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 #include <linux/hugetlb.h>
  34
  35 #include <asm/page.h>
  36 #include <asm/sections.h>
  37 #include <asm/tlbflush.h>
  38 #include <asm/pgalloc.h>
  39 #include <asm/homecache.h>
  40
  41 #include <arch/sim.h>
  42
  43 #include "migrate.h"
  44
  45
  46 /*
  47  * The noallocl2 option suppresses all use of the L2 cache to cache
  48  * locally from a remote home.
  49  */
  50 static int __ro_after_init noallocl2;
  51 static int __init set_noallocl2(char *str)
  52 {
  53         noallocl2 = 1;
  54         return 0;
  55 }
  56 early_param("noallocl2", set_noallocl2);
  57
  58
  59 /*
  60  * Update the irq_stat for cpus that we are going to interrupt
  61  * with TLB or cache flushes.  Also handle removing dataplane cpus
  62  * from the TLB flush set, and setting dataplane_tlb_state instead.
  63  */
  64 static void hv_flush_update(const struct cpumask *cache_cpumask,
  65                             struct cpumask *tlb_cpumask,
  66                             unsigned long tlb_va, unsigned long tlb_length,
  67                             HV_Remote_ASID *asids, int asidcount)
  68 {
  69         struct cpumask mask;
  70         int i, cpu;
  71
  72         cpumask_clear(&mask);
  73         if (cache_cpumask)
  74                 cpumask_or(&mask, &mask, cache_cpumask);
  75         if (tlb_cpumask && tlb_length) {
  76                 cpumask_or(&mask, &mask, tlb_cpumask);
  77         }
  78
  79         for (i = 0; i < asidcount; ++i)
  80                 cpumask_set_cpu(asids[i].y * smp_width + asids[i].x, &mask);
  81
  82         /*
  83          * Don't bother to update atomically; losing a count
  84          * here is not that critical.
  85          */
  86         for_each_cpu(cpu, &mask)
  87                 ++per_cpu(irq_stat, cpu).irq_hv_flush_count;
  88 }
  89
  90 /*
  91  * This wrapper function around hv_flush_remote() does several things:
  92  *
  93  *  - Provides a return value error-checking panic path, since
  94  *    there's never any good reason for hv_flush_remote() to fail.
  95  *  - Accepts a 32-bit PFN rather than a 64-bit PA, which generally
  96  *    is the type that Linux wants to pass around anyway.
  97  *  - Canonicalizes that lengths of zero make cpumasks NULL.
  98  *  - Handles deferring TLB flushes for dataplane tiles.
  99  *  - Tracks remote interrupts in the per-cpu irq_cpustat_t.
 100  *
 101  * Note that we have to wait until the cache flush completes before
 102  * updating the per-cpu last_cache_flush word, since otherwise another
 103  * concurrent flush can race, conclude the flush has already
 104  * completed, and start to use the page while it's still dirty
 105  * remotely (running concurrently with the actual evict, presumably).
 106  */
 107 void flush_remote(unsigned long cache_pfn, unsigned long cache_control,
 108                   const struct cpumask *cache_cpumask_orig,
 109                   HV_VirtAddr tlb_va, unsigned long tlb_length,
 110                   unsigned long tlb_pgsize,
 111                   const struct cpumask *tlb_cpumask_orig,
 112                   HV_Remote_ASID *asids, int asidcount)
 113 {
 114         int rc;
 115         struct cpumask cache_cpumask_copy, tlb_cpumask_copy;
 116         struct cpumask *cache_cpumask, *tlb_cpumask;
 117         HV_PhysAddr cache_pa;
 118
 119         mb();   /* provided just to simplify "magic hypervisor" mode */
 120
 121         /*
 122          * Canonicalize and copy the cpumasks.
