arch/sparc/kernel/adi_64.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* adi_64.c: support for ADI (Application Data Integrity) feature on
   3  * sparc m7 and newer processors. This feature is also known as
   4  * SSM (Silicon Secured Memory).
   5  *
   6  * Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
   7  * Author: Khalid Aziz (khalid.aziz@oracle.com)
   8  */
   9 #include <linux/init.h>
  10 #include <linux/slab.h>
  11 #include <linux/mm_types.h>
  12 #include <asm/mdesc.h>
  13 #include <asm/adi_64.h>
  14 #include <asm/mmu_64.h>
  15 #include <asm/pgtable_64.h>
  16
  17 /* Each page of storage for ADI tags can accommodate tags for 128
  18  * pages. When ADI enabled pages are being swapped out, it would be
  19  * prudent to allocate at least enough tag storage space to accommodate
  20  * SWAPFILE_CLUSTER number of pages. Allocate enough tag storage to
  21  * store tags for four SWAPFILE_CLUSTER pages to reduce need for
  22  * further allocations for same vma.
  23  */
  24 #define TAG_STORAGE_PAGES       8
  25
  26 struct adi_config adi_state;
  27 EXPORT_SYMBOL(adi_state);
  28
  29 /* mdesc_adi_init() : Parse machine description provided by the
  30  *      hypervisor to detect ADI capabilities
  31  *
  32  * Hypervisor reports ADI capabilities of platform in "hwcap-list" property
  33  * for "cpu" node. If the platform supports ADI, "hwcap-list" property
  34  * contains the keyword "adp". If the platform supports ADI, "platform"
  35  * node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
  36  * to describe the ADI capabilities.
  37  */
  38 void __init mdesc_adi_init(void)
  39 {
  40         struct mdesc_handle *hp = mdesc_grab();
  41         const char *prop;
  42         u64 pn, *val;
  43         int len;
  44
  45         if (!hp)
  46                 goto adi_not_found;
  47
  48         pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
  49         if (pn == MDESC_NODE_NULL)
  50                 goto adi_not_found;
  51
  52         prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
  53         if (!prop)
  54                 goto adi_not_found;
  55
  56         /*
  57          * Look for "adp" keyword in hwcap-list which would indicate
  58          * ADI support
  59          */
  60         adi_state.enabled = false;
  61         while (len) {
  62                 int plen;
  63
  64                 if (!strcmp(prop, "adp")) {
  65                         adi_state.enabled = true;
  66                         break;
  67                 }
  68
  69                 plen = strlen(prop) + 1;
  70                 prop += plen;
  71                 len -= plen;
  72         }
  73
  74         if (!adi_state.enabled)
  75                 goto adi_not_found;
  76
  77         /* Find the ADI properties in "platform" node. If all ADI
  78          * properties are not found, ADI support is incomplete and
  79          * do not enable ADI in the kernel.
  80          */
  81         pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
  82         if (pn == MDESC_NODE_NULL)
  83                 goto adi_not_found;
  84
  85         val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
  86         if (!val)
  87                 goto adi_not_found;
  88         adi_state.caps.blksz = *val;
  89
  90         val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
  91         if (!val)
  92                 goto adi_not_found;
  93         adi_state.caps.nbits = *val;
  94
  95         val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
  96         if (!val)
  97                 goto adi_not_found;
  98         adi_state.caps.ue_on_adi = *val;
  99
 100         /* Some of the code to support swapping ADI tags is written
 101          * assumption that two ADI tags can fit inside one byte. If
 102          * this assumption is broken by a future architecture change,
 103          * that code will have to be revisited. If that were to happen,
 104          * disable ADI support so we do not get unpredictable results
 105          * with programs trying to use ADI and their pages getting
 106          * swapped out
 107          */
 108         if (adi_state.caps.nbits > 4) {
 109                 pr_warn("WARNING: ADI tag size >4 on this platform. Disabling AADI support\n");
 110                 adi_state.enabled = false;
 111         }
 112
 113         mdesc_release(hp);
 114         return;
 115
 116 adi_not_found:
 117         adi_state.enabled = false;
 118         adi_state.caps.blksz = 0;
 119         adi_state.caps.nbits = 0;
 120         if (hp)
 121                 mdesc_release(hp);
 122 }
 123
 124 tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
 125                                    struct vm_area_struct *vma,
 126                                    unsigned long addr)
 127 {
 128         tag_storage_desc_t *tag_desc = NULL;
 129         unsigned long i, max_desc, flags;
 130
 131         /* Check if this vma already has tag storage descriptor
 132          * allocated for it.
