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
24int 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
36static 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 */
75static 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
120#ifdef CONFIG_CRASH_DUMP
121static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
122{
123	unsigned int *nr_ranges = arg;
124
125	(*nr_ranges)++;
126	return 0;
127}
128
129static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
130{
131	struct crash_mem *cmem = arg;
132
133	cmem->ranges[cmem->nr_ranges].start = res->start;
134	cmem->ranges[cmem->nr_ranges].end = res->end;
135	cmem->nr_ranges++;
136
137	return 0;
138}
139
140static int prepare_elf_headers(void **addr, unsigned long *sz)
141{
142	struct crash_mem *cmem;
143	unsigned int nr_ranges;
144	int ret;
145
146	nr_ranges = 1; /* For exclusion of crashkernel region */
147	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
148
149	cmem = kmalloc(struct_size(cmem, ranges, nr_ranges), GFP_KERNEL);
150	if (!cmem)
151		return -ENOMEM;
152
153	cmem->max_nr_ranges = nr_ranges;
154	cmem->nr_ranges = 0;
155	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
156	if (ret)
157		goto out;
158
159	/* Exclude crashkernel region */
160	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
161	if (!ret)
162		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
163
164out:
165	kfree(cmem);
166	return ret;
167}
168
169static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
170				 unsigned long cmdline_len)
171{
172	int elfcorehdr_strlen;
173	char *cmdline_ptr;
174
175	cmdline_ptr = kzalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
176	if (!cmdline_ptr)
177		return NULL;
178
179	elfcorehdr_strlen = sprintf(cmdline_ptr, "elfcorehdr=0x%lx ",
180		image->elf_load_addr);
181
182	if (elfcorehdr_strlen + cmdline_len > COMMAND_LINE_SIZE) {
183		pr_err("Appending elfcorehdr=<addr> exceeds cmdline size\n");
184		kfree(cmdline_ptr);
185		return NULL;
186	}
187
188	memcpy(cmdline_ptr + elfcorehdr_strlen, cmdline, cmdline_len);
189	/* Ensure it's nul terminated */
190	cmdline_ptr[COMMAND_LINE_SIZE - 1] = '\0';
191	return cmdline_ptr;
192}
193#endif
194
195static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
196			    unsigned long kernel_len, char *initrd,
197			    unsigned long initrd_len, char *cmdline,
198			    unsigned long cmdline_len)
199{
200	int ret;
201	void *fdt;
202	unsigned long old_kernel_pbase = ULONG_MAX;
203	unsigned long new_kernel_pbase = 0UL;
204	unsigned long initrd_pbase = 0UL;
205	unsigned long kernel_start;
206	struct elfhdr ehdr;
207	struct kexec_buf kbuf;
208	struct kexec_elf_info elf_info;
209	char *modified_cmdline = NULL;
210
211	ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
212	if (ret)
213		return ERR_PTR(ret);
214
215	ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
216			     &old_kernel_pbase, &new_kernel_pbase);
217	if (ret)
218		goto out;
219	kernel_start = 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#ifdef CONFIG_CRASH_DUMP
232	/* Add elfcorehdr */
233	if (image->type == KEXEC_TYPE_CRASH) {
234		void *headers;
235		unsigned long headers_sz;
236		ret = prepare_elf_headers(&headers, &headers_sz);
237		if (ret) {
238			pr_err("Preparing elf core header failed\n");
239			goto out;
240		}
241
242		kbuf.buffer = headers;
243		kbuf.bufsz = headers_sz;
244		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
245		kbuf.memsz = headers_sz;
246		kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
247		kbuf.top_down = true;
248
249		ret = kexec_add_buffer(&kbuf);
250		if (ret) {
251			vfree(headers);
