arch/sparc/mm/tsb.c

   1 /* arch/sparc64/mm/tsb.c
   2  *
   3  * Copyright (C) 2006, 2008 David S. Miller <[email protected]>
   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 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 #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 static struct kmem_cache *tsb_caches[8] __read_mostly;
 239
 240 static const char *tsb_cache_names[8] = {
 241         "tsb_8KB",
 242         "tsb_16KB",
 243         "tsb_32KB",
 244         "tsb_64KB",
 245         "tsb_128KB",
 246         "tsb_256KB",
 247         "tsb_512KB",
 248         "tsb_1MB",
 249 };
 250
 251 void __init pgtable_cache_init(void)
 252 {
 253         unsigned long i;
 254
 255         for (i = 0; i < 8; i++) {
 256                 unsigned long size = 8192 << i;
 257                 const char *name = tsb_cache_names[i];
 258
 259                 tsb_caches[i] = kmem_cache_create(name,
 260                                                   size, size,
 261                                                   0, NULL);
 262                 if (!tsb_caches[i]) {
 263                         prom_printf("Could not create %s cache\n", name);
 264                         prom_halt();
 265                 }
 266         }
 267 }
 268
 269 int sysctl_tsb_ratio = -2;
 270
 271 static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
 272 {
 273         unsigned long num_ents = (new_size / sizeof(struct tsb));
 274
 275         if (sysctl_tsb_ratio < 0)
 276                 return num_ents - (num_ents >> -sysctl_tsb_ratio);
 277         else
 278                 return num_ents + (num_ents >> sysctl_tsb_ratio);
 279 }
 280
 281 /* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
 282  * do_sparc64_fault() invokes this routine to try and grow it.
 283  *
 284  * When we reach the maximum TSB size supported, we stick ~0UL into
 285  * tsb_rss_limit for that TSB so the grow checks in do_sparc64_fault()
 286  * will not trigger any longer.
 287  *
 288  * The TSB can be anywhere from 8K to 1MB in size, in increasing powers
 289  * of two.  The TSB must be aligned to it's size, so f.e. a 512K TSB
 290  * must be 512K aligned.  It also must be physically contiguous, so we
 291  * cannot use vmalloc().
 292  *
 293  * The idea here is to grow the TSB when the RSS of the process approaches
 294  * the number of entries that the current TSB can hold at once.  Currently,
 295  * we trigger when the RSS hits 3/4 of the TSB capacity.
 296  */
 297 void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
 298 {
 299         unsigned long max_tsb_size = 1 * 1024 * 1024;
 300         unsigned long new_size, old_size, flags;
 301         struct tsb *old_tsb, *new_tsb;
 302         unsigned long new_cache_index, old_cache_index;
 303         unsigned long new_rss_limit;
 304         gfp_t gfp_flags;
 305
 306         if (max_tsb_size > (PAGE_SIZE << MAX_ORDER))
 307                 max_tsb_size = (PAGE_SIZE << MAX_ORDER);
 308
 309         new_cache_index = 0;
 310         for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
 311                 new_rss_limit = tsb_size_to_rss_limit(new_size);
 312                 if (new_rss_limit > rss)
 313                         break;
 314                 new_cache_index++;
 315         }
 316
 317         if (new_size == max_tsb_size)
 318                 new_rss_limit = ~0UL;
 319
 320 retry_tsb_alloc:
 321         gfp_flags = GFP_KERNEL;
 322         if (new_size > (PAGE_SIZE * 2))
 323                 gfp_flags = __GFP_NOWARN | __GFP_NORETRY;
 324
 325         new_tsb = kmem_cache_alloc_node(tsb_caches[new_cache_index],
 326                                         gfp_flags, numa_node_id());
 327         if (unlikely(!new_tsb)) {
 328                 /* Not being able to fork due to a high-order TSB
 329                  * allocation failure is very bad behavior.  Just back
 330                  * down to a 0-order allocation and force no TSB
 331                  * growing for this address space.
 332                  */
 333                 if (mm->context.tsb_block[tsb_index].tsb == NULL &&
 334                     new_cache_index > 0) {
 335                         new_cache_index = 0;
 336                         new_size = 8192;
 337                         new_rss_limit = ~0UL;
 338                         goto retry_tsb_alloc;
 339                 }
 340
 341                 /* If we failed on a TSB grow, we are under serious
 342                  * memory pressure so don't try to grow any more.
 343                  */
 344                 if (mm->context.tsb_block[tsb_index].tsb != NULL)
 345                         mm->context.tsb_block[tsb_index].tsb_rss_limit = ~0UL;
 346                 return;
 347         }
 348
 349         /* Mark all tags as invalid.  */
 350         tsb_init(new_tsb, new_size);
 351
 352         /* Ok, we are about to commit the changes.  If we are
 353          * growing an existing TSB the locking is very tricky,
 354          * so WATCH OUT!
 355          *
 356          * We have to hold mm->context.lock while committing to the
 357          * new TSB, this synchronizes us with processors in
 358          * flush_tsb_user() and switch_mm() for this address space.
 359          *
 360          * But even with that lock held, processors run asynchronously
 361          * accessing the old TSB via TLB miss handling.  This is OK
 362          * because those actions are just propagating state from the
 363          * Linux page tables into the TSB, page table mappings are not
 364          * being changed.  If a real fault occurs, the processor will
 365          * synchronize with us when it hits flush_tsb_user(), this is
 366          * also true for the case where vmscan is modifying the page
 367          * tables.  The only thing we need to be careful with is to
 368          * skip any locked TSB entries during copy_tsb().
