1 // SPDX-License-Identifier: GPL-2.0 2 #define boot_fmt(fmt) "startup: " fmt 3 #include <linux/string.h> 4 #include <linux/elf.h> 5 #include <asm/page-states.h> 6 #include <asm/boot_data.h> 7 #include <asm/extmem.h> 8 #include <asm/sections.h> 9 #include <asm/maccess.h> 10 #include <asm/machine.h> 11 #include <asm/sysinfo.h> 12 #include <asm/cpu_mf.h> 13 #include <asm/setup.h> 14 #include <asm/timex.h> 15 #include <asm/kasan.h> 16 #include <asm/kexec.h> 17 #include <asm/sclp.h> 18 #include <asm/diag.h> 19 #include <asm/uv.h> 20 #include <asm/abs_lowcore.h> 21 #include <asm/physmem_info.h> 22 #include "decompressor.h" 23 #include "boot.h" 24 #include "uv.h" 25 26 struct vm_layout __bootdata_preserved(vm_layout); 27 unsigned long __bootdata_preserved(__abs_lowcore); 28 unsigned long __bootdata_preserved(__memcpy_real_area); 29 pte_t *__bootdata_preserved(memcpy_real_ptep); 30 unsigned long __bootdata_preserved(VMALLOC_START); 31 unsigned long __bootdata_preserved(VMALLOC_END); 32 struct page *__bootdata_preserved(vmemmap); 33 unsigned long __bootdata_preserved(vmemmap_size); 34 unsigned long __bootdata_preserved(MODULES_VADDR); 35 unsigned long __bootdata_preserved(MODULES_END); 36 unsigned long __bootdata_preserved(max_mappable); 37 unsigned long __bootdata_preserved(page_noexec_mask); 38 unsigned long __bootdata_preserved(segment_noexec_mask); 39 unsigned long __bootdata_preserved(region_noexec_mask); 40 union tod_clock __bootdata_preserved(tod_clock_base); 41 u64 __bootdata_preserved(clock_comparator_max) = -1UL; 42 43 u64 __bootdata_preserved(stfle_fac_list[16]); 44 struct oldmem_data __bootdata_preserved(oldmem_data); 45 46 void error(char *x) 47 { 48 boot_emerg("%s\n", x); 49 boot_emerg(" -- System halted\n"); 50 disabled_wait(); 51 } 52 53 static char sysinfo_page[PAGE_SIZE] __aligned(PAGE_SIZE); 54 55 static void detect_machine_type(void) 56 { 57 struct sysinfo_3_2_2 *vmms = (struct sysinfo_3_2_2 *)&sysinfo_page; 58 59 /* Check current-configuration-level */ 60 if (stsi(NULL, 0, 0, 0) <= 2) { 61 set_machine_feature(MFEATURE_LPAR); 62 return; 63 } 64 /* Get virtual-machine cpu information. */ 65 if (stsi(vmms, 3, 2, 2) || !vmms->count) 66 return; 67 /* Detect known hypervisors */ 68 if (!memcmp(vmms->vm[0].cpi, "\xd2\xe5\xd4", 3)) 69 set_machine_feature(MFEATURE_KVM); 70 else if (!memcmp(vmms->vm[0].cpi, "\xa9\x61\xe5\xd4", 4)) 71 set_machine_feature(MFEATURE_VM); 72 } 73 74 static void detect_diag9c(void) 75 { 76 unsigned int cpu; 77 int rc = 1; 78 79 cpu = stap(); 80 asm_inline volatile( 81 " diag %[cpu],%%r0,0x9c\n" 82 "0: lhi %[rc],0\n" 83 "1:\n" 84 EX_TABLE(0b, 1b) 85 : [rc] "+d" (rc) 86 : [cpu] "d" (cpu) 87 : "cc", "memory"); 88 if (!rc) 89 set_machine_feature(MFEATURE_DIAG9C); 90 } 91 92 static void reset_tod_clock(void) 93 { 94 union tod_clock clk; 95 96 if (store_tod_clock_ext_cc(&clk) == 0) 97 return; 98 /* TOD clock not running. Set the clock to Unix Epoch. */ 99 if (set_tod_clock(TOD_UNIX_EPOCH) || store_tod_clock_ext_cc(&clk)) 100 disabled_wait(); 101 memset(&tod_clock_base, 0, sizeof(tod_clock_base)); 102 tod_clock_base.tod = TOD_UNIX_EPOCH; 103 get_lowcore()->last_update_clock = TOD_UNIX_EPOCH; 104 } 105 106 static void detect_facilities(void) 