1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2015 Imagination Technologies
4 * Author: Alex Smith <alex.smith@imgtec.com>
5 */
6
7 /*
8 * This tool is used to generate the real VDSO images from the raw image. It
9 * first patches up the MIPS ABI flags and GNU attributes sections defined in
10 * elf.S to have the correct name and type. It then generates a C source file
11 * to be compiled into the kernel containing the VDSO image data and a
12 * mips_vdso_image struct for it, including symbol offsets extracted from the
13 * image.
14 *
15 * We need to be passed both a stripped and unstripped VDSO image. The stripped
16 * image is compiled into the kernel, but we must also patch up the unstripped
17 * image's ABI flags sections so that it can be installed and used for
18 * debugging.
19 */
20
21 #include <sys/mman.h>
22 #include <sys/stat.h>
23 #include <sys/types.h>
24
25 #include <byteswap.h>
26 #include <elf.h>
27 #include <errno.h>
28 #include <fcntl.h>
29 #include <inttypes.h>
30 #include <stdarg.h>
31 #include <stdbool.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36
37 /* Define these in case the system elf.h is not new enough to have them. */
38 #ifndef SHT_GNU_ATTRIBUTES
39 # define SHT_GNU_ATTRIBUTES 0x6ffffff5
40 #endif
41 #ifndef SHT_MIPS_ABIFLAGS
42 # define SHT_MIPS_ABIFLAGS 0x7000002a
43 #endif
44
45 enum {
46 ABI_O32 = (1 << 0),
47 ABI_N32 = (1 << 1),
48 ABI_N64 = (1 << 2),
49
50 ABI_ALL = ABI_O32 | ABI_N32 | ABI_N64,
51 };
52
53 /* Symbols the kernel requires offsets for. */
54 static struct {
55 const char *name;
56 const char *offset_name;
57 unsigned int abis;
58 } vdso_symbols[] = {
59 { "__vdso_sigreturn", "off_sigreturn", ABI_O32 },
60 { "__vdso_rt_sigreturn", "off_rt_sigreturn", ABI_ALL },
61 {}
62 };
63
64 static const char *program_name;
65 static const char *vdso_name;
66 static unsigned char elf_class;
67 static unsigned int elf_abi;
68 static bool need_swap;
69 static FILE *out_file;
70
71 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
72 # define HOST_ORDER ELFDATA2LSB
73 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
74 # define HOST_ORDER ELFDATA2MSB
75 #endif
76
77 #define BUILD_SWAP(bits) \
78 static uint##bits##_t swap_uint##bits(uint##bits##_t val) \
79 { \
80 return need_swap ? bswap_##bits(val) : val; \
81 }
82
83 BUILD_SWAP(16)
84 BUILD_SWAP(32)
85 BUILD_SWAP(64)
86
87 #define __FUNC(name, bits) name##bits
88 #define _FUNC(name, bits) __FUNC(name, bits)
89 #define FUNC(name) _FUNC(name, ELF_BITS)
90
91 #define __ELF(x, bits) Elf##bits##_##x
92 #define _ELF(x, bits) __ELF(x, bits)
93 #define ELF(x) _ELF(x, ELF_BITS)
94
95 /*
96 * Include genvdso.h twice with ELF_BITS defined differently to get functions
97 * for both ELF32 and ELF64.
98 */
99
100 #define ELF_BITS 64
101 #include "genvdso.h"
102 #undef ELF_BITS
103
104 #define ELF_BITS 32
105 #include "genvdso.h"
106 #undef ELF_BITS
107
108 static void *map_vdso(const char *path, size_t *_size)
109 {
110 int fd;
111 struct stat stat;
112 void *addr;
113 const Elf32_Ehdr *ehdr;
114
115 fd = open(path, O_RDWR);
116 if (fd < 0) {
117 fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
118 path, strerror(errno));
119 return NULL;
120 }
121
122 if (fstat(fd, &stat) != 0) {
123 fprintf(stderr, "%s: Failed to stat '%s': %s\n", program_name,
124 path, strerror(errno));
125 close(fd);
126 return NULL;
127 }
128
129 addr = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
130 0);
131 if (addr == MAP_FAILED) {
132 fprintf(stderr, "%s: Failed to map '%s': %s\n", program_name,
133 path, strerror(errno));
134 close(fd);
135 return NULL;
136 }
137
138 /* ELF32/64 header formats are the same for the bits we're checking. */
139 ehdr = addr;
140
141 if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
142 fprintf(stderr, "%s: '%s' is not an ELF file\n", program_name,
143 path);
144 close(fd);
145 return NULL;
146 }
147
148 elf_class = ehdr->e_ident[EI_CLASS];
149 switch (elf_class) {
150 case ELFCLASS32:
151 case ELFCLASS64:
152 break;
153 default:
154 fprintf(stderr, "%s: '%s' has invalid ELF class\n",
155 program_name, path);
156 close(fd);
157 return NULL;
158 }
159
160 switch (ehdr->e_ident[EI_DATA]) {
161 case ELFDATA2LSB:
162 case ELFDATA2MSB:
163 need_swap = ehdr->e_ident[EI_DATA] != HOST_ORDER;
164 break;
165 default:
