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/hashtable.h>
11#include <linux/kernel.h>
12#include <linux/log2.h>
13#include <linux/moduleloader.h>
14#include <linux/sizes.h>
15#include <linux/pgtable.h>
16#include <asm/alternative.h>
17#include <asm/sections.h>
18
19struct used_bucket {
20 struct list_head head;
21 struct hlist_head *bucket;
22};
23
24struct relocation_head {
25 struct hlist_node node;
26 struct list_head rel_entry;
27 void *location;
28};
29
30struct relocation_entry {
31 struct list_head head;
32 Elf_Addr value;
33 unsigned int type;
34};
35
36struct relocation_handlers {
37 int (*reloc_handler)(struct module *me, void *location, Elf_Addr v);
38 int (*accumulate_handler)(struct module *me, void *location,
39 long buffer);
40};
41
42/*
43 * The auipc+jalr instruction pair can reach any PC-relative offset
44 * in the range [-2^31 - 2^11, 2^31 - 2^11)
45 */
46static bool riscv_insn_valid_32bit_offset(ptrdiff_t val)
47{
48#ifdef CONFIG_32BIT
49 return true;
50#else
51 return (-(1L << 31) - (1L << 11)) <= val && val < ((1L << 31) - (1L << 11));
52#endif
53}
54
55static int riscv_insn_rmw(void *location, u32 keep, u32 set)
56{
57 __le16 *parcel = location;
58 u32 insn = (u32)le16_to_cpu(parcel[0]) | (u32)le16_to_cpu(parcel[1]) << 16;
59
60 insn &= keep;
61 insn |= set;
62
63 parcel[0] = cpu_to_le16(insn);
64 parcel[1] = cpu_to_le16(insn >> 16);
65 return 0;
66}
67
68static int riscv_insn_rvc_rmw(void *location, u16 keep, u16 set)
69{
70 __le16 *parcel = location;
71 u16 insn = le16_to_cpu(*parcel);
72
73 insn &= keep;
74 insn |= set;
75
76 *parcel = cpu_to_le16(insn);
77 return 0;
78}
79
80static int apply_r_riscv_32_rela(struct module *me, void *location, Elf_Addr v)
81{
82 if (v != (u32)v) {
83 pr_err("%s: value %016llx out of range for 32-bit field\n",
84 me->name, (long long)v);
85 return -EINVAL;
86 }
87 *(u32 *)location = v;
88 return 0;
89}
90
91static int apply_r_riscv_64_rela(struct module *me, void *location, Elf_Addr v)
92{
93 *(u64 *)location = v;
94 return 0;
95}
96
97static int apply_r_riscv_branch_rela(struct module *me, void *location,
98 Elf_Addr v)
99{
100 ptrdiff_t offset = (void *)v - location;
101 u32 imm12 = (offset & 0x1000) << (31 - 12);
102 u32 imm11 = (offset & 0x800) >> (11 - 7);
103 u32 imm10_5 = (offset & 0x7e0) << (30 - 10);
104 u32 imm4_1 = (offset & 0x1e) << (11 - 4);
105
106 return riscv_insn_rmw(location, keep: 0x1fff07f, set: imm12 | imm11 | imm10_5 | imm4_1);
107}
108
109static int apply_r_riscv_jal_rela(struct module *me, void *location,
110 Elf_Addr v)
111{
112 ptrdiff_t offset = (void *)v - location;
113 u32 imm20 = (offset & 0x100000) << (31 - 20);
114 u32 imm19_12 = (offset & 0xff000);
115 u32 imm11 = (offset & 0x800) << (20 - 11);
116 u32 imm10_1 = (offset & 0x7fe) << (30 - 10);
117
118 return riscv_insn_rmw(location, keep: 0xfff, set: imm20 | imm19_12 | imm11 | imm10_1);
119}
120
121static int apply_r_riscv_rvc_branch_rela(struct module *me, void *location,
122 Elf_Addr v)
123{
124 ptrdiff_t offset = (void *)v - location;
125 u16 imm8 = (offset & 0x100) << (12 - 8);
126 u16 imm7_6 = (offset & 0xc0) >> (6 - 5);
127 u16 imm5 = (offset & 0x20) >> (5 - 2);
128 u16 imm4_3 = (offset & 0x18) << (12 - 5);
129 u16 imm2_1 = (offset & 0x6) << (12 - 10);
130
131 return riscv_insn_rvc_rmw(location, keep: 0xe383,
132 set: imm8 | imm7_6 | imm5 | imm4_3 | imm2_1);
133}
134
135static int apply_r_riscv_rvc_jump_rela(struct module *me, void *location,
136 Elf_Addr v)
137{
