arch/tile/mm/homecache.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * This code maintains the "home" for each page in the system.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/list.h>
  21 #include <linux/bootmem.h>
  22 #include <linux/rmap.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/mutex.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/sysctl.h>
  27 #include <linux/pagevec.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/timex.h>
  30 #include <linux/cache.h>
  31 #include <linux/smp.h>
  32 #include <linux/module.h>
  33
  34 #include <asm/page.h>
  35 #include <asm/sections.h>
  36 #include <asm/tlbflush.h>
  37 #include <asm/pgalloc.h>
  38 #include <asm/homecache.h>
  39
  40 #include <arch/sim.h>
  41
  42 #include "migrate.h"
  43
  44
  45 #if CHIP_HAS_COHERENT_LOCAL_CACHE()
  46
  47 /*
  48  * The noallocl2 option suppresses all use of the L2 cache to cache
  49  * locally from a remote home.  There's no point in using it if we
  50  * don't have coherent local caching, though.
  51  */
  52 static int __write_once noallocl2;
  53 static int __init set_noallocl2(char *str)
  54 {
  55         noallocl2 = 1;
  56         return 0;
  57 }
  58 early_param("noallocl2", set_noallocl2);
  59
  60 #else
  61
  62 #define noallocl2 0
  63
  64 #endif
  65
  66 /* Provide no-op versions of these routines to keep flush_remote() cleaner. */
  67 #define mark_caches_evicted_start() 0
  68 #define mark_caches_evicted_finish(mask, timestamp) do {} while (0)
  69
  70
  71 /*
  72  * Update the irq_stat for cpus that we are going to interrupt
  73  * with TLB or cache flushes.  Also handle removing dataplane cpus
  74  * from the TLB flush set, and setting dataplane_tlb_state instead.
  75  */
  76 static void hv_flush_update(const struct cpumask *cache_cpumask,
  77                             struct cpumask *tlb_cpumask,
  78                             unsigned long tlb_va, unsigned long tlb_length,
  79                             HV_Remote_ASID *asids, int asidcount)
  80 {
  81         struct cpumask mask;
  82         int i, cpu;
  83
  84         cpumask_clear(&mask);
  85         if (cache_cpumask)
  86                 cpumask_or(&mask, &mask, cache_cpumask);
  87         if (tlb_cpumask && tlb_length) {
  88                 cpumask_or(&mask, &mask, tlb_cpumask);
  89         }
  90
  91         for (i = 0; i < asidcount; ++i)
  92                 cpumask_set_cpu(asids[i].y * smp_width + asids[i].x, &mask);
  93
  94         /*
  95          * Don't bother to update atomically; losing a count
  96          * here is not that critical.
  97          */
  98         for_each_cpu(cpu, &mask)
  99                 ++per_cpu(irq_stat, cpu).irq_hv_flush_count;
 100 }
 101
 102 /*
 103  * This wrapper function around hv_flush_remote() does several things:
 104  *
 105  *  - Provides a return value error-checking panic path, since
 106  *    there's never any good reason for hv_flush_remote() to fail.
 107  *  - Accepts a 32-bit PFN rather than a 64-bit PA, which generally
 108  *    is the type that Linux wants to pass around anyway.
 109  *  - Centralizes the mark_caches_evicted() handling.
 110  *  - Canonicalizes that lengths of zero make cpumasks NULL.
 111  *  - Handles deferring TLB flushes for dataplane tiles.
 112  *  - Tracks remote interrupts in the per-cpu irq_cpustat_t.
 113  *
 114  * Note that we have to wait until the cache flush completes before
 115  * updating the per-cpu last_cache_flush word, since otherwise another
 116  * concurrent flush can race, conclude the flush has already
 117  * completed, and start to use the page while it's still dirty
 118  * remotely (running concurrently with the actual evict, presumably).
