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ebb5e78c AS |
1 | /* |
2 | * Copyright (C) 2015 Imagination Technologies | |
3 | * Author: Alex Smith <alex.smith@imgtec.com> | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License as published by the | |
7 | * Free Software Foundation; either version 2 of the License, or (at your | |
8 | * option) any later version. | |
9 | */ | |
10 | ||
11 | static inline bool FUNC(patch_vdso)(const char *path, void *vdso) | |
12 | { | |
13 | const ELF(Ehdr) *ehdr = vdso; | |
14 | void *shdrs; | |
15 | ELF(Shdr) *shdr; | |
16 | char *shstrtab, *name; | |
17 | uint16_t sh_count, sh_entsize, i; | |
18 | unsigned int local_gotno, symtabno, gotsym; | |
19 | ELF(Dyn) *dyn = NULL; | |
20 | ||
21 | shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff); | |
22 | sh_count = swap_uint16(ehdr->e_shnum); | |
23 | sh_entsize = swap_uint16(ehdr->e_shentsize); | |
24 | ||
25 | shdr = shdrs + (sh_entsize * swap_uint16(ehdr->e_shstrndx)); | |
26 | shstrtab = vdso + FUNC(swap_uint)(shdr->sh_offset); | |
27 | ||
28 | for (i = 0; i < sh_count; i++) { | |
29 | shdr = shdrs + (i * sh_entsize); | |
30 | name = shstrtab + swap_uint32(shdr->sh_name); | |
31 | ||
32 | /* | |
33 | * Ensure there are no relocation sections - ld.so does not | |
34 | * relocate the VDSO so if there are relocations things will | |
35 | * break. | |
36 | */ | |
37 | switch (swap_uint32(shdr->sh_type)) { | |
38 | case SHT_REL: | |
39 | case SHT_RELA: | |
40 | fprintf(stderr, | |
41 | "%s: '%s' contains relocation sections\n", | |
42 | program_name, path); | |
43 | return false; | |
44 | case SHT_DYNAMIC: | |
45 | dyn = vdso + FUNC(swap_uint)(shdr->sh_offset); | |
46 | break; | |
47 | } | |
48 | ||
49 | /* Check for existing sections. */ | |
50 | if (strcmp(name, ".MIPS.abiflags") == 0) { | |
51 | fprintf(stderr, | |
52 | "%s: '%s' already contains a '.MIPS.abiflags' section\n", | |
53 | program_name, path); | |
54 | return false; | |
55 | } | |
56 | ||
57 | if (strcmp(name, ".mips_abiflags") == 0) { | |
58 | strcpy(name, ".MIPS.abiflags"); | |
59 | shdr->sh_type = swap_uint32(SHT_MIPS_ABIFLAGS); | |
60 | shdr->sh_entsize = shdr->sh_size; | |
61 | } | |
62 | } | |
63 | ||
64 | /* | |
65 | * Ensure the GOT has no entries other than the standard 2, for the same | |
66 | * reason we check that there's no relocation sections above. | |
67 | * The standard two entries are: | |
68 | * - Lazy resolver | |
69 | * - Module pointer | |
70 | */ | |
71 | if (dyn) { | |
72 | local_gotno = symtabno = gotsym = 0; | |
73 | ||
74 | while (FUNC(swap_uint)(dyn->d_tag) != DT_NULL) { | |
75 | switch (FUNC(swap_uint)(dyn->d_tag)) { | |
76 | /* | |
77 | * This member holds the number of local GOT entries. | |
78 | */ | |
79 | case DT_MIPS_LOCAL_GOTNO: | |
80 | local_gotno = FUNC(swap_uint)(dyn->d_un.d_val); | |
81 | break; | |
82 | /* | |
83 | * This member holds the number of entries in the | |
84 | * .dynsym section. | |
85 | */ | |
86 | case DT_MIPS_SYMTABNO: | |
87 | symtabno = FUNC(swap_uint)(dyn->d_un.d_val); | |
