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
45enum {
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. */
54static 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
64static const char *program_name;
65static const char *vdso_name;
66static unsigned char elf_class;
67static unsigned int elf_abi;
68static bool need_swap;
69static 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
83BUILD_SWAP(16)
84BUILD_SWAP(32)
85BUILD_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
108static 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
191static 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
199static 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
207int 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