summaryrefslogtreecommitdiff
path: root/arch/riscv/kernel/elf_kexec.c
blob: 54260c16f9912aa81a738d783863cb97030aac8e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Load ELF vmlinux file for the kexec_file_load syscall.
 *
 * Copyright (C) 2021 Huawei Technologies Co, Ltd.
 *
 * Author: Liao Chang (liaochang1@huawei.com)
 *
 * Based on kexec-tools' kexec-elf-riscv.c, heavily modified
 * for kernel.
 */

#define pr_fmt(fmt)	"kexec_image: " fmt

#include <linux/elf.h>
#include <linux/kexec.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/libfdt.h>
#include <linux/types.h>
#include <linux/memblock.h>
#include <asm/setup.h>

int arch_kimage_file_post_load_cleanup(struct kimage *image)
{
	kvfree(image->arch.fdt);
	image->arch.fdt = NULL;

	vfree(image->elf_headers);
	image->elf_headers = NULL;
	image->elf_headers_sz = 0;

	return kexec_image_post_load_cleanup_default(image);
}

static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
				struct kexec_elf_info *elf_info, unsigned long old_pbase,
				unsigned long new_pbase)
{
	int i;
	int ret = 0;
	size_t size;
	struct kexec_buf kbuf;
	const struct elf_phdr *phdr;

	kbuf.image = image;

	for (i = 0; i < ehdr->e_phnum; i++) {
		phdr = &elf_info->proghdrs[i];
		if (phdr->p_type != PT_LOAD)
			continue;

		size = phdr->p_filesz;
		if (size > phdr->p_memsz)
			size = phdr->p_memsz;

		kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
		kbuf.bufsz = size;
		kbuf.buf_align = phdr->p_align;
		kbuf.mem = phdr->p_paddr - old_pbase + new_pbase;
		kbuf.memsz = phdr->p_memsz;
		kbuf.top_down = false;
		ret = kexec_add_buffer(&kbuf);
		if (ret)
			break;
	}

	return ret;
}

/*
 * Go through the available phsyical memory regions and find one that hold
 * an image of the specified size.
 */
static int 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)
{
	int i;
	int ret;
	struct kexec_buf kbuf;
	const struct elf_phdr *phdr;
	unsigned long lowest_paddr = ULONG_MAX;
	unsigned long lowest_vaddr = ULONG_MAX;

	for (i = 0; i < ehdr->e_phnum; i++) {
		phdr = &elf_info->proghdrs[i];
		if (phdr->p_type != PT_LOAD)
			continue;

		if (lowest_paddr > phdr->p_paddr)
			lowest_paddr = phdr->p_paddr;

		if (lowest_vaddr > phdr->p_vaddr)
			lowest_vaddr = phdr->p_vaddr;
	}

	kbuf.image = image;
	kbuf.buf_min = lowest_paddr;
	kbuf.buf_max = ULONG_MAX;

	/*
	 * Current riscv boot protocol requires 2MB alignment for
	 * RV64 and 4MB alignment for RV32
	 *
	 */
	kbuf.buf_align = PMD_SIZE;
	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
	kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
	kbuf.top_down = false;
	ret = arch_kexec_locate_mem_hole(&kbuf);
	if (!ret) {
		*old_pbase = lowest_paddr;
		*new_pbase = kbuf.mem;
		image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
	}
	return ret;
}

#ifdef CONFIG_CRASH_DUMP
static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
{
	unsigned int *nr_ranges = arg;

	(*nr_ranges)++;
	return 0;
}

static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
	struct crash_mem *cmem = arg;

	cmem->ranges[cmem->nr_ranges].start = res->start;
	cmem->ranges[cmem->nr_ranges].end = res->end;
	cmem->nr_ranges++;

	return 0;
}

static int prepare_elf_headers(void **addr, unsigned long *sz)
{
	struct crash_mem *cmem;
	unsigned int nr_ranges;
	int ret;

	nr_ranges = 1; /* For exclusion of crashkernel region */
	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);

	cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
	if (!cmem)
		return -ENOMEM;

	cmem->max_nr_ranges = nr_ranges;
	cmem->nr_ranges = 0;
	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
	if (ret)
		goto out;

