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
arch_kimage_file_post_load_cleanup(struct kimage * image)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
riscv_kexec_elf_load(struct kimage * image,struct elfhdr * ehdr,struct kexec_elf_info * elf_info,unsigned long old_pbase,unsigned long new_pbase)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 */
elf_find_pbase(struct kimage * image,unsigned long kernel_len,struct elfhdr * ehdr,struct kexec_elf_info * elf_info,unsigned long * old_pbase,unsigned long * new_pbase)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
102 /*
103 * Current riscv boot protocol requires 2MB alignment for
104 * RV64 and 4MB alignment for RV32
105 *
106 */
107 kbuf.buf_align = PMD_SIZE;
108 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
109 kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
110 kbuf.top_down = false;
111 ret = arch_kexec_locate_mem_hole(&kbuf);
112 if (!ret) {
113 *old_pbase = lowest_paddr;
114 *new_pbase = kbuf.mem;
115 image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
116 }
117 return ret;
118 }
119
get_nr_ram_ranges_callback(struct resource * res,void * arg)120 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
121 {
122 unsigned int *nr_ranges = arg;
123
124 (*nr_ranges)++;
125 return 0;
126 }
127
prepare_elf64_ram_headers_callback(struct resource * res,void * arg)128 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
129 {
130 struct crash_mem *cmem = arg;
131
132 cmem->ranges[cmem->nr_ranges].start = res->start;
133 cmem->ranges[cmem->nr_ranges].end = res->end;
134 cmem->nr_ranges++;
135
136 return 0;
137 }
138
prepare_elf_headers(void ** addr,unsigned long * sz)139 static int prepare_elf_headers(void **addr, unsigned long *sz)
140 {
141 struct crash_mem *cmem;
142 unsigned int nr_ranges;
143 int ret;
144
145 nr_ranges = 1; /* For exclusion of crashkernel region */
146 walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
147
148 cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
149 if (!cmem)
150 return -ENOMEM;
151
152 cmem->max_nr_ranges = nr_ranges;
153 cmem->nr_ranges = 0;
154 ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
155 if (ret)
156 goto out;
157
158 /* Exclude crashkernel region */
159 ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
160 if (!ret)
161 ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
162
163 out:
164 kfree(cmem);
165 return ret;
166 }
167
setup_kdump_cmdline(struct kimage * image,char * cmdline,unsigned long cmdline_len)168 static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
169 unsigned long cmdline_len)
170 {
171 int elfcorehdr_strlen;
172 char *cmdline_ptr;
173
174 cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
175 if (!cmdline_ptr)
176 return NULL;
177
178 elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ",
179 image->elf_load_addr);
180
181 if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) {
182 pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n");
183 kfree(cmdline_ptr);
184 return NULL;
185 }
186
187 memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len);
188 /* Ensure it's nul terminated */
189 cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0';
190 return cmdline_ptr;
191 }
192
elf_kexec_load(struct kimage * image,char * kernel_buf,unsigned long kernel_len,char * initrd,unsigned long initrd_len,char * cmdline,unsigned long cmdline_len)193 static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
194 unsigned long kernel_len, char *initrd,
195 unsigned long initrd_len, char *cmdline,
196 unsigned long cmdline_len)
197 {
198 int ret;
199 unsigned long old_kernel_pbase = ULONG_MAX;
200 unsigned long new_kernel_pbase = 0UL;
201 unsigned long initrd_pbase = 0UL;
202 unsigned long headers_sz;
203 unsigned long kernel_start;
204 void *fdt, *headers;
205 struct elfhdr ehdr;
206 struct kexec_buf kbuf;
207 struct kexec_elf_info elf_info;
208 char *modified_cmdline = NULL;
209
210 ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
211 if (ret)
212 return ERR_PTR(ret);
213
214 ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
