1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright 2015 Mentor Graphics Corporation. |
4 | * |
5 | * vdsomunge - Host program which produces a shared object |
6 | * architecturally specified to be usable by both soft- and hard-float |
7 | * programs. |
8 | * |
9 | * The Procedure Call Standard for the ARM Architecture (ARM IHI |
10 | * 0042E) says: |
11 | * |
12 | * 6.4.1 VFP and Base Standard Compatibility |
13 | * |
14 | * Code compiled for the VFP calling standard is compatible with |
15 | * the base standard (and vice-versa) if no floating-point or |
16 | * containerized vector arguments or results are used. |
17 | * |
18 | * And ELF for the ARM Architecture (ARM IHI 0044E) (Table 4-2) says: |
19 | * |
20 | * If both EF_ARM_ABI_FLOAT_XXXX bits are clear, conformance to the |
21 | * base procedure-call standard is implied. |
22 | * |
23 | * The VDSO is built with -msoft-float, as with the rest of the ARM |
24 | * kernel, and uses no floating point arguments or results. The build |
25 | * process will produce a shared object that may or may not have the |
26 | * EF_ARM_ABI_FLOAT_SOFT flag set (it seems to depend on the binutils |
27 | * version; binutils starting with 2.24 appears to set it). The |
28 | * EF_ARM_ABI_FLOAT_HARD flag should definitely not be set, and this |
29 | * program will error out if it is. |
30 | * |
31 | * If the soft-float flag is set, this program clears it. That's all |
32 | * it does. |
33 | */ |
34 | |
35 | #include <elf.h> |
36 | #include <errno.h> |
37 | #include <fcntl.h> |
38 | #include <stdarg.h> |
39 | #include <stdbool.h> |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | #include <string.h> |
43 | #include <sys/mman.h> |
44 | #include <sys/stat.h> |
45 | #include <sys/types.h> |
46 | #include <unistd.h> |
47 | |
48 | #define swab16(x) \ |
49 | ((((x) & 0x00ff) << 8) | \ |
50 | (((x) & 0xff00) >> 8)) |
51 | |
52 | #define swab32(x) \ |
53 | ((((x) & 0x000000ff) << 24) | \ |
54 | (((x) & 0x0000ff00) << 8) | \ |
55 | (((x) & 0x00ff0000) >> 8) | \ |
56 | (((x) & 0xff000000) >> 24)) |
57 | |
58 | #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ |
59 | #define HOST_ORDER ELFDATA2LSB |
60 | #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ |
61 | #define HOST_ORDER ELFDATA2MSB |
62 | #endif |
63 | |
64 | /* Some of the ELF constants we'd like to use were added to <elf.h> |
65 | * relatively recently. |
66 | */ |
67 | #ifndef EF_ARM_EABI_VER5 |
68 | #define EF_ARM_EABI_VER5 0x05000000 |
69 | #endif |
70 | |
71 | #ifndef EF_ARM_ABI_FLOAT_SOFT |
72 | #define EF_ARM_ABI_FLOAT_SOFT 0x200 |
73 | #endif |
74 | |
75 | #ifndef EF_ARM_ABI_FLOAT_HARD |
76 | #define EF_ARM_ABI_FLOAT_HARD 0x400 |
77 | #endif |
78 | |
79 | static int failed; |
80 | static const char *argv0; |
81 | static const char *outfile; |
82 | |
83 | static void fail(const char *fmt, ...) |
84 | { |
85 | va_list ap; |
86 | |
87 | failed = 1; |
88 | fprintf(stderr, "%s: " , argv0); |
89 | va_start(ap, fmt); |
90 | vfprintf(stderr, fmt, ap); |
91 | va_end(ap); |
92 | exit(EXIT_FAILURE); |
93 | } |
94 | |
95 | static void cleanup(void) |
96 | { |
97 | if (failed && outfile != NULL) |
98 | unlink(outfile); |
99 | } |
100 | |
101 | static Elf32_Word read_elf_word(Elf32_Word word, bool swap) |
102 | { |
