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1/*
2 * This program is free software; you can redistribute it and/or modify
3 * it under the terms of the GNU General Public License as published by
4 * the Free Software Foundation; either version 2 of the License, or
5 * (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * Copyright (C) 2017 Zihao Yu
13 */
14
15#include <linux/elf.h>
16#include <linux/err.h>
17#include <linux/errno.h>
18#include <linux/moduleloader.h>
19
20static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
21{
22 *(u64 *)location = v;
23 return 0;
24}
25
26static int apply_r_riscv_branch_rela(struct module *me, u32 *location,
27 Elf_Addr v)
28{
29 s64 offset = (void *)v - (void *)location;
30 u32 imm12 = (offset & 0x1000) << (31 - 12);
31 u32 imm11 = (offset & 0x800) >> (11 - 7);
32 u32 imm10_5 = (offset & 0x7e0) << (30 - 10);
33 u32 imm4_1 = (offset & 0x1e) << (11 - 4);
34
35 *location = (*location & 0x1fff07f) | imm12 | imm11 | imm10_5 | imm4_1;
36 return 0;
37}
38
39static int apply_r_riscv_jal_rela(struct module *me, u32 *location,
40 Elf_Addr v)
41{
42 s64 offset = (void *)v - (void *)location;
43 u32 imm20 = (offset & 0x100000) << (31 - 20);
44 u32 imm19_12 = (offset & 0xff000);
45 u32 imm11 = (offset & 0x800) << (20 - 11);
46 u32 imm10_1 = (offset & 0x7fe) << (30 - 10);
47
48 *location = (*location & 0xfff) | imm20 | imm19_12 | imm11 | imm10_1;
49 return 0;
50}
51
52static int apply_r_riscv_rcv_branch_rela(struct module *me, u32 *location,
53 Elf_Addr v)
54{
55 s64 offset = (void *)v - (void *)location;
56 u16 imm8 = (offset & 0x100) << (12 - 8);
57 u16 imm7_6 = (offset & 0xc0) >> (6 - 5);
58 u16 imm5 = (offset & 0x20) >> (5 - 2);
59 u16 imm4_3 = (offset & 0x18) << (12 - 5);
60 u16 imm2_1 = (offset & 0x6) << (12 - 10);
61
62 *(u16 *)location = (*(u16 *)location & 0xe383) |
63 imm8 | imm7_6 | imm5 | imm4_3 | imm2_1;
64 return 0;
65}
66
67static int apply_r_riscv_rvc_jump_rela(struct module *me, u32 *location,
68 Elf_Addr v)
69{
70 s64 offset = (void *)v - (void *)location;
71 u16 imm11 = (offset & 0x800) << (12 - 11);
72 u16 imm10 = (offset & 0x400) >> (10 - 8);
73 u16 imm9_8 = (offset & 0x300) << (12 - 11);
74 u16 imm7 = (offset & 0x80) >> (7 - 6);
75 u16 imm6 = (offset & 0x40) << (12 - 11);
76 u16 imm5 = (offset & 0x20) >> (5 - 2);
77 u16 imm4 = (offset & 0x10) << (12 - 5);
78 u16 imm3_1 = (offset & 0xe) << (12 - 10);
79
80 *(u16 *)location = (*(u16 *)location & 0xe003) |
81 imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1;
82 return 0;
83}
84
85static int apply_r_riscv_pcrel_hi20_rela(struct module *me, u32 *location,
86 Elf_Addr v)
87{
88 s64 offset = (void *)v - (void *)location;
89 s32 hi20;
90
91 if (offset != (s32)offset) {
92 pr_err(
93 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
94 me->name, v, location);
95 return -EINVAL;
96 }
97
98 hi20 = (offset + 0x800) & 0xfffff000;
99 *location = (*location & 0xfff) | hi20;
100 return 0;
101}
102
103static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, u32 *location,
104 Elf_Addr v)
105{
106 /*
107 * v is the lo12 value to fill. It is calculated before calling this
108 * handler.
109 */
110 *location = (*location & 0xfffff) | ((v & 0xfff) << 20);
111 return 0;
112}
113
114static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location,
115 Elf_Addr v)
116{
117 /*
118 * v is the lo12 value to fill. It is calculated before calling this
119 * handler.
