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 <linux/vmalloc.h>
23 #include <asm/setup.h>
24
25 int arch_kimage_file_post_load_cleanup(struct kimage *image)
26 {
27 kvfree(image->arch.fdt);
28 image->arch.fdt = NULL;
29
30 vfree(image->elf_headers);
31 image->elf_headers = NULL;
32 image->elf_headers_sz = 0;
33
34 return kexec_image_post_load_cleanup_default(image);
35 }
36
37 static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
38 struct kexec_elf_info *elf_info, unsigned long old_pbase,
39 unsigned long new_pbase)
40 {
41 int i;
42 int ret = 0;
43 size_t size;
44 struct kexec_buf kbuf;
45 const struct elf_phdr *phdr;
46
47 kbuf.image = image;
48
49 for (i = 0; i < ehdr->e_phnum; i++) {
50 phdr = &elf_info->proghdrs[i];
51 if (phdr->p_type != PT_LOAD)
52 continue;
53
54 size = phdr->p_filesz;
55 if (size > phdr->p_memsz)
56 size = phdr->p_memsz;
57
58 kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
59 kbuf.bufsz = size;
60 kbuf.buf_align = phdr->p_align;
61 kbuf.mem = phdr->p_paddr - old_pbase + new_pbase;
62 kbuf.memsz = phdr->p_memsz;
63 kbuf.top_down = false;
64 ret = kexec_add_buffer(&kbuf);
65 if (ret)
66 break;
67 }
68
69 return ret;
70 }
71
72 /*
73 * Go through the available phsyical memory regions and find one that hold
74 * an image of the specified size.
75 */
76 static int elf_find_pbase(struct kimage *image, unsigned long kernel_len,
77 struct elfhdr *ehdr, struct kexec_elf_info *elf_info,
78 unsigned long *old_pbase, unsigned long *new_pbase)
79 {
80 int i;
81 int ret;
82 struct kexec_buf kbuf;
83 const struct elf_phdr *phdr;
84 unsigned long lowest_paddr = ULONG_MAX;
85 unsigned long lowest_vaddr = ULONG_MAX;
86
87 for (i = 0; i < ehdr->e_phnum; i++) {
88 phdr = &elf_info->proghdrs[i];
89 if (phdr->p_type != PT_LOAD)
90 continue;
91
92 if (lowest_paddr > phdr->p_paddr)
93 lowest_paddr = phdr->p_paddr;
94
95 if (lowest_vaddr > phdr->p_vaddr)
96 lowest_vaddr = phdr->p_vaddr;
97 }
98
99 kbuf.image = image;
100 kbuf.buf_min = lowest_paddr;
101 kbuf.buf_max = ULONG_MAX;
102
103 /*
104 * Current riscv boot protocol requires 2MB alignment for
105 * RV64 and 4MB alignment for RV32
106 *
107 */
108 kbuf.buf_align = PMD_SIZE;
109 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
110 kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
111 kbuf.top_down = false;
112 ret = arch_kexec_locate_mem_hole(&kbuf);
113 if (!ret) {
114 *old_pbase = lowest_paddr;
115 *new_pbase = kbuf.mem;
116 image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
117 }
118 return ret;
119 }
120
121 #ifdef CONFIG_CRASH_DUMP
122 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
123 {
124 unsigned int *nr_ranges = arg;
125
126 (*nr_ranges)++;
127 return 0;
128 }
129
130 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
131 {
132 struct crash_mem *cmem = arg;
133
134 cmem->ranges[cmem->nr_ranges].start = res->start;
135 cmem->ranges[cmem->nr_ranges].end = res->end;
136 cmem->nr_ranges++;
137
138 return 0;
139 }
140
141 static int prepare_elf_headers(void **addr, unsigned long *sz)
142 {
143 struct crash_mem *cmem;
144 unsigned int nr_ranges;
145 int ret;
146
147 nr_ranges = 1; /* For exclusion of crashkernel region */
148 walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
149
150 cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
151 if (!cmem)
152 return -ENOMEM;
153
154 cmem->max_nr_ranges = nr_ranges;
155 cmem->nr_ranges = 0;
156 ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
157 if (ret)
158 goto out;
159
160 /* Exclude crashkernel region */
161 ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
162 if (!ret)
163 ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
164
165 out:
166 kfree(cmem);
167 return ret;
168 }
169
170 static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
171 unsigned long cmdline_len)
172 {
173 int elfcorehdr_strlen;
174 char *cmdline_ptr;
175
176 cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
177 if (!cmdline_ptr)
178 return NULL;
179
180 elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ",
181 image->elf_load_addr);
182
183 if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) {
184 pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n");
185 kfree(cmdline_ptr);
186 return NULL;
187 }
188
189 memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len);
190 /* Ensure it's nul terminated */
191 cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0';
192 return cmdline_ptr;
193 }
194 #endif