107 { 108 if (cpu_has_edat1()) 109 local_ctl_set_bit(0, CR0_EDAT_BIT); 110 page_noexec_mask = -1UL; 111 segment_noexec_mask = -1UL; 112 region_noexec_mask = -1UL; 113 if (!cpu_has_nx()) { 114 page_noexec_mask &= ~_PAGE_NOEXEC; 115 segment_noexec_mask &= ~_SEGMENT_ENTRY_NOEXEC; 116 region_noexec_mask &= ~_REGION_ENTRY_NOEXEC; 117 } 118 if (IS_ENABLED(CONFIG_PCI) && test_facility(153)) 119 set_machine_feature(MFEATURE_PCI_MIO); 120 reset_tod_clock(); 121 if (test_facility(139) && (tod_clock_base.tod >> 63)) { 122 /* Enable signed clock comparator comparisons */ 123 set_machine_feature(MFEATURE_SCC); 124 clock_comparator_max = -1UL >> 1; 125 local_ctl_set_bit(0, CR0_CLOCK_COMPARATOR_SIGN_BIT); 126 } 127 if (test_facility(50) && test_facility(73)) { 128 set_machine_feature(MFEATURE_TX); 129 local_ctl_set_bit(0, CR0_TRANSACTIONAL_EXECUTION_BIT); 130 } 131 if (cpu_has_vx()) 132 local_ctl_set_bit(0, CR0_VECTOR_BIT); 133 } 134 135 static int cmma_test_essa(void) 136 { 137 unsigned long tmp = 0; 138 int rc = 1; 139 140 /* Test ESSA_GET_STATE */ 141 asm_inline volatile( 142 " .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n" 143 "0: lhi %[rc],0\n" 144 "1:\n" 145 EX_TABLE(0b, 1b) 146 : [rc] "+d" (rc), [tmp] "+d" (tmp) 147 : [cmd] "i" (ESSA_GET_STATE) 148 : "cc", "memory"); 149 return rc; 150 } 151 152 static void cmma_init(void) 153 { 154 if (!cmma_flag) 155 return; 156 if (cmma_test_essa()) { 157 cmma_flag = 0; 158 return; 159 } 160 if (test_facility(147)) 161 cmma_flag = 2; 162 } 163 164 static void setup_lpp(void) 165 { 166 get_lowcore()->current_pid = 0; 167 get_lowcore()->lpp = LPP_MAGIC; 168 if (test_facility(40)) 169 lpp(&get_lowcore()->lpp); 170 } 171 172 #ifdef CONFIG_KERNEL_UNCOMPRESSED 173 static unsigned long mem_safe_offset(void) 174 { 175 return (unsigned long)_compressed_start; 176 } 177 178 static void deploy_kernel(void *output) 179 { 180 void *uncompressed_start = (void *)_compressed_start; 181 182 if (output == uncompressed_start) 183 return; 184 memmove(output, uncompressed_start, vmlinux.image_size); 185 memset(uncompressed_start, 0, vmlinux.image_size); 186 } 187 #endif 188 189 static void rescue_initrd(unsigned long min, unsigned long max) 190 { 191 unsigned long old_addr, addr, size; 192 193 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD)) 194 return; 195 if (!get_physmem_reserved(RR_INITRD, &addr, &size)) 196 return; 197 if (addr >= min && addr + size <= max) 198 return; 199 old_addr = addr; 200 physmem_free(RR_INITRD); 201 addr = physmem_alloc_or_die(RR_INITRD, size, 0); 202 memmove((void *)addr, (void *)old_addr, size); 203 } 204 205 static void copy_bootdata(void) 206 { 207 if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size) 208 error(".boot.data section size mismatch"); 209 memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size); 210 if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size) 211 error(".boot.preserved.data section size mismatch"); 212 memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size); 213 } 214 215 static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr, 216 unsigned long offset, unsigned long phys_offset) 217 { 218 int *reloc; 219 long loc; 220 221 /* Adjust R_390_64 relocations */ 222 for (reloc = (int *)__vmlinux_relocs_64_start; reloc < (int *)__vmlinux_relocs_64_end; reloc++) { 223 loc = (long)*reloc + phys_offset; 224 if (loc < min_addr || loc > max_addr) 225 error("64-bit relocation outside of kernel!