 123          */
 124         if (cache_cpumask_orig && cache_control) {
 125                 cpumask_copy(&cache_cpumask_copy, cache_cpumask_orig);
 126                 cache_cpumask = &cache_cpumask_copy;
 127         } else {
 128                 cpumask_clear(&cache_cpumask_copy);
 129                 cache_cpumask = NULL;
 130         }
 131         if (cache_cpumask == NULL)
 132                 cache_control = 0;
 133         if (tlb_cpumask_orig && tlb_length) {
 134                 cpumask_copy(&tlb_cpumask_copy, tlb_cpumask_orig);
 135                 tlb_cpumask = &tlb_cpumask_copy;
 136         } else {
 137                 cpumask_clear(&tlb_cpumask_copy);
 138                 tlb_cpumask = NULL;
 139         }
 140
 141         hv_flush_update(cache_cpumask, tlb_cpumask, tlb_va, tlb_length,
 142                         asids, asidcount);
 143         cache_pa = (HV_PhysAddr)cache_pfn << PAGE_SHIFT;
 144         rc = hv_flush_remote(cache_pa, cache_control,
 145                              cpumask_bits(cache_cpumask),
 146                              tlb_va, tlb_length, tlb_pgsize,
 147                              cpumask_bits(tlb_cpumask),
 148                              asids, asidcount);
 149         if (rc == 0)
 150                 return;
 151
 152         pr_err("hv_flush_remote(%#llx, %#lx, %p [%*pb], %#lx, %#lx, %#lx, %p [%*pb], %p, %d) = %d\n",
 153                cache_pa, cache_control, cache_cpumask,
 154                cpumask_pr_args(&cache_cpumask_copy),
 155                (unsigned long)tlb_va, tlb_length, tlb_pgsize, tlb_cpumask,
 156                cpumask_pr_args(&tlb_cpumask_copy), asids, asidcount, rc);
 157         panic("Unsafe to continue.");
 158 }
 159
 160 static void homecache_finv_page_va(void* va, int home)
 161 {
 162         int cpu = get_cpu();
 163         if (home == cpu) {
 164                 finv_buffer_local(va, PAGE_SIZE);
 165         } else if (home == PAGE_HOME_HASH) {
 166                 finv_buffer_remote(va, PAGE_SIZE, 1);
 167         } else {
 168                 BUG_ON(home < 0 || home >= NR_CPUS);
 169                 finv_buffer_remote(va, PAGE_SIZE, 0);
 170         }
 171         put_cpu();
 172 }
 173
 174 void homecache_finv_map_page(struct page *page, int home)
 175 {
 176         unsigned long flags;
 177         unsigned long va;
 178         pte_t *ptep;
 179         pte_t pte;
 180
 181         if (home == PAGE_HOME_UNCACHED)
 182                 return;
 183         local_irq_save(flags);
 184 #ifdef CONFIG_HIGHMEM
 185         va = __fix_to_virt(FIX_KMAP_BEGIN + kmap_atomic_idx_push() +
 186                            (KM_TYPE_NR * smp_processor_id()));
 187 #else
 188         va = __fix_to_virt(FIX_HOMECACHE_BEGIN + smp_processor_id());
 189 #endif
 190         ptep = virt_to_kpte(va);
 191         pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL);
 192         __set_pte(ptep, pte_set_home(pte, home));
 193         homecache_finv_page_va((void *)va, home);
 194         __pte_clear(ptep);
 195         hv_flush_page(va, PAGE_SIZE);
 196 #ifdef CONFIG_HIGHMEM
 197         kmap_atomic_idx_pop();
 198 #endif
 199         local_irq_restore(flags);
 200 }
 201
 202 static void homecache_finv_page_home(struct page *page, int home)
 203 {
 204         if (!PageHighMem(page) && home == page_home(page))
 205                 homecache_finv_page_va(page_address(page), home);
 206         else
 207                 homecache_finv_map_page(page, home);
 208 }
 209
 210 static inline bool incoherent_home(int home)
 211 {
 212         return home == PAGE_HOME_IMMUTABLE || home == PAGE_HOME_INCOHERENT;
 213 }
 214
 215 static void homecache_finv_page_internal(struct page *page, int force_map)
 216 {
 217         int home = page_home(page);
 218         if (home == PAGE_HOME_UNCACHED)
 219                 return;
 220         if (incoherent_home(home)) {
 221                 int cpu;
 222                 for_each_cpu(cpu, &cpu_cacheable_map)
 223                         homecache_finv_map_page(page, cpu);
 224         } else if (force_map) {
 225                 /* Force if, e.g., the normal mapping is migrating. */
 226                 homecache_finv_map_page(page, home);
 227         } else {
 228                 homecache_finv_page_home(page, home);
 229         }
 230         sim_validate_lines_evicted(PFN_PHYS(page_to_pfn(page)), PAGE_SIZE);
 231 }
 232
 233 void homecache_finv_page(struct page *page)
 234 {
 235         homecache_finv_page_internal(page, 0);
 236 }
 237
 238 void homecache_evict(const struct cpumask *mask)
