1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Load ELF vmlinux file for the kexec_file_load syscall. 4 * 5 * Copyright (C) 2021 Huawei Technologies Co, Ltd. 6 * 7 * Author: Liao Chang (liaochang1@huawei.com) 8 * 9 * Based on kexec-tools' kexec-elf-riscv.c, heavily modified 10 * for kernel. 11 */ 12 13 #define pr_fmt(fmt) "kexec_image: " fmt 14 15 #include <linux/elf.h> 16 #include <linux/kexec.h> 17 #include <linux/slab.h> 18 #include <linux/of.h> 19 #include <linux/libfdt.h> 20 #include <linux/types.h> 21 #include <linux/memblock.h> 22 #include <asm/setup.h> 23 24 static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr, 25 struct kexec_elf_info *elf_info, unsigned long old_pbase, 26 unsigned long new_pbase) 27 { 28 int i; 29 int ret = 0; 30 size_t size; 31 struct kexec_buf kbuf; 32 const struct elf_phdr *phdr; 33 34 kbuf.image = image; 35 36 for (i = 0; i < ehdr->e_phnum; i++) { 37 phdr = &elf_info->proghdrs[i]; 38 if (phdr->p_type != PT_LOAD) 39 continue; 40 41 size = phdr->p_filesz; 42 if (size > phdr->p_memsz) 43 size = phdr->p_memsz; 44 45 kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset; 46 kbuf.bufsz = size; 47 kbuf.buf_align = phdr->p_align; 48 kbuf.mem = phdr->p_paddr - old_pbase + new_pbase; 49 kbuf.memsz = phdr->p_memsz; 50 kbuf.top_down = false; 51 ret = kexec_add_buffer(&kbuf); 52 if (ret) 53 break; 54 } 55 56 return ret; 57 } 58 59 /* 60 * Go through the available phsyical memory regions and find one that hold 61 * an image of the specified size. 62 */ 63 static int elf_find_pbase(struct kimage *image, unsigned long kernel_len, 64 struct elfhdr *ehdr, struct kexec_elf_info *elf_info, 65 unsigned long *old_pbase, unsigned long *new_pbase) 66 { 67 int i; 68 int ret; 69 struct kexec_buf kbuf; 70 const struct elf_phdr *phdr; 71 unsigned long lowest_paddr = ULONG_MAX; 72 unsigned long lowest_vaddr = ULONG_MAX; 73 74 for (i = 0; i < ehdr->e_phnum; i++) { 75 phdr = &elf_info->proghdrs[i]; 76 if (phdr->p_type != PT_LOAD) 77 continue; 78 79 if (lowest_paddr > phdr->p_paddr) 80 lowest_paddr = phdr->p_paddr; 81 82 if (lowest_vaddr > phdr->p_vaddr) 83 lowest_vaddr = phdr->p_vaddr; 84 } 85 86 kbuf.image = image; 87 kbuf.buf_min = lowest_paddr; 88 kbuf.buf_max = ULONG_MAX; 89 kbuf.buf_align = PAGE_SIZE; 90 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; 91 kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE); 92 kbuf.top_down = false; 93 ret = arch_kexec_locate_mem_hole(&kbuf); 94 if (!ret) { 95 *old_pbase = lowest_paddr; 96 *new_pbase = kbuf.mem; 97 image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem; 98 } 99 return ret; 100 } 101 102 static int get_nr_ram_ranges_callback(struct resource *res, void *arg) 103 { 104 unsigned int *nr_ranges = arg; 105 106 (*nr_ranges)++; 107 return 0; 108 } 109 110 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg) 111 { 112 struct crash_mem *cmem = arg; 113 114 cmem->ranges[cmem->nr_ranges].start = res->start; 115 cmem->ranges[cmem->nr_ranges].end = res->end; 116 cmem->nr_ranges++; 117 118 return 0; 119 } 120 121 static int prepare_elf_headers(void **addr, unsigned long *sz) 122 { 123 struct crash_mem *cmem; 124 unsigned int nr_ranges; 125 int ret; 126 127 nr_ranges = 1; /* For exclusion of crashkernel region */ 128 walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback); 129 130 cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL); 131 if (!cmem) 132 return -ENOMEM; 133 134 cmem->max_nr_ranges = nr_ranges; 135 cmem->nr_ranges = 0; 136 ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback); 137 if (ret) 138 goto out; 139 140 /* Exclude crashkernel region */ 141 ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end); 142 if (!ret) 143 ret = crash_prepare_elf64_headers(cmem, true, addr, sz); 144 145 out: 146 kfree(cmem); 147 return ret; 148 } 149 150 static char *setup_kdump_cmdline(struct kimage *image, char *cmdline, 151 unsigned long cmdline_len) 152 { 153 int elfcorehdr_strlen; 154 char *cmdline_ptr; 155 156 cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL); 157 if (!cmdline_ptr) 158 return NULL; 159 160 elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ", 161 image->elf_load_addr); 162 163 if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) { 164 pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n"); 165 kfree(cmdline_ptr); 166 return NULL; 167 } 168 169 memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len); 