 119  */
 120 void flush_remote(unsigned long cache_pfn, unsigned long cache_control,
 121                   const struct cpumask *cache_cpumask_orig,
 122                   HV_VirtAddr tlb_va, unsigned long tlb_length,
 123                   unsigned long tlb_pgsize,
 124                   const struct cpumask *tlb_cpumask_orig,
 125                   HV_Remote_ASID *asids, int asidcount)
 126 {
 127         int rc;
 128         int timestamp = 0;  /* happy compiler */
 129         struct cpumask cache_cpumask_copy, tlb_cpumask_copy;
 130         struct cpumask *cache_cpumask, *tlb_cpumask;
 131         HV_PhysAddr cache_pa;
 132         char cache_buf[NR_CPUS*5], tlb_buf[NR_CPUS*5];
 133
 134         mb();   /* provided just to simplify "magic hypervisor" mode */
 135
 136         /*
 137          * Canonicalize and copy the cpumasks.
 138          */
 139         if (cache_cpumask_orig && cache_control) {
 140                 cpumask_copy(&cache_cpumask_copy, cache_cpumask_orig);
 141                 cache_cpumask = &cache_cpumask_copy;
 142         } else {
 143                 cpumask_clear(&cache_cpumask_copy);
 144                 cache_cpumask = NULL;
 145         }
 146         if (cache_cpumask == NULL)
 147                 cache_control = 0;
 148         if (tlb_cpumask_orig && tlb_length) {
 149                 cpumask_copy(&tlb_cpumask_copy, tlb_cpumask_orig);
 150                 tlb_cpumask = &tlb_cpumask_copy;
 151         } else {
 152                 cpumask_clear(&tlb_cpumask_copy);
 153                 tlb_cpumask = NULL;
 154         }
 155
 156         hv_flush_update(cache_cpumask, tlb_cpumask, tlb_va, tlb_length,
 157                         asids, asidcount);
 158         cache_pa = (HV_PhysAddr)cache_pfn << PAGE_SHIFT;
 159         if (cache_control & HV_FLUSH_EVICT_L2)
 160                 timestamp = mark_caches_evicted_start();
 161         rc = hv_flush_remote(cache_pa, cache_control,
 162                              cpumask_bits(cache_cpumask),
 163                              tlb_va, tlb_length, tlb_pgsize,
 164                              cpumask_bits(tlb_cpumask),
 165                              asids, asidcount);
 166         if (cache_control & HV_FLUSH_EVICT_L2)
 167                 mark_caches_evicted_finish(cache_cpumask, timestamp);
 168         if (rc == 0)
 169                 return;
 170         cpumask_scnprintf(cache_buf, sizeof(cache_buf), &cache_cpumask_copy);
 171         cpumask_scnprintf(tlb_buf, sizeof(tlb_buf), &tlb_cpumask_copy);
 172
 173         pr_err("hv_flush_remote(%#llx, %#lx, %p [%s],"
 174                " %#lx, %#lx, %#lx, %p [%s], %p, %d) = %d\n",
 175                cache_pa, cache_control, cache_cpumask, cache_buf,
 176                (unsigned long)tlb_va, tlb_length, tlb_pgsize,
 177                tlb_cpumask, tlb_buf,
 178                asids, asidcount, rc);
 179         panic("Unsafe to continue.");
 180 }
 181
 182 void homecache_evict(const struct cpumask *mask)
 183 {
 184         flush_remote(0, HV_FLUSH_EVICT_L2, mask, 0, 0, 0, NULL, NULL, 0);
 185 }
 186
 187 /* Return a mask of the cpus whose caches currently own these pages. */
 188 static void homecache_mask(struct page *page, int pages,
 189                            struct cpumask *home_mask)
 190 {
 191         int i;
 192         cpumask_clear(home_mask);
 193         for (i = 0; i < pages; ++i) {
 194                 int home = page_home(&page[i]);
 195                 if (home == PAGE_HOME_IMMUTABLE ||
 196                     home == PAGE_HOME_INCOHERENT) {
 197                         cpumask_copy(home_mask, cpu_possible_mask);
 198                         return;
 199                 }
 200 #if CHIP_HAS_CBOX_HOME_MAP()
 201                 if (home == PAGE_HOME_HASH) {
 202                         cpumask_or(home_mask, home_mask, &hash_for_home_map);
 203                         continue;
 204                 }
 205 #endif
 206                 if (home == PAGE_HOME_UNCACHED)
 207                         continue;
 208                 BUG_ON(home < 0 || home >= NR_CPUS);
 209                 cpumask_set_cpu(home, home_mask);
 210         }
 211 }
 212
 213 /*
 214  * Return the passed length, or zero if it's long enough that we
 215  * believe we should evict the whole L2 cache.
