arch/s390/mm/kasan_init.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kasan.h>
   3 #include <linux/sched/task.h>
   4 #include <linux/memblock.h>
   5 #include <asm/pgalloc.h>
   6 #include <asm/pgtable.h>
   7 #include <asm/kasan.h>
   8 #include <asm/mem_detect.h>
   9 #include <asm/processor.h>
  10 #include <asm/sclp.h>
  11 #include <asm/facility.h>
  12 #include <asm/sections.h>
  13 #include <asm/setup.h>
  14
  15 static unsigned long segment_pos __initdata;
  16 static unsigned long segment_low __initdata;
  17 static unsigned long pgalloc_pos __initdata;
  18 static unsigned long pgalloc_low __initdata;
  19 static unsigned long pgalloc_freeable __initdata;
  20 static bool has_edat __initdata;
  21 static bool has_nx __initdata;
  22
  23 #define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x))
  24
  25 static pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
  26
  27 static void __init kasan_early_panic(const char *reason)
  28 {
  29         sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n");
  30         sclp_early_printk(reason);
  31         disabled_wait();
  32 }
  33
  34 static void * __init kasan_early_alloc_segment(void)
  35 {
  36         segment_pos -= _SEGMENT_SIZE;
  37
  38         if (segment_pos < segment_low)
  39                 kasan_early_panic("out of memory during initialisation\n");
  40
  41         return (void *)segment_pos;
  42 }
  43
  44 static void * __init kasan_early_alloc_pages(unsigned int order)
  45 {
  46         pgalloc_pos -= (PAGE_SIZE << order);
  47
  48         if (pgalloc_pos < pgalloc_low)
  49                 kasan_early_panic("out of memory during initialisation\n");
  50
  51         return (void *)pgalloc_pos;
  52 }
  53
  54 static void * __init kasan_early_crst_alloc(unsigned long val)
  55 {
  56         unsigned long *table;
  57
  58         table = kasan_early_alloc_pages(CRST_ALLOC_ORDER);
  59         if (table)
  60                 crst_table_init(table, val);
  61         return table;
  62 }
  63
  64 static pte_t * __init kasan_early_pte_alloc(void)
  65 {
  66         static void *pte_leftover;
  67         pte_t *pte;
  68
  69         BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE);
  70
  71         if (!pte_leftover) {
  72                 pte_leftover = kasan_early_alloc_pages(0);
  73                 pte = pte_leftover + _PAGE_TABLE_SIZE;
  74         } else {
  75                 pte = pte_leftover;
  76                 pte_leftover = NULL;
  77         }
  78         memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
  79         return pte;
  80 }
  81
  82 enum populate_mode {
  83         POPULATE_ONE2ONE,
  84         POPULATE_MAP,
  85         POPULATE_ZERO_SHADOW
  86 };
  87 static void __init kasan_early_vmemmap_populate(unsigned long address,
  88                                                 unsigned long end,
  89                                                 enum populate_mode mode)
  90 {
  91         unsigned long pgt_prot_zero, pgt_prot, sgt_prot;
  92         pgd_t *pg_dir;
  93         p4d_t *p4_dir;
  94         pud_t *pu_dir;
  95         pmd_t *pm_dir;
  96         pte_t *pt_dir;
  97
  98         pgt_prot_zero = pgprot_val(PAGE_KERNEL_RO);
  99         if (!has_nx)
 100                 pgt_prot_zero &= ~_PAGE_NOEXEC;
 101         pgt_prot = pgprot_val(PAGE_KERNEL_EXEC);
 102         sgt_prot = pgprot_val(SEGMENT_KERNEL_EXEC);
 103
 104         /*
 105          * The first 1MB of 1:1 mapping is mapped with 4KB pages
 106          */
 107         while (address < end) {
 108                 pg_dir = pgd_offset_k(address);
 109                 if (pgd_none(*pg_dir)) {
 110                         if (mode == POPULATE_ZERO_SHADOW &&
 111                             IS_ALIGNED(address, PGDIR_SIZE) &&
 112                             end - address >= PGDIR_SIZE) {
 113                                 pgd_populate(&init_mm, pg_dir,
 114                                                 kasan_early_shadow_p4d);
 115                                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 116                                 continue;
 117                         }