252			goto out;
253		}
254		image->elf_headers = headers;
255		image->elf_load_addr = kbuf.mem;
256		image->elf_headers_sz = headers_sz;
257
258		kexec_dprintk("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
259			      image->elf_load_addr, kbuf.bufsz, kbuf.memsz);
260
261		/* Setup cmdline for kdump kernel case */
262		modified_cmdline = setup_kdump_cmdline(image, cmdline,
263						       cmdline_len);
264		if (!modified_cmdline) {
265			pr_err("Setting up cmdline for kdump kernel failed\n");
266			ret = -EINVAL;
267			goto out;
268		}
269		cmdline = modified_cmdline;
270	}
271#endif
272
273#ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
274	/* Add purgatory to the image */
275	kbuf.top_down = true;
276	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
277	ret = kexec_load_purgatory(image, &kbuf);
278	if (ret) {
279		pr_err("Error loading purgatory ret=%d\n", ret);
280		goto out;
281	}
282	kexec_dprintk("Loaded purgatory at 0x%lx\n", kbuf.mem);
283
284	ret = kexec_purgatory_get_set_symbol(image, "riscv_kernel_entry",
285					     &kernel_start,
286					     sizeof(kernel_start), 0);
287	if (ret)
288		pr_err("Error update purgatory ret=%d\n", ret);
289#endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
290
291	/* Add the initrd to the image */
292	if (initrd != NULL) {
293		kbuf.buffer = initrd;
294		kbuf.bufsz = kbuf.memsz = initrd_len;
295		kbuf.buf_align = PAGE_SIZE;
296		kbuf.top_down = true;
297		kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
298		ret = kexec_add_buffer(&kbuf);
299		if (ret)
300			goto out;
301		initrd_pbase = kbuf.mem;
302		kexec_dprintk("Loaded initrd at 0x%lx\n", initrd_pbase);
303	}
304
305	/* Add the DTB to the image */
306	fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
307					   initrd_len, cmdline, 0);
308	if (!fdt) {
309		pr_err("Error setting up the new device tree.\n");
310		ret = -EINVAL;
311		goto out;
312	}
313
314	fdt_pack(fdt);
315	kbuf.buffer = fdt;
316	kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
317	kbuf.buf_align = PAGE_SIZE;
318	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
319	kbuf.top_down = true;
320	ret = kexec_add_buffer(&kbuf);
321	if (ret) {
322		pr_err("Error add DTB kbuf ret=%d\n", ret);
323		goto out_free_fdt;
324	}
325	/* Cache the fdt buffer address for memory cleanup */
326	image->arch.fdt = fdt;
327	kexec_dprintk("Loaded device tree at 0x%lx\n", kbuf.mem);
328	goto out;
329
330out_free_fdt:
331	kvfree(fdt);
332out:
333	kfree(modified_cmdline);
334	kexec_free_elf_info(&elf_info);
335	return ret ? ERR_PTR(ret) : NULL;
336}
337
338#define RV_X(x, s, n)  (((x) >> (s)) & ((1 << (n)) - 1))
339#define RISCV_IMM_BITS 12
340#define RISCV_IMM_REACH (1LL << RISCV_IMM_BITS)
341#define RISCV_CONST_HIGH_PART(x) \
342	(((x) + (RISCV_IMM_REACH >> 1)) & ~(RISCV_IMM_REACH - 1))
343#define RISCV_CONST_LOW_PART(x) ((x) - RISCV_CONST_HIGH_PART(x))
344
345#define ENCODE_ITYPE_IMM(x) \
346	(RV_X(x, 0, 12) << 20)
347#define ENCODE_BTYPE_IMM(x) \
348	((RV_X(x, 1, 4) << 8) | (RV_X(x, 5, 6) << 25) | \
349	(RV_X(x, 11, 1) << 7) | (RV_X(x, 12, 1) << 31))
350#define ENCODE_UTYPE_IMM(x) \
351	(RV_X(x, 12, 20) << 12)
352#define ENCODE_JTYPE_IMM(x) \
353	((RV_X(x, 1, 10) << 21) | (RV_X(x, 11, 1) << 20) | \
354	(RV_X(x, 12, 8) << 12) | (RV_X(x, 20, 1) << 31))
355#define ENCODE_CBTYPE_IMM(x) \
356	((RV_X(x, 1, 2) << 3) | (RV_X(x, 3, 2) << 10) | (RV_X(x, 5, 1) << 2) | \
357	(RV_X(x, 6, 2) << 5) | (RV_X(x, 8, 1) << 12))
358#define ENCODE_CJTYPE_IMM(x) \
359	((RV_X(x, 1, 3) << 3) | (RV_X(x, 4, 1) << 11) | (RV_X(x, 5, 1) << 2) | \
360	(RV_X(x, 6, 1) << 7) | (RV_X(x, 7, 1) << 6) | (RV_X(x, 8, 2) << 9) | \