138 ptrdiff_t offset = (void *)v - location;
139 u16 imm11 = (offset & 0x800) << (12 - 11);
140 u16 imm10 = (offset & 0x400) >> (10 - 8);
141 u16 imm9_8 = (offset & 0x300) << (12 - 11);
142 u16 imm7 = (offset & 0x80) >> (7 - 6);
143 u16 imm6 = (offset & 0x40) << (12 - 11);
144 u16 imm5 = (offset & 0x20) >> (5 - 2);
145 u16 imm4 = (offset & 0x10) << (12 - 5);
146 u16 imm3_1 = (offset & 0xe) << (12 - 10);
147
148 return riscv_insn_rvc_rmw(location, keep: 0xe003,
149 set: imm11 | imm10 | imm9_8 | imm7 | imm6 | imm5 | imm4 | imm3_1);
150}
151
152static int apply_r_riscv_pcrel_hi20_rela(struct module *me, void *location,
153 Elf_Addr v)
154{
155 ptrdiff_t offset = (void *)v - location;
156
157 if (!riscv_insn_valid_32bit_offset(val: offset)) {
158 pr_err(
159 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
160 me->name, (long long)v, location);
161 return -EINVAL;
162 }
163
164 return riscv_insn_rmw(location, keep: 0xfff, set: (offset + 0x800) & 0xfffff000);
165}
166
167static int apply_r_riscv_pcrel_lo12_i_rela(struct module *me, void *location,
168 Elf_Addr v)
169{
170 /*
171 * v is the lo12 value to fill. It is calculated before calling this
172 * handler.
173 */
174 return riscv_insn_rmw(location, keep: 0xfffff, set: (v & 0xfff) << 20);
175}
176
177static int apply_r_riscv_pcrel_lo12_s_rela(struct module *me, void *location,
178 Elf_Addr v)
179{
180 /*
181 * v is the lo12 value to fill. It is calculated before calling this
182 * handler.
183 */
184 u32 imm11_5 = (v & 0xfe0) << (31 - 11);
185 u32 imm4_0 = (v & 0x1f) << (11 - 4);
186
187 return riscv_insn_rmw(location, keep: 0x1fff07f, set: imm11_5 | imm4_0);
188}
189
190static int apply_r_riscv_hi20_rela(struct module *me, void *location,
191 Elf_Addr v)
192{
193 if (IS_ENABLED(CONFIG_CMODEL_MEDLOW)) {
194 pr_err(
195 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
196 me->name, (long long)v, location);
197 return -EINVAL;
198 }
199
200 return riscv_insn_rmw(location, keep: 0xfff, set: ((s32)v + 0x800) & 0xfffff000);
201}
202
203static int apply_r_riscv_lo12_i_rela(struct module *me, void *location,
204 Elf_Addr v)
205{
206 /* Skip medlow checking because of filtering by HI20 already */
207 s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
208 s32 lo12 = ((s32)v - hi20);
209
210 return riscv_insn_rmw(location, keep: 0xfffff, set: (lo12 & 0xfff) << 20);
211}
212
213static int apply_r_riscv_lo12_s_rela(struct module *me, void *location,
214 Elf_Addr v)
215{
216 /* Skip medlow checking because of filtering by HI20 already */
217 s32 hi20 = ((s32)v + 0x800) & 0xfffff000;
218 s32 lo12 = ((s32)v - hi20);
219 u32 imm11_5 = (lo12 & 0xfe0) << (31 - 11);
220 u32 imm4_0 = (lo12 & 0x1f) << (11 - 4);
221
222 return riscv_insn_rmw(location, keep: 0x1fff07f, set: imm11_5 | imm4_0);
223}
224
225static int apply_r_riscv_got_hi20_rela(struct module *me, void *location,
226 Elf_Addr v)
227{
228 ptrdiff_t offset = (void *)v - location;
229
230 /* Always emit the got entry */
231 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
232 offset = (void *)module_emit_got_entry(me, v) - location;
233 } else {
234 pr_err(
235 "%s: can not generate the GOT entry for symbol = %016llx from PC = %p\n",
236 me->name, (long long)v, location);
237 return -EINVAL;
238 }
239
240 return riscv_insn_rmw(location, keep: 0xfff, set: (offset + 0x800) & 0xfffff000);
241}
242
243static int apply_r_riscv_call_plt_rela(struct module *me, void *location,
244 Elf_Addr v)
245{
246 ptrdiff_t offset = (void *)v - location;
