1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/string.h> 3 #include <linux/elf.h> 4 #include <asm/boot_data.h> 5 #include <asm/sections.h> 6 #include <asm/maccess.h> 7 #include <asm/cpu_mf.h> 8 #include <asm/setup.h> 9 #include <asm/kasan.h> 10 #include <asm/kexec.h> 11 #include <asm/sclp.h> 12 #include <asm/diag.h> 13 #include <asm/uv.h> 14 #include <asm/abs_lowcore.h> 15 #include <asm/physmem_info.h> 16 #include "decompressor.h" 17 #include "boot.h" 18 #include "uv.h" 19 20 unsigned long __bootdata_preserved(__kaslr_offset); 21 unsigned long __bootdata_preserved(__abs_lowcore); 22 unsigned long __bootdata_preserved(__memcpy_real_area); 23 pte_t *__bootdata_preserved(memcpy_real_ptep); 24 unsigned long __bootdata_preserved(VMALLOC_START); 25 unsigned long __bootdata_preserved(VMALLOC_END); 26 struct page *__bootdata_preserved(vmemmap); 27 unsigned long __bootdata_preserved(vmemmap_size); 28 unsigned long __bootdata_preserved(MODULES_VADDR); 29 unsigned long __bootdata_preserved(MODULES_END); 30 unsigned long __bootdata_preserved(max_mappable); 31 unsigned long __bootdata(ident_map_size); 32 33 u64 __bootdata_preserved(stfle_fac_list[16]); 34 u64 __bootdata_preserved(alt_stfle_fac_list[16]); 35 struct oldmem_data __bootdata_preserved(oldmem_data); 36 37 struct machine_info machine; 38 39 void error(char *x) 40 { 41 sclp_early_printk("\n\n"); 42 sclp_early_printk(x); 43 sclp_early_printk("\n\n -- System halted"); 44 45 disabled_wait(); 46 } 47 48 static void detect_facilities(void) 49 { 50 if (test_facility(8)) { 51 machine.has_edat1 = 1; 52 __ctl_set_bit(0, 23); 53 } 54 if (test_facility(78)) 55 machine.has_edat2 = 1; 56 if (!noexec_disabled && test_facility(130)) { 57 machine.has_nx = 1; 58 __ctl_set_bit(0, 20); 59 } 60 } 61 62 static void setup_lpp(void) 63 { 64 S390_lowcore.current_pid = 0; 65 S390_lowcore.lpp = LPP_MAGIC; 66 if (test_facility(40)) 67 lpp(&S390_lowcore.lpp); 68 } 69 70 #ifdef CONFIG_KERNEL_UNCOMPRESSED 71 unsigned long mem_safe_offset(void) 72 { 73 return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size; 74 } 75 #endif 76 77 static void rescue_initrd(unsigned long min, unsigned long max) 78 { 79 unsigned long old_addr, addr, size; 80 81 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD)) 82 return; 83 if (!get_physmem_reserved(RR_INITRD, &addr, &size)) 84 return; 85 if (addr >= min && addr + size <= max) 86 return; 87 old_addr = addr; 88 physmem_free(RR_INITRD); 89 addr = physmem_alloc_top_down(RR_INITRD, size, 0); 90 memmove((void *)addr, (void *)old_addr, size); 91 } 92 93 static void copy_bootdata(void) 94 { 95 if (__boot_data_end - __boot_data_start != vmlinux.bootdata_size) 96 error(".boot.data section size mismatch"); 97 memcpy((void *)vmlinux.bootdata_off, __boot_data_start, vmlinux.bootdata_size); 98 if (__boot_data_preserved_end - __boot_data_preserved_start != vmlinux.bootdata_preserved_size) 99 error(".boot.preserved.data section size mismatch"); 100 memcpy((void *)vmlinux.bootdata_preserved_off, __boot_data_preserved_start, vmlinux.bootdata_preserved_size); 101 } 102 103 static void handle_relocs(unsigned long offset) 104 { 105 Elf64_Rela *rela_start, *rela_end, *rela; 106 int r_type, r_sym, rc; 107 Elf64_Addr loc, val; 108 Elf64_Sym *dynsym; 109 110 rela_start = (Elf64_Rela *) vmlinux.rela_dyn_start; 111 