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