summaryrefslogtreecommitdiffstats
path: root/arch/mips/vdso/genvdso.c
blob: b66b6b1c4aeb9298d8ee4d30b7db9433f7df5f29 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2015 Imagination Technologies
 * Author: Alex Smith <alex.smith@imgtec.com>
 */

/*
 * This tool is used to generate the real VDSO images from the raw image. It
 * first patches up the MIPS ABI flags and GNU attributes sections defined in
 * elf.S to have the correct name and type. It then generates a C source file
 * to be compiled into the kernel containing the VDSO image data and a
 * mips_vdso_image struct for it, including symbol offsets extracted from the
 * image.
 *
 * We need to be passed both a stripped and unstripped VDSO image. The stripped
 * image is compiled into the kernel, but we must also patch up the unstripped
 * image's ABI flags sections so that it can be installed and used for
 * debugging.
 */

#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <byteswap.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/* Define these in case the system elf.h is not new enough to have them. */
#ifndef SHT_GNU_ATTRIBUTES
# define SHT_GNU_ATTRIBUTES	0x6ffffff5
#endif
#ifndef SHT_MIPS_ABIFLAGS
# define SHT_MIPS_ABIFLAGS	0x7000002a
#endif

enum {
	ABI_O32 = (1 << 0),
	ABI_N32 = (1 << 1),
	ABI_N64 = (1 << 2),

	ABI_ALL = ABI_O32 | ABI_N32 | ABI_N64,
};

/* Symbols the kernel requires offsets for. */
static struct {
	const char *name;
	const char *offset_name;
	unsigned int abis;
} vdso_symbols[] = {
	{ "__vdso_sigreturn", "off_sigreturn", ABI_O32 },
	{ "__vdso_rt_sigreturn", "off_rt_sigreturn", ABI_ALL },
	{}
};

static const char *program_name;
static const char *vdso_name;
static unsigned char elf_class;
static unsigned int elf_abi;
static bool need_swap;
static FILE *out_file;

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define HOST_ORDER		ELFDATA2LSB
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define HOST_ORDER		ELFDATA2MSB
#endif

#define BUILD_SWAP(bits)						\
	static uint##bits##_t swap_uint##bits(uint##bits##_t val)	\
	{								\
		return need_swap ? bswap_##bits(val) : val;		\
	}

BUILD_SWAP(16)
BUILD_SWAP(32)
BUILD_SWAP(64)

#define __FUNC(name, bits) name##bits
#define _FUNC(name, bits) __FUNC(name, bits)
#define FUNC(name) _FUNC(name, ELF_BITS)

#define __ELF(x, bits) Elf##bits##_##x
#define _ELF(x, bits) __ELF(x, bits)
#define ELF(x) _ELF(x, ELF_BITS)

/*
 * Include genvdso.h twice with ELF_BITS defined differently to get functions
 * for both ELF32 and ELF64.
 */

#define ELF_BITS 64
#include "genvdso.h"
#undef ELF_BITS

#define ELF_BITS 32
#include "genvdso.h"
#undef ELF_BITS

static void *map_vdso(const char *path, size_t *_size)
{
	int fd;
	struct stat stat;
	void *addr;
	const Elf32_Ehdr *ehdr;

	fd = open(path, O_RDWR);
	if (fd < 0) {
		fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
			path, strerror(errno));
		return NULL;
	}

	if (fstat(fd, &stat) != 0) {
		fprintf(stderr, "%s: Failed to stat '%s': %s\n", program_name,
			path, strerror(errno));
		return NULL;
	}

	addr = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
		    0);
	if (addr == MAP_FAILED) {
		fprintf(stderr, "%s: Failed to map '%s': %s\n", program_name,
			path, strerror(errno));
		return NULL;
	}

	/* ELF32/64 header formats are the same for the bits we're checking. */
	ehdr = addr;

	if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
		fprintf(stderr, "%s: '%s' is not an ELF file\n", program_name,
			path);
		return NULL;
	}

	elf_class = ehdr->e_ident[EI_CLASS];
	switch (elf_class) {
	case ELFCLASS32:
	case ELFCLASS64:
		break;
	default:
		fprintf(stderr, "%s: '%s' has invalid ELF class\n",
			program_name, path);
		return NULL;
	}

	switch (ehdr->e_ident[EI_DATA]) {
	case ELFDATA2LSB:
	case ELFDATA2MSB:
		need_swap = ehdr->e_ident[EI_DATA] != HOST_ORDER;
		break;
	default:
		fprintf(stderr, "%s: '%s' has invalid ELF data order\n",
			program_name, path);
		return NULL;
	}

	if (swap_uint16(ehdr->e_machine) != EM_MIPS) {
		fprintf(stderr,
			"%s: '%s' has invalid ELF machine (expected EM_MIPS)\n",
			program_name, path);
		return NULL;
	} else if (swap_uint16(ehdr->e_type) != ET_DYN) {
		fprintf(stderr,
			"%s: '%s' has invalid ELF type (expected ET_DYN)\n",
			program_name, path);
		return NULL;
	}

