Commit | Line | Data |
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1da177e4 LT |
1 | /* Kernel module help for PPC. |
2 | Copyright (C) 2001 Rusty Russell. | |
3 | ||
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 2 of the License, or | |
7 | (at your option) any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program; if not, write to the Free Software | |
16 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
17 | */ | |
c7d1f6af AB |
18 | |
19 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
20 | ||
1da177e4 LT |
21 | #include <linux/module.h> |
22 | #include <linux/moduleloader.h> | |
23 | #include <linux/elf.h> | |
24 | #include <linux/vmalloc.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/string.h> | |
27 | #include <linux/kernel.h> | |
7cc45e64 | 28 | #include <linux/ftrace.h> |
1da177e4 | 29 | #include <linux/cache.h> |
73c9ceab | 30 | #include <linux/bug.h> |
eda09fbd | 31 | #include <linux/sort.h> |
b88c4767 | 32 | #include <asm/setup.h> |
21c4ff80 | 33 | |
1da177e4 LT |
34 | /* Count how many different relocations (different symbol, different |
35 | addend) */ | |
36 | static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num) | |
37 | { | |
eda09fbd EM |
38 | unsigned int i, r_info, r_addend, _count_relocs; |
39 | ||
40 | _count_relocs = 0; | |
41 | r_info = 0; | |
42 | r_addend = 0; | |
43 | for (i = 0; i < num; i++) | |
44 | /* Only count 24-bit relocs, others don't need stubs */ | |
45 | if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 && | |
46 | (r_info != ELF32_R_SYM(rela[i].r_info) || | |
47 | r_addend != rela[i].r_addend)) { | |
48 | _count_relocs++; | |
49 | r_info = ELF32_R_SYM(rela[i].r_info); | |
50 | r_addend = rela[i].r_addend; | |
1da177e4 | 51 | } |
eda09fbd | 52 | |
7cc45e64 SR |
53 | #ifdef CONFIG_DYNAMIC_FTRACE |
54 | _count_relocs++; /* add one for ftrace_caller */ | |
55 | #endif | |
eda09fbd EM |
56 | return _count_relocs; |
57 | } | |
58 | ||
59 | static int relacmp(const void *_x, const void *_y) | |
60 | { | |
61 | const Elf32_Rela *x, *y; | |
62 | ||
63 | y = (Elf32_Rela *)_x; | |
64 | x = (Elf32_Rela *)_y; | |
65 | ||
66 | /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to | |
67 | * make the comparison cheaper/faster. It won't affect the sorting or | |
68 | * the counting algorithms' performance | |
69 | */ | |
70 | if (x->r_info < y->r_info) | |
71 | return -1; | |
72 | else if (x->r_info > y->r_info) | |
73 | return 1; | |
74 | else if (x->r_addend < y->r_addend) | |
75 | return -1; | |
76 | else if (x->r_addend > y->r_addend) | |
77 | return 1; | |
78 | else | |
79 | return 0; | |
80 | } | |
81 | ||
82 | static void relaswap(void *_x, void *_y, int size) | |
83 | { | |
84 | uint32_t *x, *y, tmp; | |
85 | int i; | |
86 | ||
87 | y = (uint32_t *)_x; | |
88 | x = (uint32_t *)_y; | |
89 | ||
90 | for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) { | |
91 | tmp = x[i]; | |
92 | x[i] = y[i]; | |
93 | y[i] = tmp; | |
1da177e4 | 94 | } |
1da177e4 LT |
95 | } |
96 | ||
97 | /* Get the potential trampolines size required of the init and | |
98 | non-init sections */ | |
99 | static unsigned long get_plt_size(const Elf32_Ehdr *hdr, | |
100 | const Elf32_Shdr *sechdrs, | |
101 | const char *secstrings, | |
102 | int is_init) | |
103 | { | |
104 | unsigned long ret = 0; | |
105 | unsigned i; | |
106 | ||
107 | /* Everything marked ALLOC (this includes the exported | |
108 | symbols) */ | |
109 | for (i = 1; i < hdr->e_shnum; i++) { | |
110 | /* If it's called *.init*, and we're not init, we're | |
111 | not interested */ | |
112 | if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0) | |
113 | != is_init) | |
114 | continue; | |
115 | ||
116 | /* We don't want to look at debug sections. */ | |