166 fprintf(stderr, "%s: '%s' has invalid ELF data order\n",
167 program_name, path);
168 close(fd);
169 return NULL;
170 }
171
172 if (swap_uint16(ehdr->e_machine) != EM_MIPS) {
173 fprintf(stderr,
174 "%s: '%s' has invalid ELF machine (expected EM_MIPS)\n",
175 program_name, path);
176 close(fd);
177 return NULL;
178 } else if (swap_uint16(ehdr->e_type) != ET_DYN) {
179 fprintf(stderr,
180 "%s: '%s' has invalid ELF type (expected ET_DYN)\n",
181 program_name, path);
182 close(fd);
183 return NULL;
184 }
185
186 *_size = stat.st_size;
187 close(fd);
188 return addr;
189 }
190
191 static bool patch_vdso(const char *path, void *vdso)
192 {
193 if (elf_class == ELFCLASS64)
194 return patch_vdso64(path, vdso);
195 else
196 return patch_vdso32(path, vdso);
197 }
198
199 static bool get_symbols(const char *path, void *vdso)
200 {
201 if (elf_class == ELFCLASS64)
202 return get_symbols64(path, vdso);
203 else
204 return get_symbols32(path, vdso);
205 }
206
207 int main(int argc, char **argv)
208 {
209 const char *dbg_vdso_path, *vdso_path, *out_path;
210 void *dbg_vdso, *vdso;
211 size_t dbg_vdso_size, vdso_size, i;
212
213 program_name = argv[0];
214
215 if (argc < 4 || argc > 5) {
216 fprintf(stderr,
217 "Usage: %s <debug VDSO> <stripped VDSO> <output file> [<name>]\n",
218 program_name);
219 return EXIT_FAILURE;
220 }
221
222 dbg_vdso_path = argv[1];
223 vdso_path = argv[2];
224 out_path = argv[3];
225 vdso_name = (argc > 4) ? argv[4] : "";
226
227 dbg_vdso = map_vdso(dbg_vdso_path, &dbg_vdso_size);
228 if (!dbg_vdso)
229 return EXIT_FAILURE;
230
231 vdso = map_vdso(vdso_path, &vdso_size);
232 if (!vdso)
233 return EXIT_FAILURE;
234
235 /* Patch both the VDSOs' ABI flags sections. */
236 if (!patch_vdso(dbg_vdso_path, dbg_vdso))
237 return EXIT_FAILURE;
238 if (!patch_vdso(vdso_path, vdso))
239 return EXIT_FAILURE;
240
241 if (msync(dbg_vdso, dbg_vdso_size, MS_SYNC) != 0) {
242 fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
243 dbg_vdso_path, strerror(errno));
244 return EXIT_FAILURE;
245 } else if (msync(vdso, vdso_size, MS_SYNC) != 0) {
246 fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
247 vdso_path, strerror(errno));
248 return EXIT_FAILURE;
249 }
250
251 out_file = fopen(out_path, "w");
252 if (!out_file) {
253 fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
254 out_path, strerror(errno));
255 return EXIT_FAILURE;
256 }
257
258 fprintf(out_file, "/* Automatically generated - do not edit */\n");
259 fprintf(out_file, "#include <linux/linkage.h>\n");
260 fprintf(out_file, "#include <linux/mm.h>\n");
261 fprintf(out_file, "#include <asm/vdso.h>\n");
262 fprintf(out_file, "static int vdso_mremap(\n");
263 fprintf(out_file, " const struct vm_special_mapping *sm,\n");
264 fprintf(out_file, " struct vm_area_struct *new_vma)\n");
265 fprintf(out_file, "{\n");
266 fprintf(out_file, " current->mm->context.vdso =\n");
267 fprintf(out_file, " (void *)(new_vma->vm_start);\n");
268 fprintf(out_file, " return 0;\n");
269 fprintf(out_file, "}\n");
270
271 /* Write out the stripped VDSO data. */
272 fprintf(out_file,
273 "static unsigned char vdso_data[PAGE_ALIGN(%zu)] __page_aligned_data = {\n\t",
274 vdso_size);
275 for (i = 0; i < vdso_size; i++) {
276 if (!(i % 10))
277 fprintf(out_file, "\n\t");
278 fprintf(out_file, "0x%02x, ", ((unsigned char *)vdso)[i]);
279 }
280 fprintf(out_file, "\n};\n");
281
282 /* Preallocate a page array. */
283 fprintf(out_file,
284 "static struct page *vdso_pages[PAGE_ALIGN(%zu) / PAGE_SIZE];\n",
285 vdso_size);
286
287 fprintf(out_file, "struct mips_vdso_image vdso_image%s%s = {\n",
288 (vdso_name[0]) ? "_" : "", vdso_name);
289 fprintf(out_file, "\t.data = vdso_data,\n");
290 fprintf(out_file, "\t.size = PAGE_ALIGN(%zu),\n", vdso_size);
291 fprintf(out_file, "\t.mapping = {\n");
292 fprintf(out_file, "\t\t.name = \"[vdso]\",\n");
293 fprintf(out_file, "\t\t.pages = vdso_pages,\n");
294 fprintf(out_file, "\t\t.mremap = vdso_mremap,\n");
295 fprintf(out_file, "\t},\n");
296
297 /* Calculate and write symbol offsets to <output file> */
298 if (!get_symbols(dbg_vdso_path, dbg_vdso)) {
299 unlink(out_path);
300 fclose(out_file);
301 return EXIT_FAILURE;
302 }
303
304 fprintf(out_file, "};\n");
305 fclose(out_file);
306
307 return EXIT_SUCCESS;
308 }
309
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