	/* Exclude crashkernel region */
	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
	if (!ret)
		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);

out:
	kfree(cmem);
	return ret;
}

static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
				 unsigned long cmdline_len)
{
	int elfcorehdr_strlen;
	char *cmdline_ptr;

	cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
	if (!cmdline_ptr)
		return NULL;

	elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ",
		image->elf_load_addr);

	if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) {
		pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n");
		kfree(cmdline_ptr);
		return NULL;
	}

	memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len);
	/* Ensure it's nul terminated */
	cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0';
	return cmdline_ptr;
}
#endif

static void *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)
{
	int ret;
	void *fdt;
	unsigned long old_kernel_pbase = ULONG_MAX;
	unsigned long new_kernel_pbase = 0UL;
	unsigned long initrd_pbase = 0UL;
	unsigned long kernel_start;
	struct elfhdr ehdr;
	struct kexec_buf kbuf;
	struct kexec_elf_info elf_info;
	char *modified_cmdline = NULL;

	ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
	if (ret)
		return ERR_PTR(ret);

	ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
			     &old_kernel_pbase, &new_kernel_pbase);
	if (ret)
		goto out;
	kernel_start = image->start;

	/* Add the kernel binary to the image */
	ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
				   old_kernel_pbase, new_kernel_pbase);
	if (ret)
		goto out;

	kbuf.image = image;
	kbuf.buf_min = new_kernel_pbase + kernel_len;
	kbuf.buf_max = ULONG_MAX;

#ifdef CONFIG_CRASH_DUMP
	/* Add elfcorehdr */
	if (image->type == KEXEC_TYPE_CRASH) {
		void *headers;
		unsigned long headers_sz;
		ret = prepare_elf_headers(&headers, &headers_sz);
		if (ret) {
			pr_err("Preparing elf core header failed\n");
			goto out;
		}

		kbuf.buffer = headers;
		kbuf.bufsz = headers_sz;
		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
		kbuf.memsz = headers_sz;
		kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
		kbuf.top_down = true;

		ret = kexec_add_buffer(&kbuf);
		if (ret) {
			vfree(headers);
			goto out;
		}
		image->elf_headers = headers;
		image->elf_load_addr = kbuf.mem;
		image->elf_headers_sz = headers_sz;

		kexec_dprintk("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
			      image->elf_load_addr, kbuf.bufsz, kbuf.memsz);

		/* Setup cmdline for kdump kernel case */
		modified_cmdline = setup_kdump_cmdline(image, cmdline,
						       cmdline_len);
		if (!modified_cmdline) {
			pr_err("Setting up cmdline for kdump kernel failed\n");
			ret = -EINVAL;
			goto out;
		}
		cmdline = modified_cmdline;
	}
#endif

#ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
	/* Add purgatory to the image */
	kbuf.top_down = true;
	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
	ret = kexec_load_purgatory(image, &kbuf);
	if (ret) {
		pr_err("Error loading purgatory ret=%d\n", ret);
		goto out;
	}
	kexec_dprintk("Loaded purgatory at 0x%lx\n", kbuf.mem);

	ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
					     &kernel_start,
					     sizeof(kernel_start), 0);
	if (ret)
		pr_err("Error update purgatory ret=%d\n", ret);
#endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */

	/* Add the initrd to the image */
	if (initrd != NULL) {
		kbuf.buffer = initrd;
		kbuf.bufsz = kbuf.memsz = initrd_len;
		kbuf.buf_align = PAGE_SIZE;
		kbuf.top_down = true;
		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
		ret = kexec_add_buffer(&kbuf);
		if (ret)
			goto out;
		initrd_pbase = kbuf.mem;
		kexec_dprintk("Loaded initrd at 0x%lx\n", initrd_pbase);
	}

	/* Add the DTB to the image */
	fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
					   initrd_len, cmdline, 0);
	if (!fdt) {
		pr_err("Error setting up the new device tree.\n");
		ret = -EINVAL;
		goto out;
	}

	fdt_pack(fdt);
	kbuf.buffer = fdt;
	kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
	kbuf.buf_align = PAGE_SIZE;
	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
	kbuf.top_down = true;
	ret = kexec_add_buffer(&kbuf);
	if (ret) {
		pr_err("Error add DTB kbuf ret=%d\n", ret);
		goto out_free_fdt;
	}
	/* Cache the fdt buffer address for memory cleanup */
	image->arch.fdt = fdt;
	kexec_dprintk("Loaded device tree at 0x%lx\n", kbuf.mem);
	goto out;

out_free_fdt:
	kvfree(fdt);
out:
	kfree(modified_cmdline);
	kexec_free_elf_info(&elf_info);
	return ret ? ERR_PTR(ret) : NULL;
}

