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         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,
 111                                                 kasan_early_shadow_p4d);
 112                                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 113                                 continue;
 114                         }
 115                         p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
 116                         pgd_populate(&init_mm, pg_dir, p4_dir);
 117                 }
 118
 119                 p4_dir = p4d_offset(pg_dir, address);
 120                 if (p4d_none(*p4_dir)) {
 121                         if (mode == POPULATE_ZERO_SHADOW &&
 122                             IS_ALIGNED(address, P4D_SIZE) &&
 123                             end - address >= P4D_SIZE) {
 124                                 p4d_populate(&init_mm, p4_dir,
 125                                                 kasan_early_shadow_pud);
 126                                 address = (address + P4D_SIZE) & P4D_MASK;
 127                                 continue;
 128                         }
 129                         pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
 130                         p4d_populate(&init_mm, p4_dir, pu_dir);
 131                 }
 132
 133                 pu_dir = pud_offset(p4_dir, address);
 134                 if (pud_none(*pu_dir)) {
 135                         if (mode == POPULATE_ZERO_SHADOW &&
 136                             IS_ALIGNED(address, PUD_SIZE) &&
 137                             end - address >= PUD_SIZE) {
 138                                 pud_populate(&init_mm, pu_dir,
 139                                                 kasan_early_shadow_pmd);
 140                                 address = (address + PUD_SIZE) & PUD_MASK;
 141                                 continue;
 142                         }
 143                         pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 144                         pud_populate(&init_mm, pu_dir, pm_dir);
 145                 }
 146
 147                 pm_dir = pmd_offset(pu_dir, address);
 148                 if (pmd_none(*pm_dir)) {
 149                         if (mode == POPULATE_ZERO_SHADOW &&
 150                             IS_ALIGNED(address, PMD_SIZE) &&
 151                             end - address >= PMD_SIZE) {
 152                                 pmd_populate(&init_mm, pm_dir,
 153                                                 kasan_early_shadow_pte);
 154                                 address = (address + PMD_SIZE) & PMD_MASK;
 155                                 continue;
 156                         }
 157                         /* the first megabyte of 1:1 is mapped with 4k pages */
 158                         if (has_edat && address && end - address >= PMD_SIZE &&
 159                             mode != POPULATE_ZERO_SHADOW) {
 160                                 void *page;
 161
 162                                 if (mode == POPULATE_ONE2ONE) {
 163                                         page = (void *)address;
 164                                 } else {
 165                                         page = kasan_early_alloc_segment();
 166                                         memset(page, 0, _SEGMENT_SIZE);
 167                                 }
 168                                 pmd_val(*pm_dir) = __pa(page) | sgt_prot;
 169                                 address = (address + PMD_SIZE) & PMD_MASK;
 170                                 continue;
 171                         }
 172
 173                         pt_dir = kasan_early_pte_alloc();
 174                         pmd_populate(&init_mm, pm_dir, pt_dir);
 175                 } else if (pmd_large(*pm_dir)) {
 176                         address = (address + PMD_SIZE) & PMD_MASK;
 177                         continue;
 178                 }
 179
 180                 pt_dir = pte_offset_kernel(pm_dir, address);
 181                 if (pte_none(*pt_dir)) {
 182                         void *page;
 183
 184                         switch (mode) {
 185                         case POPULATE_ONE2ONE:
 186                                 page = (void *)address;
 187                                 pte_val(*pt_dir) = __pa(page) | pgt_prot;
 188                                 break;
 189                         case POPULATE_MAP:
