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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Kernel module help for s390.
4 *
5 * S390 version
6 * Copyright IBM Corp. 2002, 2003
7 * Author(s): Arnd Bergmann ([email protected])
8 * Martin Schwidefsky ([email protected])
9 *
10 * based on i386 version
11 * Copyright (C) 2001 Rusty Russell.
12 */
13#include <linux/module.h>
14#include <linux/elf.h>
15#include <linux/vmalloc.h>
16#include <linux/fs.h>
17#include <linux/ftrace.h>
18#include <linux/string.h>
19#include <linux/kernel.h>
20#include <linux/kasan.h>
21#include <linux/moduleloader.h>
22#include <linux/bug.h>
23#include <linux/memory.h>
24#include <linux/execmem.h>
25#include <asm/arch-stackprotector.h>
26#include <asm/alternative.h>
27#include <asm/nospec-branch.h>
28#include <asm/facility.h>
29#include <asm/ftrace.lds.h>
30#include <asm/set_memory.h>
31#include <asm/setup.h>
32#include <asm/asm-offsets.h>
33
34#if 0
35#define DEBUGP printk
36#else
37#define DEBUGP(fmt , ...)
38#endif
39
40#define PLT_ENTRY_SIZE 22
41
42#ifdef CONFIG_FUNCTION_TRACER
43void module_arch_cleanup(struct module *mod)
44{
45 execmem_free(mod->arch.trampolines_start);
46}
47#endif
48
49void module_arch_freeing_init(struct module *mod)
50{
51 if (is_livepatch_module(mod) &&
52 mod->state == MODULE_STATE_LIVE)
53 return;
54
55 vfree(mod->arch.syminfo);
56 mod->arch.syminfo = NULL;
57}
58
59static void check_rela(Elf_Rela *rela, struct module *me)
60{
61 struct mod_arch_syminfo *info;
62
63 info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
64 switch (ELF_R_TYPE (rela->r_info)) {
65 case R_390_GOT12: /* 12 bit GOT offset. */
66 case R_390_GOT16: /* 16 bit GOT offset. */
67 case R_390_GOT20: /* 20 bit GOT offset. */
68 case R_390_GOT32: /* 32 bit GOT offset. */
69 case R_390_GOT64: /* 64 bit GOT offset. */
70 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
71 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
72 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
73 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
74 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
75 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
76 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
77 if (info->got_offset == -1UL) {
78 info->got_offset = me->arch.got_size;
79 me->arch.got_size += sizeof(void*);
80 }
81 break;
82 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
83 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
84 case R_390_PLT32: /* 32 bit PC relative PLT address. */
85 case R_390_PLT64: /* 64 bit PC relative PLT address. */
86 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
87 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
88 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
89 if (info->plt_offset == -1UL) {
90 info->plt_offset = me->arch.plt_size;
91 me->arch.plt_size += PLT_ENTRY_SIZE;
92 }
93 break;
94 case R_390_COPY:
95 case R_390_GLOB_DAT:
96 case R_390_JMP_SLOT:
97 case R_390_RELATIVE:
98 /* Only needed if we want to support loading of
99 modules linked with -shared. */
100 break;
101 }
102}
103
104/*
105 * Account for GOT and PLT relocations. We can't add sections for
106 * got and plt but we can increase the core module size.
