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(0);
  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         while (address < end) {
 105                 pg_dir = pgd_offset_k(address);
 106                 if (pgd_none(*pg_dir)) {
 107                         if (mode == POPULATE_ZERO_SHADOW &&
 108                             IS_ALIGNED(address, PGDIR_SIZE) &&
 109                             end - address >= PGDIR_SIZE) {
 110                                 pgd_populate(&init_mm, pg_dir, kasan_zero_p4d);
 111                                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 112                                 continue;
 113                         }
 114                         p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
 115                         pgd_populate(&init_mm, pg_dir, p4_dir);
 116                 }
 117
 118                 p4_dir = p4d_offset(pg_dir, address);
 119                 if (p4d_none(*p4_dir)) {
 120                         if (mode == POPULATE_ZERO_SHADOW &&
 121                             IS_ALIGNED(address, P4D_SIZE) &&
 122                             end - address >= P4D_SIZE) {
 123                                 p4d_populate(&init_mm, p4_dir, kasan_zero_pud);
 124                                 address = (address + P4D_SIZE) & P4D_MASK;
 125                                 continue;
 126                         }
 127                         pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
 128                         p4d_populate(&init_mm, p4_dir, pu_dir);
 129                 }
 130
 131                 pu_dir = pud_offset(p4_dir, address);
 132                 if (pud_none(*pu_dir)) {
 133                         if (mode == POPULATE_ZERO_SHADOW &&
 134                             IS_ALIGNED(address, PUD_SIZE) &&
 135                             end - address >= PUD_SIZE) {
 136                                 pud_populate(&init_mm, pu_dir, kasan_zero_pmd);
 137                                 address = (address + PUD_SIZE) & PUD_MASK;
 138                                 continue;
 139                         }
 140                         pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 141                         pud_populate(&init_mm, pu_dir, pm_dir);
 142                 }
 143
 144                 pm_dir = pmd_offset(pu_dir, address);
 145                 if (pmd_none(*pm_dir)) {
 146                         if (mode == POPULATE_ZERO_SHADOW &&
 147                             IS_ALIGNED(address, PMD_SIZE) &&
 148                             end - address >= PMD_SIZE) {
 149                                 pmd_populate(&init_mm, pm_dir, kasan_zero_pte);
 150                                 address = (address + PMD_SIZE) & PMD_MASK;
 151                                 continue;
 152                         }
 153                         /* the first megabyte of 1:1 is mapped with 4k pages */
 154                         if (has_edat && address && end - address >= PMD_SIZE &&
 155                             mode != POPULATE_ZERO_SHADOW) {
 156                                 void *page;
 157
 158                                 if (mode == POPULATE_ONE2ONE) {
 159                                         page = (void *)address;
 160                                 } else {
 161                                         page = kasan_early_alloc_segment();
 162                                         memset(page, 0, _SEGMENT_SIZE);
 163                                 }
 164                                 pmd_val(*pm_dir) = __pa(page) | sgt_prot;
 165                                 address = (address + PMD_SIZE) & PMD_MASK;
 166                                 continue;
 167                         }
 168
 169                         pt_dir = kasan_early_pte_alloc();
 170                         pmd_populate(&init_mm, pm_dir, pt_dir);
 171                 } else if (pmd_large(*pm_dir)) {
 172                         address = (address + PMD_SIZE) & PMD_MASK;
 173                         continue;
 174                 }
 175
 176                 pt_dir = pte_offset_kernel(pm_dir, address);
 177                 if (pte_none(*pt_dir)) {
 178                         void *page;
 179
 180                         switch (mode) {
 181                         case POPULATE_ONE2ONE:
 182                                 page = (void *)address;
 183                                 pte_val(*pt_dir) = __pa(page) | pgt_prot;