 133          */
 134         max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
 135         if (mm->context.tag_store) {
 136                 tag_desc = mm->context.tag_store;
 137                 spin_lock_irqsave(&mm->context.tag_lock, flags);
 138                 for (i = 0; i < max_desc; i++) {
 139                         if ((addr >= tag_desc->start) &&
 140                             ((addr + PAGE_SIZE - 1) <= tag_desc->end))
 141                                 break;
 142                         tag_desc++;
 143                 }
 144                 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
 145
 146                 /* If no matching entries were found, this must be a
 147                  * freshly allocated page
 148                  */
 149                 if (i >= max_desc)
 150                         tag_desc = NULL;
 151         }
 152
 153         return tag_desc;
 154 }
 155
 156 tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
 157                                     struct vm_area_struct *vma,
 158                                     unsigned long addr)
 159 {
 160         unsigned char *tags;
 161         unsigned long i, size, max_desc, flags;
 162         tag_storage_desc_t *tag_desc, *open_desc;
 163         unsigned long end_addr, hole_start, hole_end;
 164
 165         max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
 166         open_desc = NULL;
 167         hole_start = 0;
 168         hole_end = ULONG_MAX;
 169         end_addr = addr + PAGE_SIZE - 1;
 170
 171         /* Check if this vma already has tag storage descriptor
 172          * allocated for it.
 173          */
 174         spin_lock_irqsave(&mm->context.tag_lock, flags);
 175         if (mm->context.tag_store) {
 176                 tag_desc = mm->context.tag_store;
 177
 178                 /* Look for a matching entry for this address. While doing
 179                  * that, look for the first open slot as well and find
 180                  * the hole in already allocated range where this request
 181                  * will fit in.
 182                  */
 183                 for (i = 0; i < max_desc; i++) {
 184                         if (tag_desc->tag_users == 0) {
 185                                 if (open_desc == NULL)
 186                                         open_desc = tag_desc;
 187                         } else {
 188                                 if ((addr >= tag_desc->start) &&
 189                                     (tag_desc->end >= (addr + PAGE_SIZE - 1))) {
 190                                         tag_desc->tag_users++;
 191                                         goto out;
 192                                 }
 193                         }
 194                         if ((tag_desc->start > end_addr) &&
 195                             (tag_desc->start < hole_end))
 196                                 hole_end = tag_desc->start;
 197                         if ((tag_desc->end < addr) &&
 198                             (tag_desc->end > hole_start))
 199                                 hole_start = tag_desc->end;
 200                         tag_desc++;
 201                 }
 202
 203         } else {
 204                 size = sizeof(tag_storage_desc_t)*max_desc;
 205                 mm->context.tag_store = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
 206                 if (mm->context.tag_store == NULL) {
 207                         tag_desc = NULL;
 208                         goto out;
 209                 }
 210                 tag_desc = mm->context.tag_store;
 211                 for (i = 0; i < max_desc; i++, tag_desc++)
 212                         tag_desc->tag_users = 0;
 213                 open_desc = mm->context.tag_store;
 214                 i = 0;
 215         }
 216
 217         /* Check if we ran out of tag storage descriptors */
 218         if (open_desc == NULL) {
 219                 tag_desc = NULL;
 220                 goto out;
 221         }
 222
 223         /* Mark this tag descriptor slot in use and then initialize it */
 224         tag_desc = open_desc;
 225         tag_desc->tag_users = 1;
 226
 227         /* Tag storage has not been allocated for this vma and space
 228          * is available in tag storage descriptor. Since this page is
 229          * being swapped out, there is high probability subsequent pages
 230          * in the VMA will be swapped out as well. Allocate pages to
 231          * store tags for as many pages in this vma as possible but not
 232          * more than TAG_STORAGE_PAGES. Each byte in tag space holds
 233          * two ADI tags since each ADI tag is 4 bits. Each ADI tag
 234          * covers adi_blksize() worth of addresses. Check if the hole is
 235          * big enough to accommodate full address range for using
 236          * TAG_STORAGE_PAGES number of tag pages.
 237          */
 238         size = TAG_STORAGE_PAGES * PAGE_SIZE;
 239         end_addr = addr + (size*2*adi_blksize()) - 1;
 240         /* Check for overflow. If overflow occurs, allocate only one page */
 241         if (end_addr < addr) {
 242                 size = PAGE_SIZE;
 243                 end_addr = addr + (size*2*adi_blksize()) - 1;
 244                 /* If overflow happens with the minimum tag storage
 245                  * allocation as well, adjust ending address for this
 246                  * tag storage.
 247                  */
 248                 if (end_addr < addr)
 249                         end_addr = ULONG_MAX;
 250         }
 251         if (hole_end < end_addr) {
 252                 /* Available hole is too small on the upper end of
 253                  * address. Can we expand the range towards the lower
 254                  * address and maximize use of this slot?
 255                  */
 256                 unsigned long tmp_addr;
 257
 258                 end_addr = hole_end - 1;
 259                 tmp_addr = end_addr - (size*2*adi_blksize()) + 1;
 260                 /* Check for underflow. If underflow occurs, allocate
 261                  * only one page for storing ADI tags
 262                  */
 263                 if (tmp_addr > addr) {
 264                         size = PAGE_SIZE;
 265                         tmp_addr = end_addr - (size*2*adi_blksize()) - 1;
 266                         /* If underflow happens with the minimum tag storage
 267                          * allocation as well, adjust starting address for
 268                          * this tag storage.