247 u32 hi20, lo12;
248
249 if (!riscv_insn_valid_32bit_offset(val: offset)) {
250 /* Only emit the plt entry if offset over 32-bit range */
251 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
252 offset = (void *)module_emit_plt_entry(me, v) - location;
253 } else {
254 pr_err(
255 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
256 me->name, (long long)v, location);
257 return -EINVAL;
258 }
259 }
260
261 hi20 = (offset + 0x800) & 0xfffff000;
262 lo12 = (offset - hi20) & 0xfff;
263 riscv_insn_rmw(location, keep: 0xfff, set: hi20);
264 return riscv_insn_rmw(location: location + 4, keep: 0xfffff, set: lo12 << 20);
265}
266
267static int apply_r_riscv_call_rela(struct module *me, void *location,
268 Elf_Addr v)
269{
270 ptrdiff_t offset = (void *)v - location;
271 u32 hi20, lo12;
272
273 if (!riscv_insn_valid_32bit_offset(val: offset)) {
274 pr_err(
275 "%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
276 me->name, (long long)v, location);
277 return -EINVAL;
278 }
279
280 hi20 = (offset + 0x800) & 0xfffff000;
281 lo12 = (offset - hi20) & 0xfff;
282 riscv_insn_rmw(location, keep: 0xfff, set: hi20);
283 return riscv_insn_rmw(location: location + 4, keep: 0xfffff, set: lo12 << 20);
284}
285
286static int apply_r_riscv_relax_rela(struct module *me, void *location,
287 Elf_Addr v)
288{
289 return 0;
290}
291
292static int apply_r_riscv_align_rela(struct module *me, void *location,
293 Elf_Addr v)
294{
295 pr_err(
296 "%s: The unexpected relocation type 'R_RISCV_ALIGN' from PC = %p\n",
297 me->name, location);
298 return -EINVAL;
299}
300
301static int apply_r_riscv_add8_rela(struct module *me, void *location, Elf_Addr v)
302{
303 *(u8 *)location += (u8)v;
304 return 0;
305}
306
307static int apply_r_riscv_add16_rela(struct module *me, void *location,
308 Elf_Addr v)
309{
310 *(u16 *)location += (u16)v;
311 return 0;
312}
313
314static int apply_r_riscv_add32_rela(struct module *me, void *location,
315 Elf_Addr v)
316{
317 *(u32 *)location += (u32)v;
318 return 0;
319}
320
321static int apply_r_riscv_add64_rela(struct module *me, void *location,
322 Elf_Addr v)
323{
324 *(u64 *)location += (u64)v;
325 return 0;
326}
327
328static int apply_r_riscv_sub8_rela(struct module *me, void *location, Elf_Addr v)
329{
330 *(u8 *)location -= (u8)v;
331 return 0;
332}
333
334static int apply_r_riscv_sub16_rela(struct module *me, void *location,
335 Elf_Addr v)
336{
337 *(u16 *)location -= (u16)v;
338 return 0;
339}
340
341static int apply_r_riscv_sub32_rela(struct module *me, void *location,
342 Elf_Addr v)
343{
344 *(u32 *)location -= (u32)v;
345 return 0;
346}
347
348static int apply_r_riscv_sub64_rela(struct module *me, void *location,
349 Elf_Addr v)
350{
351 *(u64 *)location -= (u64)v;
352 return 0;
353}
354
355static int dynamic_linking_not_supported(struct module *me, void *location,
356 Elf_Addr v)
357{
358 pr_err("%s: Dynamic linking not supported in kernel modules PC = %p\n",
359 me->name, location);
360 return -EINVAL;
361}
362
363static int tls_not_supported(struct module *me, void *location, Elf_Addr v)
364{
365 pr_err("%s: Thread local storage not supported in kernel modules PC = %p\n",
366 me->name, location);
367 return -EINVAL;
368}
369
370static int apply_r_riscv_sub6_rela(struct module *me, void *location, Elf_Addr v)
371{
372 u8 *byte = location;
373 u8 value = v;
374
375 *byte = (*byte - (value & 0x3f)) & 0x3f;
376 return 0;
377}
378
379static int apply_r_riscv_set6_rela(struct module *me, void *location, Elf_Addr v)