\n"); 226 *(u64 *)loc += offset; 227 } 228 } 229 230 static void kaslr_adjust_got(unsigned long offset) 231 { 232 u64 *entry; 233 234 /* 235 * Adjust GOT entries, except for ones for undefined weak symbols 236 * that resolved to zero. This also skips the first three reserved 237 * entries on s390x that are zero. 238 */ 239 for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++) { 240 if (*entry) 241 *entry += offset; 242 } 243 } 244 245 /* 246 * Merge information from several sources into a single ident_map_size value. 247 * "ident_map_size" represents the upper limit of physical memory we may ever 248 * reach. It might not be all online memory, but also include standby (offline) 249 * memory or memory areas reserved for other means (e.g., memory devices such as 250 * virtio-mem). 251 * 252 * "ident_map_size" could be lower then actual standby/reserved or even online 253 * memory present, due to limiting factors. We should never go above this limit. 254 * It is the size of our identity mapping. 255 * 256 * Consider the following factors: 257 * 1. max_physmem_end - end of physical memory online, standby or reserved. 258 * Always >= end of the last online memory range (get_physmem_online_end()). 259 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the 260 * kernel is able to support. 261 * 3. "mem=" kernel command line option which limits physical memory usage. 262 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as 263 * crash kernel. 264 * 5. "hsa" size which is a memory limit when the kernel is executed during 265 * zfcp/nvme dump. 266 */ 267 static void setup_ident_map_size(unsigned long max_physmem_end) 268 { 269 unsigned long hsa_size; 270 271 ident_map_size = max_physmem_end; 272 if (memory_limit) 273 ident_map_size = min(ident_map_size, memory_limit); 274 ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS); 275 276 #ifdef CONFIG_CRASH_DUMP 277 if (oldmem_data.start) { 278 __kaslr_enabled = 0; 279 ident_map_size = min(ident_map_size, oldmem_data.size); 280 boot_debug("kdump memory limit: 0x%016lx\n", oldmem_data.size); 281 } else if (ipl_block_valid && is_ipl_block_dump()) { 282 __kaslr_enabled = 0; 283 if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size) { 284 ident_map_size = min(ident_map_size, hsa_size); 285 boot_debug("Stand-alone dump limit: 0x%016lx\n", hsa_size); 286 } 287 } 288 #endif 289 boot_debug("Identity map size: 0x%016lx\n", ident_map_size); 290 } 291 292 #define FIXMAP_SIZE round_up(MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore)) 293 294 static unsigned long get_vmem_size(unsigned long identity_size, 295 unsigned long vmemmap_size, 296 unsigned long vmalloc_size, 297 unsigned long rte_size) 298 { 299 unsigned long max_mappable, vsize; 300 301 max_mappable = max(identity_size, MAX_DCSS_ADDR); 302 vsize = round_up(SZ_2G + max_mappable, rte_size) + 303 round_up(vmemmap_size, rte_size) + 304 FIXMAP_SIZE + MODULES_LEN + KASLR_LEN; 305 if (IS_ENABLED(CONFIG_KMSAN)) 306 vsize += MODULES_LEN * 2; 307 return size_add(vsize, vmalloc_size); 308 } 309 310 static unsigned long setup_kernel_memory_layout(unsigned long kernel_size) 311 { 312 unsigned long vmemmap_start; 313 unsigned long kernel_start; 314 unsigned long asce_limit; 315 unsigned long rte_size; 316 unsigned long pages; 317 unsigned long vsize; 318 unsigned long vmax; 319 320 pages = ident_map_size / PAGE_SIZE; 321 /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */ 322 vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page); 323 324 /* choose kernel address space layout: 4 or 3 levels. */ 325 BUILD_BUG_ON(!IS_ALIGNED(TEXT_OFFSET, THREAD_SIZE)); 326 BUILD_BUG_ON(!IS_ALIGNED(__NO_KASLR_START_KERNEL, THREAD_SIZE)); 327 BUILD_BUG_ON(__NO_KASLR_END_KERNEL > _REGION1_SIZE); 328 vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE); 329 boot_debug("vmem size estimated: 0x%016lx\n", vsize); 330 if (IS_ENABLED(CONFIG_KASAN) || __NO_KASLR_END_KERNEL > _REGION2_SIZE || 331 (vsize > _REGION2_SIZE && kaslr_enabled())) { 332 asce_limit = _REGION1_SIZE; 333 if (__NO_KASLR_END_KERNEL > _REGION2_SIZE) { 334 rte_size = _REGION2_SIZE; 335 vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION2_SIZE); 336 } else { 337 rte_size = _REGION3_SIZE; 338 } 339 } else { 340 asce_limit = _REGION2_SIZE; 341 rte_size = _REGION3_SIZE; 342 } 343 344 /* 345 * Forcing modules and vmalloc area under the ultravisor 346 * secure storage limit, so that any vmalloc allocation 347 * we do could be used to back secure guest storage. 348 * 349 * Assume the secure storage limit always exceeds _REGION2_SIZE, 350 * otherwise asce_limit and rte_size would have been adjusted. 351 */ 352 vmax = adjust_to_uv_max(asce_limit); 353 boot_debug("%d level paging 0x%016lx vmax\n", vmax == _REGION1_SIZE ? 4 : 3, vmax); 354 #ifdef CONFIG_KASAN 355 BUILD_BUG_ON(__NO_KASLR_END_KERNEL > KASAN_SHADOW_START); 356 boot_debug("KASAN shadow area: 0x%016lx-0x%016lx\n", KASAN_SHADOW_START, KASAN_SHADOW_END); 357 /* force vmalloc and modules below kasan shadow */ 358 vmax = min(vmax, KASAN_SHADOW_START); 359 #endif 360 vsize = min(vsize, vmax); 361 if (kaslr_enabled()) { 362 unsigned long kernel_end, kaslr_len, slots, pos; 363 364 kaslr_len = max(KASLR_LEN, vmax - vsize); 365 slots = DIV_ROUND_UP(kaslr_len - kernel_size, THREAD_SIZE); 366 if (get_random(slots, &pos)) 367 pos = 0; 368 kernel_end = vmax - pos * THREAD_SIZE; 369 kernel_start = round_down(kernel_end - kernel_size, THREAD_SIZE); 370 boot_debug("Randomization range: 0x%016lx-0x%016lx\n", vmax - kaslr_len, vmax); 371 boot_debug("kernel image: 0x%016lx-0x%016lx (kaslr)\n", kernel_start, 372 kernel_size + kernel_size); 373 } else if (vmax < __NO_KASLR_END_KERNEL || vsize > __NO_KASLR_END_KERNEL) { 374 kernel_start = round_down(vmax - kernel_size, THREAD_SIZE); 375 boot_debug("kernel image: 0x%016lx-0x%016lx (constrained)\n", kernel_start, 376 kernel_start + kernel_size); 377 } else { 378 kernel_start = __NO_KASLR_START_KERNEL; 379 boot_debug("kernel image: 0x%016lx-0x%016lx (nokaslr)\n", kernel_start, 380 kernel_start + kernel_size); 381 } 382 __kaslr_offset = kernel_start; 383 boot_debug("__kaslr_offset: 0x%016lx\n", __kaslr_offset); 384 385 MODULES_END = round_down(kernel_start, _SEGMENT_SIZE); 386 MODULES_VADDR = MODULES_END - MODULES_LEN; 387 VMALLOC_END = MODULES_VADDR; 388 if (IS_ENABLED(CONFIG_KMSAN)) 389 VMALLOC_END -= MODULES_LEN * 2; 390 boot_debug("modules area: 0x%016lx-0x%016lx\n", MODULES_VADDR, MODULES_END); 391 392 /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ 393 vsize = (VMALLOC_END - FIXMAP_SIZE) / 2; 394 vsize = round_down(vsize, _SEGMENT_SIZE); 395 vmalloc_size = min(vmalloc_size, vsize); 396 if (IS_ENABLED(CONFIG_KMSAN)) { 397 /* take 2/3 of vmalloc area for KMSAN shadow and origins */ 398 vmalloc_size = round_down(vmalloc_size / 3, _SEGMENT_SIZE); 399 VMALLOC_END -= vmalloc_size * 2; 400 } 401 VMALLOC_START = VMALLOC_END - vmalloc_size; 402 boot_debug("vmalloc area: 0x%016lx-0x%016lx\n", VMALLOC_START, VMALLOC_END); 403 404 __memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE); 405 boot_debug("memcpy real area: 0x%016lx-0x%016lx\n", __memcpy_real_area, 406 __memcpy_real_area + MEMCPY_REAL_SIZE); 407 __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE, 408 sizeof(struct lowcore)); 409 boot_debug("abs lowcore: 0x%016lx-0x%016lx\n", __abs_lowcore, 410 __abs_lowcore + ABS_LOWCORE_MAP_SIZE); 411 412 /* split remaining virtual space between 1:1 mapping & vmemmap array */ 413 pages = __abs_lowcore / (PAGE_SIZE + sizeof(struct page)); 414 pages = SECTION_ALIGN_UP(pages); 415 /* keep vmemmap_start aligned to a top level region table entry */ 416 vmemmap_start = round_down(__abs_lowcore - pages * sizeof(struct page), rte_size); 417 /* make sure identity map doesn't overlay with vmemmap */ 418 ident_map_size = min(ident_map_size, vmemmap_start); 419 vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page); 420 /* make sure vmemmap doesn't overlay with absolute lowcore area */ 421 if (vmemmap_start + vmemmap_size > __abs_lowcore) { 422 vmemmap_size = SECTION_ALIGN_DOWN(ident_map_size / PAGE_SIZE) * sizeof(struct page); 423 ident_map_size = vmemmap_size / sizeof(struct page) * PAGE_SIZE; 424 } 425 vmemmap = (struct page *)vmemmap_start; 426 /* maximum address for which linear mapping could be created (DCSS, memory) */ 427 BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS)); 428 max_mappable = max(ident_map_size, MAX_DCSS_ADDR); 429 max_mappable = min(max_mappable, vmemmap_start); 430 #ifdef CONFIG_RANDOMIZE_IDENTITY_BASE 431 __identity_base = round_down(vmemmap_start - max_mappable, rte_size); 432 #endif 433 boot_debug("identity map: 0x%016lx-0x%016lx\n", __identity_base, 434 __identity_base + ident_map_size); 435 436 return asce_limit; 437 } 438 439 /* 440 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's. 441 */ 442 static void clear_bss_section(unsigned long kernel_start) 443 { 444 memset((void *)kernel_start + vmlinux.image_size, 0, vmlinux.bss_size); 445 } 446 447 /* 448 * Set vmalloc area size to an 8th of (potential) physical memory 449 * size, unless size has been set by kernel command line parameter. 