215 &old_kernel_pbase, &new_kernel_pbase);
216 if (ret)
217 goto out;
218 kernel_start = image->start;
219 pr_notice("The entry point of kernel at 0x%lx\n", image->start);
220
221 /* Add the kernel binary to the image */
222 ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
223 old_kernel_pbase, new_kernel_pbase);
224 if (ret)
225 goto out;
226
227 kbuf.image = image;
228 kbuf.buf_min = new_kernel_pbase + kernel_len;
229 kbuf.buf_max = ULONG_MAX;
230
231 /* Add elfcorehdr */
232 if (image->type == KEXEC_TYPE_CRASH) {
233 ret = prepare_elf_headers(&headers, &headers_sz);
234 if (ret) {
235 pr_err("Preparing elf core header failed\n");
236 goto out;
237 }
238
239 kbuf.buffer = headers;
240 kbuf.bufsz = headers_sz;
241 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
242 kbuf.memsz = headers_sz;
243 kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
244 kbuf.top_down = true;
245
246 ret = kexec_add_buffer(&kbuf);
247 if (ret) {
248 vfree(headers);
249 goto out;
250 }
251 image->elf_headers = headers;
252 image->elf_load_addr = kbuf.mem;
253 image->elf_headers_sz = headers_sz;
254
255 pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
256 image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
257
258 /* Setup cmdline for kdump kernel case */
259 modified_cmdline = setup_kdump_cmdline(image, cmdline,
260 cmdline_len);
261 if (!modified_cmdline) {
262 pr_err("Setting up cmdline for kdump kernel failed\n");
263 ret = -EINVAL;
264 goto out;
265 }
266 cmdline = modified_cmdline;
267 }
268
269 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
270 /* Add purgatory to the image */
271 kbuf.top_down = true;
272 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
273 ret = kexec_load_purgatory(image, &kbuf);
274 if (ret) {
275 pr_err("Error loading purgatory ret=%d\n", ret);
276 goto out;
277 }
278 ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
279 &kernel_start,
280 sizeof(kernel_start), 0);
281 if (ret)
282 pr_err("Error update purgatory ret=%d\n", ret);
283 #endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
284
285 /* Add the initrd to the image */
286 if (initrd != NULL) {
287 kbuf.buffer = initrd;
288 kbuf.bufsz = kbuf.memsz = initrd_len;
289 kbuf.buf_align = PAGE_SIZE;
290 kbuf.top_down = true;
291 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
292 ret = kexec_add_buffer(&kbuf);
293 if (ret)
294 goto out;
295 initrd_pbase = kbuf.mem;
296 pr_notice("Loaded initrd at 0x%lx\n", initrd_pbase);
297 }
298
299 /* Add the DTB to the image */
300 fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
301 initrd_len, cmdline, 0);
302 if (!fdt) {
303 pr_err("Error setting up the new device tree.\n");
304 ret = -EINVAL;
305 goto out;
306 }
307
308 fdt_pack(fdt);
309 kbuf.buffer = fdt;
310 kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
311 kbuf.buf_align = PAGE_SIZE;
312 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
313 kbuf.top_down = true;
314 ret = kexec_add_buffer(&kbuf);
315 if (ret) {
316 pr_err("Error add DTB kbuf ret=%d\n", ret);
317 goto out_free_fdt;
318 }
319 /* Cache the fdt buffer address for memory cleanup */
320 image->arch.fdt = fdt;
321 pr_notice("Loaded device tree at 0x%lx\n", kbuf.mem);
322 goto out;
323
324 out_free_fdt:
325 kvfree(fdt);
326 out:
327 kfree(modified_cmdline);
328 kexec_free_elf_info(&elf_info);
329 return ret ? ERR_PTR(ret) : NULL;
330 }
331
332 #define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1))
333 #define RISCV_IMM_BITS 12
334 #define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
335 #define RISCV_CONST_HIGH_PART(x) \
336 (((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
337 #define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))
338
339 #define ENCODE_ITYPE_IMM(x) \
340 (RV_X(x, 0, 12) << 20)
341 #define ENCODE_BTYPE_IMM(x) \
342 ((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
343 (RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
344 #define ENCODE_UTYPE_IMM(x) \
345 (RV_X(x, 12, 20) << 12)
346 #define ENCODE_JTYPE_IMM(x) \