 190                                 page = kasan_early_alloc_pages(0);
 191                                 memset(page, 0, PAGE_SIZE);
 192                                 pte_val(*pt_dir) = __pa(page) | pgt_prot;
 193                                 break;
 194                         case POPULATE_ZERO_SHADOW:
 195                                 page = kasan_early_shadow_page;
 196                                 pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;
 197                                 break;
 198                         }
 199                 }
 200                 address += PAGE_SIZE;
 201         }
 202 }
 203
 204 static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type)
 205 {
 206         unsigned long asce_bits;
 207
 208         asce_bits = asce_type | _ASCE_TABLE_LENGTH;
 209         S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits;
 210         S390_lowcore.user_asce = S390_lowcore.kernel_asce;
 211
 212         __ctl_load(S390_lowcore.kernel_asce, 1, 1);
 213         __ctl_load(S390_lowcore.kernel_asce, 7, 7);
 214         __ctl_load(S390_lowcore.kernel_asce, 13, 13);
 215 }
 216
 217 static void __init kasan_enable_dat(void)
 218 {
 219         psw_t psw;
 220
 221         psw.mask = __extract_psw();
 222         psw_bits(psw).dat = 1;
 223         psw_bits(psw).as = PSW_BITS_AS_HOME;
 224         __load_psw_mask(psw.mask);
 225 }
 226
 227 static void __init kasan_early_detect_facilities(void)
 228 {
 229         if (test_facility(8)) {
 230                 has_edat = true;
 231                 __ctl_set_bit(0, 23);
 232         }
 233         if (!noexec_disabled && test_facility(130)) {
 234                 has_nx = true;
 235                 __ctl_set_bit(0, 20);
 236         }
 237 }
 238
 239 static unsigned long __init get_mem_detect_end(void)
 240 {
 241         unsigned long start;
 242         unsigned long end;
 243
 244         if (mem_detect.count) {
 245                 __get_mem_detect_block(mem_detect.count - 1, &start, &end);
 246                 return end;
 247         }
 248         return 0;
 249 }
 250
 251 void __init kasan_early_init(void)
 252 {
 253         unsigned long untracked_mem_end;
 254         unsigned long shadow_alloc_size;
 255         unsigned long initrd_end;
 256         unsigned long asce_type;
 257         unsigned long memsize;
 258         unsigned long vmax;
 259         unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO);
 260         pte_t pte_z;
 261         pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
 262         pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
 263         p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
 264
 265         kasan_early_detect_facilities();
 266         if (!has_nx)
 267                 pgt_prot &= ~_PAGE_NOEXEC;
 268         pte_z = __pte(__pa(kasan_early_shadow_page) | pgt_prot);
 269
 270         memsize = get_mem_detect_end();
 271         if (!memsize)
 272                 kasan_early_panic("cannot detect physical memory size\n");
 273         /* respect mem= cmdline parameter */
 274         if (memory_end_set && memsize > memory_end)
 275                 memsize = memory_end;
 276         memsize = min(memsize, KASAN_SHADOW_START);
 277
 278         if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)) {
 279                 /* 4 level paging */
 280                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
 281                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
 282                 crst_table_init((unsigned long *)early_pg_dir,
 283                                 _REGION2_ENTRY_EMPTY);
 284                 untracked_mem_end = vmax = _REGION1_SIZE;
 285                 asce_type = _ASCE_TYPE_REGION2;
 286         } else {
 287                 /* 3 level paging */
 288                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE));
 289                 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE));
 290                 crst_table_init((unsigned long *)early_pg_dir,
 291                                 _REGION3_ENTRY_EMPTY);
 292                 untracked_mem_end = vmax = _REGION2_SIZE;
 293                 asce_type = _ASCE_TYPE_REGION3;
 294         }
 295
 296         /* init kasan zero shadow */
 297         crst_table_init((unsigned long *)kasan_early_shadow_p4d,
 298                                 p4d_val(p4d_z));
 299         crst_table_init((unsigned long *)kasan_early_shadow_pud,
