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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *
4 * Copyright (C) 2017 Zihao Yu
5 */
6
7#include <linux/elf.h>
8#include <linux/err.h>
9#include <linux/errno.h>
10#include <linux/moduleloader.h>
11
12static int apply_r_riscv_32_rela(struct module *me, u32 *location, Elf_Addr v)
13{
14 if (v != (u32)v) {
15 pr_err("%s: value %016llx out of range for 32-bit field\n",
16 me->name, (long long)v);
17 return -EINVAL;
18 }
19 *location = v;
20 return 0;
21}
22
23static int apply_r_riscv_64_rela(struct module *me, u32 *location, Elf_Addr v)
24{
25 *(u64 *)location = v;
26 return 0;
27}
28
29static int apply_r_riscv_branch_rela(struct module *me, u32 *location,
30 Elf_Addr v)
31{
32 ptrdiff_t offset = (void *)v - (void *)location;
33 u32 imm12 = (offset & 0x1000) << (31 - 12);
34 u32 imm11 = (offset & 0x800) >> (11 - 7);
35 u32 imm10_5 = (offset & 0x7e0) << (30 - 10);
36 u32 imm4_1 = (offset & 0x1e) << (11 - 4);
37
38 *location = (*location & 0x1fff07f) | imm12 | imm11 | imm10_5 | imm4_1;
39 return 0;
40}
41
42static int apply_r_riscv_jal_rela(struct module *me, u32 *location,
43 Elf_Addr v)
44{
45 ptrdiff_t offset = (void *)v - (void *)location;
46 u32 imm20 = (offset & 0x100000) << (31 - 20);
47 u32 imm19_12 = (offset & 0xff000);
48 u32 imm11 = (offset & 0x800) << (20 - 11);
49 u32 imm10_1 = (offset & 0x7fe) << (30 - 10);
50
51 *location = (*location & 0xfff) | imm20 | imm19_12 | imm11 | imm10_1;
52 return 0;
53}
54
55static int apply_r_riscv_rcv_branch_rela(struct module *me, u32 *location,
56 Elf_Addr v)
57{
58 ptrdiff_t offset = (void *)v - (void *)location;
59 u16 imm8 = (offset & 0x100) << (12 - 8);
60 u16 imm7_6 = (offset & 0xc0) >> (6 - 5);
61 u16 imm5 = (offset & 0x20) >> (5 - 2);
62 u16 imm4_3 = (offset & 0x18) << (12 - 5);
63 u16 imm2_1 = (offset & 0x6) << (12 - 10);
64
65 *(u16 *)location = (*(u16 *)location & 0xe383) |
66 imm8 | imm7_6 | imm5 | imm4_3 | imm2_1;
67 return 0;
68}
69
70static int apply_r_riscv_rvc_jump_rela(struct module *me, u32 *location,
71 Elf_Addr v)
72{
73 ptrdiff_t offset = (void *)v - (void *)location;
74 u16 imm11 = (offset & 0x800) << (12 - 11);
75 u16 imm10 = (offset & 0x400) >> (10 - 8);
76 u16 imm9_8 = (offset & 0x300) << (12 - 11);
77 u16 imm7 = (offset & 0x80) >> (7 - 6);
78 u16 imm6 = (offset & 0x40) << (12 - 11);
79 u16 imm5 = (offset & 0x20) >> (5 - 2);
80 u16 imm4 = (offset & 0x10) << (12 - 5);
81 u16 imm3_1 = (offset & 0xe) << (12 - 10);
82
83 *(u16 *)location = (*(u16 *)location & 0xe003) |
84 imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1;
85 return 0;
86}
87
88static int apply_r_riscv_pcrel_hi20_rela(struct module *me, u32 *location,
89 Elf_Addr v)
90{
91 ptrdiff_t offset = (void *)v - (void *)location;
92 s32 hi20;
93
94 if (offset != (s32)offset) {
95 pr_err(
96 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
97 me->name, (long long)v, location);
98 return -EINVAL;
99 }
100
101 hi20 = (offset + 0x800) & 0xfffff000;
102 *location = (*location & 0xfff) | hi20;
103 return 0;
104}
105
106static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, u32 *location,
107 Elf_Addr v)
108{
109 /*
110 * v is the lo12 value to fill. It is calculated before calling this
111 * handler.
112 */
113 *location = (*location & 0xfffff) | ((v & 0xfff) << 20);
114 return 0;
115}
116
117static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, u32 *location,
118 Elf_Addr v)
119{
120 /*
121 * v is the lo12 value to fill. It is calculated before calling this
122 * handler.