	*_size = stat.st_size;
	return addr;
}

static bool patch_vdso(const char *path, void *vdso)
{
	if (elf_class == ELFCLASS64)
		return patch_vdso64(path, vdso);
	else
		return patch_vdso32(path, vdso);
}

static bool get_symbols(const char *path, void *vdso)
{
	if (elf_class == ELFCLASS64)
		return get_symbols64(path, vdso);
	else
		return get_symbols32(path, vdso);
}

int main(int argc, char **argv)
{
	const char *dbg_vdso_path, *vdso_path, *out_path;
	void *dbg_vdso, *vdso;
	size_t dbg_vdso_size, vdso_size, i;

	program_name = argv[0];

	if (argc < 4 || argc > 5) {
		fprintf(stderr,
			"Usage: %s <debug VDSO> <stripped VDSO> <output file> [<name>]\n",
			program_name);
		return EXIT_FAILURE;
	}

	dbg_vdso_path = argv[1];
	vdso_path = argv[2];
	out_path = argv[3];
	vdso_name = (argc > 4) ? argv[4] : "";

	dbg_vdso = map_vdso(dbg_vdso_path, &dbg_vdso_size);
	if (!dbg_vdso)
		return EXIT_FAILURE;

	vdso = map_vdso(vdso_path, &vdso_size);
	if (!vdso)
		return EXIT_FAILURE;

	/* Patch both the VDSOs' ABI flags sections. */
	if (!patch_vdso(dbg_vdso_path, dbg_vdso))
		return EXIT_FAILURE;
	if (!patch_vdso(vdso_path, vdso))
		return EXIT_FAILURE;

	if (msync(dbg_vdso, dbg_vdso_size, MS_SYNC) != 0) {
		fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
			dbg_vdso_path, strerror(errno));
		return EXIT_FAILURE;
	} else if (msync(vdso, vdso_size, MS_SYNC) != 0) {
		fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
			vdso_path, strerror(errno));
		return EXIT_FAILURE;
	}

	out_file = fopen(out_path, "w");
	if (!out_file) {
		fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
			out_path, strerror(errno));
		return EXIT_FAILURE;
	}

	fprintf(out_file, "/* Automatically generated - do not edit */\n");
	fprintf(out_file, "#include <linux/linkage.h>\n");
	fprintf(out_file, "#include <linux/mm.h>\n");
	fprintf(out_file, "#include <asm/vdso.h>\n");

	/* Write out the stripped VDSO data. */
	fprintf(out_file,
		"static unsigned char vdso_data[PAGE_ALIGN(%zu)] __page_aligned_data = {\n\t",
		vdso_size);
	for (i = 0; i < vdso_size; i++) {
		if (!(i % 10))
			fprintf(out_file, "\n\t");
		fprintf(out_file, "0x%02x, ", ((unsigned char *)vdso)[i]);
	}
	fprintf(out_file, "\n};\n");

	/* Preallocate a page array. */
	fprintf(out_file,
		"static struct page *vdso_pages[PAGE_ALIGN(%zu) / PAGE_SIZE];\n",
		vdso_size);

	fprintf(out_file, "struct mips_vdso_image vdso_image%s%s = {\n",
		(vdso_name[0]) ? "_" : "", vdso_name);
	fprintf(out_file, "\t.data = vdso_data,\n");
	fprintf(out_file, "\t.size = PAGE_ALIGN(%zu),\n", vdso_size);
	fprintf(out_file, "\t.mapping = {\n");
	fprintf(out_file, "\t\t.name = \"[vdso]\",\n");
	fprintf(out_file, "\t\t.pages = vdso_pages,\n");
	fprintf(out_file, "\t},\n");

	/* Calculate and write symbol offsets to <output file> */
	if (!get_symbols(dbg_vdso_path, dbg_vdso)) {
		unlink(out_path);
		return EXIT_FAILURE;
	}

	fprintf(out_file, "};\n");

	return EXIT_SUCCESS;
}