450 */ 451 static void setup_vmalloc_size(void) 452 { 453 unsigned long size; 454 455 if (vmalloc_size_set) 456 return; 457 size = round_up(ident_map_size / 8, _SEGMENT_SIZE); 458 vmalloc_size = max(size, vmalloc_size); 459 } 460 461 static void kaslr_adjust_vmlinux_info(long offset) 462 { 463 vmlinux.bootdata_off += offset; 464 vmlinux.bootdata_preserved_off += offset; 465 vmlinux.got_start += offset; 466 vmlinux.got_end += offset; 467 vmlinux.init_mm_off += offset; 468 vmlinux.swapper_pg_dir_off += offset; 469 vmlinux.invalid_pg_dir_off += offset; 470 vmlinux.alt_instructions += offset; 471 vmlinux.alt_instructions_end += offset; 472 #ifdef CONFIG_KASAN 473 vmlinux.kasan_early_shadow_page_off += offset; 474 vmlinux.kasan_early_shadow_pte_off += offset; 475 vmlinux.kasan_early_shadow_pmd_off += offset; 476 vmlinux.kasan_early_shadow_pud_off += offset; 477 vmlinux.kasan_early_shadow_p4d_off += offset; 478 #endif 479 } 480 481 void startup_kernel(void) 482 { 483 unsigned long vmlinux_size = vmlinux.image_size + vmlinux.bss_size; 484 unsigned long nokaslr_text_lma, text_lma = 0, amode31_lma = 0; 485 unsigned long kernel_size = TEXT_OFFSET + vmlinux_size; 486 unsigned long kaslr_large_page_offset; 487 unsigned long max_physmem_end; 488 unsigned long asce_limit; 489 unsigned long safe_addr; 490 psw_t psw; 491 492 setup_lpp(); 493 store_ipl_parmblock(); 494 uv_query_info(); 495 setup_boot_command_line(); 496 parse_boot_command_line(); 497 498 /* 499 * Non-randomized kernel physical start address must be _SEGMENT_SIZE 500 * aligned (see blow). 501 */ 502 nokaslr_text_lma = ALIGN(mem_safe_offset(), _SEGMENT_SIZE); 503 safe_addr = PAGE_ALIGN(nokaslr_text_lma + vmlinux_size); 504 505 /* 506 * Reserve decompressor memory together with decompression heap, 507 * buffer and memory which might be occupied by uncompressed kernel 508 * (if KASLR is off or failed). 509 */ 510 physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr); 511 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size) 512 physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size); 513 oldmem_data.start = parmarea.oldmem_base; 514 oldmem_data.size = parmarea.oldmem_size; 515 516 read_ipl_report(); 517 sclp_early_read_info(); 518 sclp_early_detect_machine_features(); 519 detect_facilities(); 520 detect_diag9c(); 521 detect_machine_type(); 522 cmma_init(); 523 sanitize_prot_virt_host(); 524 max_physmem_end = detect_max_physmem_end(); 525 setup_ident_map_size(max_physmem_end); 526 setup_vmalloc_size(); 527 asce_limit = setup_kernel_memory_layout(kernel_size); 528 /* got final ident_map_size, physmem allocations could be performed now */ 529 physmem_set_usable_limit(ident_map_size); 530 detect_physmem_online_ranges(max_physmem_end); 531 save_ipl_cert_comp_list(); 532 rescue_initrd(safe_addr, ident_map_size); 533 534 /* 535 * __kaslr_offset_phys must be _SEGMENT_SIZE aligned, so the lower 536 * 20 bits (the offset within a large page) are zero. Copy the last 537 * 20 bits of __kaslr_offset, which is THREAD_SIZE aligned, to 538 * __kaslr_offset_phys. 539 * 540 * With this the last 20 bits of __kaslr_offset_phys and __kaslr_offset 541 * are identical, which is required to allow for large mappings of the 542 * kernel image. 543 */ 544 kaslr_large_page_offset = __kaslr_offset & ~_SEGMENT_MASK; 545 if (kaslr_enabled()) { 546 unsigned long size = vmlinux_size + kaslr_large_page_offset; 547 548 text_lma = randomize_within_range(size, _SEGMENT_SIZE, TEXT_OFFSET, ident_map_size); 549 } 550 if (!text_lma) 551 text_lma = nokaslr_text_lma; 552 text_lma |= kaslr_large_page_offset; 553 554 /* 555 * [__kaslr_offset_phys..