1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/string.h> 3 #include <linux/elf.h> 4 #include <asm/page-states.h> 5 #include <asm/boot_data.h> 6 #include <asm/extmem.h> 7 #include <asm/sections.h> 8 #include <asm/maccess.h> 9 #include <asm/cpu_mf.h> 10 #include <asm/setup.h> 11 #include <asm/kasan.h> 12 #include <asm/kexec.h> 13 #include <asm/sclp.h> 14 #include <asm/diag.h> 15 #include <asm/uv.h> 16 #include <asm/abs_lowcore.h> 17 #include <asm/physmem_info.h> 18 #include "decompressor.h" 19 #include "boot.h" 20 #include "uv.h" 21 22 struct vm_layout __bootdata_preserved(vm_layout); 23 unsigned long __bootdata_preserved(__abs_lowcore); 24 unsigned long __bootdata_preserved(__memcpy_real_area); 25 pte_t *__bootdata_preserved(memcpy_real_ptep); 26 unsigned long __bootdata_preserved(VMALLOC_START); 27 unsigned long __bootdata_preserved(VMALLOC_END); 28 struct page *__bootdata_preserved(vmemmap); 29 unsigned long __bootdata_preserved(vmemmap_size); 30 unsigned long __bootdata_preserved(MODULES_VADDR); 31 unsigned long __bootdata_preserved(MODULES_END); 32 unsigned long __bootdata_preserved(max_mappable); 33 34 u64 __bootdata_preserved(stfle_fac_list[16]); 35 u64 __bootdata_preserved(alt_stfle_fac_list[16]); 36 struct oldmem_data __bootdata_preserved(oldmem_data); 37 38 struct machine_info machine; 39 40 void error(char *x) 41 { 42 sclp_early_printk("\n\n"); 43 sclp_early_printk(x); 44 sclp_early_printk("\n\n -- System halted"); 45 46 disabled_wait(); 47 } 48 49 static void detect_facilities(void) 50 { 51 if (test_facility(8)) { 52 machine.has_edat1 = 1; 53 local_ctl_set_bit(0, CR0_EDAT_BIT); 54 } 55 if (test_facility(78)) 56 machine.has_edat2 = 1; 57 if (test_facility(130)) 58 machine.has_nx = 1; 59 } 60 61 static int cmma_test_essa(void) 62 { 63 unsigned long reg1, reg2, tmp = 0; 64 int rc = 1; 65 psw_t old; 66 67 /* Test ESSA_GET_STATE */ 68 asm volatile( 69 " mvc 0(16,%[psw_old]),0(%[psw_pgm])\n" 70 " epsw %[reg1],%[reg2]\n" 71 " st %[reg1],0(%[psw_pgm])\n" 72 " st %[reg2],4(%[psw_pgm])\n" 73 " larl %[reg1],1f\n" 74 " stg %[reg1],8(%[psw_pgm])\n" 75 " .insn rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n" 76 " la %[rc],0\n" 77 "1: mvc 0(16,%[psw_pgm]),0(%[psw_old])\n" 78 : [reg1] "=&d" (reg1), 79 [reg2] "=&a" (reg2), 80 [rc] "+&d" (rc), 81 [tmp] "=&d" (tmp), 82 "+Q" (S390_lowcore.program_new_psw), 83 "=Q" (old) 84 : [psw_old] "a" (&old), 85 [psw_pgm] "a" (&S390_lowcore.program_new_psw), 86 [cmd] "i" (ESSA_GET_STATE) 87 : "cc", "memory"); 88 return rc; 89 } 90 91 static void cmma_init(void) 92 { 93 if (!cmma_flag) 94 return; 95 if (cmma_test_essa()) { 96 cmma_flag = 0; 97 return; 98 } 99 if (test_facility(147)) 100 cmma_flag = 2; 101 } 102 103 static void setup_lpp(void) 104 { 105 S390_lowcore.current_pid = 0; 106 S390_lowcore.lpp = LPP_MAGIC; 107 if (test_facility(40)) 108 lpp(&S390_lowcore.lpp); 109 } 110 111 #ifdef CONFIG_KERNEL_UNCOMPRESSED 112 unsigned long mem_safe_offset(void) 113 { 114 return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size; 115 } 116 #endif 117 118 static void rescue_initrd(unsigned long min, unsigned long max) 119 { 120 unsigned long old_addr, addr, size; 121 122 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD)) 123 return; 124 if (!get_physmem_reserved(RR_INITRD, &addr, &size)) 125 return; 126 if (addr >= min && addr + size <= max) 127 return; 128 old_addr = addr; 129 physmem_free(RR_INITRD); 130 addr = physmem_alloc_top_down(RR_INITRD, size, 0); 131 memmove((void *)addr, (void *)old_addr, size); 132 } 133 134 static void copy_bootdata(void) 135 { 136 if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size) 137 error(".boot.data section size mismatch"); 138 memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size); 139 if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size) 140 error(".boot.preserved.data section size mismatch"); 141 memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size); 142 } 143 144 #ifdef CONFIG_PIE_BUILD 145 static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr, 146 unsigned long offset, unsigned long phys_offset) 147 { 148 Elf64_Rela *rela_start, *rela_end, *rela; 149 int r_type, r_sym, rc; 150 Elf64_Addr loc, val; 151 Elf64_Sym *dynsym; 152 153 rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start; 154 rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end; 155 dynsym = (Elf64_Sym *) vmlinux.dynsym_start; 156 for (rela = rela_start; rela < rela_end; rela++) { 157 loc = rela->r_offset + phys_offset; 158 val = rela->r_addend; 159 r_sym = ELF64_R_SYM(rela->r_info); 160 if (r_sym) { 161 if (dynsym[r_sym].st_shndx != SHN_UNDEF) 162 val += dynsym[r_sym].st_value + offset; 163 } else { 164 /* 165 * 0 == undefined symbol table index (STN_UNDEF), 166 * used for R_390_RELATIVE, only add KASLR offset 167 */ 168 val += offset; 169 } 170 r_type = ELF64_R_TYPE(rela->r_info); 171 rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0); 172 if (rc) 173 error("Unknown relocation type"); 174 } 175 } 176 177 static void kaslr_adjust_got(unsigned long offset) {} 178 static void rescue_relocs(void) {} 179 static void free_relocs(void) {} 180 #else 181 static int *vmlinux_relocs_64_start; 182 static int *vmlinux_relocs_64_end; 183 184 static void rescue_relocs(void) 185 { 186 unsigned long size = __vmlinux_relocs_64_end - __vmlinux_relocs_64_start; 187 188 vmlinux_relocs_64_start = (void *)physmem_alloc_top_down(RR_RELOC, size, 0); 189 vmlinux_relocs_64_end = (void *)vmlinux_relocs_64_start + size; 190 memmove(vmlinux_relocs_64_start, __vmlinux_relocs_64_start, size); 191 } 192 193 static void free_relocs(void) 194 { 195 physmem_free(RR_RELOC); 196 } 197 198 static void kaslr_adjust_relocs(unsigned long min_addr, unsigned long max_addr, 199 unsigned long offset, unsigned long phys_offset) 200 { 201 int *reloc; 202 long loc; 203 204 /* Adjust R_390_64 relocations */ 205 for (reloc = vmlinux_relocs_64_start; reloc < vmlinux_relocs_64_end; reloc++) { 206 loc = (long)*reloc + phys_offset; 207 if (loc < min_addr || loc > max_addr) 208 error("64-bit relocation outside of kernel!\n"); 209 *(u64 *)loc += offset; 210 } 211 } 212 213 static void kaslr_adjust_got(unsigned long offset) 214 { 215 u64 *entry; 216 217 /* 218 * Even without -fPIE, Clang still uses a global offset table for some 219 * reason. Adjust the GOT entries. 220 */ 221 for (entry = (u64 *)vmlinux.got_start; entry < (u64 *)vmlinux.got_end; entry++) 222 *entry += offset; 223 } 224 #endif 225 226 /* 227 * Merge information from several sources into a single ident_map_size value. 228 * "ident_map_size" represents the upper limit of physical memory we may ever 229 * reach. It might not be all online memory, but also include standby (offline) 230 * memory. "ident_map_size" could be lower then actual standby or even online 231 * memory present, due to limiting factors. We should never go above this limit. 232 * It is the size of our identity mapping. 233 * 234 * Consider the following factors: 235 * 1. max_physmem_end - end of physical memory online or standby. 