#define RV_X(x, s, n)  (((x) >> (s)) & ((1 << (n)) - 1))
#define RISCV_IMM_BITS 12
#define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
#define RISCV_CONST_HIGH_PART(x) \
	(((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
#define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))

#define ENCODE_ITYPE_IMM(x) \
	(RV_X(x, 0, 12) << 20)
#define ENCODE_BTYPE_IMM(x) \
	((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
	(RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
#define ENCODE_UTYPE_IMM(x) \
	(RV_X(x, 12, 20) << 12)
#define ENCODE_JTYPE_IMM(x) \
	((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
	(RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
#define ENCODE_CBTYPE_IMM(x) \
	((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
	(RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
#define ENCODE_CJTYPE_IMM(x) \
	((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
	(RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
	(RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
#define ENCODE_UJTYPE_IMM(x) \
	(ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
	(ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
#define ENCODE_UITYPE_IMM(x) \
	(ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))

#define CLEAN_IMM(type, x) \
	((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))

int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
				     Elf_Shdr *section,
				     const Elf_Shdr *relsec,
				     const Elf_Shdr *symtab)
{
	const char *strtab, *name, *shstrtab;
	const Elf_Shdr *sechdrs;
	Elf64_Rela *relas;
	int i, r_type;

	/* String & section header string table */
	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
	strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
	shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;

	relas = (void *)pi->ehdr + relsec->sh_offset;

	for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
		const Elf_Sym *sym;	/* symbol to relocate */
		unsigned long addr;	/* final location after relocation */
		unsigned long val;	/* relocated symbol value */
		unsigned long sec_base;	/* relocated symbol value */
		void *loc;		/* tmp location to modify */

		sym = (void *)pi->ehdr + symtab->sh_offset;
		sym += ELF64_R_SYM(relas[i].r_info);

		if (sym->st_name)
			name = strtab + sym->st_name;
		else
			name = shstrtab + sechdrs[sym->st_shndx].sh_name;

		loc = pi->purgatory_buf;
		loc += section->sh_offset;
		loc += relas[i].r_offset;

		if (sym->st_shndx == SHN_ABS)
			sec_base = 0;
		else if (sym->st_shndx >= pi->ehdr->e_shnum) {
			pr_err("Invalid section %d for symbol %s\n",
			       sym->st_shndx, name);
			return -ENOEXEC;
		} else
			sec_base = pi->sechdrs[sym->st_shndx].sh_addr;

		val = sym->st_value;
		val += sec_base;
		val += relas[i].r_addend;

		addr = section->sh_addr + relas[i].r_offset;

		r_type = ELF64_R_TYPE(relas[i].r_info);

		switch (r_type) {
		case R_RISCV_BRANCH:
			*(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
				 ENCODE_BTYPE_IMM(val - addr);
			break;
		case R_RISCV_JAL:
			*(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
				 ENCODE_JTYPE_IMM(val - addr);
			break;
		/*
		 * With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
		 * sym is expected to be next to R_RISCV_PCREL_HI20
		 * in purgatory relsec. Handle it like R_RISCV_CALL
		 * sym, instead of searching the whole relsec.
		 */
		case R_RISCV_PCREL_HI20:
		case R_RISCV_CALL_PLT:
		case R_RISCV_CALL:
			*(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
				 ENCODE_UJTYPE_IMM(val - addr);
			break;
		case R_RISCV_RVC_BRANCH:
			*(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
				 ENCODE_CBTYPE_IMM(val - addr);
			break;
		case R_RISCV_RVC_JUMP:
			*(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
				 ENCODE_CJTYPE_IMM(val - addr);
			break;
		case R_RISCV_ADD32:
			*(u32 *)loc += val;
			break;
		case R_RISCV_SUB32:
			*(u32 *)loc -= val;
			break;
		/* It has been applied by R_RISCV_PCREL_HI20 sym */
		case R_RISCV_PCREL_LO12_I:
		case R_RISCV_ALIGN:
		case R_RISCV_RELAX:
			break;
		default:
			pr_err("Unknown rela relocation: %d\n", r_type);
			return -ENOEXEC;
		}
	}
	return 0;
}

const struct kexec_file_ops elf_kexec_ops = {
	.probe = kexec_elf_probe,
	.load  = elf_kexec_load,
};