380{
381 u8 *byte = location;
382 u8 value = v;
383
384 *byte = (*byte & 0xc0) | (value & 0x3f);
385 return 0;
386}
387
388static int apply_r_riscv_set8_rela(struct module *me, void *location, Elf_Addr v)
389{
390 *(u8 *)location = (u8)v;
391 return 0;
392}
393
394static int apply_r_riscv_set16_rela(struct module *me, void *location,
395 Elf_Addr v)
396{
397 *(u16 *)location = (u16)v;
398 return 0;
399}
400
401static int apply_r_riscv_set32_rela(struct module *me, void *location,
402 Elf_Addr v)
403{
404 *(u32 *)location = (u32)v;
405 return 0;
406}
407
408static int apply_r_riscv_32_pcrel_rela(struct module *me, void *location,
409 Elf_Addr v)
410{
411 *(u32 *)location = v - (uintptr_t)location;
412 return 0;
413}
414
415static int apply_r_riscv_plt32_rela(struct module *me, void *location,
416 Elf_Addr v)
417{
418 ptrdiff_t offset = (void *)v - location;
419
420 if (!riscv_insn_valid_32bit_offset(val: offset)) {
421 /* Only emit the plt entry if offset over 32-bit range */
422 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
423 offset = (void *)module_emit_plt_entry(me, v) - location;
424 } else {
425 pr_err("%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
426 me->name, (long long)v, location);
427 return -EINVAL;
428 }
429 }
430
431 *(u32 *)location = (u32)offset;
432 return 0;
433}
434
435static int apply_r_riscv_set_uleb128(struct module *me, void *location, Elf_Addr v)
436{
437 *(long *)location = v;
438 return 0;
439}
440
441static int apply_r_riscv_sub_uleb128(struct module *me, void *location, Elf_Addr v)
442{
443 *(long *)location -= v;
444 return 0;
445}
446
447static int apply_6_bit_accumulation(struct module *me, void *location, long buffer)
448{
449 u8 *byte = location;
450 u8 value = buffer;
451
452 if (buffer > 0x3f) {
453 pr_err("%s: value %ld out of range for 6-bit relocation.\n",
454 me->name, buffer);
455 return -EINVAL;
456 }
457
458 *byte = (*byte & 0xc0) | (value & 0x3f);
459 return 0;
460}
461
462static int apply_8_bit_accumulation(struct module *me, void *location, long buffer)
463{
464 if (buffer > U8_MAX) {
465 pr_err("%s: value %ld out of range for 8-bit relocation.\n",
466 me->name, buffer);
467 return -EINVAL;
468 }
469 *(u8 *)location = (u8)buffer;
470 return 0;
471}
472
473static int apply_16_bit_accumulation(struct module *me, void *location, long buffer)
474{
475 if (buffer > U16_MAX) {
476 pr_err("%s: value %ld out of range for 16-bit relocation.\n",
477 me->name, buffer);
478 return -EINVAL;
479 }
480 *(u16 *)location = (u16)buffer;
481 return 0;
482}
483
484static int apply_32_bit_accumulation(struct module *me, void *location, long buffer)
485{
486 if (buffer > U32_MAX) {
487 pr_err("%s: value %ld out of range for 32-bit relocation.\n",
488 me->name, buffer);
489 return -EINVAL;
490 }
491 *(u32 *)location = (u32)buffer;
492 return 0;
493}
494
495static int apply_64_bit_accumulation(struct module *me, void *location, long buffer)
496{
497 *(u64 *)location = (u64)buffer;
498 return 0;
499}
500
501static int apply_uleb128_accumulation(struct module *me, void *location, long buffer)
502{
503 /*
504 * ULEB128 is a variable length encoding. Encode the buffer into
505 * the ULEB128 data format.
506 */
507 u8 *p = location;
508
509 while (buffer != 0) {
510 u8 value = buffer & 0x7f;
511
512 buffer >>= 7;
513 value |= (!!buffer) << 7;
514
515 *p++ = value;
516 }
517 return 0;
518}
519
520/*
521 * Relocations defined in the riscv-elf-psabi-doc.