103 | return swap ? swab32(word) : word; |
104 | } |
105 | |
106 | static Elf32_Half read_elf_half(Elf32_Half half, bool swap) |
107 | { |
108 | return swap ? swab16(half) : half; |
109 | } |
110 | |
111 | static void write_elf_word(Elf32_Word val, Elf32_Word *dst, bool swap) |
112 | { |
113 | *dst = swap ? swab32(val) : val; |
114 | } |
115 | |
116 | int main(int argc, char **argv) |
117 | { |
118 | const Elf32_Ehdr *inhdr; |
119 | bool clear_soft_float; |
120 | const char *infile; |
121 | Elf32_Word e_flags; |
122 | const void *inbuf; |
123 | struct stat stat; |
124 | void *outbuf; |
125 | bool swap; |
126 | int outfd; |
127 | int infd; |
128 | |
129 | atexit(cleanup); |
130 | argv0 = argv[0]; |
131 | |
132 | if (argc != 3) |
133 | fail(fmt: "Usage: %s [infile] [outfile]\n" , argv[0]); |
134 | |
135 | infile = argv[1]; |
136 | outfile = argv[2]; |
137 | |
138 | infd = open(infile, O_RDONLY); |
139 | if (infd < 0) |
140 | fail(fmt: "Cannot open %s: %s\n" , infile, strerror(errno)); |
141 | |
142 | if (fstat(infd, &stat) != 0) |
143 | fail(fmt: "Failed stat for %s: %s\n" , infile, strerror(errno)); |
144 | |
145 | inbuf = mmap(NULL, stat.st_size, PROT_READ, MAP_PRIVATE, infd, 0); |
146 | if (inbuf == MAP_FAILED) |
147 | fail(fmt: "Failed to map %s: %s\n" , infile, strerror(errno)); |
148 | |
149 | close(infd); |
150 | |
151 | inhdr = inbuf; |
152 | |
153 | if (memcmp(&inhdr->e_ident, ELFMAG, SELFMAG) != 0) |
154 | fail(fmt: "Not an ELF file\n" ); |
155 | |
156 | if (inhdr->e_ident[EI_CLASS] != ELFCLASS32) |
157 | fail(fmt: "Unsupported ELF class\n" ); |
158 | |
159 | swap = inhdr->e_ident[EI_DATA] != HOST_ORDER; |
160 | |
161 | if (read_elf_half(inhdr->e_type, swap) != ET_DYN) |
162 | fail(fmt: "Not a shared object\n" ); |
163 | |
164 | if (read_elf_half(inhdr->e_machine, swap) != EM_ARM) |
165 | fail(fmt: "Unsupported architecture %#x\n" , inhdr->e_machine); |
166 | |
167 | e_flags = read_elf_word(inhdr->e_flags, swap); |
168 | |
169 | if (EF_ARM_EABI_VERSION(e_flags) != EF_ARM_EABI_VER5) { |
170 | fail("Unsupported EABI version %#x\n" , |
171 | EF_ARM_EABI_VERSION(e_flags)); |
172 | } |
173 | |
174 | if (e_flags & EF_ARM_ABI_FLOAT_HARD) |
175 | fail(fmt: "Unexpected hard-float flag set in e_flags\n" ); |
176 | |
177 | clear_soft_float = !!(e_flags & EF_ARM_ABI_FLOAT_SOFT); |
178 | |
179 | outfd = open(outfile, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR); |
180 | if (outfd < 0) |
181 | fail("Cannot open %s: %s\n" , outfile, strerror(errno)); |
182 | |
183 | if (ftruncate(outfd, stat.st_size) != 0) |
184 | fail("Cannot truncate %s: %s\n" , outfile, strerror(errno)); |
185 | |
186 | outbuf = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, |
187 | outfd, 0); |
188 | if (outbuf == MAP_FAILED) |
189 | fail("Failed to map %s: %s\n" , outfile, strerror(errno)); |
190 | |
191 | close(outfd); |
192 | |
193 | memcpy(outbuf, inbuf, stat.st_size); |
194 | |
195 | if (clear_soft_float) { |
196 | Elf32_Ehdr *outhdr; |
197 | |
198 | outhdr = outbuf; |
199 | e_flags &= ~EF_ARM_ABI_FLOAT_SOFT; |
200 | write_elf_word(e_flags, &outhdr->e_flags, swap); |
201 | } |
202 | |
203 | if (msync(outbuf, stat.st_size, MS_SYNC) != 0) |
204 | fail("Failed to sync %s: %s\n" , outfile, strerror(errno)); |
205 | |
206 | return EXIT_SUCCESS; |
207 | } |
208 | |