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 (arndb@de.ibm.com)
8 * Martin Schwidefsky (schwidefsky@de.ibm.com)
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/string.h>
18 #include <linux/kernel.h>
19 #include <linux/kasan.h>
20 #include <linux/moduleloader.h>
21 #include <linux/bug.h>
22 #include <linux/memory.h>
23 #include <asm/alternative.h>
24 #include <asm/nospec-branch.h>
25 #include <asm/facility.h>
26
27 #if 0
28 #define DEBUGP printk
29 #else
30 #define DEBUGP(fmt , ...)
31 #endif
32
33 #define PLT_ENTRY_SIZE 22
34
module_alloc(unsigned long size)35 void *module_alloc(unsigned long size)
36 {
37 void *p;
38
39 if (PAGE_ALIGN(size) > MODULES_LEN)
40 return NULL;
41 p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,
42 GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
43 __builtin_return_address(0));
44 if (p && (kasan_module_alloc(p, size) < 0)) {
45 vfree(p);
46 return NULL;
47 }
48 return p;
49 }
50
module_arch_freeing_init(struct module * mod)51 void module_arch_freeing_init(struct module *mod)
52 {
53 if (is_livepatch_module(mod) &&
54 mod->state == MODULE_STATE_LIVE)
55 return;
56
57 vfree(mod->arch.syminfo);
58 mod->arch.syminfo = NULL;
59 }
60
check_rela(Elf_Rela * rela,struct module * me)61 static void check_rela(Elf_Rela *rela, struct module *me)
62 {
63 struct mod_arch_syminfo *info;
64
65 info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
66 switch (ELF_R_TYPE (rela->r_info)) {
67 case R_390_GOT12: /* 12 bit GOT offset. */
68 case R_390_GOT16: /* 16 bit GOT offset. */
69 case R_390_GOT20: /* 20 bit GOT offset. */
70 case R_390_GOT32: /* 32 bit GOT offset. */
71 case R_390_GOT64: /* 64 bit GOT offset. */
72 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
73 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
74 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
75 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
76 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
77 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
78 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
79 if (info->got_offset == -1UL) {
80 info->got_offset = me->arch.got_size;
81 me->arch.got_size += sizeof(void*);
82 }
83 break;
84 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
85 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
86 case R_390_PLT32: /* 32 bit PC relative PLT address. */
87 case R_390_PLT64: /* 64 bit PC relative PLT address. */
88 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
89 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
90 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
91 if (info->plt_offset == -1UL) {
92 info->plt_offset = me->arch.plt_size;
93 me->arch.plt_size += PLT_ENTRY_SIZE;
94 }
95 break;
96 case R_390_COPY:
97 case R_390_GLOB_DAT:
98 case R_390_JMP_SLOT:
99 case R_390_RELATIVE:
100 /* Only needed if we want to support loading of
101 modules linked with -shared. */
102 break;
103 }
104 }
105
106 /*
107 * Account for GOT and PLT relocations. We can't add sections for
108 * got and plt but we can increase the core module size.