195
196 static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
197 unsigned long kernel_len, char *initrd,
198 unsigned long initrd_len, char *cmdline,
199 unsigned long cmdline_len)
200 {
201 int ret;
202 void *fdt;
203 unsigned long old_kernel_pbase = ULONG_MAX;
204 unsigned long new_kernel_pbase = 0UL;
205 unsigned long initrd_pbase = 0UL;
206 unsigned long kernel_start;
207 struct elfhdr ehdr;
208 struct kexec_buf kbuf;
209 struct kexec_elf_info elf_info;
210 char *modified_cmdline = NULL;
211
212 ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
213 if (ret)
214 return ERR_PTR(ret);
215
216 ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
217 &old_kernel_pbase, &new_kernel_pbase);
218 if (ret)
219 goto out;
220 kernel_start = image->start;
221
222 /* Add the kernel binary to the image */
223 ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
224 old_kernel_pbase, new_kernel_pbase);
225 if (ret)
226 goto out;
227
228 kbuf.image = image;
229 kbuf.buf_min = new_kernel_pbase + kernel_len;
230 kbuf.buf_max = ULONG_MAX;
231
232 #ifdef CONFIG_CRASH_DUMP
233 /* Add elfcorehdr */
234 if (image->type == KEXEC_TYPE_CRASH) {
235 void *headers;
236 unsigned long headers_sz;
237 ret = prepare_elf_headers(&headers, &headers_sz);
238 if (ret) {
239 pr_err("Preparing elf core header failed\n");
240 goto out;
241 }
242
243 kbuf.buffer = headers;
244 kbuf.bufsz = headers_sz;
245 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
246 kbuf.memsz = headers_sz;
247 kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
248 kbuf.top_down = true;
249
250 ret = kexec_add_buffer(&kbuf);
251 if (ret) {
252 vfree(headers);
253 goto out;
254 }
255 image->elf_headers = headers;
256 image->elf_load_addr = kbuf.mem;
257 image->elf_headers_sz = headers_sz;
258
259 kexec_dprintk("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
260 image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
261
262 /* Setup cmdline for kdump kernel case */
263 modified_cmdline = setup_kdump_cmdline(image, cmdline,
264 cmdline_len);
265 if (!modified_cmdline) {
266 pr_err("Setting up cmdline for kdump kernel failed\n");
267 ret = -EINVAL;
268 goto out;
269 }
270 cmdline = modified_cmdline;
271 }
272 #endif
273
274 #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
275 /* Add purgatory to the image */
276 kbuf.top_down = true;
277 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
278 ret = kexec_load_purgatory(image, &kbuf);
279 if (ret) {
280 pr_err("Error loading purgatory ret=%d\n", ret);
281 goto out;
282 }
283 kexec_dprintk("Loaded purgatory at 0x%lx\n", kbuf.mem);
284
285 ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
286 &kernel_start,
287 sizeof(kernel_start), 0);
288 if (ret)
289 pr_err("Error update purgatory ret=%d\n", ret);
290 #endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
291
292 /* Add the initrd to the image */
293 if (initrd != NULL) {
294 kbuf.buffer = initrd;
295 kbuf.bufsz = kbuf.memsz = initrd_len;
296 kbuf.buf_align = PAGE_SIZE;
297 kbuf.top_down = true;
298 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
299 ret = kexec_add_buffer(&kbuf);
300 if (ret)
301 goto out;
302 initrd_pbase = kbuf.mem;
303 kexec_dprintk("Loaded initrd at 0x%lx\n", initrd_pbase);
304 }
305
306 /* Add the DTB to the image */
307 fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
308 initrd_len, cmdline, 0);
309 if (!fdt) {
310 pr_err("Error setting up the new device tree.\n");
311 ret = -EINVAL;
312 goto out;
313 }
314
315 fdt_pack(fdt);
316 kbuf.buffer = fdt;
317 kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
318 kbuf.buf_align = PAGE_SIZE;
319 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
320 kbuf.top_down = true;
321 ret = kexec_add_buffer(&kbuf);
322 if (ret) {
323 pr_err("Error add DTB kbuf ret=%d\n", ret);
324 goto out_free_fdt;
325 }
326 /* Cache the fdt buffer address for memory cleanup */
327 image->arch.fdt = fdt;
328 kexec_dprintk("Loaded device tree at 0x%lx\n", kbuf.mem);
329 goto out;
330
331 out_free_fdt:
332 kvfree(fdt);
333 out:
334 kfree(modified_cmdline);
335 kexec_free_elf_info(&elf_info);
336 return ret ? ERR_PTR(ret) : NULL;
337 }
338
339 #define RV_X(x, s, n) (((x) >> (s)) & ((1 << (n)) - 1))
340 #define RISCV_IMM_BITS 12
341 #define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
342 #define RISCV_CONST_HIGH_PART(x) \
343 (((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
344 #define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))