107 */
108int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
109 char *secstrings, struct module *me)
110{
111 Elf_Shdr *symtab;
112 Elf_Sym *symbols;
113 Elf_Rela *rela;
114 char *strings;
115 int nrela, i, j;
116 struct module_memory *mod_mem;
117
118 /* Find symbol table and string table. */
119 symtab = NULL;
120 for (i = 0; i < hdr->e_shnum; i++)
121 switch (sechdrs[i].sh_type) {
122 case SHT_SYMTAB:
123 symtab = sechdrs + i;
124 break;
125 }
126 if (!symtab) {
127 printk(KERN_ERR "module %s: no symbol table\n", me->name);
128 return -ENOEXEC;
129 }
130
131 /* Allocate one syminfo structure per symbol. */
132 me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
133 me->arch.syminfo = vmalloc(array_size(sizeof(struct mod_arch_syminfo),
134 me->arch.nsyms));
135 if (!me->arch.syminfo)
136 return -ENOMEM;
137 symbols = (void *) hdr + symtab->sh_offset;
138 strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
139 for (i = 0; i < me->arch.nsyms; i++) {
140 if (symbols[i].st_shndx == SHN_UNDEF &&
141 strcmp(strings + symbols[i].st_name,
142 "_GLOBAL_OFFSET_TABLE_") == 0)
143 /* "Define" it as absolute. */
144 symbols[i].st_shndx = SHN_ABS;
145 me->arch.syminfo[i].got_offset = -1UL;
146 me->arch.syminfo[i].plt_offset = -1UL;
147 me->arch.syminfo[i].got_initialized = 0;
148 me->arch.syminfo[i].plt_initialized = 0;
149 }
150
151 /* Search for got/plt relocations. */
152 me->arch.got_size = me->arch.plt_size = 0;
153 for (i = 0; i < hdr->e_shnum; i++) {
154 if (sechdrs[i].sh_type != SHT_RELA)
155 continue;
156 nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
157 rela = (void *) hdr + sechdrs[i].sh_offset;
158 for (j = 0; j < nrela; j++)
159 check_rela(rela + j, me);
160 }
161
162 /* Increase core size by size of got & plt and set start
163 offsets for got and plt. */
164 mod_mem = &me->mem[MOD_TEXT];
165 mod_mem->size = ALIGN(mod_mem->size, 4);
166 me->arch.got_offset = mod_mem->size;
167 mod_mem->size += me->arch.got_size;
168 me->arch.plt_offset = mod_mem->size;
169 if (me->arch.plt_size) {
170 if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
171 me->arch.plt_size += PLT_ENTRY_SIZE;
172 mod_mem->size += me->arch.plt_size;
173 }
174 return 0;
175}
176
177static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
178 int sign, int bits, int shift,
179 void *(*write)(void *dest, const void *src, size_t len))
180{
181 unsigned long umax;
182 long min, max;
183 void *dest = (void *)loc;
184
185 if (val & ((1UL << shift) - 1))
186 return -ENOEXEC;
187 if (sign) {
188 val = (Elf_Addr)(((long) val) >> shift);
189 min = -(1L << (bits - 1));
190 max = (1L << (bits - 1)) - 1;
191 if ((long) val < min || (long) val > max)
192 return -ENOEXEC;
193 } else {
194 val >>= shift;
195 umax = ((1UL << (bits - 1)) << 1) - 1;
196 if ((unsigned long) val > umax)
197 return -ENOEXEC;
198 }
199
200 if (bits == 8) {
201 unsigned char tmp = val;
202 write(dest, &tmp, 1);
203 } else if (bits == 12) {
204 unsigned short tmp = (val & 0xfff) |
205 (*(unsigned short *) loc & 0xf000);
206 write(dest, &tmp, 2);
207 } else if (bits == 16) {
208 unsigned short tmp = val;
209 write(dest, &tmp, 2);
210 } else if (bits == 20) {
211 unsigned int tmp = (val & 0xfff) << 16 |
212 (val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
213 write(dest, &tmp, 4);
214 } else if (bits == 32) {
215 unsigned int tmp = val;
216 write(dest, &tmp, 4);
217 } else if (bits == 64) {
218 unsigned long tmp = val;
219 write(dest, &tmp, 8);
220 }
221 return 0;
222}
223
224static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
225 const char *strtab, struct module *me,
226 void *(*write)(void *dest, const void *src, size_t len))
227{
228 struct mod_arch_syminfo *info;