347 ((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
348 (RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
349 #define ENCODE_CBTYPE_IMM(x) \
350 ((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
351 (RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
352 #define ENCODE_CJTYPE_IMM(x) \
353 ((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
354 (RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
355 (RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
356 #define ENCODE_UJTYPE_IMM(x) \
357 (ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
358 (ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
359 #define ENCODE_UITYPE_IMM(x) \
360 (ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))
361
362 #define CLEAN_IMM(type, x) \
363 ((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))
364
arch_kexec_apply_relocations_add(struct purgatory_info * pi,Elf_Shdr * section,const Elf_Shdr * relsec,const Elf_Shdr * symtab)365 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
366 Elf_Shdr *section,
367 const Elf_Shdr *relsec,
368 const Elf_Shdr *symtab)
369 {
370 const char *strtab, *name, *shstrtab;
371 const Elf_Shdr *sechdrs;
372 Elf64_Rela *relas;
373 int i, r_type;
374
375 /* String & section header string table */
376 sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
377 strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
378 shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
379
380 relas = (void *)pi->ehdr + relsec->sh_offset;
381
382 for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
383 const Elf_Sym *sym; /* symbol to relocate */
384 unsigned long addr; /* final location after relocation */
385 unsigned long val; /* relocated symbol value */
386 unsigned long sec_base; /* relocated symbol value */
387 void *loc; /* tmp location to modify */
388
389 sym = (void *)pi->ehdr + symtab->sh_offset;
390 sym += ELF64_R_SYM(relas[i].r_info);
391
392 if (sym->st_name)
393 name = strtab + sym->st_name;
394 else
395 name = shstrtab + sechdrs[sym->st_shndx].sh_name;
396
397 loc = pi->purgatory_buf;
398 loc += section->sh_offset;
399 loc += relas[i].r_offset;
400
401 if (sym->st_shndx == SHN_ABS)
402 sec_base = 0;
403 else if (sym->st_shndx >= pi->ehdr->e_shnum) {
404 pr_err("Invalid section %d for symbol %s\n",
405 sym->st_shndx, name);
406 return -ENOEXEC;
407 } else
408 sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
409
410 val = sym->st_value;
411 val += sec_base;
412 val += relas[i].r_addend;
413
414 addr = section->sh_addr + relas[i].r_offset;
415
416 r_type = ELF64_R_TYPE(relas[i].r_info);
417
418 switch (r_type) {
419 case R_RISCV_BRANCH:
420 *(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
421 ENCODE_BTYPE_IMM(val - addr);
422 break;
423 case R_RISCV_JAL:
424 *(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
425 ENCODE_JTYPE_IMM(val - addr);
426 break;
427 /*
428 * With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
429 * sym is expected to be next to R_RISCV_PCREL_HI20
430 * in purgatory relsec. Handle it like R_RISCV_CALL
431 * sym, instead of searching the whole relsec.
432 */
433 case R_RISCV_PCREL_HI20:
434 case R_RISCV_CALL_PLT:
435 case R_RISCV_CALL:
436 *(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
437 ENCODE_UJTYPE_IMM(val - addr);
438 break;
439 case R_RISCV_RVC_BRANCH:
440 *(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
441 ENCODE_CBTYPE_IMM(val - addr);
442 break;
443 case R_RISCV_RVC_JUMP:
444 *(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
445 ENCODE_CJTYPE_IMM(val - addr);
446 break;
447 case R_RISCV_ADD32:
448 *(u32 *)loc += val;
449 break;
450 case R_RISCV_SUB32:
451 *(u32 *)loc -= val;
452 break;
453 /* It has been applied by R_RISCV_PCREL_HI20 sym */
454 case R_RISCV_PCREL_LO12_I:
455 case R_RISCV_ALIGN:
456 case R_RISCV_RELAX:
457 break;
458 default:
459 pr_err("Unknown rela relocation: %d\n", r_type);
460 return -ENOEXEC;
461 }
462 }
463 return 0;
464 }
465
466 const struct kexec_file_ops elf_kexec_ops = {
467 .probe = kexec_elf_probe,
468 .load = elf_kexec_load,
469 };
470