 239 {
 240         flush_remote(0, HV_FLUSH_EVICT_L2, mask, 0, 0, 0, NULL, NULL, 0);
 241 }
 242
 243 /* Report the home corresponding to a given PTE. */
 244 static int pte_to_home(pte_t pte)
 245 {
 246         if (hv_pte_get_nc(pte))
 247                 return PAGE_HOME_IMMUTABLE;
 248         switch (hv_pte_get_mode(pte)) {
 249         case HV_PTE_MODE_CACHE_TILE_L3:
 250                 return get_remote_cache_cpu(pte);
 251         case HV_PTE_MODE_CACHE_NO_L3:
 252                 return PAGE_HOME_INCOHERENT;
 253         case HV_PTE_MODE_UNCACHED:
 254                 return PAGE_HOME_UNCACHED;
 255         case HV_PTE_MODE_CACHE_HASH_L3:
 256                 return PAGE_HOME_HASH;
 257         }
 258         panic("Bad PTE %#llx\n", pte.val);
 259 }
 260
 261 /* Update the home of a PTE if necessary (can also be used for a pgprot_t). */
 262 pte_t pte_set_home(pte_t pte, int home)
 263 {
 264 #if CHIP_HAS_MMIO()
 265         /* Check for MMIO mappings and pass them through. */
 266         if (hv_pte_get_mode(pte) == HV_PTE_MODE_MMIO)
 267                 return pte;
 268 #endif
 269
 270
 271         /*
 272          * Only immutable pages get NC mappings.  If we have a
 273          * non-coherent PTE, but the underlying page is not
 274          * immutable, it's likely the result of a forced
 275          * caching setting running up against ptrace setting
 276          * the page to be writable underneath.  In this case,
 277          * just keep the PTE coherent.
 278          */
 279         if (hv_pte_get_nc(pte) && home != PAGE_HOME_IMMUTABLE) {
 280                 pte = hv_pte_clear_nc(pte);
 281                 pr_err("non-immutable page incoherently referenced: %#llx\n",
 282                        pte.val);
 283         }
 284
 285         switch (home) {
 286
 287         case PAGE_HOME_UNCACHED:
 288                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
 289                 break;
 290
 291         case PAGE_HOME_INCOHERENT:
 292                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 293                 break;
 294
 295         case PAGE_HOME_IMMUTABLE:
 296                 /*
 297                  * We could home this page anywhere, since it's immutable,
 298                  * but by default just home it to follow "hash_default".
 299                  */
 300                 BUG_ON(hv_pte_get_writable(pte));
 301                 if (pte_get_forcecache(pte)) {
 302                         /* Upgrade "force any cpu" to "No L3" for immutable. */
 303                         if (hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_TILE_L3
 304                             && pte_get_anyhome(pte)) {
 305                                 pte = hv_pte_set_mode(pte,
 306                                                       HV_PTE_MODE_CACHE_NO_L3);
 307                         }
 308                 } else
 309                 if (hash_default)
 310                         pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
 311                 else
 312                         pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_NO_L3);
 313                 pte = hv_pte_set_nc(pte);
 314                 break;
 315
 316         case PAGE_HOME_HASH:
 317                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_HASH_L3);
 318                 break;
 319
 320         default:
 321                 BUG_ON(home < 0 || home >= NR_CPUS ||
 322                        !cpu_is_valid_lotar(home));
 323                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
 324                 pte = set_remote_cache_cpu(pte, home);
 325                 break;
 326         }
 327
 328         if (noallocl2)
 329                 pte = hv_pte_set_no_alloc_l2(pte);
 330
 331         /* Simplify "no local and no l3" to "uncached" */
 332         if (hv_pte_get_no_alloc_l2(pte) && hv_pte_get_no_alloc_l1(pte) &&
 333             hv_pte_get_mode(pte) == HV_PTE_MODE_CACHE_NO_L3) {
 334                 pte = hv_pte_set_mode(pte, HV_PTE_MODE_UNCACHED);
 335         }
 336
 337         /* Checking this case here gives a better panic than from the hv. */
 338         BUG_ON(hv_pte_get_mode(pte) == 0);
 339
 340         return pte;
 341 }
 342 EXPORT_SYMBOL(pte_set_home);
 343
 344 /*
 345  * The routines in this section are the "static" versions of the normal
 346  * dynamic homecaching routines; they just set the home cache
 347  * of a kernel page once, and require a full-chip cache/TLB flush,
 348  * so they're not suitable for anything but infrequent use.