 184                                 break;
 185                         case POPULATE_MAP:
 186                                 page = kasan_early_alloc_pages(0);
 187                                 memset(page, 0, PAGE_SIZE);
 188                                 pte_val(*pt_dir) = __pa(page) | pgt_prot;
 189                                 break;
 190                         case POPULATE_ZERO_SHADOW:
 191                                 page = kasan_zero_page;
 192                                 pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;
 193                                 break;
 194                         }
 195                 }
 196                 address += PAGE_SIZE;
 197         }
 198 }
 199
 200 static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type)
 201 {
 202         unsigned long asce_bits;
 203
 204         asce_bits = asce_type | _ASCE_TABLE_LENGTH;
 205         S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits;
 206         S390_lowcore.user_asce = S390_lowcore.kernel_asce;
 207
 208         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
 209         __ctl_load(S390_lowcore.kernel_asce, 7, 7);
 210         __ctl_load(S390_lowcore.kernel_asce, 13, 13);
 211 }
 212
 213 static void __init kasan_enable_dat(void)
 214 {
 215         psw_t psw;
 216
 217         psw.mask = __extract_psw();
 218         psw_bits(psw).dat = 1;
 219         psw_bits(psw).as = PSW_BITS_AS_HOME;
 220         __load_psw_mask(psw.mask);
 221 }
 222
 223 static void __init kasan_early_detect_facilities(void)
 224 {
 225         __stfle(S390_lowcore.stfle_fac_list,
 226                 ARRAY_SIZE(S390_lowcore.stfle_fac_list));
 227         if (test_facility(8)) {
 228                 has_edat = true;
 229                 __ctl_set_bit(0, 23);
 230         }
 231         if (!noexec_disabled && test_facility(130)) {
 232                 has_nx = true;
 233                 __ctl_set_bit(0, 20);
 234         }
 235 }
 236
 237 static unsigned long __init get_mem_detect_end(void)
 238 {
 239         unsigned long start;
 240         unsigned long end;
 241
 242         if (mem_detect.count) {
 243                 __get_mem_detect_block(mem_detect.count - 1, &start, &end);
 244                 return end;
 245         }
 246         return 0;
 247 }
 248
 249 void __init kasan_early_init(void)
 250 {
 251         unsigned long untracked_mem_end;
 252         unsigned long shadow_alloc_size;
 253         unsigned long initrd_end;
 254         unsigned long asce_type;
 255         unsigned long memsize;
 256         unsigned long vmax;
 257         unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO);
 258         pte_t pte_z;
 259         pmd_t pmd_z = __pmd(__pa(kasan_zero_pte) | _SEGMENT_ENTRY);
 260         pud_t pud_z = __pud(__pa(kasan_zero_pmd) | _REGION3_ENTRY);
 261         p4d_t p4d_z = __p4d(__pa(kasan_zero_pud) | _REGION2_ENTRY);
 262
 263         kasan_early_detect_facilities();
 264         if (!has_nx)
 265                 pgt_prot &= ~_PAGE_NOEXEC;
 266         pte_z = __pte(__pa(kasan_zero_page) | pgt_prot);
 267
 268         memsize = get_mem_detect_end();
 269         if (!memsize)
 270                 kasan_early_panic("cannot detect physical memory size\n");
 271         /* respect mem= cmdline parameter */
 272         if (memory_end_set && memsize > memory_end)
 273                 memsize = memory_end;
 274         memsize = min(memsize, KASAN_SHADOW_START);
 275
 276         if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)) {
 277                 /* 4 level paging */
 278                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
 279                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
 280                 crst_table_init((unsigned long *)early_pg_dir,
 281                                 _REGION2_ENTRY_EMPTY);
 282                 untracked_mem_end = vmax = _REGION1_SIZE;
 283                 asce_type = _ASCE_TYPE_REGION2;
 284         } else {
 285                 /* 3 level paging */
 286                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE));
 287                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE));
 288                 crst_table_init((unsigned long *)early_pg_dir,
 289                                 _REGION3_ENTRY_EMPTY);
 290                 untracked_mem_end = vmax = _REGION2_SIZE;
 291                 asce_type = _ASCE_TYPE_REGION3;
 292         }
 293
 294         /* init kasan zero shadow */
