arch/sparc/kernel/adi_64.c

   1 /* adi_64.c: support for ADI (Application Data Integrity) feature on
   2  * sparc m7 and newer processors. This feature is also known as
   3  * SSM (Silicon Secured Memory).
   4  *
   5  * Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
   6  * Author: Khalid Aziz (khalid.aziz@oracle.com)
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2.
   9  */
  10 #include <linux/init.h>
  11 #include <linux/slab.h>
  12 #include <linux/mm_types.h>
  13 #include <asm/mdesc.h>
  14 #include <asm/adi_64.h>
  15 #include <asm/mmu_64.h>
  16 #include <asm/pgtable_64.h>
  17
  18 /* Each page of storage for ADI tags can accommodate tags for 128
  19  * pages. When ADI enabled pages are being swapped out, it would be
  20  * prudent to allocate at least enough tag storage space to accommodate
  21  * SWAPFILE_CLUSTER number of pages. Allocate enough tag storage to
  22  * store tags for four SWAPFILE_CLUSTER pages to reduce need for
  23  * further allocations for same vma.
  24  */
  25 #define TAG_STORAGE_PAGES       8
  26
  27 struct adi_config adi_state;
  28 EXPORT_SYMBOL(adi_state);
  29
  30 /* mdesc_adi_init() : Parse machine description provided by the
  31  *      hypervisor to detect ADI capabilities
  32  *
  33  * Hypervisor reports ADI capabilities of platform in "hwcap-list" property
  34  * for "cpu" node. If the platform supports ADI, "hwcap-list" property
  35  * contains the keyword "adp". If the platform supports ADI, "platform"
  36  * node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
  37  * to describe the ADI capabilities.
  38  */
  39 void __init mdesc_adi_init(void)
  40 {
  41         struct mdesc_handle *hp = mdesc_grab();
  42         const char *prop;
  43         u64 pn, *val;
  44         int len;
  45
  46         if (!hp)
  47                 goto adi_not_found;
  48
  49         pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
  50         if (pn == MDESC_NODE_NULL)
  51                 goto adi_not_found;
  52
  53         prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
  54         if (!prop)
  55                 goto adi_not_found;
  56
  57         /*
  58          * Look for "adp" keyword in hwcap-list which would indicate
  59          * ADI support
  60          */
  61         adi_state.enabled = false;
  62         while (len) {
  63                 int plen;
  64
  65                 if (!strcmp(prop, "adp")) {
  66                         adi_state.enabled = true;
  67                         break;
  68                 }
  69
  70                 plen = strlen(prop) + 1;
  71                 prop += plen;
  72                 len -= plen;
  73         }
  74
  75         if (!adi_state.enabled)
  76                 goto adi_not_found;
  77
  78         /* Find the ADI properties in "platform" node. If all ADI
  79          * properties are not found, ADI support is incomplete and
  80          * do not enable ADI in the kernel.
  81          */
  82         pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
  83         if (pn == MDESC_NODE_NULL)
  84                 goto adi_not_found;
  85
  86         val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
  87         if (!val)
  88                 goto adi_not_found;
  89         adi_state.caps.blksz = *val;
  90
  91         val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
  92         if (!val)
  93                 goto adi_not_found;
  94         adi_state.caps.nbits = *val;
  95
  96         val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
  97         if (!val)
  98                 goto adi_not_found;
  99         adi_state.caps.ue_on_adi = *val;
 100
 101         /* Some of the code to support swapping ADI tags is written
 102          * assumption that two ADI tags can fit inside one byte. If
 103          * this assumption is broken by a future architecture change,
 104          * that code will have to be revisited. If that were to happen,
 105          * disable ADI support so we do not get unpredictable results
 106          * with programs trying to use ADI and their pages getting
 107          * swapped out
 108          */
 109         if (adi_state.caps.nbits > 4) {
 110                 pr_warn("WARNING: ADI tag size >4 on this platform. Disabling AADI support\n");
 111                 adi_state.enabled = false;
 112         }
 113
 114         mdesc_release(hp);
 115         return;
 116
 117 adi_not_found:
 118         adi_state.enabled = false;
 119         adi_state.caps.blksz = 0;
 120         adi_state.caps.nbits = 0;
 121         if (hp)
 122                 mdesc_release(hp);
 123 }
 124
 125 tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
 126                                    struct vm_area_struct *vma,
 127                                    unsigned long addr)
 128 {
 129         tag_storage_desc_t *tag_desc = NULL;
 130         unsigned long i, max_desc, flags;
 131
 132         /* Check if this vma already has tag storage descriptor
 133          * allocated for it.
