summaryrefslogtreecommitdiffstats
path: root/arch/x86/vdso/vdso2c.c
blob: deabaf5bfb899d24e1a2f796489f806d55c39b3e (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
#include <inttypes.h>
#include <stdint.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <err.h>

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

#include <linux/elf.h>
#include <linux/types.h>

const char *outfilename;

/* Symbols that we need in vdso2c. */
enum {
	sym_vvar_page,
	sym_hpet_page,
	sym_end_mapping,
};

const int special_pages[] = {
	sym_vvar_page,
	sym_hpet_page,
};

char const * const required_syms[] = {
	[sym_vvar_page] = "vvar_page",
	[sym_hpet_page] = "hpet_page",
	[sym_end_mapping] = "end_mapping",
	"VDSO32_NOTE_MASK",
	"VDSO32_SYSENTER_RETURN",
	"__kernel_vsyscall",
	"__kernel_sigreturn",
	"__kernel_rt_sigreturn",
};

__attribute__((format(printf, 1, 2))) __attribute__((noreturn))
static void fail(const char *format, ...)
{
	va_list ap;
	va_start(ap, format);
	fprintf(stderr, "Error: ");
	vfprintf(stderr, format, ap);
	unlink(outfilename);
	exit(1);
	va_end(ap);
}

/*
 * Evil macros to do a little-endian read.
 */
#define GLE(x, bits, ifnot)						\
	__builtin_choose_expr(						\
		(sizeof(x) == bits/8),					\
		(__typeof__(x))le##bits##toh(x), ifnot)

extern void bad_get_le(uint64_t);
#define LAST_LE(x)							\
	__builtin_choose_expr(sizeof(x) == 1, (x), bad_get_le(x))

#define GET_LE(x)							\
	GLE(x, 64, GLE(x, 32, GLE(x, 16, LAST_LE(x))))

#define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))

#define BITS 64
#define GOFUNC go64
#define Elf_Ehdr Elf64_Ehdr
#define Elf_Shdr Elf64_Shdr
#define Elf_Phdr Elf64_Phdr
#define Elf_Sym Elf64_Sym
#define Elf_Dyn Elf64_Dyn
#include "vdso2c.h"
#undef BITS
#undef GOFUNC
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Phdr
#undef Elf_Sym
#undef Elf_Dyn

#define BITS 32
#define GOFUNC go32
#define Elf_Ehdr Elf32_Ehdr
#define Elf_Shdr Elf32_Shdr
#define Elf_Phdr Elf32_Phdr
#define Elf_Sym Elf32_Sym
#define Elf_Dyn Elf32_Dyn
#include "vdso2c.h"
#undef BITS
#undef GOFUNC
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Phdr
#undef Elf_Sym
#undef Elf_Dyn

static void go(void *addr, size_t len, FILE *outfile, const char *name)
{
	Elf64_Ehdr *hdr = (Elf64_Ehdr *)addr;

	if (hdr->e_ident[EI_CLASS] == ELFCLASS64) {
		go64(addr, len, outfile, name);
	} else if (hdr->e_ident[EI_CLASS] == ELFCLASS32) {
		go32(addr, len, outfile, name);
	} else {
		fail("unknown ELF class\n");
	}
}

int main(int argc, char **argv)
{
	int fd;
	off_t len;
	void *addr;
	FILE *outfile;
	char *name, *tmp;
	int namelen;

	if (argc != 3) {
		printf("Usage: vdso2c INPUT OUTPUT\n");
		return 1;
	}

	/*
	 * Figure out the struct name.  If we're writing to a .so file,
	 * generate raw output insted.
	 */
	name = strdup(argv[2]);
	namelen = strlen(name);
	if (namelen >= 3 && !strcmp(name + namelen - 3, ".so")) {
		name = NULL;
	} else {
		tmp = strrchr(name, '/');
		if (tmp)
			name = tmp + 1;
		tmp = strchr(name, '.');
		if (tmp)
			*tmp = '\0';
		for (tmp = name; *tmp; tmp++)
			if (*tmp == '-')
				*tmp = '_';
	}

	fd = open(argv[1], O_RDONLY);
	if (fd == -1)
		err(1, "%s", argv[1]);

	len = lseek(fd, 0, SEEK_END);
	if (len == (off_t)-1)
		err(1, "lseek");

	addr = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
	if (addr == MAP_FAILED)
		err(1, "mmap");

	outfilename = argv[2];
	outfile = fopen(outfilename, "w");
	if (!outfile)
		err(1, "%s", argv[2]);

	go(addr, (size_t)len, outfile, name);

	munmap(addr, len);
	fclose(outfile);

	return 0;
}