arch/riscv/kernel/elf_kexec.c

   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 ([email protected])
   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 int arch_kimage_file_post_load_cleanup(struct kimage *image)
  25 {
  26         kvfree(image->arch.fdt);
  27         image->arch.fdt = NULL;
  28
  29         vfree(image->elf_headers);
  30         image->elf_headers = NULL;
  31         image->elf_headers_sz = 0;
  32
  33         return kexec_image_post_load_cleanup_default(image);
  34 }
  35
  36 static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
  37                                 struct kexec_elf_info *elf_info, unsigned long old_pbase,
  38                                 unsigned long new_pbase)
  39 {
  40         int i;
  41         int ret = 0;
  42         size_t size;
  43         struct kexec_buf kbuf;
  44         const struct elf_phdr *phdr;
  45
  46         kbuf.image = image;
  47
  48         for (i = 0; i < ehdr->e_phnum; i++) {
  49                 phdr = &elf_info->proghdrs[i];
  50                 if (phdr->p_type != PT_LOAD)
  51                         continue;
  52
  53                 size = phdr->p_filesz;
  54                 if (size > phdr->p_memsz)
  55                         size = phdr->p_memsz;
  56
  57                 kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
  58                 kbuf.bufsz = size;
  59                 kbuf.buf_align = phdr->p_align;
  60                 kbuf.mem = phdr->p_paddr - old_pbase + new_pbase;
  61                 kbuf.memsz = phdr->p_memsz;
  62                 kbuf.top_down = false;
  63                 ret = kexec_add_buffer(&kbuf);
  64                 if (ret)
  65                         break;
  66         }
  67
  68         return ret;
  69 }
  70
  71 /*
  72  * Go through the available phsyical memory regions and find one that hold
  73  * an image of the specified size.
  74  */
  75 static int elf_find_pbase(struct kimage *image, unsigned long kernel_len,
  76                           struct elfhdr *ehdr, struct kexec_elf_info *elf_info,
  77                           unsigned long *old_pbase, unsigned long *new_pbase)
  78 {
  79         int i;
  80         int ret;
  81         struct kexec_buf kbuf;
  82         const struct elf_phdr *phdr;
  83         unsigned long lowest_paddr = ULONG_MAX;
  84         unsigned long lowest_vaddr = ULONG_MAX;
  85
  86         for (i = 0; i < ehdr->e_phnum; i++) {
  87                 phdr = &elf_info->proghdrs[i];
  88                 if (phdr->p_type != PT_LOAD)
  89                         continue;
  90
  91                 if (lowest_paddr > phdr->p_paddr)
  92                         lowest_paddr = phdr->p_paddr;
  93
  94                 if (lowest_vaddr > phdr->p_vaddr)
  95                         lowest_vaddr = phdr->p_vaddr;
  96         }
  97
  98         kbuf.image = image;
  99         kbuf.buf_min = lowest_paddr;
 100         kbuf.buf_max = ULONG_MAX;
 101         kbuf.buf_align = PAGE_SIZE;
 102         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 103         kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
 104         kbuf.top_down = false;
 105         ret = arch_kexec_locate_mem_hole(&kbuf);
 106         if (!ret) {
 107                 *old_pbase = lowest_paddr;
 108                 *new_pbase = kbuf.mem;
 109                 image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
 110         }
 111         return ret;
 112 }
 113
 114 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
 115 {
 116         unsigned int *nr_ranges = arg;
 117
 118         (*nr_ranges)++;
 119         return 0;
 120 }
 121
 122 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 123 {
 124         struct crash_mem *cmem = arg;
 125
 126         cmem->ranges[cmem->nr_ranges].start = res->start;
 127         cmem->ranges[cmem->nr_ranges].end = res->end;
 128         cmem->nr_ranges++;
 129
 130         return 0;
 131 }
 132
 133 static int prepare_elf_headers(void **addr, unsigned long *sz)
 134 {
 135         struct crash_mem *cmem;
 136         unsigned int nr_ranges;
 137         int ret;
 138
 139         nr_ranges = 1; /* For exclusion of crashkernel region */
 140         walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
 141
 142         cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
 143         if (!cmem)
 144                 return -ENOMEM;
 145
 146         cmem->max_nr_ranges = nr_ranges;
 147         cmem->nr_ranges = 0;
 148         ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
 149         if (ret)
 150                 goto out;
 151
 152         /* Exclude crashkernel region */
 153         ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
 154         if (!ret)
 155                 ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
 156
 157 out:
 158         kfree(cmem);
 159         return ret;
 160 }
 161
 162 static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
 163                                  unsigned long cmdline_len)
 164 {
 165         int elfcorehdr_strlen;
 166         char *cmdline_ptr;
 167
 168         cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
 169         if (!cmdline_ptr)
 170                 return NULL;
 171
 172         elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ",
 173                 image->elf_load_addr);
 174
 175         if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) {
 176                 pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n");
 177                 kfree(cmdline_ptr);
 178                 return NULL;
 179         }
 180
 181         memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len);
 182         /* Ensure it's nul terminated */
 183         cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0';
 184         return cmdline_ptr;
 185 }
 186
 187 static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
 188                             unsigned long kernel_len, char *initrd,
 189                             unsigned long initrd_len, char *cmdline,