88 | break; | |
89 | /* | |
90 | * This member holds the index of the first dynamic | |
91 | * symbol table entry that corresponds to an entry in | |
92 | * the GOT. | |
93 | */ | |
94 | case DT_MIPS_GOTSYM: | |
95 | gotsym = FUNC(swap_uint)(dyn->d_un.d_val); | |
96 | break; | |
97 | } | |
98 | ||
99 | dyn++; | |
100 | } | |
101 | ||
102 | if (local_gotno > 2 || symtabno - gotsym) { | |
103 | fprintf(stderr, | |
104 | "%s: '%s' contains unexpected GOT entries\n", | |
105 | program_name, path); | |
106 | return false; | |
107 | } | |
108 | } | |
109 | ||
110 | return true; | |
111 | } | |
112 | ||
113 | static inline bool FUNC(get_symbols)(const char *path, void *vdso) | |
114 | { | |
115 | const ELF(Ehdr) *ehdr = vdso; | |
116 | void *shdrs, *symtab; | |
117 | ELF(Shdr) *shdr; | |
118 | const ELF(Sym) *sym; | |
119 | char *strtab, *name; | |
120 | uint16_t sh_count, sh_entsize, st_count, st_entsize, i, j; | |
121 | uint64_t offset; | |
122 | uint32_t flags; | |
123 | ||
124 | shdrs = vdso + FUNC(swap_uint)(ehdr->e_shoff); | |
125 | sh_count = swap_uint16(ehdr->e_shnum); | |
126 | sh_entsize = swap_uint16(ehdr->e_shentsize); | |
127 | ||
128 | for (i = 0; i < sh_count; i++) { | |
129 | shdr = shdrs + (i * sh_entsize); | |
130 | ||
131 | if (swap_uint32(shdr->sh_type) == SHT_SYMTAB) | |
132 | break; | |
133 | } | |
134 | ||
135 | if (i == sh_count) { | |
136 | fprintf(stderr, "%s: '%s' has no symbol table\n", program_name, | |
137 | path); | |
138 | return false; | |
139 | } | |
140 | ||
141 | /* Get flags */ | |
142 | flags = swap_uint32(ehdr->e_flags); | |
143 | if (elf_class == ELFCLASS64) | |
144 | elf_abi = ABI_N64; | |
145 | else if (flags & EF_MIPS_ABI2) | |
146 | elf_abi = ABI_N32; | |
147 | else | |
148 | elf_abi = ABI_O32; | |
149 | ||
150 | /* Get symbol table. */ | |
151 | symtab = vdso + FUNC(swap_uint)(shdr->sh_offset); | |
152 | st_entsize = FUNC(swap_uint)(shdr->sh_entsize); | |
153 | st_count = FUNC(swap_uint)(shdr->sh_size) / st_entsize; | |
154 | ||
155 | /* Get string table. */ | |
156 | shdr = shdrs + (swap_uint32(shdr->sh_link) * sh_entsize); | |
157 | strtab = vdso + FUNC(swap_uint)(shdr->sh_offset); | |
158 | ||
159 | /* Write offsets for symbols needed by the kernel. */ | |
160 | for (i = 0; vdso_symbols[i].name; i++) { | |
161 | if (!(vdso_symbols[i].abis & elf_abi)) | |
162 | continue; | |
163 | ||
164 | for (j = 0; j < st_count; j++) { | |
165 | sym = symtab + (j * st_entsize); | |
166 | name = strtab + swap_uint32(sym->st_name); | |
167 | ||
168 | if (!strcmp(name, vdso_symbols[i].name)) { | |
169 | offset = FUNC(swap_uint)(sym->st_value); | |
170 | ||
171 | fprintf(out_file, | |
172 | "\t.%s = 0x%" PRIx64 ",\n", | |
173 | vdso_symbols[i].offset_name, offset); | |
174 | break; | |
175 | } | |
176 | } | |
177 | ||
178 | if (j == st_count) { | |
179 | fprintf(stderr, | |
180 | "%s: '%s' is missing required symbol '%s'\n", | |
181 | program_name, path, vdso_symbols[i].name); | |
182 | return false; | |
183 | } | |
184 | } | |
185 | ||
186 | return true; | |
187 | } |