 300                                 pud_val(pud_z));
 301         crst_table_init((unsigned long *)kasan_early_shadow_pmd,
 302                                 pmd_val(pmd_z));
 303         memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);
 304
 305         shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT;
 306         pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE);
 307         if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) {
 308                 initrd_end =
 309                     round_up(INITRD_START + INITRD_SIZE, _SEGMENT_SIZE);
 310                 pgalloc_low = max(pgalloc_low, initrd_end);
 311         }
 312
 313         if (pgalloc_low + shadow_alloc_size > memsize)
 314                 kasan_early_panic("out of memory during initialisation\n");
 315
 316         if (has_edat) {
 317                 segment_pos = round_down(memsize, _SEGMENT_SIZE);
 318                 segment_low = segment_pos - shadow_alloc_size;
 319                 pgalloc_pos = segment_low;
 320         } else {
 321                 pgalloc_pos = memsize;
 322         }
 323         init_mm.pgd = early_pg_dir;
 324         /*
 325          * Current memory layout:
 326          * +- 0 -------------+   +- shadow start -+
 327          * | 1:1 ram mapping |  /| 1/8 ram        |
 328          * +- end of ram ----+ / +----------------+
 329          * | ... gap ...     |/  |      kasan     |
 330          * +- shadow start --+   |      zero      |
 331          * | 1/8 addr space  |   |      page      |
 332          * +- shadow end    -+   |      mapping   |
 333          * | ... gap ...     |\  |    (untracked) |
 334          * +- modules vaddr -+ \ +----------------+
 335          * | 2Gb             |  \|      unmapped  | allocated per module
 336          * +-----------------+   +- shadow end ---+
 337          */
 338         /* populate kasan shadow (for identity mapping and zero page mapping) */
 339         kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
 340         if (IS_ENABLED(CONFIG_MODULES))
 341                 untracked_mem_end = vmax - MODULES_LEN;
 342         kasan_early_vmemmap_populate(__sha(max_physmem_end),
 343                                      __sha(untracked_mem_end),
 344                                      POPULATE_ZERO_SHADOW);
 345         /* memory allocated for identity mapping structs will be freed later */
 346         pgalloc_freeable = pgalloc_pos;
 347         /* populate identity mapping */
 348         kasan_early_vmemmap_populate(0, memsize, POPULATE_ONE2ONE);
 349         kasan_set_pgd(early_pg_dir, asce_type);
 350         kasan_enable_dat();
 351         /* enable kasan */
 352         init_task.kasan_depth = 0;
 353         memblock_reserve(pgalloc_pos, memsize - pgalloc_pos);
 354         sclp_early_printk("KernelAddressSanitizer initialized\n");
 355 }
 356
 357 void __init kasan_copy_shadow(pgd_t *pg_dir)
 358 {
 359         /*
 360          * At this point we are still running on early pages setup early_pg_dir,
 361          * while swapper_pg_dir has just been initialized with identity mapping.
 362          * Carry over shadow memory region from early_pg_dir to swapper_pg_dir.
 363          */
 364
 365         pgd_t *pg_dir_src;
 366         pgd_t *pg_dir_dst;
 367         p4d_t *p4_dir_src;
 368         p4d_t *p4_dir_dst;
 369         pud_t *pu_dir_src;
 370         pud_t *pu_dir_dst;
 371
 372         pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START);
 373         pg_dir_dst = pgd_offset_raw(pg_dir, KASAN_SHADOW_START);
 374         p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START);
 375         p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START);
 376         if (!p4d_folded(*p4_dir_src)) {
 377                 /* 4 level paging */
 378                 memcpy(p4_dir_dst, p4_dir_src,
 379                        (KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t));
 380                 return;
 381         }
 382         /* 3 level paging */
 383         pu_dir_src = pud_offset(p4_dir_src, KASAN_SHADOW_START);
 384         pu_dir_dst = pud_offset(p4_dir_dst, KASAN_SHADOW_START);
 385         memcpy(pu_dir_dst, pu_dir_src,
 386                (KASAN_SHADOW_SIZE >> PUD_SHIFT) * sizeof(pud_t));
 387 }
 388
 389 void __init kasan_free_early_identity(void)
 390 {
 391         memblock_free(pgalloc_pos, pgalloc_freeable - pgalloc_pos);
 392 }