 190                             unsigned long cmdline_len)
 191 {
 192         int ret;
 193         unsigned long old_kernel_pbase = ULONG_MAX;
 194         unsigned long new_kernel_pbase = 0UL;
 195         unsigned long initrd_pbase = 0UL;
 196         unsigned long headers_sz;
 197         unsigned long kernel_start;
 198         void *fdt, *headers;
 199         struct elfhdr ehdr;
 200         struct kexec_buf kbuf;
 201         struct kexec_elf_info elf_info;
 202         char *modified_cmdline = NULL;
 203
 204         ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
 205         if (ret)
 206                 return ERR_PTR(ret);
 207
 208         ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
 209                              &old_kernel_pbase, &new_kernel_pbase);
 210         if (ret)
 211                 goto out;
 212         kernel_start = image->start;
 213         pr_notice("The entry point of kernel at 0x%lx\n", image->start);
 214
 215         /* Add the kernel binary to the image */
 216         ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
 217                                    old_kernel_pbase, new_kernel_pbase);
 218         if (ret)
 219                 goto out;
 220
 221         kbuf.image = image;
 222         kbuf.buf_min = new_kernel_pbase + kernel_len;
 223         kbuf.buf_max = ULONG_MAX;
 224
 225         /* Add elfcorehdr */
 226         if (image->type == KEXEC_TYPE_CRASH) {
 227                 ret = prepare_elf_headers(&headers, &headers_sz);
 228                 if (ret) {
 229                         pr_err("Preparing elf core header failed\n");
 230                         goto out;
 231                 }
 232
 233                 kbuf.buffer = headers;
 234                 kbuf.bufsz = headers_sz;
 235                 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 236                 kbuf.memsz = headers_sz;
 237                 kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
 238                 kbuf.top_down = true;
 239
 240                 ret = kexec_add_buffer(&kbuf);
 241                 if (ret) {
 242                         vfree(headers);
 243                         goto out;
 244                 }
 245                 image->elf_headers = headers;
 246                 image->elf_load_addr = kbuf.mem;
 247                 image->elf_headers_sz = headers_sz;
 248
 249                 pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
 250                          image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
 251
 252                 /* Setup cmdline for kdump kernel case */
 253                 modified_cmdline = setup_kdump_cmdline(image, cmdline,
 254                                                        cmdline_len);
 255                 if (!modified_cmdline) {
 256                         pr_err("Setting up cmdline for kdump kernel failed\n");
 257                         ret = -EINVAL;
 258                         goto out;
 259                 }
 260                 cmdline = modified_cmdline;
 261         }
 262
 263 #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
 264         /* Add purgatory to the image */
 265         kbuf.top_down = true;
 266         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 267         ret = kexec_load_purgatory(image, &kbuf);
 268         if (ret) {
 269                 pr_err("Error loading purgatory ret=%d\n", ret);
 270                 goto out;
 271         }
 272         ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
 273                                              &kernel_start,
 274                                              sizeof(kernel_start), 0);
 275         if (ret)
 276                 pr_err("Error update purgatory ret=%d\n", ret);
 277 #endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
 278
 279         /* Add the initrd to the image */
 280         if (initrd != NULL) {
 281                 kbuf.buffer = initrd;
 282                 kbuf.bufsz = kbuf.memsz = initrd_len;
 283                 kbuf.buf_align = PAGE_SIZE;
 284                 kbuf.top_down = false;
 285                 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 286                 ret = kexec_add_buffer(&kbuf);
 287                 if (ret)
 288                         goto out;
 289                 initrd_pbase = kbuf.mem;
 290                 pr_notice("Loaded initrd at 0x%lx\n", initrd_pbase);
 291         }
 292
 293         /* Add the DTB to the image */
 294         fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
 295                                            initrd_len, cmdline, 0);
 296         if (!fdt) {
 297                 pr_err("Error setting up the new device tree.\n");
 298                 ret = -EINVAL;
 299                 goto out;
 300         }
 301
 302         fdt_pack(fdt);
 303         kbuf.buffer = fdt;
 304         kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
 305         kbuf.buf_align = PAGE_SIZE;
 306         kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
 307         kbuf.top_down = true;
 308         ret = kexec_add_buffer(&kbuf);
 309         if (ret) {
 310                 pr_err("Error add DTB kbuf ret=%d\n", ret);
 311                 goto out_free_fdt;
 312         }
 313         /* Cache the fdt buffer address for memory cleanup */
 314         image->arch.fdt = fdt;
 315         pr_notice("Loaded device tree at 0x%lx\n", kbuf.mem);
 316         goto out;
 317
 318 out_free_fdt:
 319         kvfree(fdt);
 320 out:
 321         kfree(modified_cmdline);
 322         kexec_free_elf_info(&elf_info);
 323         return ret ? ERR_PTR(ret) : NULL;
 324 }
 325
 326 #define RV_X(x, s, n)  (((x) >> (s)) & ((1 << (n)) - 1))
 327 #define RISCV_IMM_BITS 12
 328 #define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
 329 #define RISCV_CONST_HIGH_PART(x) \
 330         (((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
 331 #define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))
 332
 333 #define ENCODE_ITYPE_IMM(x) \
 334         (RV_X(x, 0, 12) << 20)