 118                         p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
 119                         pgd_populate(&init_mm, pg_dir, p4_dir);
 120                 }
 121
 122                 p4_dir = p4d_offset(pg_dir, address);
 123                 if (p4d_none(*p4_dir)) {
 124                         if (mode == POPULATE_ZERO_SHADOW &&
 125                             IS_ALIGNED(address, P4D_SIZE) &&
 126                             end - address >= P4D_SIZE) {
 127                                 p4d_populate(&init_mm, p4_dir,
 128                                                 kasan_early_shadow_pud);
 129                                 address = (address + P4D_SIZE) & P4D_MASK;
 130                                 continue;
 131                         }
 132                         pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
 133                         p4d_populate(&init_mm, p4_dir, pu_dir);
 134                 }
 135
 136                 pu_dir = pud_offset(p4_dir, address);
 137                 if (pud_none(*pu_dir)) {
 138                         if (mode == POPULATE_ZERO_SHADOW &&
 139                             IS_ALIGNED(address, PUD_SIZE) &&
 140                             end - address >= PUD_SIZE) {
 141                                 pud_populate(&init_mm, pu_dir,
 142                                                 kasan_early_shadow_pmd);
 143                                 address = (address + PUD_SIZE) & PUD_MASK;
 144                                 continue;
 145                         }
 146                         pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 147                         pud_populate(&init_mm, pu_dir, pm_dir);
 148                 }
 149
 150                 pm_dir = pmd_offset(pu_dir, address);
 151                 if (pmd_none(*pm_dir)) {
 152                         if (IS_ALIGNED(address, PMD_SIZE) &&
 153                             end - address >= PMD_SIZE) {
 154                                 if (mode == POPULATE_ZERO_SHADOW) {
 155                                         pmd_populate(&init_mm, pm_dir, kasan_early_shadow_pte);
 156                                         address = (address + PMD_SIZE) & PMD_MASK;
 157                                         continue;
 158                                 } else if (has_edat && address) {
 159                                         void *page;
 160
 161                                         if (mode == POPULATE_ONE2ONE) {
 162                                                 page = (void *)address;
 163                                         } else {
 164                                                 page = kasan_early_alloc_segment();
 165                                                 memset(page, 0, _SEGMENT_SIZE);
 166                                         }
 167                                         pmd_val(*pm_dir) = __pa(page) | sgt_prot;
 168                                         address = (address + PMD_SIZE) & PMD_MASK;
 169                                         continue;
 170                                 }
 171                         }
 172                         pt_dir = kasan_early_pte_alloc();
 173                         pmd_populate(&init_mm, pm_dir, pt_dir);
 174                 } else if (pmd_large(*pm_dir)) {
 175                         address = (address + PMD_SIZE) & PMD_MASK;
 176                         continue;
 177                 }
 178
 179                 pt_dir = pte_offset_kernel(pm_dir, address);
 180                 if (pte_none(*pt_dir)) {
 181                         void *page;
 182
 183                         switch (mode) {
 184                         case POPULATE_ONE2ONE:
 185                                 page = (void *)address;
 186                                 pte_val(*pt_dir) = __pa(page) | pgt_prot;
 187                                 break;
 188                         case POPULATE_MAP:
 189                                 page = kasan_early_alloc_pages(0);
 190                                 memset(page, 0, PAGE_SIZE);
 191                                 pte_val(*pt_dir) = __pa(page) | pgt_prot;
 192                                 break;