123 */
124 u32 imm11_5 = (v & 0xfe0) << (31 - 11);
125 u32 imm4_0 = (v & 0x1f) << (11 - 4);
126
127 *location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
128 return 0;
129}
130
131static int apply_r_riscv_hi20_rela(struct module *me, u32 *location,
132 Elf_Addr v)
133{
134 s32 hi20;
135
136 if (IS_ENABLED(CONFIG_CMODEL_MEDLOW)) {
137 pr_err(
138 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
139 me->name, (long long)v, location);
140 return -EINVAL;
141 }
142
143 hi20 = ((s32)v + 0x800) & 0xfffff000;
144 *location = (*location & 0xfff) | hi20;
145 return 0;
146}
147
148static int apply_r_riscv_lo12_i_rela(struct module *me, u32 *location,
149 Elf_Addr v)
150{
151 /* Skip medlow checking because of filtering by HI20 already */
152 s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
153 s32 lo12 = ((s32)v - hi20);
154 *location = (*location & 0xfffff) | ((lo12 & 0xfff) << 20);
155 return 0;
156}
157
158static int apply_r_riscv_lo12_s_rela(struct module *me, u32 *location,
159 Elf_Addr v)
160{
161 /* Skip medlow checking because of filtering by HI20 already */
162 s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
163 s32 lo12 = ((s32)v - hi20);
164 u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11);
165 u32 imm4_0 = (lo12 & 0x1f) << (11 - 4);
166 *location = (*location & 0x1fff07f) | imm11_5 | imm4_0;
167 return 0;
168}
169
170static int apply_r_riscv_got_hi20_rela(struct module *me, u32 *location,
171 Elf_Addr v)
172{
173 ptrdiff_t offset = (void *)v - (void *)location;
174 s32 hi20;
175
176 /* Always emit the got entry */
177 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
178 offset = module_emit_got_entry(me, v);
179 offset = (void *)offset - (void *)location;
180 } else {
181 pr_err(
182 "%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n",
183 me->name, (long long)v, location);
184 return -EINVAL;
185 }
186
187 hi20 = (offset + 0x800) & 0xfffff000;
188 *location = (*location & 0xfff) | hi20;
189 return 0;
190}
191
192static int apply_r_riscv_call_plt_rela(struct module *me, u32 *location,
193 Elf_Addr v)
194{
195 ptrdiff_t offset = (void *)v - (void *)location;
196 s32 fill_v = offset;
197 u32 hi20, lo12;
198
199 if (offset != fill_v) {
200 /* Only emit the plt entry if offset over 32-bit range */
201 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
202 offset = module_emit_plt_entry(me, v);
203 offset = (void *)offset - (void *)location;
204 } else {
205 pr_err(
206 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
207 me->name, (long long)v, location);
208 return -EINVAL;
209 }
210 }
211
212 hi20 = (offset + 0x800) & 0xfffff000;
213 lo12 = (offset - hi20) & 0xfff;
214 *location = (*location & 0xfff) | hi20;
215 *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
216 return 0;
217}
218
219static int apply_r_riscv_call_rela(struct module *me, u32 *location,
220 Elf_Addr v)
221{
222 ptrdiff_t offset = (void *)v - (void *)location;
223 s32 fill_v = offset;
224 u32 hi20, lo12;
225
226 if (offset != fill_v) {
227 pr_err(
228 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
229 me->name, (long long)v, location);
230 return -EINVAL;
231 }
232
233 hi20 = (offset + 0x800) & 0xfffff000;
234 lo12 = (offset - hi20) & 0xfff;
235 *location = (*location & 0xfff) | hi20;
236 *(location + 1) = (*(location + 1) & 0xfffff) | (lo12 << 20);
237 return 0;
238}
239
240static int apply_r_riscv_relax_rela(struct module *me, u32 *location,
241 Elf_Addr v)
242{
243 return 0;
244}
245
246static int apply_r_riscv_align_rela(struct module *me, u32 *location,
247 Elf_Addr v)
248{
249 pr_err(
250 "%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n",
251 me->name, location);
252 return -EINVAL;
253}
254
255static int apply_r_riscv_add32_rela(struct module *me, u32 *location,
256 Elf_Addr v)
257{
258 *(u32 *)location += (u32)v;
259 return 0;
260}
261