120 */
121 u32 imm11_5 = (v & 0xfe0) << (31 - 11);
122 u32 imm4_0 = (v & 0x1f) << (11 - 4);
123
124 *location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
125 return 0;
126}
127
128static int apply_r_riscv_hi20_rela(struct module *me, u32 *location,
129 Elf_Addr v)
130{
131 s32 hi20;
132
133 if (IS_ENABLED(CMODEL_MEDLOW)) {
134 pr_err(
135 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
136 me->name, v, location);
137 return -EINVAL;
138 }
139
140 hi20 = ((s32)v + 0x800) & 0xfffff000;
141 *location = (*location & 0xfff) | hi20;
142 return 0;
143}
144
145static int apply_r_riscv_lo12_i_rela(struct module *me, u32 *location,
146 Elf_Addr v)
147{
148 /* Skip medlow checking because of filtering by HI20 already */
149 s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
150 s32 lo12 = ((s32)v - hi20);
151 *location = (*location & 0xfffff) | ((lo12 & 0xfff) << 20);
152 return 0;
153}
154
155static int apply_r_riscv_lo12_s_rela(struct module *me, u32 *location,
156 Elf_Addr v)
157{
158 /* Skip medlow checking because of filtering by HI20 already */
159 s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
160 s32 lo12 = ((s32)v - hi20);
161 u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11);
162 u32 imm4_0 = (lo12 & 0x1f) << (11 - 4);
163 *location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
164 return 0;
165}
166
167static int apply_r_riscv_got_hi20_rela(struct module *me, u32 *location,
168 Elf_Addr v)
169{
170 s64 offset = (void *)v - (void *)location;
171 s32 hi20;
172
173 /* Always emit the got entry */
174 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
175 offset = module_emit_got_entry(me, v);
176 offset = (void *)offset - (void *)location;
177 } else {
178 pr_err(
179 "%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n",
180 me->name, v, location);
181 return -EINVAL;
182 }
183
184 hi20 = (offset + 0x800) & 0xfffff000;
185 *location = (*location & 0xfff) | hi20;
186 return 0;
187}
188
189static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location,
190 Elf_Addr v)
191{
192 s64 offset = (void *)v - (void *)location;
193 s32 fill_v = offset;
194 u32 hi20, lo12;
195
196 if (offset != fill_v) {
197 /* Only emit the plt entry if offset over 32-bit range */
198 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
199 offset = module_emit_plt_entry(me, v);
200 offset = (void *)offset - (void *)location;
201 } else {
202 pr_err(
203 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
204 me->name, v, location);
205 return -EINVAL;
206 }
207 }
208
209 hi20 = (offset + 0x800) & 0xfffff000;
210 lo12 = (offset - hi20) & 0xfff;
211 *location = (*location & 0xfff) | hi20;
212 *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
213 return 0;
214}
215
216static int apply_r_riscv_call_rela(struct module *me, u32 *location,
217 Elf_Addr v)
218{
219 s64 offset = (void *)v - (void *)location;
220 s32 fill_v = offset;
221 u32 hi20, lo12;
222
223 if (offset != fill_v) {
224 pr_err(
225 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
226 me->name, v, location);
227 return -EINVAL;
228 }
229
230 hi20 = (offset + 0x800) & 0xfffff000;
231 lo12 = (offset - hi20) & 0xfff;
232 *location = (*location & 0xfff) | hi20;
233 *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
234 return 0;
235}
236
237static int apply_r_riscv_relax_rela(struct module *me, u32 *location,
238 Elf_Addr v)
239{
240 return 0;
241}
242
243static int apply_r_riscv_align_rela(struct module *me, u32 *location,
244 Elf_Addr v)
245{
246 pr_err(
247 "%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n",
248 me->name, location);
249 return -EINVAL;
250}
251
252static int apply_r_riscv_add32_rela(struct module *me, u32 *location,
253 Elf_Addr v)
254{
255 *(u32 *)location += (*(u32 *)v);
256 return 0;
257}
258