522 * This handles static linking only.
523 */
524static const struct relocation_handlers reloc_handlers[] = {
525 [R_RISCV_32] = { .reloc_handler = apply_r_riscv_32_rela },
526 [R_RISCV_64] = { .reloc_handler = apply_r_riscv_64_rela },
527 [R_RISCV_RELATIVE] = { .reloc_handler = dynamic_linking_not_supported },
528 [R_RISCV_COPY] = { .reloc_handler = dynamic_linking_not_supported },
529 [R_RISCV_JUMP_SLOT] = { .reloc_handler = dynamic_linking_not_supported },
530 [R_RISCV_TLS_DTPMOD32] = { .reloc_handler = dynamic_linking_not_supported },
531 [R_RISCV_TLS_DTPMOD64] = { .reloc_handler = dynamic_linking_not_supported },
532 [R_RISCV_TLS_DTPREL32] = { .reloc_handler = dynamic_linking_not_supported },
533 [R_RISCV_TLS_DTPREL64] = { .reloc_handler = dynamic_linking_not_supported },
534 [R_RISCV_TLS_TPREL32] = { .reloc_handler = dynamic_linking_not_supported },
535 [R_RISCV_TLS_TPREL64] = { .reloc_handler = dynamic_linking_not_supported },
536 /* 12-15 undefined */
537 [R_RISCV_BRANCH] = { .reloc_handler = apply_r_riscv_branch_rela },
538 [R_RISCV_JAL] = { .reloc_handler = apply_r_riscv_jal_rela },
539 [R_RISCV_CALL] = { .reloc_handler = apply_r_riscv_call_rela },
540 [R_RISCV_CALL_PLT] = { .reloc_handler = apply_r_riscv_call_plt_rela },
541 [R_RISCV_GOT_HI20] = { .reloc_handler = apply_r_riscv_got_hi20_rela },
542 [R_RISCV_TLS_GOT_HI20] = { .reloc_handler = tls_not_supported },
543 [R_RISCV_TLS_GD_HI20] = { .reloc_handler = tls_not_supported },
544 [R_RISCV_PCREL_HI20] = { .reloc_handler = apply_r_riscv_pcrel_hi20_rela },
545 [R_RISCV_PCREL_LO12_I] = { .reloc_handler = apply_r_riscv_pcrel_lo12_i_rela },
546 [R_RISCV_PCREL_LO12_S] = { .reloc_handler = apply_r_riscv_pcrel_lo12_s_rela },
547 [R_RISCV_HI20] = { .reloc_handler = apply_r_riscv_hi20_rela },
548 [R_RISCV_LO12_I] = { .reloc_handler = apply_r_riscv_lo12_i_rela },
549 [R_RISCV_LO12_S] = { .reloc_handler = apply_r_riscv_lo12_s_rela },
550 [R_RISCV_TPREL_HI20] = { .reloc_handler = tls_not_supported },
551 [R_RISCV_TPREL_LO12_I] = { .reloc_handler = tls_not_supported },
552 [R_RISCV_TPREL_LO12_S] = { .reloc_handler = tls_not_supported },
553 [R_RISCV_TPREL_ADD] = { .reloc_handler = tls_not_supported },
554 [R_RISCV_ADD8] = { .reloc_handler = apply_r_riscv_add8_rela,
555 .accumulate_handler = apply_8_bit_accumulation },
556 [R_RISCV_ADD16] = { .reloc_handler = apply_r_riscv_add16_rela,
557 .accumulate_handler = apply_16_bit_accumulation },
558 [R_RISCV_ADD32] = { .reloc_handler = apply_r_riscv_add32_rela,
559 .accumulate_handler = apply_32_bit_accumulation },
560 [R_RISCV_ADD64] = { .reloc_handler = apply_r_riscv_add64_rela,
561 .accumulate_handler = apply_64_bit_accumulation },
562 [R_RISCV_SUB8] = { .reloc_handler = apply_r_riscv_sub8_rela,