 216  */
 217 static unsigned long cache_flush_length(unsigned long length)
 218 {
 219         return (length >= CHIP_L2_CACHE_SIZE()) ? HV_FLUSH_EVICT_L2 : length;
 220 }
 221
 222 /* Flush a page out of whatever cache(s) it is in. */
 223 void homecache_flush_cache(struct page *page, int order)
 224 {
 225         int pages = 1 << order;
 226         int length = cache_flush_length(pages * PAGE_SIZE);
 227         unsigned long pfn = page_to_pfn(page);
 228         struct cpumask home_mask;
 229
 230         homecache_mask(page, pages, &home_mask);
 231         flush_remote(pfn, length, &home_mask, 0, 0, 0, NULL, NULL, 0);
 232         sim_validate_lines_evicted(PFN_PHYS(pfn), pages * PAGE_SIZE);
 233 }
 234
 235
 236 /* Report the home corresponding to a given PTE. */
 237 static int pte_to_home(pte_t pte)
 238 {
 239         if (hv_pte_get_nc(pte))
 240                 return PAGE_HOME_IMMUTABLE;
 241         switch (hv_pte_get_mode(pte)) {
 242         case HV_PTE_MODE_CACHE_TILE_L3:
 243                 return get_remote_cache_cpu(pte);
 244         case HV_PTE_MODE_CACHE_NO_L3:
 245                 return PAGE_HOME_INCOHERENT;
 246         case HV_PTE_MODE_UNCACHED:
 247                 return PAGE_HOME_UNCACHED;
 248 #if CHIP_HAS_CBOX_HOME_MAP()
 249         case HV_PTE_MODE_CACHE_HASH_L3:
 250                 return PAGE_HOME_HASH;
 251 #endif
 252         }
 253         panic("Bad PTE %#llx\n", pte.val);
 254 }
 255
 256 /* Update the home of a PTE if necessary (can also be used for a pgprot_t). */
 257 pte_t pte_set_home(pte_t pte, int home)
 258 {
 259         /* Check for non-linear file mapping "PTEs" and pass them through. */
 260         if (pte_file(pte))
 261                 return pte;
 262
 263 #if CHIP_HAS_MMIO()
 264         /* Check for MMIO mappings and pass them through. */
 265         if (hv_pte_get_mode(pte) == HV_PTE_MODE_MMIO)
 266                 return pte;
 267 #endif
 268
 269
 270         /*
 271          * Only immutable pages get NC mappings.  If we have a
 272          * non-coherent PTE, but the underlying page is not
 273          * immutable, it's likely the result of a forced
 274          * caching setting running up against ptrace setting
 275          * the page to be writable underneath.  In this case,
 276          * just keep the PTE coherent.
 277          */
 278         if (hv_pte_get_nc(pte) && home != PAGE_HOME_IMMUTABLE) {
 279                 pte = hv_pte_clear_nc(pte);
 280                 pr_err("non-immutable page incoherently referenced: %#llx\n",
 281                        pte.val);
 282         }
 283
 284         switch (home) {
 285
 286         case PAGE_HOME_UNCACHED:
 287                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
 288                 break;
 289
 290         case PAGE_HOME_INCOHERENT:
 291                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 292                 break;
 293
 294         case PAGE_HOME_IMMUTABLE:
 295                 /*
 296                  * We could home this page anywhere, since it's immutable,
 297                  * but by default just home it to follow "hash_default".