229 Elf_Addr loc, val;
230 int r_type, r_sym;
231 int rc = -ENOEXEC;
232
233 /* This is where to make the change */
234 loc = base + rela->r_offset;
235 /* This is the symbol it is referring to. Note that all
236 undefined symbols have been resolved. */
237 r_sym = ELF_R_SYM(rela->r_info);
238 r_type = ELF_R_TYPE(rela->r_info);
239 info = me->arch.syminfo + r_sym;
240 val = symtab[r_sym].st_value;
241
242 switch (r_type) {
243 case R_390_NONE: /* No relocation. */
244 rc = 0;
245 break;
246 case R_390_8: /* Direct 8 bit. */
247 case R_390_12: /* Direct 12 bit. */
248 case R_390_16: /* Direct 16 bit. */
249 case R_390_20: /* Direct 20 bit. */
250 case R_390_32: /* Direct 32 bit. */
251 case R_390_64: /* Direct 64 bit. */
252 val += rela->r_addend;
253 if (r_type == R_390_8)
254 rc = apply_rela_bits(loc, val, 0, 8, 0, write);
255 else if (r_type == R_390_12)
256 rc = apply_rela_bits(loc, val, 0, 12, 0, write);
257 else if (r_type == R_390_16)
258 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
259 else if (r_type == R_390_20)
260 rc = apply_rela_bits(loc, val, 1, 20, 0, write);
261 else if (r_type == R_390_32)
262 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
263 else if (r_type == R_390_64)
264 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
265 break;
266 case R_390_PC16: /* PC relative 16 bit. */
267 case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
268 case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
269 case R_390_PC32: /* PC relative 32 bit. */
270 case R_390_PC64: /* PC relative 64 bit. */
271 val += rela->r_addend - loc;
272 if (r_type == R_390_PC16)
273 rc = apply_rela_bits(loc, val, 1, 16, 0, write);
274 else if (r_type == R_390_PC16DBL)
275 rc = apply_rela_bits(loc, val, 1, 16, 1, write);
276 else if (r_type == R_390_PC32DBL)
277 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
278 else if (r_type == R_390_PC32)
279 rc = apply_rela_bits(loc, val, 1, 32, 0, write);
280 else if (r_type == R_390_PC64)
281 rc = apply_rela_bits(loc, val, 1, 64, 0, write);
282 break;
283 case R_390_GOT12: /* 12 bit GOT offset. */
284 case R_390_GOT16: /* 16 bit GOT offset. */
285 case R_390_GOT20: /* 20 bit GOT offset. */
286 case R_390_GOT32: /* 32 bit GOT offset. */
287 case R_390_GOT64: /* 64 bit GOT offset. */
288 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
289 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
290 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
291 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
292 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
293 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
294 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
295 if (info->got_initialized == 0) {
296 Elf_Addr *gotent = me->mem[MOD_TEXT].base +
297 me->arch.got_offset +
298 info->got_offset;
299
300 write(gotent, &val, sizeof(*gotent));
301 info->got_initialized = 1;
302 }
303 val = info->got_offset + rela->r_addend;
304 if (r_type == R_390_GOT12 ||
305 r_type == R_390_GOTPLT12)
306 rc = apply_rela_bits(loc, val, 0, 12, 0, write);
307 else if (r_type == R_390_GOT16 ||
308 r_type == R_390_GOTPLT16)
309 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
310 else if (r_type == R_390_GOT20 ||
311 r_type == R_390_GOTPLT20)
312 rc = apply_rela_bits(loc, val, 1, 20, 0, write);
313 else if (r_type == R_390_GOT32 ||
314 r_type == R_390_GOTPLT32)
315 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
316 else if (r_type == R_390_GOT64 ||
317 r_type == R_390_GOTPLT64)
318 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
319 else if (r_type == R_390_GOTENT ||
320 r_type == R_390_GOTPLTENT) {
321 val += (Elf_Addr)me->mem[MOD_TEXT].base +