 369          *
 370          * When we finish committing to the new TSB, we have to drop
 371          * the lock and ask all other cpus running this address space
 372          * to run tsb_context_switch() to see the new TSB table.
 373          */
 374         spin_lock_irqsave(&mm->context.lock, flags);
 375
 376         old_tsb = mm->context.tsb_block[tsb_index].tsb;
 377         old_cache_index =
 378                 (mm->context.tsb_block[tsb_index].tsb_reg_val & 0x7UL);
 379         old_size = (mm->context.tsb_block[tsb_index].tsb_nentries *
 380                     sizeof(struct tsb));
 381
 382
 383         /* Handle multiple threads trying to grow the TSB at the same time.
 384          * One will get in here first, and bump the size and the RSS limit.
 385          * The others will get in here next and hit this check.
 386          */
 387         if (unlikely(old_tsb &&
 388                      (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
 389                 spin_unlock_irqrestore(&mm->context.lock, flags);
 390
 391                 kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
 392                 return;
 393         }
 394
 395         mm->context.tsb_block[tsb_index].tsb_rss_limit = new_rss_limit;
 396
 397         if (old_tsb) {
 398                 extern void copy_tsb(unsigned long old_tsb_base,
 399                                      unsigned long old_tsb_size,
 400                                      unsigned long new_tsb_base,
 401                                      unsigned long new_tsb_size);
 402                 unsigned long old_tsb_base = (unsigned long) old_tsb;
 403                 unsigned long new_tsb_base = (unsigned long) new_tsb;
 404
 405                 if (tlb_type == cheetah_plus || tlb_type == hypervisor) {
 406                         old_tsb_base = __pa(old_tsb_base);
 407                         new_tsb_base = __pa(new_tsb_base);
 408                 }
 409                 copy_tsb(old_tsb_base, old_size, new_tsb_base, new_size);
 410         }
 411
 412         mm->context.tsb_block[tsb_index].tsb = new_tsb;
 413         setup_tsb_params(mm, tsb_index, new_size);
 414
 415         spin_unlock_irqrestore(&mm->context.lock, flags);
 416
 417         /* If old_tsb is NULL, we're being invoked for the first time
 418          * from init_new_context().
 419          */
 420         if (old_tsb) {
 421                 /* Reload it on the local cpu.  */
 422                 tsb_context_switch(mm);
 423
 424                 /* Now force other processors to do the same.  */
 425                 preempt_disable();
 426                 smp_tsb_sync(mm);
 427                 preempt_enable();
 428
 429                 /* Now it is safe to free the old tsb.  */
 430                 kmem_cache_free(tsb_caches[old_cache_index], old_tsb);
 431         }
 432 }
 433
 434 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 435 {
 436 #ifdef CONFIG_HUGETLB_PAGE
 437         unsigned long huge_pte_count;
 438 #endif
 439         unsigned int i;
 440
 441         spin_lock_init(&mm->context.lock);
 442
 443         mm->context.sparc64_ctx_val = 0UL;
 444
 445 #ifdef CONFIG_HUGETLB_PAGE
 446         /* We reset it to zero because the fork() page copying
 447          * will re-increment the counters as the parent PTEs are
 448          * copied into the child address space.
 449          */
 450         huge_pte_count = mm->context.huge_pte_count;
 451         mm->context.huge_pte_count = 0;
 452 #endif
 453
 454         /* copy_mm() copies over the parent's mm_struct before calling
 455          * us, so we need to zero out the TSB pointer or else tsb_grow()
 456          * will be confused and think there is an older TSB to free up.
 457          */
 458         for (i = 0; i < MM_NUM_TSBS; i++)
 459                 mm->context.tsb_block[i].tsb = NULL;
 460
 461         /* If this is fork, inherit the parent's TSB size.  We would
 462          * grow it to that size on the first page fault anyways.
 463          */
 464         tsb_grow(mm, MM_TSB_BASE, get_mm_rss(mm));
 465
 466 #ifdef CONFIG_HUGETLB_PAGE
 467         if (unlikely(huge_pte_count))
 468                 tsb_grow(mm, MM_TSB_HUGE, huge_pte_count);
 469 #endif
 470
 471         if (unlikely(!mm->context.tsb_block[MM_TSB_BASE].tsb))
 472                 return -ENOMEM;
 473
 474         return 0;
 475 }
 476
 477 static void tsb_destroy_one(struct tsb_config *tp)
 478 {
 479         unsigned long cache_index;
 480
 481         if (!tp->tsb)
 482                 return;
 483         cache_index = tp->tsb_reg_val & 0x7UL;
 484         kmem_cache_free(tsb_caches[cache_index], tp->tsb);
 485         tp->tsb = NULL;
 486         tp->tsb_reg_val = 0UL;
 487 }
 488
 489 void destroy_context(struct mm_struct *mm)
 490 {
 491         unsigned long flags, i;
 492
 493         for (i = 0; i < MM_NUM_TSBS; i++)
 494                 tsb_destroy_one(&mm->context.tsb_block[i]);
 495
 496         spin_lock_irqsave(&ctx_alloc_lock, flags);
 497
 498         if (CTX_VALID(mm->context)) {
 499                 unsigned long nr = CTX_NRBITS(mm->context);
 500                 mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
 501         }
 502
 503         spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 504 }