_user(), this is
 378          * also true for the case where vmscan is modifying the page
 379          * tables.  The only thing we need to be careful with is to
 380          * skip any locked TSB entries during copy_tsb().
 381          *
 382          * When we finish committing to the new TSB, we have to drop
 383          * the lock and ask all other cpus running this address space
 384          * to run tsb_context_switch() to see the new TSB table.
 385          */
 386         spin_lock_irqsave(&mm->context.lock, flags);
 387
 388         old_tsb = mm->context.tsb_block[tsb_index].tsb;
 389         old_cache_index =
 390                 (mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
 391         old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
 392                     sizeof(struct tsb));
 393
 394
 395         /* Handle multiple threads trying to grow the TSB at the same time.
 396          * One will get in here first, and bump the size and the RSS limit.
 397          * The others will get in here next and hit this check.
 398          */
 399         if (unlikely(old_tsb &&
 400                      (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
 401                 spin_unlock_irqrestore(&mm->context.lock, flags);
 402
 403                 kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
 404                 return;
 405         }
 406
 407         mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;
 408
 409         if (old_tsb) {
 410                 extern void copy_tsb(unsigned long old_tsb_base,
 411                                      unsigned long old_tsb_size,
 412                                      unsigned long new_tsb_base,
 413                                      unsigned long new_tsb_size);
 414                 unsigned long old_tsb_base = (unsigned long) old_tsb;
 415                 unsigned long new_tsb_base = (unsigned long) new_tsb;
 416
 417                 if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 418                         old_tsb_base = __pa(old_tsb_base);
 419                         new_tsb_base = __pa(new_tsb_base);
 420                 }
 421                 copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
 422         }
 423
 424         mm->context.tsb_block[tsb_index].tsb = new_tsb;
 425         setup_tsb_params(mm, tsb_index, new_size);
 426
 427         spin_unlock_irqrestore(&mm->context.lock, flags);
 428
 429         /* If old_tsb is NULL, we're being invoked for the first time
 430          * from init_new_context().
 431          */
 432         if (old_tsb) {
 433                 /* Reload it on the local cpu.  */
 434                 tsb_context_switch(mm);
 435
 436                 /* Now force other processors to do the same.  */
 437                 preempt_disable();
 438                 smp_tsb_sync(mm);
 439                 preempt_enable();
 440
 441                 /* Now it is safe to free the old tsb.  */
 442                 kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
 443         }
 444 }
 445
 446 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 447 {
 448 #ifdef CONFIG_HUGETLB_PAGE
 449         unsigned long huge_pte_count;
 450 #endif
 451         unsigned int i;
 452
 453         spin_lock_init(&mm->context.lock);
 454
 455         mm->context.sparc64_ctx_val = 0UL;
 456
 457 #ifdef CONFIG_HUGETLB_PAGE
 458         /* We reset it to zero because the fork() page copying
 459          * will re-increment the counters as the parent PTEs are
 460          * copied into the child address space.
 461          */
 462         huge_pte_count = mm->context.huge_pte_count;
 463         mm->context.huge_pte_count = 0;
 464 #endif
 465
 466         /* copy_mm() copies over the parent's mm_struct before calling
 467          * us, so we need to zero out the TSB pointer or else tsb_grow()
 468          * will be confused and think there is an older TSB to free up.
 469          */
 470         for (i = 0; i < MM_NUM_TSBS; i++)
 471                 mm->context.tsb_block[i].tsb = NULL;
 472
 473         /* If this is fork, inherit the parent's TSB size.  We would
 474          * grow it to that size on the first page fault anyways.
 475          */
 476         tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));
 477
 478 #ifdef CONFIG_HUGETLB_PAGE
 479         if (unlikely(huge_pte_count))
 480                 tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
 481 #endif
 482
 483         if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
 484                 return -ENOMEM;
 485
 486         return 0;
 487 }
 488
 489 static void tsb_destroy_one(struct tsb_config *tp)
 490 {
 491         unsigned long cache_index;
 492
 493         if (!tp->tsb)
 494                 return;
 495         cache_index = tp->tsb_reg_val & 0x7UL;
 496         kmem_cache_free(tsb_caches[cache_index], tp->tsb);
 497         tp->tsb = NULL;
 498         tp->tsb_reg_val = 0UL;
 499 }
 500
 501 void destroy_context(struct mm_struct *mm)
 502 {
 503         unsigned long flags, i;
 504
 505         for (i = 0; i < MM_NUM_TSBS; i++)
 506                 tsb_destroy_one(&mm->context.tsb_block[i]);
 507
 508         spin_lock_irqsave(&ctx_alloc_lock, flags);
 509
 510         if (CTX_VALID(mm->context)) {
 511                 unsigned long nr = CTX_NRBITS(mm->context);
 512                 mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
 513         }
 514
 515         spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 516 }