 269                          */
 270                         if (tmp_addr > addr)
 271                                 tmp_addr = 0;
 272                 }
 273                 if (tmp_addr < hole_start) {
 274                         /* Available hole is restricted on lower address
 275                          * end as well
 276                          */
 277                         tmp_addr = hole_start + 1;
 278                 }
 279                 addr = tmp_addr;
 280                 size = (end_addr + 1 - addr)/(2*adi_blksize());
 281                 size = (size + (PAGE_SIZE-adi_blksize()))/PAGE_SIZE;
 282                 size = size * PAGE_SIZE;
 283         }
 284         tags = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
 285         if (tags == NULL) {
 286                 tag_desc->tag_users = 0;
 287                 tag_desc = NULL;
 288                 goto out;
 289         }
 290         tag_desc->start = addr;
 291         tag_desc->tags = tags;
 292         tag_desc->end = end_addr;
 293
 294 out:
 295         spin_unlock_irqrestore(&mm->context.tag_lock, flags);
 296         return tag_desc;
 297 }
 298
 299 void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
 300 {
 301         unsigned long flags;
 302         unsigned char *tags = NULL;
 303
 304         spin_lock_irqsave(&mm->context.tag_lock, flags);
 305         tag_desc->tag_users--;
 306         if (tag_desc->tag_users == 0) {
 307                 tag_desc->start = tag_desc->end = 0;
 308                 /* Do not free up the tag storage space allocated
 309                  * by the first descriptor. This is persistent
 310                  * emergency tag storage space for the task.
 311                  */
 312                 if (tag_desc != mm->context.tag_store) {
 313                         tags = tag_desc->tags;
 314                         tag_desc->tags = NULL;
 315                 }
 316         }
 317         spin_unlock_irqrestore(&mm->context.tag_lock, flags);
 318         kfree(tags);
 319 }
 320
 321 #define tag_start(addr, tag_desc)               \
 322         ((tag_desc)->tags + ((addr - (tag_desc)->start)/(2*adi_blksize())))
 323
 324 /* Retrieve any saved ADI tags for the page being swapped back in and
 325  * restore these tags to the newly allocated physical page.
 326  */
 327 void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
 328                       unsigned long addr, pte_t pte)
 329 {
 330         unsigned char *tag;
 331         tag_storage_desc_t *tag_desc;
 332         unsigned long paddr, tmp, version1, version2;
 333
 334         /* Check if the swapped out page has an ADI version
 335          * saved. If yes, restore version tag to the newly
 336          * allocated page.
 337          */
 338         tag_desc = find_tag_store(mm, vma, addr);
 339         if (tag_desc == NULL)
 340                 return;
 341
 342         tag = tag_start(addr, tag_desc);
 343         paddr = pte_val(pte) & _PAGE_PADDR_4V;
 344         for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
 345                 version1 = (*tag) >> 4;
 346                 version2 = (*tag) & 0x0f;
 347                 *tag++ = 0;
 348                 asm volatile("stxa %0, [%1] %2\n\t"
 349                         :
 350                         : "r" (version1), "r" (tmp),
 351                           "i" (ASI_MCD_REAL));
 352                 tmp += adi_blksize();
 353                 asm volatile("stxa %0, [%1] %2\n\t"
 354                         :
 355                         : "r" (version2), "r" (tmp),
 356                           "i" (ASI_MCD_REAL));
 357         }
 358         asm volatile("membar #Sync\n\t");
 359
 360         /* Check and mark this tag space for release later if
 361          * the swapped in page was the last user of tag space
 362          */
 363         del_tag_store(tag_desc, mm);
 364 }
 365
 366 /* A page is about to be swapped out. Save any ADI tags associated with
 367  * this physical page so they can be restored later when the page is swapped
 368  * back in.
 369  */
 370 int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
 371                   unsigned long addr, pte_t oldpte)
 372 {
 373         unsigned char *tag;
 374         tag_storage_desc_t *tag_desc;
 375         unsigned long version1, version2, paddr, tmp;
 376
 377         tag_desc = alloc_tag_store(mm, vma, addr);
 378         if (tag_desc == NULL)
 379                 return -1;
 380
 381         tag = tag_start(addr, tag_desc);
 382         paddr = pte_val(oldpte) & _PAGE_PADDR_4V;
 383         for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
 384                 asm volatile("ldxa [%1] %2, %0\n\t"
 385                                 : "=r" (version1)
 386                                 : "r" (tmp), "i" (ASI_MCD_REAL));
 387                 tmp += adi_blksize();
 388                 asm volatile("ldxa [%1] %2, %0\n\t"
 389                                 : "=r" (version2)
 390                                 : "r" (tmp), "i" (ASI_MCD_REAL));
 391                 *tag = (version1 << 4) | version2;
 392                 tag++;
 393         }
 394
 395         return 0;
 396 }