361	(RV_X(x, 10, 1) << 8) | (RV_X(x, 11, 1) << 12))
362#define ENCODE_UJTYPE_IMM(x) \
363	(ENCODE_UTYPE_IMM(RISCV_CONST_HIGH_PART(x)) | \
364	(ENCODE_ITYPE_IMM(RISCV_CONST_LOW_PART(x)) << 32))
365#define ENCODE_UITYPE_IMM(x) \
366	(ENCODE_UTYPE_IMM(x) | (ENCODE_ITYPE_IMM(x) << 32))
367
368#define CLEAN_IMM(type, x) \
369	((~ENCODE_##type##_IMM((uint64_t)(-1))) & (x))
370
371int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
372				     Elf_Shdr *section,
373				     const Elf_Shdr *relsec,
374				     const Elf_Shdr *symtab)
375{
376	const char *strtab, *name, *shstrtab;
377	const Elf_Shdr *sechdrs;
378	Elf64_Rela *relas;
379	int i, r_type;
380
381	/* String & section header string table */
382	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
383	strtab = (char *)pi->ehdr + sechdrs[symtab->sh_link].sh_offset;
384	shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
385
386	relas = (void *)pi->ehdr + relsec->sh_offset;
387
388	for (i = 0; i < relsec->sh_size / sizeof(*relas); i++) {
389		const Elf_Sym *sym;	/* symbol to relocate */
390		unsigned long addr;	/* final location after relocation */
391		unsigned long val;	/* relocated symbol value */
392		unsigned long sec_base;	/* relocated symbol value */
393		void *loc;		/* tmp location to modify */
394
395		sym = (void *)pi->ehdr + symtab->sh_offset;
396		sym += ELF64_R_SYM(relas[i].r_info);
397
398		if (sym->st_name)
399			name = strtab + sym->st_name;
400		else
401			name = shstrtab + sechdrs[sym->st_shndx].sh_name;
402
403		loc = pi->purgatory_buf;
404		loc += section->sh_offset;
405		loc += relas[i].r_offset;
406
407		if (sym->st_shndx == SHN_ABS)
408			sec_base = 0;
409		else if (sym->st_shndx >= pi->ehdr->e_shnum) {
410			pr_err("Invalid section %d for symbol %s\n",
411			       sym->st_shndx, name);
412			return -ENOEXEC;
413		} else
414			sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
415
416		val = sym->st_value;
417		val += sec_base;
418		val += relas[i].r_addend;
419
420		addr = section->sh_addr + relas[i].r_offset;
421
422		r_type = ELF64_R_TYPE(relas[i].r_info);
423
424		switch (r_type) {
425		case R_RISCV_BRANCH:
426			*(u32 *)loc = CLEAN_IMM(BTYPE, *(u32 *)loc) |
427				 ENCODE_BTYPE_IMM(val - addr);
428			break;
429		case R_RISCV_JAL:
430			*(u32 *)loc = CLEAN_IMM(JTYPE, *(u32 *)loc) |
431				 ENCODE_JTYPE_IMM(val - addr);
432			break;
433		/*
434		 * With no R_RISCV_PCREL_LO12_S, R_RISCV_PCREL_LO12_I
435		 * sym is expected to be next to R_RISCV_PCREL_HI20
436		 * in purgatory relsec. Handle it like R_RISCV_CALL
437		 * sym, instead of searching the whole relsec.
438		 */
439		case R_RISCV_PCREL_HI20:
440		case R_RISCV_CALL_PLT:
441		case R_RISCV_CALL:
442			*(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
443				 ENCODE_UJTYPE_IMM(val - addr);
444			break;
445		case R_RISCV_RVC_BRANCH:
446			*(u32 *)loc = CLEAN_IMM(CBTYPE, *(u32 *)loc) |
447				 ENCODE_CBTYPE_IMM(val - addr);
448			break;
449		case R_RISCV_RVC_JUMP:
450			*(u32 *)loc = CLEAN_IMM(CJTYPE, *(u32 *)loc) |
451				 ENCODE_CJTYPE_IMM(val - addr);
452			break;
453		case R_RISCV_ADD32:
454			*(u32 *)loc += val;
455			break;
456		case R_RISCV_SUB32:
457			*(u32 *)loc -= val;
458			break;
459		/* It has been applied by R_RISCV_PCREL_HI20 sym */
460		case R_RISCV_PCREL_LO12_I:
461		case R_RISCV_ALIGN:
462		case R_RISCV_RELAX:
463			break;
464		default:
465			pr_err("Unknown rela relocation: %d\n", r_type);
466			return -ENOEXEC;
467		}
468	}
469	return 0;
470}
471
472const struct kexec_file_ops elf_kexec_ops = {
473	.probe = kexec_elf_probe,
474	.load  = elf_kexec_load,
475};
476