 298                  */
 299                 BUG_ON(hv_pte_get_writable(pte));
 300                 if (pte_get_forcecache(pte)) {
 301                         /* Upgrade "force any cpu" to "No L3" for immutable. */
 302                         if (hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_TILE_L3
 303                             && pte_get_anyhome(pte)) {
 304                                 pte = hv_pte_set_mode(pte,
 305                                                       HV_PTE_MODE_CACHE_NO_L3);
 306                         }
 307                 } else
 308 #if CHIP_HAS_CBOX_HOME_MAP()
 309                 if (hash_default)
 310                         pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
 311                 else
 312 #endif
 313                         pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 314                 pte = hv_pte_set_nc(pte);
 315                 break;
 316
 317 #if CHIP_HAS_CBOX_HOME_MAP()
 318         case PAGE_HOME_HASH:
 319                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
 320                 break;
 321 #endif
 322
 323         default:
 324                 BUG_ON(home < 0 || home >= NR_CPUS ||
 325                        !cpu_is_valid_lotar(home));
 326                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
 327                 pte = set_remote_cache_cpu(pte, home);
 328                 break;
 329         }
 330
 331 #if CHIP_HAS_NC_AND_NOALLOC_BITS()
 332         if (noallocl2)
 333                 pte = hv_pte_set_no_alloc_l2(pte);
 334
 335         /* Simplify "no local and no l3" to "uncached" */
 336         if (hv_pte_get_no_alloc_l2(pte) && hv_pte_get_no_alloc_l1(pte) &&
 337             hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_NO_L3) {
 338                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
 339         }
 340 #endif
 341
 342         /* Checking this case here gives a better panic than from the hv. */
 343         BUG_ON(hv_pte_get_mode(pte) == 0);
 344
 345         return pte;
 346 }
 347 EXPORT_SYMBOL(pte_set_home);
 348
 349 /*
 350  * The routines in this section are the "static" versions of the normal
 351  * dynamic homecaching routines; they just set the home cache
 352  * of a kernel page once, and require a full-chip cache/TLB flush,
 353  * so they're not suitable for anything but infrequent use.
 354  */
 355
 356 #if CHIP_HAS_CBOX_HOME_MAP()
 357 static inline int initial_page_home(void) { return PAGE_HOME_HASH; }
 358 #else
 359 static inline int initial_page_home(void) { return 0; }
 360 #endif
 361
 362 int page_home(struct page *page)
 363 {
 364         if (PageHighMem(page)) {
 365                 return initial_page_home();
 366         } else {
 367                 unsigned long kva = (unsigned long)page_address(page);
 368                 return pte_to_home(*virt_to_pte(NULL, kva));
 369         }
 370 }
 371
 372 void homecache_change_page_home(struct page *page, int order, int home)
 373 {
 374         int i, pages = (1 << order);
 375         unsigned long kva;
 376
 377         BUG_ON(PageHighMem(page));
 378         BUG_ON(page_count(page) > 1);
 379         BUG_ON(page_mapcount(page) != 0);
 380         kva = (unsigned long) page_address(page);
 381         flush_remote(0, HV_FLUSH_EVICT_L2, &cpu_cacheable_map,
 382                      kva, pages * PAGE_SIZE, PAGE_SIZE, cpu_online_mask,
 383                      NULL, 0);
 384
 385         for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
 386                 pte_t *ptep = virt_to_pte(NULL, kva);
 387                 pte_t pteval = *ptep;
 388                 BUG_ON(!pte_present(pteval) || pte_huge(pteval));
 389                 *ptep = pte_set_home(pteval, home);
 390         }
 391 }
 392
 393 struct page *homecache_alloc_pages(gfp_t gfp_mask,
 394                                    unsigned int order, int home)
 395 {
 396         struct page *page;
 397         BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
 398         page = alloc_pages(gfp_mask, order);
 399         if (page)
 400                 homecache_change_page_home(page, order, home);
 401         return page;
 402 }
 403 EXPORT_SYMBOL(homecache_alloc_pages);
 404
 405 struct page *homecache_alloc_pages_node(int nid, gfp_t gfp_mask,
 406                                         unsigned int order, int home)
 407 {
 408         struct page *page;
 409         BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
 410         page = alloc_pages_node(nid, gfp_mask, order);
 411         if (page)
 412                 homecache_change_page_home(page, order, home);
 413         return page;
 414 }
 415
 416 void homecache_free_pages(unsigned long addr, unsigned int order)
 417 {
 418         struct page *page;
 419
 420         if (addr == 0)
 421                 return;
 422
 423         VM_BUG_ON(!virt_addr_valid((void *)addr));
 424         page = virt_to_page((void *)addr);
 425         if (put_page_testzero(page)) {
 426                 int pages = (1 << order);
 427                 homecache_change_page_home(page, order, initial_page_home());
 428                 while (pages--)
 429                         __free_page(page++);
 430         }
 431 }