262static int apply_r_riscv_sub32_rela(struct module *me, u32 *location,
263 Elf_Addr v)
264{
265 *(u32 *)location -= (u32)v;
266 return 0;
267}
268
269static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
270 Elf_Addr v) = {
271 [R_RISCV_32] = apply_r_riscv_32_rela,
272 [R_RISCV_64] = apply_r_riscv_64_rela,
273 [R_RISCV_BRANCH] = apply_r_riscv_branch_rela,
274 [R_RISCV_JAL] = apply_r_riscv_jal_rela,
275 [R_RISCV_RVC_BRANCH] = apply_r_riscv_rcv_branch_rela,
276 [R_RISCV_RVC_JUMP] = apply_r_riscv_rvc_jump_rela,
277 [R_RISCV_PCREL_HI20] = apply_r_riscv_pcrel_hi20_rela,
278 [R_RISCV_PCREL_LO12_I] = apply_r_riscv_pcrel_lo12_i_rela,
279 [R_RISCV_PCREL_LO12_S] = apply_r_riscv_pcrel_lo12_s_rela,
280 [R_RISCV_HI20] = apply_r_riscv_hi20_rela,
281 [R_RISCV_LO12_I] = apply_r_riscv_lo12_i_rela,
282 [R_RISCV_LO12_S] = apply_r_riscv_lo12_s_rela,
283 [R_RISCV_GOT_HI20] = apply_r_riscv_got_hi20_rela,
284 [R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela,
285 [R_RISCV_CALL] = apply_r_riscv_call_rela,
286 [R_RISCV_RELAX] = apply_r_riscv_relax_rela,
287 [R_RISCV_ALIGN] = apply_r_riscv_align_rela,
288 [R_RISCV_ADD32] = apply_r_riscv_add32_rela,
289 [R_RISCV_SUB32] = apply_r_riscv_sub32_rela,
290};
291
292int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
293 unsigned int symindex, unsigned int relsec,
294 struct module *me)
295{
296 Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
297 int (*handler)(struct module *me, u32 *location, Elf_Addr v);
298 Elf_Sym *sym;
299 u32 *location;
300 unsigned int i, type;
301 Elf_Addr v;
302 int res;
303
304 pr_debug("Applying relocate section %u to %u\n", relsec,
305 sechdrs[relsec].sh_info);
306
307 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
308 /* This is where to make the change */
309 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
310 + rel[i].r_offset;
311 /* This is the symbol it is referring to */
312 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
313 + ELF_RISCV_R_SYM(rel[i].r_info);
314 if (IS_ERR_VALUE(sym->st_value)) {
315 /* Ignore unresolved weak symbol */
316 if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
317 continue;
318 pr_warning("%s: Unknown symbol %s\n",
319 me->name, strtab + sym->st_name);
320 return -ENOENT;
321 }
322
323 type = ELF_RISCV_R_TYPE(rel[i].r_info);
324
325 if (type < ARRAY_SIZE(reloc_handlers_rela))
326 handler = reloc_handlers_rela[type];
327 else
328 handler = NULL;
329
330 if (!handler) {
331 pr_err("%s: Unknown relocation type %u\n",
332 me->name, type);
333 return -EINVAL;
334 }
335
336 v = sym->st_value + rel[i].r_addend;
337
338 if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
339 unsigned int j;
340
341 for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) {
342 unsigned long hi20_loc =
343 sechdrs[sechdrs[relsec].sh_info].sh_addr
344 + rel[j].r_offset;
345 u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
346
347 /* Find the corresponding HI20 relocation entry */
348 if (hi20_loc == sym->st_value
349 && (hi20_type == R_RISCV_PCREL_HI20
350 || hi20_type == R_RISCV_GOT_HI20)) {
351 s32 hi20, lo12;
352 Elf_Sym *hi20_sym =
353 (Elf_Sym *)sechdrs[symindex].sh_addr
354 + ELF_RISCV_R_SYM(rel[j].r_info);
355 unsigned long hi20_sym_val =
356 hi20_sym->st_value
357 + rel[j].r_addend;
358
359 /* Calculate lo12 */
360 size_t offset = hi20_sym_val - hi20_loc;
361 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
362 && hi20_type == R_RISCV_GOT_HI20) {
363 offset = module_emit_got_entry(
364 me, hi20_sym_val);
365 offset = offset - hi20_loc;
366 }
367 hi20 = (offset + 0x800) & 0xfffff000;
368 lo12 = offset - hi20;
369 v = lo12;
370
371 break;
372 }
373 }
374 if (j == sechdrs[relsec].sh_size / sizeof(*rel)) {
375 pr_err(
376 "%s: Can not find HI20 relocation information\n",
377 me->name);
378 return -EINVAL;
379 }
380 }
381
382 res = handler(me, location, v);
383 if (res)
384 return res;
385 }
386
387 return 0;
388}