rela_end = (Elf64_Rela *) vmlinux.rela_dyn_end; 112 dynsym = (Elf64_Sym *) vmlinux.dynsym_start; 113 for (rela = rela_start; rela < rela_end; rela++) { 114 loc = rela->r_offset + offset; 115 val = rela->r_addend; 116 r_sym = ELF64_R_SYM(rela->r_info); 117 if (r_sym) { 118 if (dynsym[r_sym].st_shndx != SHN_UNDEF) 119 val += dynsym[r_sym].st_value + offset; 120 } else { 121 /* 122 * 0 == undefined symbol table index (STN_UNDEF), 123 * used for R_390_RELATIVE, only add KASLR offset 124 */ 125 val += offset; 126 } 127 r_type = ELF64_R_TYPE(rela->r_info); 128 rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0); 129 if (rc) 130 error("Unknown relocation type"); 131 } 132 } 133 134 /* 135 * Merge information from several sources into a single ident_map_size value. 136 * "ident_map_size" represents the upper limit of physical memory we may ever 137 * reach. It might not be all online memory, but also include standby (offline) 138 * memory. "ident_map_size" could be lower then actual standby or even online 139 * memory present, due to limiting factors. We should never go above this limit. 140 * It is the size of our identity mapping. 141 * 142 * Consider the following factors: 143 * 1. max_physmem_end - end of physical memory online or standby. 144 * Always >= end of the last online memory range (get_physmem_online_end()). 145 * 2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the 146 * kernel is able to support. 147 * 3. "mem=" kernel command line option which limits physical memory usage. 148 * 4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as 149 * crash kernel. 150 * 5. "hsa" size which is a memory limit when the kernel is executed during 151 * zfcp/nvme dump. 152 */ 153 static void setup_ident_map_size(unsigned long max_physmem_end) 154 { 155 unsigned long hsa_size; 156 157 ident_map_size = max_physmem_end; 158 if (memory_limit) 159 ident_map_size = min(ident_map_size, memory_limit); 160 ident_map_size = min(ident_map_size, 1UL << MAX_PHYSMEM_BITS); 161 162 #ifdef CONFIG_CRASH_DUMP 163 if (oldmem_data.start) { 164 __kaslr_enabled = 0; 165 ident_map_size = min(ident_map_size, oldmem_data.size); 166 } else if (ipl_block_valid && is_ipl_block_dump()) { 167 __kaslr_enabled = 0; 168 if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size) 169 ident_map_size = min(ident_map_size, hsa_size); 170 } 171 #endif 172 } 173 174 static unsigned long setup_kernel_memory_layout(void) 175 { 176 unsigned long vmemmap_start; 177 unsigned long asce_limit; 178 unsigned long rte_size; 179 unsigned long pages; 180 unsigned long vmax; 181 182 pages = ident_map_size / PAGE_SIZE; 183 /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */ 184 vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page); 185 186 /* choose kernel address space layout: 4 or 3 levels. */ 187 vmemmap_start = round_up(ident_map_size, _REGION3_SIZE); 188 if (IS_ENABLED(CONFIG_KASAN) || 189 vmalloc_size > _REGION2_SIZE || 190 vmemmap_start + vmemmap_size + vmalloc_size + MODULES_LEN > 191 _REGION2_SIZE) { 192 asce_limit = _REGION1_SIZE; 193 rte_size = _REGION2_SIZE; 194 } else { 195 asce_limit = _REGION2_SIZE; 196 rte_size = _REGION3_SIZE; 197 } 198 /* 199 * forcing modules and vmalloc area under the ultravisor 200 * secure storage limit, so that any vmalloc allocation 201 * we do could be used to back secure guest storage. 