117 | if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0) | |
118 | continue; | |
119 | ||
120 | if (sechdrs[i].sh_type == SHT_RELA) { | |
c7d1f6af AB |
121 | pr_debug("Found relocations in section %u\n", i); |
122 | pr_debug("Ptr: %p. Number: %u\n", | |
1da177e4 LT |
123 | (void *)hdr + sechdrs[i].sh_offset, |
124 | sechdrs[i].sh_size / sizeof(Elf32_Rela)); | |
eda09fbd EM |
125 | |
126 | /* Sort the relocation information based on a symbol and | |
127 | * addend key. This is a stable O(n*log n) complexity | |
128 | * alogrithm but it will reduce the complexity of | |
129 | * count_relocs() to linear complexity O(n) | |
130 | */ | |
131 | sort((void *)hdr + sechdrs[i].sh_offset, | |
132 | sechdrs[i].sh_size / sizeof(Elf32_Rela), | |
133 | sizeof(Elf32_Rela), relacmp, relaswap); | |
134 | ||
1da177e4 LT |
135 | ret += count_relocs((void *)hdr |
136 | + sechdrs[i].sh_offset, | |
137 | sechdrs[i].sh_size | |
138 | / sizeof(Elf32_Rela)) | |
139 | * sizeof(struct ppc_plt_entry); | |
140 | } | |
141 | } | |
142 | ||
143 | return ret; | |
144 | } | |
145 | ||
146 | int module_frob_arch_sections(Elf32_Ehdr *hdr, | |
147 | Elf32_Shdr *sechdrs, | |
148 | char *secstrings, | |
149 | struct module *me) | |
150 | { | |
151 | unsigned int i; | |
152 | ||
153 | /* Find .plt and .init.plt sections */ | |
154 | for (i = 0; i < hdr->e_shnum; i++) { | |
155 | if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0) | |
156 | me->arch.init_plt_section = i; | |
157 | else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0) | |
158 | me->arch.core_plt_section = i; | |
159 | } | |
160 | if (!me->arch.core_plt_section || !me->arch.init_plt_section) { | |
c7d1f6af | 161 | pr_err("Module doesn't contain .plt or .init.plt sections.\n"); |
1da177e4 LT |
162 | return -ENOEXEC; |
163 | } | |
164 | ||
165 | /* Override their sizes */ | |
166 | sechdrs[me->arch.core_plt_section].sh_size | |
167 | = get_plt_size(hdr, sechdrs, secstrings, 0); | |
168 | sechdrs[me->arch.init_plt_section].sh_size | |
169 | = get_plt_size(hdr, sechdrs, secstrings, 1); | |
170 | return 0; | |
171 | } | |
172 | ||
1da177e4 LT |
173 | static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val) |
174 | { | |
3c752965 SR |
175 | if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16) |
176 | && entry->jump[1] == 0x398c0000 + (val & 0xffff)) | |
1da177e4 LT |
177 | return 1; |
178 | return 0; | |
179 | } | |
180 | ||
181 | /* Set up a trampoline in the PLT to bounce us to the distant function */ | |
182 | static uint32_t do_plt_call(void *location, | |
183 | Elf32_Addr val, | |
136cd345 | 184 | const Elf32_Shdr *sechdrs, |
1da177e4 LT |
185 | struct module *mod) |
186 | { | |
187 | struct ppc_plt_entry *entry; | |
188 | ||
c7d1f6af | 189 | pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location); |
1da177e4 | 190 | /* Init, or core PLT? */ |
7523e4dc RR |
191 | if (location >= mod->core_layout.base |
192 | && location < mod->core_layout.base + mod->core_layout.size) | |
1da177e4 LT |
193 | entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr; |
194 | else | |
195 | entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr; | |
196 | ||
197 | /* Find this entry, or if that fails, the next avail. entry */ | |
198 | while (entry->jump[0]) { | |
199 | if (entry_matches(entry, val)) return (uint32_t)entry; | |
200 | entry++; | |
201 | } | |
202 | ||
3c752965 SR |
203 | entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */ |
204 | entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/ | |
205 | entry->jump[2] = 0x7d8903a6; /* mtctr r12 */ | |
1da177e4 LT |
206 | entry->jump[3] = 0x4e800420; /* bctr */ |
207 | ||
c7d1f6af | 208 | pr_debug("Initialized plt for 0x%x at %p\n", val, entry); |