563 .accumulate_handler = apply_8_bit_accumulation },
564 [R_RISCV_SUB16] = { .reloc_handler = apply_r_riscv_sub16_rela,
565 .accumulate_handler = apply_16_bit_accumulation },
566 [R_RISCV_SUB32] = { .reloc_handler = apply_r_riscv_sub32_rela,
567 .accumulate_handler = apply_32_bit_accumulation },
568 [R_RISCV_SUB64] = { .reloc_handler = apply_r_riscv_sub64_rela,
569 .accumulate_handler = apply_64_bit_accumulation },
570 /* 41-42 reserved for future standard use */
571 [R_RISCV_ALIGN] = { .reloc_handler = apply_r_riscv_align_rela },
572 [R_RISCV_RVC_BRANCH] = { .reloc_handler = apply_r_riscv_rvc_branch_rela },
573 [R_RISCV_RVC_JUMP] = { .reloc_handler = apply_r_riscv_rvc_jump_rela },
574 /* 46-50 reserved for future standard use */
575 [R_RISCV_RELAX] = { .reloc_handler = apply_r_riscv_relax_rela },
576 [R_RISCV_SUB6] = { .reloc_handler = apply_r_riscv_sub6_rela,
577 .accumulate_handler = apply_6_bit_accumulation },
578 [R_RISCV_SET6] = { .reloc_handler = apply_r_riscv_set6_rela,
579 .accumulate_handler = apply_6_bit_accumulation },
580 [R_RISCV_SET8] = { .reloc_handler = apply_r_riscv_set8_rela,
581 .accumulate_handler = apply_8_bit_accumulation },
582 [R_RISCV_SET16] = { .reloc_handler = apply_r_riscv_set16_rela,
583 .accumulate_handler = apply_16_bit_accumulation },
584 [R_RISCV_SET32] = { .reloc_handler = apply_r_riscv_set32_rela,
585 .accumulate_handler = apply_32_bit_accumulation },
586 [R_RISCV_32_PCREL] = { .reloc_handler = apply_r_riscv_32_pcrel_rela },
587 [R_RISCV_IRELATIVE] = { .reloc_handler = dynamic_linking_not_supported },
588 [R_RISCV_PLT32] = { .reloc_handler = apply_r_riscv_plt32_rela },
589 [R_RISCV_SET_ULEB128] = { .reloc_handler = apply_r_riscv_set_uleb128,
590 .accumulate_handler = apply_uleb128_accumulation },
591 [R_RISCV_SUB_ULEB128] = { .reloc_handler = apply_r_riscv_sub_uleb128,
592 .accumulate_handler = apply_uleb128_accumulation },
593 /* 62-191 reserved for future standard use */
594 /* 192-255 nonstandard ABI extensions */
595};
596
597static void
598process_accumulated_relocations(struct module *me,
599 struct hlist_head **relocation_hashtable,
600 struct list_head *used_buckets_list)
601{
602 /*
603 * Only ADD/SUB/SET/ULEB128 should end up here.
604 *
605 * Each bucket may have more than one relocation location. All
606 * relocations for a location are stored in a list in a bucket.
607 *
608 * Relocations are applied to a temp variable before being stored to the
609 * provided location to check for overflow. This also allows ULEB128 to
610 * properly decide how many entries are needed before storing to
611 * location. The final value is stored into location using the handler
612 * for the last relocation to an address.