 134          */
 135         max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
 136         if (mm->context.tag_store) {
 137                 tag_desc = mm->context.tag_store;
 138                 spin_lock_irqsave(&mm->context.tag_lock, flags);
 139                 for (i = 0; i < max_desc; i++) {
 140                         if ((addr >= tag_desc->start) &&
 141                             ((addr + PAGE_SIZE - 1) <= tag_desc->end))
 142                                 break;
 143                         tag_desc++;
 144                 }
 145                 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
 146
 147                 /* If no matching entries were found, this must be a
 148                  * freshly allocated page
 149                  */
 150                 if (i >= max_desc)
 151                         tag_desc = NULL;
 152         }
 153
 154         return tag_desc;
 155 }
 156
 157 tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
 158                                     struct vm_area_struct *vma,
 159                                     unsigned long addr)
 160 {
 161         unsigned char *tags;
 162         unsigned long i, size, max_desc, flags;
 163         tag_storage_desc_t *tag_desc, *open_desc;
 164         unsigned long end_addr, hole_start, hole_end;
 165
 166         max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
 167         open_desc = NULL;
 168         hole_start = 0;
 169         hole_end = ULONG_MAX;
 170         end_addr = addr + PAGE_SIZE - 1;
 171
 172         /* Check if this vma already has tag storage descriptor
 173          * allocated for it.
 174          */
 175         spin_lock_irqsave(&mm->context.tag_lock, flags);
 176         if (mm->context.tag_store) {
 177                 tag_desc = mm->context.tag_store;
 178
 179                 /* Look for a matching entry for this address. While doing
 180                  * that, look for the first open slot as well and find
 181                  * the hole in already allocated range where this request
 182                  * will fit in.
 183                  */
 184                 for (i = 0; i < max_desc; i++) {
 185                         if (tag_desc->tag_users == 0) {
 186                                 if (open_desc == NULL)
 187                                         open_desc = tag_desc;
 188                         } else {
 189                                 if ((addr >= tag_desc->start) &&
 190                                     (tag_desc->end >= (addr + PAGE_SIZE - 1))) {
 191                                         tag_desc->tag_users++;
 192                                         goto out;
 193                                 }
 194                         }
 195                         if ((tag_desc->start > end_addr) &&
 196                             (tag_desc->start < hole_end))
 197                                 hole_end = tag_desc->start;
 198                         if ((tag_desc->end < addr) &&
 199                             (tag_desc->end > hole_start))
 200                                 hole_start = tag_desc->end;
 201                         tag_desc++;
 202                 }
 203
 204         } else {
 205                 size = sizeof(tag_storage_desc_t)*max_desc;
 206                 mm->context.tag_store = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
 207                 if (mm->context.tag_store == NULL) {
 208                         tag_desc = NULL;
 209                         goto out;
 210                 }
 211                 tag_desc = mm->context.tag_store;
 212                 for (i = 0; i < max_desc; i++, tag_desc++)
 213                         tag_desc->tag_users = 0;
 214                 open_desc = mm->context.tag_store;
 215                 i = 0;
 216         }
 217
 218         /* Check if we ran out of tag storage descriptors */
 219         if (open_desc == NULL) {
 220                 tag_desc = NULL;
 221                 goto out;
 222         }
 223
 224         /* Mark this tag descriptor slot in use and then initialize it */
 225         tag_desc = open_desc;
 226         tag_desc->tag_users = 1;
 227
 228         /* Tag storage has not been allocated for this vma and space
 229          * is available in tag storage descriptor. Since this page is
 230          * being swapped out, there is high probability subsequent pages
 231          * in the VMA will be swapped out as well. Allocate pages to
 232          * store tags for as many pages in this vma as possible but not
 233          * more than TAG_STORAGE_PAGES. Each byte in tag space holds
 234          * two ADI tags since each ADI tag is 4 bits. Each ADI tag
 235          * covers adi_blksize() worth of addresses. Check if the hole is
 236          * big enough to accommodate full address range for using
 237          * TAG_STORAGE_PAGES number of tag pages.
 238          */
 239         size = TAG_STORAGE_PAGES * PAGE_SIZE;
 240         end_addr = addr + (size*2*adi_blksize()) - 1;
 241         /* Check for overflow. If overflow occurs, allocate only one page */
 242         if (end_addr < addr) {
 243                 size = PAGE_SIZE;
 244                 end_addr = addr + (size*2*adi_blksize()) - 1;
 245                 /* If overflow happens with the minimum tag storage
 246                  * allocation as well, adjust ending address for this
 247                  * tag storage.
 248                  */
 249                 if (end_addr < addr)
 250                         end_addr = ULONG_MAX;
 251         }
 252         if (hole_end < end_addr) {
 253                 /* Available hole is too small on the upper end of
 254                  * address. Can we expand the range towards the lower
 255                  * address and maximize use of this slot?
 256                  */
 257                 unsigned long tmp_addr;
 258
 259                 end_addr = hole_end - 1;
 260                 tmp_addr = end_addr - (size*2*adi_blksize()) + 1;
 261                 /* Check for underflow. If underflow occurs, allocate
 262                  * only one page for storing ADI tags
 263                  */
 264                 if (tmp_addr > addr) {
 265                         size = PAGE_SIZE;
 266                         tmp_addr = end_addr - (size*2*adi_blksize()) - 1;
 267                         /* If underflow happens with the minimum tag storage
 268                          * allocation as well, adjust starting address for
 269                          * this tag storage.