202 */ 203 vmax = adjust_to_uv_max(asce_limit); 204 #ifdef CONFIG_KASAN 205 /* force vmalloc and modules below kasan shadow */ 206 vmax = min(vmax, KASAN_SHADOW_START); 207 #endif 208 __memcpy_real_area = round_down(vmax - PAGE_SIZE, PAGE_SIZE); 209 __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE, 210 sizeof(struct lowcore)); 211 MODULES_END = round_down(__abs_lowcore, _SEGMENT_SIZE); 212 MODULES_VADDR = MODULES_END - MODULES_LEN; 213 VMALLOC_END = MODULES_VADDR; 214 215 /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ 216 vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE)); 217 VMALLOC_START = VMALLOC_END - vmalloc_size; 218 219 /* split remaining virtual space between 1:1 mapping & vmemmap array */ 220 pages = VMALLOC_START / (PAGE_SIZE + sizeof(struct page)); 221 pages = SECTION_ALIGN_UP(pages); 222 /* keep vmemmap_start aligned to a top level region table entry */ 223 vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size); 224 /* vmemmap_start is the future VMEM_MAX_PHYS, make sure it is within MAX_PHYSMEM */ 225 vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS); 226 /* maximum mappable address as seen by arch_get_mappable_range() */ 227 max_mappable = vmemmap_start; 228 /* make sure identity map doesn't overlay with vmemmap */ 229 ident_map_size = min(ident_map_size, vmemmap_start); 230 vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page); 231 /* make sure vmemmap doesn't overlay with vmalloc area */ 232 VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START); 233 vmemmap = (struct page *)vmemmap_start; 234 235 return asce_limit; 236 } 237 238 /* 239 * This function clears the BSS section of the decompressed Linux kernel and NOT the decompressor's. 240 */ 241 static void clear_bss_section(unsigned long vmlinux_lma) 242 { 243 memset((void *)vmlinux_lma + vmlinux.image_size, 0, vmlinux.bss_size); 244 } 245 246 /* 247 * Set vmalloc area size to an 8th of (potential) physical memory 248 * size, unless size has been set by kernel command line parameter. 249 */ 250 static void setup_vmalloc_size(void) 251 { 252 unsigned long size; 253 254 if (vmalloc_size_set) 255 return; 256 size = round_up(ident_map_size / 8, _SEGMENT_SIZE); 257 vmalloc_size = max(size, vmalloc_size); 258 } 259 260 static void offset_vmlinux_info(unsigned long offset) 261 { 262 *(unsigned long *)(&vmlinux.entry) += offset; 263 vmlinux.bootdata_off += offset; 264 vmlinux.bootdata_preserved_off += offset; 265 vmlinux.rela_dyn_start += offset; 266 vmlinux.rela_dyn_end += offset; 267 vmlinux.dynsym_start += offset; 268 vmlinux.init_mm_off += offset; 269 vmlinux.swapper_pg_dir_off += offset; 270 vmlinux.invalid_pg_dir_off += offset; 271 #ifdef CONFIG_KASAN 272 vmlinux.kasan_early_shadow_page_off += offset; 273 vmlinux.kasan_early_shadow_pte_off += offset; 274 vmlinux.kasan_early_shadow_pmd_off += offset; 275 vmlinux.kasan_early_shadow_pud_off += offset; 276 vmlinux.kasan_early_shadow_p4d_off += offset; 277 #endif 278 } 279 280 void startup_kernel(void) 281 { 282 unsigned long max_physmem_end; 283 unsigned long vmlinux_lma = 0; 284 unsigned long amode31_lma = 0; 285 unsigned long asce_limit; 286 unsigned long safe_addr; 287 void *img; 288 psw_t psw; 289 290 setup_lpp(); 291 safe_addr = mem_safe_offset(); 292 /* 293 * reserve decompressor memory together with decompression heap, buffer and 294 * memory which might be occupied by uncompressed kernel at default 1Mb 295 * position (if KASLR is off or failed). 