236 * Always >= end of the last online memory range (get_physmem_online_end()). 237 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the 238 * kernel is able to support. 239 * 3. "mem=" kernel command line option which limits physical memory usage. 240 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as 241 * crash kernel. 242 * 5. "hsa" size which is a memory limit when the kernel is executed during 243 * zfcp/nvme dump. 244 */ 245 static void setup_ident_map_size(unsigned long max_physmem_end) 246 { 247 unsigned long hsa_size; 248 249 ident_map_size = max_physmem_end; 250 if (memory_limit) 251 ident_map_size = min(ident_map_size, memory_limit); 252 ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS); 253 254 #ifdef CONFIG_CRASH_DUMP 255 if (oldmem_data.start) { 256 __kaslr_enabled = 0; 257 ident_map_size = min(ident_map_size, oldmem_data.size); 258 } else if (ipl_block_valid && is_ipl_block_dump()) { 259 __kaslr_enabled = 0; 260 if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size) 261 ident_map_size = min(ident_map_size, hsa_size); 262 } 263 #endif 264 } 265 266 #define FIXMAP_SIZE round_up(MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore)) 267 268 static unsigned long get_vmem_size(unsigned long identity_size, 269 unsigned long vmemmap_size, 270 unsigned long vmalloc_size, 271 unsigned long rte_size) 272 { 273 unsigned long max_mappable, vsize; 274 275 max_mappable = max(identity_size, MAX_DCSS_ADDR); 276 vsize = round_up(SZ_2G + max_mappable, rte_size) + 277 round_up(vmemmap_size, rte_size) + 278 FIXMAP_SIZE + MODULES_LEN + KASLR_LEN; 279 return size_add(vsize, vmalloc_size); 280 } 281 282 static unsigned long setup_kernel_memory_layout(unsigned long kernel_size) 283 { 284 unsigned long kernel_start, kernel_end; 285 unsigned long vmemmap_start; 286 unsigned long asce_limit; 287 unsigned long rte_size; 288 unsigned long pages; 289 unsigned long vsize; 290 unsigned long vmax; 291 292 pages = ident_map_size / PAGE_SIZE; 293 /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */ 294 vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page); 295 296 /* choose kernel address space layout: 4 or 3 levels. */ 297 vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE); 298 if (IS_ENABLED(CONFIG_KASAN) || (vsize > _REGION2_SIZE)) { 299 asce_limit = _REGION1_SIZE; 300 rte_size = _REGION2_SIZE; 301 vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION2_SIZE); 302 } else { 303 asce_limit = _REGION2_SIZE; 304 rte_size = _REGION3_SIZE; 305 } 306 307 /* 308 * Forcing modules and vmalloc area under the ultravisor 309 * secure storage limit, so that any vmalloc allocation 310 * we do could be used to back secure guest storage. 311 */ 312 vmax = adjust_to_uv_max(asce_limit); 313 #ifdef CONFIG_KASAN 314 /* force vmalloc and modules below kasan shadow */ 315 vmax = min(vmax, KASAN_SHADOW_START); 316 #endif 317 kernel_end = vmax; 318 if (kaslr_enabled()) { 319 unsigned long kaslr_len, slots, pos; 320 321 vsize = min(vsize, vmax); 322 kaslr_len = max(KASLR_LEN, vmax - vsize); 323 slots = DIV_ROUND_UP(kaslr_len - kernel_size, THREAD_SIZE); 324 if (get_random(slots, &pos)) 325 pos = 0; 326 kernel_end -= pos * THREAD_SIZE; 327 } 328 kernel_start = round_down(kernel_end - kernel_size, THREAD_SIZE); 329 __kaslr_offset = kernel_start; 330 331 MODULES_END = round_down(kernel_start, _SEGMENT_SIZE); 332 MODULES_VADDR = MODULES_END - MODULES_LEN; 333 VMALLOC_END = MODULES_VADDR; 334 335 /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ 336 vsize = (VMALLOC_END - FIXMAP_SIZE) / 2; 337 vsize = round_down(vsize, _SEGMENT_SIZE); 338 vmalloc_size = min(vmalloc_size, vsize); 339 VMALLOC_START = VMALLOC_END - vmalloc_size; 340 341 __memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE); 342 __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE, 343 sizeof(struct lowcore)); 344 345 /* split remaining virtual space between 1:1 mapping & vmemmap array */ 346 pages = __abs_lowcore / (PAGE_SIZE + sizeof(struct page)); 347 pages = SECTION_ALIGN_UP(pages); 348 /* keep vmemmap_start aligned to a top level region table entry */ 349 vmemmap_start = round_down(__abs_lowcore - pages * sizeof(struct page), rte_size); 350 /* make sure identity map doesn't overlay with vmemmap */ 351 ident_map_size = min(ident_map_size, vmemmap_start); 352 vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page); 353 /* make sure vmemmap doesn't overlay with absolute lowcore area */ 354 if (vmemmap_start + vmemmap_size > __abs_lowcore) { 355 vmemmap_size = SECTION_ALIGN_DOWN(ident_map_size / PAGE_SIZE) * sizeof(struct page); 356 ident_map_size = vmemmap_size / sizeof(struct page) * PAGE_SIZE; 357 } 358 vmemmap = (struct page *)vmemmap_start; 359 /* maximum address for which linear mapping could be created (DCSS, memory) */ 360 BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS)); 361 max_mappable = max(ident_map_size, MAX_DCSS_ADDR); 362 max_mappable = min(max_mappable, vmemmap_start); 363 __identity_base = round_down(vmemmap_start - max_mappable, rte_size); 364 365 return asce_limit; 366 } 367 368 /* 369 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's. 370 */ 371 static void clear_bss_section(unsigned long vmlinux_lma) 372 { 373 memset((void *)vmlinux_lma + vmlinux.image_size, 0, vmlinux.bss_size); 374 } 375 376 /* 377 * Set vmalloc area size to an 8th of (potential) physical memory 378 * size, unless size has been set by kernel command line parameter. 379 */ 380 static void setup_vmalloc_size(void) 381 { 382 unsigned long size; 383 384 if (vmalloc_size_set) 385 return; 386 size = round_up(ident_map_size / 8, _SEGMENT_SIZE); 387 vmalloc_size = max(size, vmalloc_size); 388 } 389 390 static void kaslr_adjust_vmlinux_info(unsigned long offset) 391 { 392 vmlinux.bootdata_off += offset; 393 vmlinux.bootdata_preserved_off += offset; 394 #ifdef CONFIG_PIE_BUILD 395 vmlinux.rela_dyn_start += offset; 396 vmlinux.rela_dyn_end += offset; 397 vmlinux.dynsym_start += offset; 398 #else 399 vmlinux.got_start += offset; 400 vmlinux.got_end += offset; 401 #endif 402 vmlinux.init_mm_off += offset; 403 vmlinux.swapper_pg_dir_off += offset; 404 vmlinux.invalid_pg_dir_off += offset; 405 #ifdef CONFIG_KASAN 406 vmlinux.kasan_early_shadow_page_off += offset; 407 vmlinux.kasan_early_shadow_pte_off += offset; 408 vmlinux.kasan_early_shadow_pmd_off += offset; 409 vmlinux.kasan_early_shadow_pud_off += offset; 410 vmlinux.kasan_early_shadow_p4d_off += offset; 411 #endif 412 } 413 414 void startup_kernel(void) 415 { 416 unsigned long max_physmem_end; 417 unsigned long vmlinux_lma = 0; 418 unsigned long amode31_lma = 0; 419 unsigned long kernel_size; 420 unsigned long asce_limit; 421 unsigned long safe_addr; 422 void *img; 423 psw_t psw; 424 425 setup_lpp(); 426 safe_addr = mem_safe_offset(); 427 428 /* 429 * Reserve decompressor memory together with decompression heap, buffer and 430 * memory which might be occupied by uncompressed kernel at default 1Mb 431 * position (if KASLR is off or failed). 