109 */
module_frob_arch_sections(Elf_Ehdr * hdr,Elf_Shdr * sechdrs,char * secstrings,struct module * me)110 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
111 char *secstrings, struct module *me)
112 {
113 Elf_Shdr *symtab;
114 Elf_Sym *symbols;
115 Elf_Rela *rela;
116 char *strings;
117 int nrela, i, j;
118
119 /* Find symbol table and string table. */
120 symtab = NULL;
121 for (i = 0; i < hdr->e_shnum; i++)
122 switch (sechdrs[i].sh_type) {
123 case SHT_SYMTAB:
124 symtab = sechdrs + i;
125 break;
126 }
127 if (!symtab) {
128 printk(KERN_ERR "module %s: no symbol table\n", me->name);
129 return -ENOEXEC;
130 }
131
132 /* Allocate one syminfo structure per symbol. */
133 me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
134 me->arch.syminfo = vmalloc(array_size(sizeof(struct mod_arch_syminfo),
135 me->arch.nsyms));
136 if (!me->arch.syminfo)
137 return -ENOMEM;
138 symbols = (void *) hdr + symtab->sh_offset;
139 strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
140 for (i = 0; i < me->arch.nsyms; i++) {
141 if (symbols[i].st_shndx == SHN_UNDEF &&
142 strcmp(strings + symbols[i].st_name,
143 "_GLOBAL_OFFSET_TABLE_") == 0)
144 /* "Define" it as absolute. */
145 symbols[i].st_shndx = SHN_ABS;
146 me->arch.syminfo[i].got_offset = -1UL;
147 me->arch.syminfo[i].plt_offset = -1UL;
148 me->arch.syminfo[i].got_initialized = 0;
149 me->arch.syminfo[i].plt_initialized = 0;
150 }
151
152 /* Search for got/plt relocations. */
153 me->arch.got_size = me->arch.plt_size = 0;
154 for (i = 0; i < hdr->e_shnum; i++) {
155 if (sechdrs[i].sh_type != SHT_RELA)
156 continue;
157 nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
158 rela = (void *) hdr + sechdrs[i].sh_offset;
159 for (j = 0; j < nrela; j++)
160 check_rela(rela + j, me);
161 }
162
163 /* Increase core size by size of got & plt and set start
164 offsets for got and plt. */
165 me->core_layout.size = ALIGN(me->core_layout.size, 4);
166 me->arch.got_offset = me->core_layout.size;
167 me->core_layout.size += me->arch.got_size;
168 me->arch.plt_offset = me->core_layout.size;
169 if (me->arch.plt_size) {
170 if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
171 me->arch.plt_size += PLT_ENTRY_SIZE;
172 me->core_layout.size += me->arch.plt_size;
173 }
174 return 0;
175 }
176
apply_rela_bits(Elf_Addr loc,Elf_Addr val,int sign,int bits,int shift,void * (* write)(void * dest,const void * src,size_t len))177 static 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
apply_rela(Elf_Rela * rela,Elf_Addr base,Elf_Sym * symtab,const char * strtab,struct module * me,void * (* write)(void * dest,const void * src,size_t len))224 static 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->core_layout.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->core_layout.base - loc;
322 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
323 }
324 break;
325 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
326 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
327 case R_390_PLT32: /* 32 bit PC relative PLT address. */
328 case R_390_PLT64: /* 64 bit PC relative PLT address. */
329 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
330 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
331 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
332 if (info->plt_initialized == 0) {
333 unsigned char insn[PLT_ENTRY_SIZE];
334 char *plt_base;
335 char *ip;
336
337 plt_base = me->core_layout.base + me->arch.plt_offset;
338 ip = plt_base + info->plt_offset;
339 *(int *)insn = 0x0d10e310; /* basr 1,0 */
340 *(int *)&insn[4] = 0x100c0004; /* lg 1,12(1) */
341 if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
342 char *jump_r1;
343
344 jump_r1 = plt_base + me->arch.plt_size -
345 PLT_ENTRY_SIZE;
346 /* brcl 0xf,__jump_r1 */
347 *(short *)&insn[8] = 0xc0f4;
348 *(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
349 } else {
350 *(int *)&insn[8] = 0x07f10000; /* br %r1 */
351 }
352 *(long *)&insn[14] = val;
353
354 write(ip, insn, sizeof(insn));
355 info->plt_initialized = 1;
356 }
357 if (r_type == R_390_PLTOFF16 ||
358 r_type == R_390_PLTOFF32 ||
359 r_type == R_390_PLTOFF64)