296 */ 297 physmem_reserve(RR_DECOMPRESSOR, 0, safe_addr); 298 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && parmarea.initrd_size) 299 physmem_reserve(RR_INITRD, parmarea.initrd_start, parmarea.initrd_size); 300 oldmem_data.start = parmarea.oldmem_base; 301 oldmem_data.size = parmarea.oldmem_size; 302 303 store_ipl_parmblock(); 304 read_ipl_report(); 305 uv_query_info(); 306 sclp_early_read_info(); 307 setup_boot_command_line(); 308 parse_boot_command_line(); 309 detect_facilities(); 310 sanitize_prot_virt_host(); 311 max_physmem_end = detect_max_physmem_end(); 312 setup_ident_map_size(max_physmem_end); 313 setup_vmalloc_size(); 314 asce_limit = setup_kernel_memory_layout(); 315 /* got final ident_map_size, physmem allocations could be performed now */ 316 physmem_set_usable_limit(ident_map_size); 317 detect_physmem_online_ranges(max_physmem_end); 318 save_ipl_cert_comp_list(); 319 rescue_initrd(safe_addr, ident_map_size); 320 321 if (kaslr_enabled()) { 322 vmlinux_lma = randomize_within_range(vmlinux.image_size + vmlinux.bss_size, 323 THREAD_SIZE, vmlinux.default_lma, 324 ident_map_size); 325 if (vmlinux_lma) { 326 __kaslr_offset = vmlinux_lma - vmlinux.default_lma; 327 offset_vmlinux_info(__kaslr_offset); 328 } 329 } 330 vmlinux_lma = vmlinux_lma ?: vmlinux.default_lma; 331 physmem_reserve(RR_VMLINUX, vmlinux_lma, vmlinux.image_size + vmlinux.bss_size); 332 333 if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) { 334 img = decompress_kernel(); 335 memmove((void *)vmlinux_lma, img, vmlinux.image_size); 336 } else if (__kaslr_offset) { 337 img = (void *)vmlinux.default_lma; 338 memmove((void *)vmlinux_lma, img, vmlinux.image_size); 339 memset(img, 0, vmlinux.image_size); 340 } 341 342 /* vmlinux decompression is done, shrink reserved low memory */ 343 physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end); 344 if (kaslr_enabled()) 345 amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G); 346 amode31_lma = amode31_lma ?: vmlinux.default_lma - vmlinux.amode31_size; 347 physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size); 348 349 /* 350 * The order of the following operations is important: 351 * 352 * - handle_relocs() must follow clear_bss_section() to establish static 353 * memory references to data in .bss to be used by setup_vmem() 354 * (i.e init_mm.pgd) 355 * 356 * - setup_vmem() must follow handle_relocs() to be able using 357 * static memory references to data in .bss (i.e init_mm.pgd) 358 * 359 * - copy_bootdata() must follow setup_vmem() to propagate changes to 360 * bootdata made by setup_vmem() 361 */ 362 clear_bss_section(vmlinux_lma); 363 handle_relocs(__kaslr_offset); 364 setup_vmem(asce_limit); 365 copy_bootdata(); 366 367 /* 368 * Save KASLR offset for early dumps, before vmcore_info is set. 369 * Mark as uneven to distinguish from real vmcore_info pointer. 370 */ 371 S390_lowcore.vmcore_info = __kaslr_offset ? __kaslr_offset | 0x1UL : 0; 372 373 /* 374 * Jump to the decompressed kernel entry point and switch DAT mode on. 375 */ 376 psw.addr = vmlinux.entry; 377 psw.mask = PSW_KERNEL_BITS; 378 __load_psw(psw); 379 } 380