613 *
614 * Three layers of indexing:
615 * - Each of the buckets in use
616 * - Groups of relocations in each bucket by location address
617 * - Each relocation entry for a location address
618 */
619 struct used_bucket *bucket_iter;
620 struct used_bucket *bucket_iter_tmp;
621 struct relocation_head *rel_head_iter;
622 struct hlist_node *rel_head_iter_tmp;
623 struct relocation_entry *rel_entry_iter;
624 struct relocation_entry *rel_entry_iter_tmp;
625 int curr_type;
626 void *location;
627 long buffer;
628
629 list_for_each_entry_safe(bucket_iter, bucket_iter_tmp,
630 used_buckets_list, head) {
631 hlist_for_each_entry_safe(rel_head_iter, rel_head_iter_tmp,
632 bucket_iter->bucket, node) {
633 buffer = 0;
634 location = rel_head_iter->location;
635 list_for_each_entry_safe(rel_entry_iter,
636 rel_entry_iter_tmp,
637 &rel_head_iter->rel_entry,
638 head) {
639 curr_type = rel_entry_iter->type;
640 reloc_handlers[curr_type].reloc_handler(
641 me, &buffer, rel_entry_iter->value);
642 kfree(objp: rel_entry_iter);
643 }
644 reloc_handlers[curr_type].accumulate_handler(
645 me, location, buffer);
646 kfree(objp: rel_head_iter);
647 }
648 kfree(objp: bucket_iter);
649 }
650
651 kvfree(addr: *relocation_hashtable);
652}
653
654static int add_relocation_to_accumulate(struct module *me, int type,
655 void *location,
656 unsigned int hashtable_bits, Elf_Addr v,
657 struct hlist_head *relocation_hashtable,
658 struct list_head *used_buckets_list)
659{
660 struct relocation_entry *entry;
661 struct relocation_head *rel_head;
662 struct hlist_head *current_head;
663 struct used_bucket *bucket;
664 unsigned long hash;
665
666 entry = kmalloc(sizeof(*entry), GFP_KERNEL);
667
668 if (!entry)
669 return -ENOMEM;
670
671 INIT_LIST_HEAD(list: &entry->head);
672 entry->type = type;
673 entry->value = v;
674
675 hash = hash_min((uintptr_t)location, hashtable_bits);
676
677 current_head = &relocation_hashtable[hash];
678
679 /*
680 * Search for the relocation_head for the relocations that happen at the
681 * provided location
682 */
683 bool found = false;
684 struct relocation_head *rel_head_iter;
685
686 hlist_for_each_entry(rel_head_iter, current_head, node) {
687 if (rel_head_iter->location == location) {
688 found = true;
689 rel_head = rel_head_iter;
690 break;
691 }
692 }
693
694 /*
695 * If there has not yet been any relocations at the provided location,
696 * create a relocation_head for that location and populate it with this
697 * relocation_entry.
698 */
699 if (!found) {
700 rel_head = kmalloc(sizeof(*rel_head), GFP_KERNEL);
701
702 if (!rel_head) {
703 kfree(objp: entry);
704 return -ENOMEM;
705 }
706
707 INIT_LIST_HEAD(list: &rel_head->rel_entry);
708 rel_head->location = location;
709 INIT_HLIST_NODE(h: &rel_head->node);
710 if (!current_head->first) {
711 bucket =
712 kmalloc(sizeof(struct used_bucket), GFP_KERNEL);
713
714 if (!bucket) {
715 kfree(objp: entry);
716 kfree(objp: rel_head);
717 return -ENOMEM;
718 }
719
720 INIT_LIST_HEAD(list: &bucket->head);
721 bucket->bucket = current_head;
722 list_add(new: &bucket->head, head: used_buckets_list);
723 }
724 hlist_add_head(n: &rel_head->node, h: current_head);
725 }
726
727 /* Add relocation to head of discovered rel_head */
728 list_add_tail(new: &entry->head, head: &rel_head->rel_entry);
729
730 return 0;
731}
732
733static unsigned int
734initialize_relocation_hashtable(unsigned int num_relocations,
735 struct hlist_head **relocation_hashtable)
736{
737 /* Can safely assume that bits is not greater than sizeof(long) */
738 unsigned long hashtable_size = roundup_pow_of_two(num_relocations);
739 /*
740 * When hashtable_size == 1, hashtable_bits == 0.
741 * This is valid because the hashing algorithm returns 0 in this case.
742 */
743 unsigned int hashtable_bits = ilog2(hashtable_size);
744
745 /*
746 * Double size of hashtable if num_relocations * 1.25 is greater than
747 * hashtable_size.