170 /* Ensure it's nul terminated */ 171 cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0'; 172 return cmdline_ptr; 173 } 174 175 static void *elf_kexec_load(struct kimage *image, char *kernel_buf, 176 unsigned long kernel_len, char *initrd, 177 unsigned long initrd_len, char *cmdline, 178 unsigned long cmdline_len) 179 { 180 int ret; 181 unsigned long old_kernel_pbase = ULONG_MAX; 182 unsigned long new_kernel_pbase = 0UL; 183 unsigned long initrd_pbase = 0UL; 184 unsigned long headers_sz; 185 unsigned long kernel_start; 186 void *fdt, *headers; 187 struct elfhdr ehdr; 188 struct kexec_buf kbuf; 189 struct kexec_elf_info elf_info; 190 char *modified_cmdline = NULL; 191 192 ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info); 193 if (ret) 194 return ERR_PTR(ret); 195 196 ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info, 197 &old_kernel_pbase, &new_kernel_pbase); 198 if (ret) 199 goto out; 200 kernel_start = image->start; 201 pr_notice("The entry point of kernel at 0x%lx\n", image->start); 202 203 /* Add the kernel binary to the image */ 204 ret = riscv_kexec_elf_load(image, &ehdr, &elf_info, 205 old_kernel_pbase, new_kernel_pbase); 206 if (ret) 207 goto out; 208 209 kbuf.image = image; 210 kbuf.buf_min = new_kernel_pbase + kernel_len; 211 kbuf.buf_max = ULONG_MAX; 212 213 /* Add elfcorehdr */ 214 if (image->type == KEXEC_TYPE_CRASH) { 215 ret = prepare_elf_headers(&headers, &headers_sz); 216 if (ret) { 217 pr_err("Preparing elf core header failed\n"); 218 goto out; 219 } 220 221 kbuf.buffer = headers; 222 kbuf.bufsz = headers_sz; 223 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; 224 kbuf.memsz = headers_sz; 225 kbuf.buf_align = ELF_CORE_HEADER_ALIGN; 226 kbuf.top_down = true; 227 228 ret = kexec_add_buffer(&kbuf); 229 if (ret) { 230 vfree(headers); 231 goto out; 232 } 233 image->elf_headers = headers; 234 image->elf_load_addr = kbuf.mem; 235 image->elf_headers_sz = headers_sz; 236 237 pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n", 238 image->elf_load_addr, kbuf.bufsz, kbuf.memsz); 239 240 /* Setup cmdline for kdump kernel case */ 241 modified_cmdline = setup_kdump_cmdline(image, cmdline, 242 cmdline_len); 243 if (!modified_cmdline) { 244 pr_err("Setting up cmdline for kdump kernel failed\n"); 245 ret = -EINVAL; 246 goto out; 247 } 248 cmdline = modified_cmdline; 249 } 250 251 #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY 252 /* Add purgatory to the image */ 253 kbuf.top_down = true; 254 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; 255 ret = kexec_load_purgatory(image, &kbuf); 256 if (ret) { 257 pr_err("Error loading purgatory ret=%d\n", ret); 258 goto out; 259 } 260 ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry", 261 &kernel_start, 262 sizeof(kernel_start), 0); 263 if (ret) 264 pr_err("Error update purgatory ret=%d\n", ret); 265 #endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */ 266 267 /* Add the initrd to the image */ 268 if (initrd != NULL) { 269 kbuf.buffer = initrd; 270 kbuf.bufsz = kbuf.memsz = initrd_len; 271 kbuf.buf_align = PAGE_SIZE; 272 kbuf.top_down = false; 273 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; 274 ret = kexec_add_buffer(&kbuf); 275 if (ret) 276 goto out; 277 initrd_pbase = kbuf.mem; 278 pr_notice("Loaded initrd at 0x%lx\n", initrd_pbase); 279 } 280 281 /* Add the DTB to the image */ 282 fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase, 283 initrd_len, cmdline, 0); 284 if (!fdt) { 285 pr_err("Error setting up the new device tree.\n"); 286 ret = -EINVAL; 287 goto out; 288 } 289 290 fdt_pack(fdt); 291 kbuf.buffer = fdt; 292 kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt); 293 kbuf.buf_align = PAGE_SIZE; 294 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; 295 kbuf.top_down = true; 296 ret = kexec_add_buffer(&kbuf); 297 if (ret) { 298 pr_err("Error add DTB kbuf ret=%d\n", ret); 299 goto out_free_fdt; 300 } 301 pr_notice("Loaded device tree at 0x%lx\n", kbuf.mem); 302 goto out; 303 304 out_free_fdt: 305 kvfree(fdt); 306 out: 307 kfree(modified_cmdline); 308 kexec_free_elf_info(&elf_info); 309 return ret ? ERR_PTR(ret) : NULL; 310 } 311 312 #define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1)) 313 #define RISCV_IMM_BITS 12 314 #define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS) 315 #define RISCV_CONST_HIGH_PART(x) \ 316 (((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1)) 