345
346 #define ENCODE_ITYPE_IMM(x) \
347 (RV_X(x, 0, 12) << 20)
348 #define ENCODE_BTYPE_IMM(x) \
349 ((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
350 (RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
351 #define ENCODE_UTYPE_IMM(x) \
352 (RV_X(x, 12, 20) << 12)
353 #define ENCODE_JTYPE_IMM(x) \
354 ((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
355 (RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
356 #define ENCODE_CBTYPE_IMM(x) \
357 ((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
358 (RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
359 #define ENCODE_CJTYPE_IMM(x) \
360 ((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
361 (RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
362 (RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
363 #define ENCODE_UJTYPE_IMM(x) \
364 (ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
365 (ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
366 #define ENCODE_UITYPE_IMM(x) \
367 (ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))
368
369 #define CLEAN_IMM(type, x) \
370 ((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))
371
372 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
373 Elf_Shdr *section,
374 const Elf_Shdr *relsec,
375 const Elf_Shdr *symtab)
376 {
377 const char *strtab, *name, *shstrtab;
378 const Elf_Shdr *sechdrs;
379 Elf64_Rela *relas;
380 int i, r_type;
381
382 /* String & section header string table */
383 sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
384 strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
385 shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
386
387 relas = (void *)pi->ehdr + relsec->sh_offset;
388
389 for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
390 const Elf_Sym *sym; /* symbol to relocate */
391 unsigned long addr; /* final location after relocation */
392 unsigned long val; /* relocated symbol value */
393 unsigned long sec_base; /* relocated symbol value */
394 void *loc; /* tmp location to modify */
395
396 sym = (void *)pi->ehdr + symtab->sh_offset;
397 sym += ELF64_R_SYM(relas[i].r_info);
398
399 if (sym->st_name)
400 name = strtab + sym->st_name;
401 else
402 name = shstrtab + sechdrs[sym->st_shndx].sh_name;
403
404 loc = pi->purgatory_buf;
405 loc += section->sh_offset;
406 loc += relas[i].r_offset;
407
408 if (sym->st_shndx == SHN_ABS)
409 sec_base = 0;
410 else if (sym->st_shndx >= pi->ehdr->e_shnum) {
411 pr_err("Invalid section %d for symbol %s\n",
412 sym->st_shndx, name);
413 return -ENOEXEC;
414 } else
415 sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
416
417 val = sym->st_value;
418 val += sec_base;
419 val += relas[i].r_addend;
420
421 addr = section->sh_addr + relas[i].r_offset;
422
423 r_type = ELF64_R_TYPE(relas[i].r_info);
424
425 switch (r_type) {
426 case R_RISCV_BRANCH:
427 *(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
428 ENCODE_BTYPE_IMM(val - addr);
429 break;
430 case R_RISCV_JAL:
431 *(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
432 ENCODE_JTYPE_IMM(val - addr);
433 break;
434 /*
435 * With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
436 * sym is expected to be next to R_RISCV_PCREL_HI20
437 * in purgatory relsec. Handle it like R_RISCV_CALL
438 * sym, instead of searching the whole relsec.
439 */
440 case R_RISCV_PCREL_HI20:
441 case R_RISCV_CALL_PLT:
442 case R_RISCV_CALL:
443 *(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
444 ENCODE_UJTYPE_IMM(val - addr);
445 break;
446 case R_RISCV_RVC_BRANCH:
447 *(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
448 ENCODE_CBTYPE_IMM(val - addr);
449 break;
450 case R_RISCV_RVC_JUMP:
451 *(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
452 ENCODE_CJTYPE_IMM(val - addr);
453 break;
454 case R_RISCV_ADD16:
455 *(u16 *)loc += val;
456 break;
457 case R_RISCV_SUB16:
458 *(u16 *)loc -= val;
459 break;
460 case R_RISCV_ADD32:
461 *(u32 *)loc += val;
462 break;
463 case R_RISCV_SUB32:
464 *(u32 *)loc -= val;
465 break;
466 /* It has been applied by R_RISCV_PCREL_HI20 sym */
467 case R_RISCV_PCREL_LO12_I:
468 case R_RISCV_ALIGN:
469 case R_RISCV_RELAX:
470 break;
471 default:
472 pr_err("Unknown rela relocation: %d\n", r_type);
473 return -ENOEXEC;
474 }
475 }
476 return 0;
477 }
478
479 const struct kexec_file_ops elf_kexec_ops = {
480 .probe = kexec_elf_probe,
481 .load = elf_kexec_load,
482 };
483
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