748 */
749 int should_double_size = ((num_relocations + (num_relocations >> 2)) > (hashtable_size));
750
751 hashtable_bits += should_double_size;
752
753 hashtable_size <<= should_double_size;
754
755 /* Number of relocations may be large, so kvmalloc it */
756 *relocation_hashtable = kvmalloc_array(hashtable_size,
757 sizeof(**relocation_hashtable),
758 GFP_KERNEL);
759 if (!*relocation_hashtable)
760 return 0;
761
762 __hash_init(ht: *relocation_hashtable, sz: hashtable_size);
763
764 return hashtable_bits;
765}
766
767int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
768 unsigned int symindex, unsigned int relsec,
769 struct module *me)
770{
771 Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
772 int (*handler)(struct module *me, void *location, Elf_Addr v);
773 Elf_Sym *sym;
774 void *location;
775 unsigned int i, type;
776 unsigned int j_idx = 0;
777 Elf_Addr v;
778 int res;
779 unsigned int num_relocations = sechdrs[relsec].sh_size / sizeof(*rel);
780 struct hlist_head *relocation_hashtable;
781 unsigned int hashtable_bits;
782 LIST_HEAD(used_buckets_list);
783
784 hashtable_bits = initialize_relocation_hashtable(num_relocations,
785 relocation_hashtable: &relocation_hashtable);
786
787 if (!relocation_hashtable)
788 return -ENOMEM;
789
790 pr_debug("Applying relocate section %u to %u\n", relsec,
791 sechdrs[relsec].sh_info);
792
793 for (i = 0; i < num_relocations; i++) {
794 /* This is where to make the change */
795 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
796 + rel[i].r_offset;
797 /* This is the symbol it is referring to */
798 sym = (Elf_Sym *)sechdrs[symindex].sh_addr
799 + ELF_RISCV_R_SYM(rel[i].r_info);
800 if (IS_ERR_VALUE(sym->st_value)) {
801 /* Ignore unresolved weak symbol */
802 if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
803 continue;
804 pr_warn("%s: Unknown symbol %s\n",
805 me->name, strtab + sym->st_name);
806 return -ENOENT;
807 }
808
809 type = ELF_RISCV_R_TYPE(rel[i].r_info);
810
811 if (type < ARRAY_SIZE(reloc_handlers))
812 handler = reloc_handlers[type].reloc_handler;
813 else
814 handler = NULL;
815
816 if (!handler) {
817 pr_err("%s: Unknown relocation type %u\n",
818 me->name, type);
819 return -EINVAL;
820 }
821
822 v = sym->st_value + rel[i].r_addend;
823
824 if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
825 unsigned int j = j_idx;
826 bool found = false;
827
828 do {
829 unsigned long hi20_loc =
830 sechdrs[sechdrs[relsec].sh_info].sh_addr
831 + rel[j].r_offset;
832 u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
833
834 /* Find the corresponding HI20 relocation entry */
835 if (hi20_loc == sym->st_value
836 && (hi20_type == R_RISCV_PCREL_HI20
837 || hi20_type == R_RISCV_GOT_HI20)) {
838 s32 hi20, lo12;
839 Elf_Sym *hi20_sym =
840 (Elf_Sym *)sechdrs[symindex].sh_addr
841 + ELF_RISCV_R_SYM(rel[j].r_info);
842 unsigned long hi20_sym_val =
843 hi20_sym->st_value
844 + rel[j].r_addend;
845
846 /* Calculate lo12 */
847 size_t offset = hi20_sym_val - hi20_loc;
848 if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
849 && hi20_type == R_RISCV_GOT_HI20) {
850 offset = module_emit_got_entry(
851 me, hi20_sym_val);
852 offset = offset - hi20_loc;
853 }
854 hi20 = (offset + 0x800) & 0xfffff000;
855 lo12 = offset - hi20;
856 v = lo12;
857 found = true;
858
859 break;
860 }
861
862 j++;
863 if (j == num_relocations)
864 j = 0;
865
866 } while (j_idx != j);
867
868 if (!found) {
869 pr_err(
870 "%s: Can not find HI20 relocation information\n",
871 me->name);
872 return -EINVAL;
873 }
874
875 /* Record the previous j-loop end index */
876 j_idx = j;
877 }
878
879 if (reloc_handlers[type].accumulate_handler)
880 res = add_relocation_to_accumulate(me, type, location,
881 hashtable_bits, v,
882 relocation_hashtable,
883 used_buckets_list: &used_buckets_list);
884 else
885 res = handler(me, location, v);
886 if (res)
887 return res;
888 }
889
890 process_accumulated_relocations(me, relocation_hashtable: &relocation_hashtable,
891 used_buckets_list: &used_buckets_list);
892
893 return 0;
894}
895
896int module_finalize(const Elf_Ehdr *hdr,
897 const Elf_Shdr *sechdrs,
898 struct module *me)
899{
900 const Elf_Shdr *s;
901
902 s = find_section(hdr, sechdrs, ".alternative");
903 if (s)
904 apply_module_alternatives((void *)s->sh_addr, s->sh_size);
905
906 return 0;
907}
908

source code of linux/arch/riscv/kernel/module.c