317 #define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x)) 318 319 #define ENCODE_ITYPE_IMM(x) \ 320 (RV_X(x, 0, 12) << 20) 321 #define ENCODE_BTYPE_IMM(x) \ 322 ((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \ 323 (RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31)) 324 #define ENCODE_UTYPE_IMM(x) \ 325 (RV_X(x, 12, 20) << 12) 326 #define ENCODE_JTYPE_IMM(x) \ 327 ((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \ 328 (RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31)) 329 #define ENCODE_CBTYPE_IMM(x) \ 330 ((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \ 331 (RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12)) 332 #define ENCODE_CJTYPE_IMM(x) \ 333 ((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \ 334 (RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \ 335 (RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12)) 336 #define ENCODE_UJTYPE_IMM(x) \ 337 (ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \ 338 (ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32)) 339 #define ENCODE_UITYPE_IMM(x) \ 340 (ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32)) 341 342 #define CLEAN_IMM(type, x) \ 343 ((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x)) 344 345 int arch_kexec_apply_relocations_add(struct purgatory_info *pi, 346 Elf_Shdr *section, 347 const Elf_Shdr *relsec, 348 const Elf_Shdr *symtab) 349 { 350 const char *strtab, *name, *shstrtab; 351 const Elf_Shdr *sechdrs; 352 Elf_Rela *relas; 353 int i, r_type; 354 355 /* String & section header string table */ 356 sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff; 357 strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset; 358 shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset; 359 360 relas = (void *)pi->ehdr + relsec->sh_offset; 361 362 for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) { 363 const Elf_Sym *sym; /* symbol to relocate */ 364 unsigned long addr; /* final location after relocation */ 365 unsigned long val; /* relocated symbol value */ 366 unsigned long sec_base; /* relocated symbol value */ 367 void *loc; /* tmp location to modify */ 368 369 sym = (void *)pi->ehdr + symtab->sh_offset; 370 sym += ELF64_R_SYM(relas[i].r_info); 371 372 if (sym->st_name) 373 name = strtab + sym->st_name; 374 else 375 name = shstrtab + sechdrs[sym->st_shndx].sh_name; 376 377 loc = pi->purgatory_buf; 378 loc += section->sh_offset; 379 loc += relas[i].r_offset; 380 381 if (sym->st_shndx == SHN_ABS) 382 sec_base = 0; 383 else if (sym->st_shndx >= pi->ehdr->e_shnum) { 384 pr_err("Invalid section %d for symbol %s\n", 385 sym->st_shndx, name); 386 return -ENOEXEC; 387 } else 388 sec_base = pi->sechdrs[sym->st_shndx].sh_addr; 389 390 val = sym->st_value; 391 val += sec_base; 392 val += relas[i].r_addend; 393 394 addr = section->sh_addr + relas[i].r_offset; 395 396 r_type = ELF64_R_TYPE(relas[i].r_info); 397 398 switch (r_type) { 399 case R_RISCV_BRANCH: 400 *(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) | 401 ENCODE_BTYPE_IMM(val - addr); 402 break; 403 case R_RISCV_JAL: 404 *(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) | 405 ENCODE_JTYPE_IMM(val - addr); 406 break; 407 /* 408 * With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I 409 * sym is expected to be next to R_RISCV_PCREL_HI20 410 * in purgatory relsec. Handle it like R_RISCV_CALL 411 * sym, instead of searching the whole relsec. 412 */ 413 case R_RISCV_PCREL_HI20: 414 case R_RISCV_CALL: 415 *(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) | 416 ENCODE_UJTYPE_IMM(val - addr); 417 break; 418 case R_RISCV_RVC_BRANCH: 419 *(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) | 420 ENCODE_CBTYPE_IMM(val - addr); 421 break; 422 case R_RISCV_RVC_JUMP: 423 *(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) | 424 ENCODE_CJTYPE_IMM(val - addr); 425 break; 426 case R_RISCV_ADD32: 427 *(u32 *)loc += val; 428 break; 429 case R_RISCV_SUB32: 430 *(u32 *)loc -= val; 431 break; 432 /* It has been applied by R_RISCV_PCREL_HI20 sym */ 433 case R_RISCV_PCREL_LO12_I: 434 case R_RISCV_ALIGN: 435 case R_RISCV_RELAX: 436 break; 437 default: 438 pr_err("Unknown rela relocation: %d\n", r_type); 439 return -ENOEXEC; 440 } 441 } 442 return 0; 443 } 444 445 const struct kexec_file_ops elf_kexec_ops = { 446 .probe = kexec_elf_probe, 447 .load = elf_kexec_load, 448 }; 449