 335 #define ENCODE_BTYPE_IMM(x) \
 336         ((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
 337         (RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
 338 #define ENCODE_UTYPE_IMM(x) \
 339         (RV_X(x, 12, 20) << 12)
 340 #define ENCODE_JTYPE_IMM(x) \
 341         ((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
 342         (RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
 343 #define ENCODE_CBTYPE_IMM(x) \
 344         ((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
 345         (RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
 346 #define ENCODE_CJTYPE_IMM(x) \
 347         ((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
 348         (RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
 349         (RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
 350 #define ENCODE_UJTYPE_IMM(x) \
 351         (ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
 352         (ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
 353 #define ENCODE_UITYPE_IMM(x) \
 354         (ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))
 355
 356 #define CLEAN_IMM(type, x) \
 357         ((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))
 358
 359 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
 360                                      Elf_Shdr *section,
 361                                      const Elf_Shdr *relsec,
 362                                      const Elf_Shdr *symtab)
 363 {
 364         const char *strtab, *name, *shstrtab;
 365         const Elf_Shdr *sechdrs;
 366         Elf64_Rela *relas;
 367         int i, r_type;
 368
 369         /* String & section header string table */
 370         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 371         strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
 372         shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
 373
 374         relas = (void *)pi->ehdr + relsec->sh_offset;
 375
 376         for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
 377                 const Elf_Sym *sym;     /* symbol to relocate */
 378                 unsigned long addr;     /* final location after relocation */
 379                 unsigned long val;      /* relocated symbol value */
 380                 unsigned long sec_base; /* relocated symbol value */
 381                 void *loc;              /* tmp location to modify */
 382
 383                 sym = (void *)pi->ehdr + symtab->sh_offset;
 384                 sym += ELF64_R_SYM(relas[i].r_info);
 385
 386                 if (sym->st_name)
 387                         name = strtab + sym->st_name;
 388                 else
 389                         name = shstrtab + sechdrs[sym->st_shndx].sh_name;
 390
 391                 loc = pi->purgatory_buf;
 392                 loc += section->sh_offset;
 393                 loc += relas[i].r_offset;
 394
 395                 if (sym->st_shndx == SHN_ABS)
 396                         sec_base = 0;
 397                 else if (sym->st_shndx >= pi->ehdr->e_shnum) {
 398                         pr_err("Invalid section %d for symbol %s\n",
 399                                sym->st_shndx, name);
 400                         return -ENOEXEC;
 401                 } else
 402                         sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
 403
 404                 val = sym->st_value;
 405                 val += sec_base;
 406                 val += relas[i].r_addend;
 407
 408                 addr = section->sh_addr + relas[i].r_offset;
 409
 410                 r_type = ELF64_R_TYPE(relas[i].r_info);
 411
 412                 switch (r_type) {
 413                 case R_RISCV_BRANCH:
 414                         *(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
 415                                  ENCODE_BTYPE_IMM(val - addr);
 416                         break;
 417                 case R_RISCV_JAL:
 418                         *(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
 419                                  ENCODE_JTYPE_IMM(val - addr);
 420                         break;
 421                 /*
 422                  * With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
 423                  * sym is expected to be next to R_RISCV_PCREL_HI20
 424                  * in purgatory relsec. Handle it like R_RISCV_CALL
 425                  * sym, instead of searching the whole relsec.
 426                  */
 427                 case R_RISCV_PCREL_HI20:
 428                 case R_RISCV_CALL:
 429                         *(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
 430                                  ENCODE_UJTYPE_IMM(val - addr);
 431                         break;
 432                 case R_RISCV_RVC_BRANCH:
 433                         *(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
 434                                  ENCODE_CBTYPE_IMM(val - addr);
 435                         break;
 436                 case R_RISCV_RVC_JUMP:
 437                         *(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
 438                                  ENCODE_CJTYPE_IMM(val - addr);
 439                         break;
 440                 case R_RISCV_ADD32:
 441                         *(u32 *)loc += val;
 442                         break;
 443                 case R_RISCV_SUB32:
 444                         *(u32 *)loc -= val;
 445                         break;
 446                 /* It has been applied by R_RISCV_PCREL_HI20 sym */
 447                 case R_RISCV_PCREL_LO12_I:
 448                 case R_RISCV_ALIGN:
 449                 case R_RISCV_RELAX:
 450                         break;
 451                 default:
 452                         pr_err("Unknown rela relocation: %d\n", r_type);
 453                         return -ENOEXEC;
 454                 }
 455         }
 456         return 0;
 457 }
 458
 459 const struct kexec_file_ops elf_kexec_ops = {
 460         .probe = kexec_elf_probe,
 461         .load  = elf_kexec_load,
 462 };