 270                          */
 271                         if (tmp_addr > addr)
 272                                 tmp_addr = 0;
 273                 }
 274                 if (tmp_addr < hole_start) {
 275                         /* Available hole is restricted on lower address
 276                          * end as well
 277                          */
 278                         tmp_addr = hole_start + 1;
 279                 }
 280                 addr = tmp_addr;
 281                 size = (end_addr + 1 - addr)/(2*adi_blksize());
 282                 size = (size + (PAGE_SIZE-adi_blksize()))/PAGE_SIZE;
 283                 size = size * PAGE_SIZE;
 284         }
 285         tags = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
 286         if (tags == NULL) {
 287                 tag_desc->tag_users = 0;
 288                 tag_desc = NULL;
 289                 goto out;
 290         }
 291         tag_desc->start = addr;
 292         tag_desc->tags = tags;
 293         tag_desc->end = end_addr;
 294
 295 out:
 296         spin_unlock_irqrestore(&mm->context.tag_lock, flags);
 297         return tag_desc;
 298 }
 299
 300 void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
 301 {
 302         unsigned long flags;
 303         unsigned char *tags = NULL;
 304
 305         spin_lock_irqsave(&mm->context.tag_lock, flags);
 306         tag_desc->tag_users--;
 307         if (tag_desc->tag_users == 0) {
 308                 tag_desc->start = tag_desc->end = 0;
 309                 /* Do not free up the tag storage space allocated
 310                  * by the first descriptor. This is persistent
 311                  * emergency tag storage space for the task.
 312                  */
 313                 if (tag_desc != mm->context.tag_store) {
 314                         tags = tag_desc->tags;
 315                         tag_desc->tags = NULL;
 316                 }
 317         }
 318         spin_unlock_irqrestore(&mm->context.tag_lock, flags);
 319         kfree(tags);
 320 }
 321
 322 #define tag_start(addr, tag_desc)               \
 323         ((tag_desc)->tags + ((addr - (tag_desc)->start)/(2*adi_blksize())))
 324
 325 /* Retrieve any saved ADI tags for the page being swapped back in and
 326  * restore these tags to the newly allocated physical page.
 327  */
 328 void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
 329                       unsigned long addr, pte_t pte)
 330 {
 331         unsigned char *tag;
 332         tag_storage_desc_t *tag_desc;
 333         unsigned long paddr, tmp, version1, version2;
 334
 335         /* Check if the swapped out page has an ADI version
 336          * saved. If yes, restore version tag to the newly
 337          * allocated page.
 338          */
 339         tag_desc = find_tag_store(mm, vma, addr);
 340         if (tag_desc == NULL)
 341                 return;
 342
 343         tag = tag_start(addr, tag_desc);
 344         paddr = pte_val(pte) & _PAGE_PADDR_4V;
 345         for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
 346                 version1 = (*tag) >> 4;
 347                 version2 = (*tag) & 0x0f;
 348                 *tag++ = 0;
 349                 asm volatile("stxa %0, [%1] %2\n\t"
 350                         :
 351                         : "r" (version1), "r" (tmp),
 352                           "i" (ASI_MCD_REAL));
 353                 tmp += adi_blksize();
 354                 asm volatile("stxa %0, [%1] %2\n\t"
 355                         :
 356                         : "r" (version2), "r" (tmp),
 357                           "i" (ASI_MCD_REAL));
 358         }
 359         asm volatile("membar #Sync\n\t");
 360
 361         /* Check and mark this tag space for release later if
 362          * the swapped in page was the last user of tag space
 363          */
 364         del_tag_store(tag_desc, mm);
 365 }
 366
 367 /* A page is about to be swapped out. Save any ADI tags associated with
 368  * this physical page so they can be restored later when the page is swapped
 369  * back in.
 370  */
 371 int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
 372                   unsigned long addr, pte_t oldpte)
 373 {
 374         unsigned char *tag;
 375         tag_storage_desc_t *tag_desc;
 376         unsigned long version1, version2, paddr, tmp;
 377
 378         tag_desc = alloc_tag_store(mm, vma, addr);
 379         if (tag_desc == NULL)
 380                 return -1;
 381
 382         tag = tag_start(addr, tag_desc);
 383         paddr = pte_val(oldpte) & _PAGE_PADDR_4V;
 384         for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
 385                 asm volatile("ldxa [%1] %2, %0\n\t"
 386                                 : "=r" (version1)
 387                                 : "r" (tmp), "i" (ASI_MCD_REAL));
 388                 tmp += adi_blksize();
 389                 asm volatile("ldxa [%1] %2, %0\n\t"
 390                                 : "=r" (version2)
 391                                 : "r" (tmp), "i" (ASI_MCD_REAL));
 392                 *tag = (version1 << 4) | version2;
 393                 tag++;
 394         }
 395
 396         return 0;
 397 }