 349  */
 350
 351 int page_home(struct page *page)
 352 {
 353         if (PageHighMem(page)) {
 354                 return PAGE_HOME_HASH;
 355         } else {
 356                 unsigned long kva = (unsigned long)page_address(page);
 357                 return pte_to_home(*virt_to_kpte(kva));
 358         }
 359 }
 360 EXPORT_SYMBOL(page_home);
 361
 362 void homecache_change_page_home(struct page *page, int order, int home)
 363 {
 364         int i, pages = (1 << order);
 365         unsigned long kva;
 366
 367         BUG_ON(PageHighMem(page));
 368         BUG_ON(page_count(page) > 1);
 369         BUG_ON(page_mapcount(page) != 0);
 370         kva = (unsigned long) page_address(page);
 371         flush_remote(0, HV_FLUSH_EVICT_L2, &cpu_cacheable_map,
 372                      kva, pages * PAGE_SIZE, PAGE_SIZE, cpu_online_mask,
 373                      NULL, 0);
 374
 375         for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
 376                 pte_t *ptep = virt_to_kpte(kva);
 377                 pte_t pteval = *ptep;
 378                 BUG_ON(!pte_present(pteval) || pte_huge(pteval));
 379                 __set_pte(ptep, pte_set_home(pteval, home));
 380         }
 381 }
 382 EXPORT_SYMBOL(homecache_change_page_home);
 383
 384 struct page *homecache_alloc_pages(gfp_t gfp_mask,
 385                                    unsigned int order, int home)
 386 {
 387         struct page *page;
 388         BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
 389         page = alloc_pages(gfp_mask, order);
 390         if (page)
 391                 homecache_change_page_home(page, order, home);
 392         return page;
 393 }
 394 EXPORT_SYMBOL(homecache_alloc_pages);
 395
 396 struct page *homecache_alloc_pages_node(int nid, gfp_t gfp_mask,
 397                                         unsigned int order, int home)
 398 {
 399         struct page *page;
 400         BUG_ON(gfp_mask & __GFP_HIGHMEM);   /* must be lowmem */
 401         page = alloc_pages_node(nid, gfp_mask, order);
 402         if (page)
 403                 homecache_change_page_home(page, order, home);
 404         return page;
 405 }
 406
 407 void __homecache_free_pages(struct page *page, unsigned int order)
 408 {
 409         if (put_page_testzero(page)) {
 410                 homecache_change_page_home(page, order, PAGE_HOME_HASH);
 411                 if (order == 0) {
 412                         free_unref_page(page);
 413                 } else {
 414                         init_page_count(page);
 415                         __free_pages(page, order);
 416                 }
 417         }
 418 }
 419 EXPORT_SYMBOL(__homecache_free_pages);
 420
 421 void homecache_free_pages(unsigned long addr, unsigned int order)
 422 {
 423         if (addr != 0) {
 424                 VM_BUG_ON(!virt_addr_valid((void *)addr));
 425                 __homecache_free_pages(virt_to_page((void *)addr), order);
 426         }
 427 }
 428 EXPORT_SYMBOL(homecache_free_pages);