__kaslr_offset_phys + TEXT_OFFSET] region is 556 * never accessed via the kernel image mapping as per the linker script: 557 * 558 * . = TEXT_OFFSET; 559 * 560 * Therefore, this region could be used for something else and does 561 * not need to be reserved. See how it is skipped in setup_vmem(). 562 */ 563 __kaslr_offset_phys = text_lma - TEXT_OFFSET; 564 kaslr_adjust_vmlinux_info(__kaslr_offset_phys); 565 physmem_reserve(RR_VMLINUX, text_lma, vmlinux_size); 566 deploy_kernel((void *)text_lma); 567 568 /* vmlinux decompression is done, shrink reserved low memory */ 569 physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end); 570 571 /* 572 * In case KASLR is enabled the randomized location of .amode31 573 * section might overlap with .vmlinux.relocs section. To avoid that 574 * the below randomize_within_range() could have been called with 575 * __vmlinux_relocs_64_end as the lower range address. However, 576 * .amode31 section is written to by the decompressed kernel - at 577 * that time the contents of .vmlinux.relocs is not needed anymore. 578 * Conversely, .vmlinux.relocs is read only by the decompressor, even 579 * before the kernel started. Therefore, in case the two sections 580 * overlap there is no risk of corrupting any data. 581 */ 582 if (kaslr_enabled()) { 583 unsigned long amode31_min; 584 585 amode31_min = (unsigned long)_decompressor_end; 586 amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, amode31_min, SZ_2G); 587 } 588 if (!amode31_lma) 589 amode31_lma = text_lma - vmlinux.amode31_size; 590 physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size); 591 592 /* 593 * The order of the following operations is important: 594 * 595 * - kaslr_adjust_relocs() must follow clear_bss_section() to establish 596 * static memory references to data in .bss to be used by setup_vmem() 597 * (i.e init_mm.pgd) 598 * 599 * - setup_vmem() must follow kaslr_adjust_relocs() to be able using 600 * static memory references to data in .bss (i.e init_mm.pgd) 601 * 602 * - copy_bootdata() must follow setup_vmem() to propagate changes 603 * to bootdata made by setup_vmem() 604 */ 605 clear_bss_section(text_lma); 606 kaslr_adjust_relocs(text_lma, text_lma + vmlinux.image_size, 607 __kaslr_offset, __kaslr_offset_phys); 608 kaslr_adjust_got(__kaslr_offset); 609 setup_vmem(__kaslr_offset, __kaslr_offset + kernel_size, asce_limit); 610 dump_physmem_reserved(); 611 copy_bootdata(); 612 __apply_alternatives((struct alt_instr *)_vmlinux_info.alt_instructions, 613 (struct alt_instr *)_vmlinux_info.alt_instructions_end, 614 ALT_CTX_EARLY); 615 616 /* 617 * Save KASLR offset for early dumps, before vmcore_info is set. 618 * Mark as uneven to distinguish from real vmcore_info pointer. 619 */ 620 get_lowcore()->vmcore_info = __kaslr_offset_phys ? __kaslr_offset_phys | 0x1UL : 0; 621 622 /* 623 * Jump to the decompressed kernel entry point and switch DAT mode on. 624 */ 625 psw.addr = __kaslr_offset + vmlinux.entry; 626 psw.mask = PSW_KERNEL_BITS; 627 boot_debug("Starting kernel at: 0x%016lx\n", psw.addr); 628 __load_psw(psw); 629 } 630