322 me->arch.got_offset - loc;
323 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
324 }
325 break;
326 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
327 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
328 case R_390_PLT32: /* 32 bit PC relative PLT address. */
329 case R_390_PLT64: /* 64 bit PC relative PLT address. */
330 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
331 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
332 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
333 if (info->plt_initialized == 0) {
334 unsigned char insn[PLT_ENTRY_SIZE];
335 char *plt_base;
336 char *ip;
337
338 plt_base = me->mem[MOD_TEXT].base + me->arch.plt_offset;
339 ip = plt_base + info->plt_offset;
340 *(int *)insn = 0x0d10e310; /* basr 1,0 */
341 *(int *)&insn[4] = 0x100c0004; /* lg 1,12(1) */
342 if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
343 char *jump_r1;
344
345 jump_r1 = plt_base + me->arch.plt_size -
346 PLT_ENTRY_SIZE;
347 /* brcl 0xf,__jump_r1 */
348 *(short *)&insn[8] = 0xc0f4;
349 *(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
350 } else {
351 *(int *)&insn[8] = 0x07f10000; /* br %r1 */
352 }
353 *(long *)&insn[14] = val;
354
355 write(ip, insn, sizeof(insn));
356 info->plt_initialized = 1;
357 }
358 if (r_type == R_390_PLTOFF16 ||
359 r_type == R_390_PLTOFF32 ||
360 r_type == R_390_PLTOFF64)
361 val = me->arch.plt_offset - me->arch.got_offset +
362 info->plt_offset + rela->r_addend;
363 else {
364 if (!((r_type == R_390_PLT16DBL &&
365 val - loc + 0xffffUL < 0x1ffffeUL) ||
366 (r_type == R_390_PLT32DBL &&
367 val - loc + 0xffffffffULL < 0x1fffffffeULL)))
368 val = (Elf_Addr) me->mem[MOD_TEXT].base +
369 me->arch.plt_offset +
370 info->plt_offset;
371 val += rela->r_addend - loc;
372 }
373 if (r_type == R_390_PLT16DBL)
374 rc = apply_rela_bits(loc, val, 1, 16, 1, write);
375 else if (r_type == R_390_PLTOFF16)
376 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
377 else if (r_type == R_390_PLT32DBL)
378 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
379 else if (r_type == R_390_PLT32 ||
380 r_type == R_390_PLTOFF32)
381 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
382 else if (r_type == R_390_PLT64 ||
383 r_type == R_390_PLTOFF64)
384 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
385 break;
386 case R_390_GOTOFF16: /* 16 bit offset to GOT. */
387 case R_390_GOTOFF32: /* 32 bit offset to GOT. */
388 case R_390_GOTOFF64: /* 64 bit offset to GOT. */
389 val = val + rela->r_addend -
390 ((Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset);
391 if (r_type == R_390_GOTOFF16)
392 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
393 else if (r_type == R_390_GOTOFF32)
394 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
395 else if (r_type == R_390_GOTOFF64)
396 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
397 break;
398 case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
399 case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
400 val = (Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset +
401 rela->r_addend - loc;
402 if (r_type == R_390_GOTPC)
403 rc = apply_rela_bits(loc, val, 1, 32, 0, write);
404 else if (r_type == R_390_GOTPCDBL)
405 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
406 break;
407 case R_390_COPY:
408 case R_390_GLOB_DAT: /* Create GOT entry. */
409 case R_390_JMP_SLOT: /* Create PLT entry. */
410 case R_390_RELATIVE: /* Adjust by program base. */
411 /* Only needed if we want to support loading of
412 modules linked with -shared. */
413 return -ENOEXEC;
414 default:
415 printk(KERN_ERR "module %s: unknown relocation: %u\n",
416 me->name, r_type);
417 return -ENOEXEC;
418 }
419 if (rc) {