432 */ 433 physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr); 434 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size) 435 physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size); 436 oldmem_data.start = parmarea.oldmem_base; 437 oldmem_data.size = parmarea.oldmem_size; 438 439 store_ipl_parmblock(); 440 read_ipl_report(); 441 uv_query_info(); 442 sclp_early_read_info(); 443 setup_boot_command_line(); 444 parse_boot_command_line(); 445 detect_facilities(); 446 cmma_init(); 447 sanitize_prot_virt_host(); 448 max_physmem_end = detect_max_physmem_end(); 449 setup_ident_map_size(max_physmem_end); 450 setup_vmalloc_size(); 451 kernel_size = vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size; 452 asce_limit = setup_kernel_memory_layout(kernel_size); 453 /* got final ident_map_size, physmem allocations could be performed now */ 454 physmem_set_usable_limit(ident_map_size); 455 detect_physmem_online_ranges(max_physmem_end); 456 save_ipl_cert_comp_list(); 457 rescue_initrd(safe_addr, ident_map_size); 458 rescue_relocs(); 459 460 if (kaslr_enabled()) { 461 vmlinux_lma = randomize_within_range(vmlinux.image_size + vmlinux.bss_size, 462 THREAD_SIZE, vmlinux.default_lma, 463 ident_map_size); 464 if (vmlinux_lma) { 465 __kaslr_offset_phys = vmlinux_lma - vmlinux.default_lma; 466 kaslr_adjust_vmlinux_info(__kaslr_offset_phys); 467 } 468 } 469 vmlinux_lma = vmlinux_lma ?: vmlinux.default_lma; 470 physmem_reserve(RR_VMLINUX, vmlinux_lma, vmlinux.image_size + vmlinux.bss_size); 471 472 if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) { 473 img = decompress_kernel(); 474 memmove((void *)vmlinux_lma, img, vmlinux.image_size); 475 } else if (__kaslr_offset_phys) { 476 img = (void *)vmlinux.default_lma; 477 memmove((void *)vmlinux_lma, img, vmlinux.image_size); 478 memset(img, 0, vmlinux.image_size); 479 } 480 481 /* vmlinux decompression is done, shrink reserved low memory */ 482 physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end); 483 if (kaslr_enabled()) 484 amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G); 485 amode31_lma = amode31_lma ?: vmlinux.default_lma - vmlinux.amode31_size; 486 physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size); 487 488 /* 489 * The order of the following operations is important: 490 * 491 * - kaslr_adjust_relocs() must follow clear_bss_section() to establish 492 * static memory references to data in .bss to be used by setup_vmem() 493 * (i.e init_mm.pgd) 494 * 495 * - setup_vmem() must follow kaslr_adjust_relocs() to be able using 496 * static memory references to data in .bss (i.e init_mm.pgd) 497 * 498 * - copy_bootdata() must follow setup_vmem() to propagate changes 499 * to bootdata made by setup_vmem() 500 */ 501 clear_bss_section(vmlinux_lma); 502 kaslr_adjust_relocs(vmlinux_lma, vmlinux_lma + vmlinux.image_size, 503 __kaslr_offset, __kaslr_offset_phys); 504 kaslr_adjust_got(__kaslr_offset); 505 free_relocs(); 506 setup_vmem(__kaslr_offset, __kaslr_offset + kernel_size, asce_limit); 507 copy_bootdata(); 508 509 /* 510 * Save KASLR offset for early dumps, before vmcore_info is set. 511 * Mark as uneven to distinguish from real vmcore_info pointer. 512 */ 513 S390_lowcore.vmcore_info = __kaslr_offset_phys ? __kaslr_offset_phys | 0x1UL : 0; 514 515 /* 516 * Jump to the decompressed kernel entry point and switch DAT mode on. 517 */ 518 psw.addr = __kaslr_offset + vmlinux.entry; 519 psw.mask = PSW_KERNEL_BITS; 520 __load_psw(psw); 521 } 522