 295         crst_table_init((unsigned long *)kasan_zero_p4d, p4d_val(p4d_z));
 296         crst_table_init((unsigned long *)kasan_zero_pud, pud_val(pud_z));
 297         crst_table_init((unsigned long *)kasan_zero_pmd, pmd_val(pmd_z));
 298         memset64((u64 *)kasan_zero_pte, pte_val(pte_z), PTRS_PER_PTE);
 299
 300         shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT;
 301         pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE);
 302         if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) {
 303                 initrd_end =
 304                     round_up(INITRD_START + INITRD_SIZE, _SEGMENT_SIZE);
 305                 pgalloc_low = max(pgalloc_low, initrd_end);
 306         }
 307
 308         if (pgalloc_low + shadow_alloc_size > memsize)
 309                 kasan_early_panic("out of memory during initialisation\n");
 310
 311         if (has_edat) {
 312                 segment_pos = round_down(memsize, _SEGMENT_SIZE);
 313                 segment_low = segment_pos - shadow_alloc_size;
 314                 pgalloc_pos = segment_low;
 315         } else {
 316                 pgalloc_pos = memsize;
 317         }
 318         init_mm.pgd = early_pg_dir;
 319         /*
 320          * Current memory layout:
 321          * +- 0 -------------+   +- shadow start -+
 322          * | 1:1 ram mapping |  /| 1/8 ram        |
 323          * +- end of ram ----+ / +----------------+
 324          * | ... gap ...     |/  |      kasan     |
 325          * +- shadow start --+   |      zero      |
 326          * | 1/8 addr space  |   |      page      |
 327          * +- shadow end    -+   |      mapping   |
 328          * | ... gap ...     |\  |    (untracked) |
 329          * +- modules vaddr -+ \ +----------------+
 330          * | 2Gb             |  \|      unmapped  | allocated per module
 331          * +-----------------+   +- shadow end ---+
 332          */
 333         /* populate kasan shadow (for identity mapping and zero page mapping) */
 334         kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
 335         if (IS_ENABLED(CONFIG_MODULES))
 336                 untracked_mem_end = vmax - MODULES_LEN;
 337         kasan_early_vmemmap_populate(__sha(max_physmem_end),
 338                                      __sha(untracked_mem_end),
 339                                      POPULATE_ZERO_SHADOW);
 340         /* memory allocated for identity mapping structs will be freed later */
 341         pgalloc_freeable = pgalloc_pos;
 342         /* populate identity mapping */
 343         kasan_early_vmemmap_populate(0, memsize, POPULATE_ONE2ONE);
 344         kasan_set_pgd(early_pg_dir, asce_type);
 345         kasan_enable_dat();
 346         /* enable kasan */
 347         init_task.kasan_depth = 0;
 348         memblock_reserve(pgalloc_pos, memsize - pgalloc_pos);
 349         sclp_early_printk("KernelAddressSanitizer initialized\n");
 350 }
 351
 352 void __init kasan_copy_shadow(pgd_t *pg_dir)
 353 {
 354         /*
 355          * At this point we are still running on early pages setup early_pg_dir,
 356          * while swapper_pg_dir has just been initialized with identity mapping.
 357          * Carry over shadow memory region from early_pg_dir to swapper_pg_dir.
 358          */
 359
 360         pgd_t *pg_dir_src;
 361         pgd_t *pg_dir_dst;
 362         p4d_t *p4_dir_src;
 363         p4d_t *p4_dir_dst;
 364         pud_t *pu_dir_src;
 365         pud_t *pu_dir_dst;
 366
 367         pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START);
 368         pg_dir_dst = pgd_offset_raw(pg_dir, KASAN_SHADOW_START);
 369         p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START);
 370         p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START);
 371         if (!p4d_folded(*p4_dir_src)) {
 372                 /* 4 level paging */
 373                 memcpy(p4_dir_dst, p4_dir_src,
 374                        (KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t));
 375                 return;
 376         }
 377         /* 3 level paging */
 378         pu_dir_src = pud_offset(p4_dir_src, KASAN_SHADOW_START);
 379         pu_dir_dst = pud_offset(p4_dir_dst, KASAN_SHADOW_START);
 380         memcpy(pu_dir_dst, pu_dir_src,
 381                (KASAN_SHADOW_SIZE >> PUD_SHIFT) * sizeof(pud_t));
 382 }
 383
 384 void __init kasan_free_early_identity(void)
 385 {
 386         memblock_free(pgalloc_pos, pgalloc_freeable - pgalloc_pos);
 387 }