259static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
260 Elf_Addr v)
261{
262 *(u32 *)location -= (*(u32 *)v);
263 return 0;
264}
265
266static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
267 Elf_Addr v) = {
268 [R_RISCV_64] = apply_r_riscv_64_rela,
269 [R_RISCV_BRANCH] = apply_r_riscv_branch_rela,
270 [R_RISCV_JAL] = apply_r_riscv_jal_rela,
271 [R_RISCV_RVC_BRANCH] = apply_r_riscv_rcv_branch_rela,
272 [R_RISCV_RVC_JUMP] = apply_r_riscv_rvc_jump_rela,
273 [R_RISCV_PCREL_HI20] = apply_r_riscv_pcrel_hi20_rela,
274 [R_RISCV_PCREL_LO12_I] = apply_r_riscv_pcrel_lo12_i_rela,
275 [R_RISCV_PCREL_LO12_S] = apply_r_riscv_pcrel_lo12_s_rela,
276 [R_RISCV_HI20] = apply_r_riscv_hi20_rela,
277 [R_RISCV_LO12_I] = apply_r_riscv_lo12_i_rela,
278 [R_RISCV_LO12_S] = apply_r_riscv_lo12_s_rela,
279 [R_RISCV_GOT_HI20] = apply_r_riscv_got_hi20_rela,
280 [R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela,
281 [R_RISCV_CALL] = apply_r_riscv_call_rela,
282 [R_RISCV_RELAX] = apply_r_riscv_relax_rela,
283 [R_RISCV_ALIGN] = apply_r_riscv_align_rela,
284 [R_RISCV_ADD32] = apply_r_riscv_add32_rela,
285 [R_RISCV_SUB32] = apply_r_riscv_sub32_rela,
286};
287
288int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
289 unsigned int symindex, unsigned int relsec,
290 struct module *me)
291{
292 Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
293 int (*handler)(struct module *me, u32 *location, Elf_Addr v);
294 Elf_Sym *sym;
295 u32 *location;
296 unsigned int i, type;
297 Elf_Addr v;
298 int res;
299
300 pr_debug("Applying relocate section %u to %u\n", relsec,
301 sechdrs[relsec].sh_info);
302
303 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
304 /* This is where to make the change */
305 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
306 + rel[i].r_offset;
307 /* This is the symbol it is referring to */
308 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
309 + ELF_RISCV_R_SYM(rel[i].r_info);
310 if (IS_ERR_VALUE(sym->st_value)) {
311 /* Ignore unresolved weak symbol */
312 if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
313 continue;
314 pr_warning("%s: Unknown symbol %s\n",
315 me->name, strtab + sym->st_name);
316 return -ENOENT;
317 }
318
319 type = ELF_RISCV_R_TYPE(rel[i].r_info);
320
321 if (type < ARRAY_SIZE(reloc_handlers_rela))
322 handler = reloc_handlers_rela[type];
323 else
324 handler = NULL;
325
326 if (!handler) {
327 pr_err("%s: Unknown relocation type %u\n",
328 me->name, type);
329 return -EINVAL;
330 }
331
332 v = sym->st_value + rel[i].r_addend;
333
334 if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
335 unsigned int j;
336
337 for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) {
338 u64 hi20_loc =
339 sechdrs[sechdrs[relsec].sh_info].sh_addr
340 + rel[j].r_offset;
341 u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
342
343 /* Find the corresponding HI20 relocation entry */
344 if (hi20_loc == sym->st_value
345 && (hi20_type == R_RISCV_PCREL_HI20
346 || hi20_type == R_RISCV_GOT_HI20)) {
347 s32 hi20, lo12;
348 Elf_Sym *hi20_sym =
349 (Elf_Sym *)sechdrs[symindex].sh_addr
350 + ELF_RISCV_R_SYM(rel[j].r_info);
351 u64 hi20_sym_val =
352 hi20_sym->st_value
353 + rel[j].r_addend;
354
355 /* Calculate lo12 */
356 u64 offset = hi20_sym_val - hi20_loc;
357 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
358 && hi20_type == R_RISCV_GOT_HI20) {
359 offset = module_emit_got_entry(
360 me, hi20_sym_val);
361 offset = offset - hi20_loc;
362 }
363 hi20 = (offset + 0x800) & 0xfffff000;
364 lo12 = offset - hi20;
365 v = lo12;
366
367 break;
368 }
369 }
370 if (j == sechdrs[relsec].sh_size / sizeof(*rel)) {
371 pr_err(
372 "%s: Can not find HI20 relocation information\n",
373 me->name);
374 return -EINVAL;
375 }
376 }
377
378 res = handler(me, location, v);
379 if (res)
380 return res;
381 }
382
383 return 0;
384}