1da177e4 LT |
209 | return (uint32_t)entry; |
210 | } | |
211 | ||
212 | int apply_relocate_add(Elf32_Shdr *sechdrs, | |
213 | const char *strtab, | |
214 | unsigned int symindex, | |
215 | unsigned int relsec, | |
216 | struct module *module) | |
217 | { | |
218 | unsigned int i; | |
219 | Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr; | |
220 | Elf32_Sym *sym; | |
221 | uint32_t *location; | |
222 | uint32_t value; | |
223 | ||
c7d1f6af | 224 | pr_debug("Applying ADD relocate section %u to %u\n", relsec, |
1da177e4 LT |
225 | sechdrs[relsec].sh_info); |
226 | for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) { | |
227 | /* This is where to make the change */ | |
228 | location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr | |
229 | + rela[i].r_offset; | |
230 | /* This is the symbol it is referring to. Note that all | |
231 | undefined symbols have been resolved. */ | |
232 | sym = (Elf32_Sym *)sechdrs[symindex].sh_addr | |
233 | + ELF32_R_SYM(rela[i].r_info); | |
234 | /* `Everything is relative'. */ | |
235 | value = sym->st_value + rela[i].r_addend; | |
236 | ||
237 | switch (ELF32_R_TYPE(rela[i].r_info)) { | |
238 | case R_PPC_ADDR32: | |
239 | /* Simply set it */ | |
240 | *(uint32_t *)location = value; | |
241 | break; | |
242 | ||
243 | case R_PPC_ADDR16_LO: | |
244 | /* Low half of the symbol */ | |
245 | *(uint16_t *)location = value; | |
246 | break; | |
9a3d6458 SV |
247 | |
248 | case R_PPC_ADDR16_HI: | |
249 | /* Higher half of the symbol */ | |
250 | *(uint16_t *)location = (value >> 16); | |
251 | break; | |
252 | ||
1da177e4 LT |
253 | case R_PPC_ADDR16_HA: |
254 | /* Sign-adjusted lower 16 bits: PPC ELF ABI says: | |
255 | (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF. | |
256 | This is the same, only sane. | |
257 | */ | |
258 | *(uint16_t *)location = (value + 0x8000) >> 16; | |
259 | break; | |
260 | ||
261 | case R_PPC_REL24: | |
262 | if ((int)(value - (uint32_t)location) < -0x02000000 | |
263 | || (int)(value - (uint32_t)location) >= 0x02000000) | |
264 | value = do_plt_call(location, value, | |
265 | sechdrs, module); | |
266 | ||
267 | /* Only replace bits 2 through 26 */ | |
c7d1f6af | 268 | pr_debug("REL24 value = %08X. location = %08X\n", |
1da177e4 | 269 | value, (uint32_t)location); |
c7d1f6af | 270 | pr_debug("Location before: %08X.\n", |
1da177e4 LT |
271 | *(uint32_t *)location); |
272 | *(uint32_t *)location | |
273 | = (*(uint32_t *)location & ~0x03fffffc) | |
274 | | ((value - (uint32_t)location) | |
275 | & 0x03fffffc); | |
c7d1f6af | 276 | pr_debug("Location after: %08X.\n", |
1da177e4 | 277 | *(uint32_t *)location); |
c7d1f6af | 278 | pr_debug("ie. jump to %08X+%08X = %08X\n", |
1da177e4 LT |
279 | *(uint32_t *)location & 0x03fffffc, |
280 | (uint32_t)location, | |
281 | (*(uint32_t *)location & 0x03fffffc) | |
282 | + (uint32_t)location); | |
283 | break; | |
284 | ||
285 | case R_PPC_REL32: | |
286 | /* 32-bit relative jump. */ | |
287 | *(uint32_t *)location = value - (uint32_t)location; | |
288 | break; | |
289 | ||
290 | default: | |
c7d1f6af | 291 | pr_err("%s: unknown ADD relocation: %u\n", |
1da177e4 LT |
292 | module->name, |
293 | ELF32_R_TYPE(rela[i].r_info)); | |
294 | return -ENOEXEC; | |
295 | } | |
296 | } | |
136cd345 ME |
297 | |
298 | return 0; | |
299 | } | |
300 | ||
7cc45e64 | 301 | #ifdef CONFIG_DYNAMIC_FTRACE |
136cd345 ME |
302 | int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs) |
303 | { | |
304 | module->arch.tramp = do_plt_call(module->core_layout.base, | |
305 | (unsigned long)ftrace_caller, | |
306 | sechdrs, module); | |
307 | if (!module->arch.tramp) | |
308 | return -ENOENT; | |
309 | ||
1da177e4 LT |
310 | return 0; |
311 | } | |
136cd345 | 312 | #endif |