 193                         case POPULATE_ZERO_SHADOW:
 194                                 page = kasan_early_shadow_page;
 195                                 pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;
 196                                 break;
 197                         }
 198                 }
 199                 address += PAGE_SIZE;
 200         }
 201 }
 202
 203 static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type)
 204 {
 205         unsigned long asce_bits;
 206
 207         asce_bits = asce_type | _ASCE_TABLE_LENGTH;
 208         S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits;
 209         S390_lowcore.user_asce = S390_lowcore.kernel_asce;
 210
 211         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
 212         __ctl_load(S390_lowcore.kernel_asce, 7, 7);
 213         __ctl_load(S390_lowcore.kernel_asce, 13, 13);
 214 }
 215
 216 static void __init kasan_enable_dat(void)
 217 {
 218         psw_t psw;
 219
 220         psw.mask = __extract_psw();
 221         psw_bits(psw).dat = 1;
 222         psw_bits(psw).as = PSW_BITS_AS_HOME;
 223         __load_psw_mask(psw.mask);
 224 }
 225
 226 static void __init kasan_early_detect_facilities(void)
 227 {
 228         if (test_facility(8)) {
 229                 has_edat = true;
 230                 __ctl_set_bit(0, 23);
 231         }
 232         if (!noexec_disabled && test_facility(130)) {
 233                 has_nx = true;
 234                 __ctl_set_bit(0, 20);
 235         }
 236 }
 237
 238 void __init kasan_early_init(void)
 239 {
 240         unsigned long untracked_mem_end;
 241         unsigned long shadow_alloc_size;
 242         unsigned long initrd_end;
 243         unsigned long asce_type;
 244         unsigned long memsize;
 245         unsigned long vmax;
 246         unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO);
 247         pte_t pte_z;
 248         pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
 249         pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
 250         p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
 251
 252         kasan_early_detect_facilities();
 253         if (!has_nx)
 254                 pgt_prot &= ~_PAGE_NOEXEC;
 255         pte_z = __pte(__pa(kasan_early_shadow_page) | pgt_prot);
 256
 257         memsize = get_mem_detect_end();
 258         if (!memsize)
 259                 kasan_early_panic("cannot detect physical memory size\n");
 260         /* respect mem= cmdline parameter */
 261         if (memory_end_set && memsize > memory_end)
 262                 memsize = memory_end;
 263         if (IS_ENABLED(CONFIG_CRASH_DUMP) && OLDMEM_BASE)
 264                 memsize = min(memsize, OLDMEM_SIZE);
 265         memsize = min(memsize, KASAN_SHADOW_START);
 266
 267         if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)) {
 268                 /* 4 level paging */
 269                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
 270                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
 271                 crst_table_init((unsigned long *)early_pg_dir,
 272                                 _REGION2_ENTRY_EMPTY);
 273                 untracked_mem_end = vmax = _REGION1_SIZE;
 274                 asce_type = _ASCE_TYPE_REGION2;
 275         } else {
 276                 /* 3 level paging */
 277                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE));
 278                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE));
 279                 crst_table_init((unsigned long *)early_pg_dir,
 280                                 _REGION3_ENTRY_EMPTY);
 281                 untracked_mem_end = vmax = _REGION2_SIZE;
 282                 asce_type = _ASCE_TYPE_REGION3;
 283         }
 284
 285         /* init kasan zero shadow */
 286         crst_table_init((unsigned long *)kasan_early_shadow_p4d,
 287                                 p4d_val(p4d_z));
 288         crst_table_init((unsigned long *)kasan_early_shadow_pud,
 289                                 pud_val(pud_z));
 290         crst_table_init((unsigned long *)kasan_early_shadow_pmd,
 291                                 pmd_val(pmd_z));
 292         memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);