420 printk(KERN_ERR "module %s: relocation error for symbol %s "
421 "(r_type %i, value 0x%lx)\n",
422 me->name, strtab + symtab[r_sym].st_name,
423 r_type, (unsigned long) val);
424 return rc;
425 }
426 return 0;
427}
428
429static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
430 unsigned int symindex, unsigned int relsec,
431 struct module *me,
432 void *(*write)(void *dest, const void *src, size_t len))
433{
434 Elf_Addr base;
435 Elf_Sym *symtab;
436 Elf_Rela *rela;
437 unsigned long i, n;
438 int rc;
439
440 DEBUGP("Applying relocate section %u to %u\n",
441 relsec, sechdrs[relsec].sh_info);
442 base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
443 symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
444 rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
445 n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
446
447 for (i = 0; i < n; i++, rela++) {
448 rc = apply_rela(rela, base, symtab, strtab, me, write);
449 if (rc)
450 return rc;
451 }
452 return 0;
453}
454
455int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
456 unsigned int symindex, unsigned int relsec,
457 struct module *me)
458{
459 bool early = me->state == MODULE_STATE_UNFORMED;
460 void *(*write)(void *, const void *, size_t) = memcpy;
461
462 if (!early)
463 write = s390_kernel_write;
464
465 return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
466 write);
467}
468
469#ifdef CONFIG_FUNCTION_TRACER
470static int module_alloc_ftrace_hotpatch_trampolines(struct module *me,
471 const Elf_Shdr *s)
472{
473 char *start, *end;
474 int numpages;
475 size_t size;
476
477 size = FTRACE_HOTPATCH_TRAMPOLINES_SIZE(s->sh_size);
478 numpages = DIV_ROUND_UP(size, PAGE_SIZE);
479 start = execmem_alloc(EXECMEM_FTRACE, numpages * PAGE_SIZE);
480 if (!start)
481 return -ENOMEM;
482 set_memory_rox((unsigned long)start, numpages);
483 end = start + size;
484
485 me->arch.trampolines_start = (struct ftrace_hotpatch_trampoline *)start;
486 me->arch.trampolines_end = (struct ftrace_hotpatch_trampoline *)end;
487 me->arch.next_trampoline = me->arch.trampolines_start;
488
489 return 0;
490}
491#endif /* CONFIG_FUNCTION_TRACER */
492
493int module_finalize(const Elf_Ehdr *hdr,
494 const Elf_Shdr *sechdrs,
495 struct module *me)
496{
497 const Elf_Shdr *s;
498 char *secstrings, *secname;
499 void *aseg;
500 int rc = 0;
501
502 if (IS_ENABLED(CONFIG_EXPOLINE) &&
503 !nospec_disable && me->arch.plt_size) {
504 unsigned int *ij;
505
506 ij = me->mem[MOD_TEXT].base + me->arch.plt_offset +
507 me->arch.plt_size - PLT_ENTRY_SIZE;
508 ij[0] = 0xc6000000; /* exrl %r0,.+10 */
509 ij[1] = 0x0005a7f4; /* j . */
510 ij[2] = 0x000007f1; /* br %r1 */
511 }
512
513 secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
514 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
515 aseg = (void *) s->sh_addr;
516 secname = secstrings + s->sh_name;
517
518 if (!strcmp(".altinstructions", secname))
519 /* patch .altinstructions */
520 apply_alternatives(aseg, aseg + s->sh_size);
521
522 if (IS_ENABLED(CONFIG_EXPOLINE) &&
523 (str_has_prefix(secname, ".s390_indirect")))
524 nospec_revert(aseg, aseg + s->sh_size);
525
526 if (IS_ENABLED(CONFIG_EXPOLINE) &&
527 (str_has_prefix(secname, ".s390_return")))
528 nospec_revert(aseg, aseg + s->sh_size);
529
530 if (IS_ENABLED(CONFIG_STACKPROTECTOR) &&
531 (str_has_prefix(secname, "__stack_protector_loc"))) {
532 rc = stack_protector_apply(aseg, aseg + s->sh_size);
533 if (rc)
534 break;
535 }
536
537#ifdef CONFIG_FUNCTION_TRACER
538 if (!strcmp(FTRACE_CALLSITE_SECTION, secname)) {
539 rc = module_alloc_ftrace_hotpatch_trampolines(me, s);
540 if (rc)
541 break;
542 }
543#endif /* CONFIG_FUNCTION_TRACER */
544 }
545
546 return rc;
547}