 293
 294         shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT;
 295         pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE);
 296         if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) {
 297                 initrd_end =
 298                     round_up(INITRD_START + INITRD_SIZE, _SEGMENT_SIZE);
 299                 pgalloc_low = max(pgalloc_low, initrd_end);
 300         }
 301
 302         if (pgalloc_low + shadow_alloc_size > memsize)
 303                 kasan_early_panic("out of memory during initialisation\n");
 304
 305         if (has_edat) {
 306                 segment_pos = round_down(memsize, _SEGMENT_SIZE);
 307                 segment_low = segment_pos - shadow_alloc_size;
 308                 pgalloc_pos = segment_low;
 309         } else {
 310                 pgalloc_pos = memsize;
 311         }
 312         init_mm.pgd = early_pg_dir;
 313         /*
 314          * Current memory layout:
 315          * +- 0 -------------+   +- shadow start -+
 316          * | 1:1 ram mapping |  /| 1/8 ram        |
 317          * +- end of ram ----+ / +----------------+
 318          * | ... gap ...     |/  |      kasan     |
 319          * +- shadow start --+   |      zero      |
 320          * | 1/8 addr space  |   |      page      |
 321          * +- shadow end    -+   |      mapping   |
 322          * | ... gap ...     |\  |    (untracked) |
 323          * +- modules vaddr -+ \ +----------------+
 324          * | 2Gb             |  \|      unmapped  | allocated per module
 325          * +-----------------+   +- shadow end ---+
 326          */
 327         /* populate kasan shadow (for identity mapping and zero page mapping) */
 328         kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
 329         if (IS_ENABLED(CONFIG_MODULES))
 330                 untracked_mem_end = vmax - MODULES_LEN;
 331         kasan_early_vmemmap_populate(__sha(max_physmem_end),
 332                                      __sha(untracked_mem_end),
 333                                      POPULATE_ZERO_SHADOW);
 334         /* memory allocated for identity mapping structs will be freed later */
 335         pgalloc_freeable = pgalloc_pos;
 336         /* populate identity mapping */
 337         kasan_early_vmemmap_populate(0, memsize, POPULATE_ONE2ONE);
 338         kasan_set_pgd(early_pg_dir, asce_type);
 339         kasan_enable_dat();
 340         /* enable kasan */
 341         init_task.kasan_depth = 0;
 342         memblock_reserve(pgalloc_pos, memsize - pgalloc_pos);
 343         sclp_early_printk("KernelAddressSanitizer initialized\n");
 344 }
 345
 346 void __init kasan_copy_shadow(pgd_t *pg_dir)
 347 {
 348         /*
 349          * At this point we are still running on early pages setup early_pg_dir,
 350          * while swapper_pg_dir has just been initialized with identity mapping.
 351          * Carry over shadow memory region from early_pg_dir to swapper_pg_dir.
 352          */
 353
 354         pgd_t *pg_dir_src;
 355         pgd_t *pg_dir_dst;
 356         p4d_t *p4_dir_src;
 357         p4d_t *p4_dir_dst;
 358         pud_t *pu_dir_src;
 359         pud_t *pu_dir_dst;
 360
 361         pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START);
 362         pg_dir_dst = pgd_offset_raw(pg_dir, KASAN_SHADOW_START);
 363         p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START);
 364         p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START);
 365         if (!p4d_folded(*p4_dir_src)) {
 366                 /* 4 level paging */
 367                 memcpy(p4_dir_dst, p4_dir_src,
 368                        (KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t));
 369                 return;
 370         }
 371         /* 3 level paging */
 372         pu_dir_src = pud_offset(p4_dir_src, KASAN_SHADOW_START);
 373         pu_dir_dst = pud_offset(p4_dir_dst, KASAN_SHADOW_START);
 374         memcpy(pu_dir_dst, pu_dir_src,
 375                (KASAN_SHADOW_SIZE >> PUD_SHIFT) * sizeof(pud_t));
 376 }
 377
 378 void __init kasan_free_early_identity(void)
 379 {
 380         memblock_free(pgalloc_pos, pgalloc_freeable - pgalloc_pos);
 381 }