360 val = me->arch.plt_offset - me->arch.got_offset +
361 info->plt_offset + rela->r_addend;
362 else {
363 if (!((r_type == R_390_PLT16DBL &&
364 val - loc + 0xffffUL < 0x1ffffeUL) ||
365 (r_type == R_390_PLT32DBL &&
366 val - loc + 0xffffffffULL < 0x1fffffffeULL)))
367 val = (Elf_Addr) me->core_layout.base +
368 me->arch.plt_offset +
369 info->plt_offset;
370 val += rela->r_addend - loc;
371 }
372 if (r_type == R_390_PLT16DBL)
373 rc = apply_rela_bits(loc, val, 1, 16, 1, write);
374 else if (r_type == R_390_PLTOFF16)
375 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
376 else if (r_type == R_390_PLT32DBL)
377 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
378 else if (r_type == R_390_PLT32 ||
379 r_type == R_390_PLTOFF32)
380 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
381 else if (r_type == R_390_PLT64 ||
382 r_type == R_390_PLTOFF64)
383 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
384 break;
385 case R_390_GOTOFF16: /* 16 bit offset to GOT. */
386 case R_390_GOTOFF32: /* 32 bit offset to GOT. */
387 case R_390_GOTOFF64: /* 64 bit offset to GOT. */
388 val = val + rela->r_addend -
389 ((Elf_Addr) me->core_layout.base + me->arch.got_offset);
390 if (r_type == R_390_GOTOFF16)
391 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
392 else if (r_type == R_390_GOTOFF32)
393 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
394 else if (r_type == R_390_GOTOFF64)
395 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
396 break;
397 case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
398 case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
399 val = (Elf_Addr) me->core_layout.base + me->arch.got_offset +
400 rela->r_addend - loc;
401 if (r_type == R_390_GOTPC)
402 rc = apply_rela_bits(loc, val, 1, 32, 0, write);
403 else if (r_type == R_390_GOTPCDBL)
404 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
405 break;
406 case R_390_COPY:
407 case R_390_GLOB_DAT: /* Create GOT entry. */
408 case R_390_JMP_SLOT: /* Create PLT entry. */
409 case R_390_RELATIVE: /* Adjust by program base. */
410 /* Only needed if we want to support loading of
411 modules linked with -shared. */
412 return -ENOEXEC;
413 default:
414 printk(KERN_ERR "module %s: unknown relocation: %u\n",
415 me->name, r_type);
416 return -ENOEXEC;
417 }
418 if (rc) {
419 printk(KERN_ERR "module %s: relocation error for symbol %s "
420 "(r_type %i, value 0x%lx)\n",
421 me->name, strtab + symtab[r_sym].st_name,
422 r_type, (unsigned long) val);
423 return rc;
424 }
425 return 0;
426 }
427
__apply_relocate_add(Elf_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me,void * (* write)(void * dest,const void * src,size_t len))428 static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
429 unsigned int symindex, unsigned int relsec,
430 struct module *me,
431 void *(*write)(void *dest, const void *src, size_t len))
432 {
433 Elf_Addr base;
434 Elf_Sym *symtab;
435 Elf_Rela *rela;
436 unsigned long i, n;
437 int rc;
438
439 DEBUGP("Applying relocate section %u to %u\n",
440 relsec, sechdrs[relsec].sh_info);
441 base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
442 symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
443 rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
444 n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
445
446 for (i = 0; i < n; i++, rela++) {
447 rc = apply_rela(rela, base, symtab, strtab, me, write);
448 if (rc)
449 return rc;
450 }
451 return 0;
452 }
453
apply_relocate_add(Elf_Shdr * sechdrs,const char * strtab,unsigned int symindex,unsigned int relsec,struct module * me)454 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
455 unsigned int symindex, unsigned int relsec,
456 struct module *me)
457 {
458 bool early = me->state == MODULE_STATE_UNFORMED;
459 void *(*write)(void *, const void *, size_t) = memcpy;
460
461 if (!early)
462 write = s390_kernel_write;
463
464 return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
465 write);
466 }
467
module_finalize(const Elf_Ehdr * hdr,const Elf_Shdr * sechdrs,struct module * me)468 int module_finalize(const Elf_Ehdr *hdr,
469 const Elf_Shdr *sechdrs,
470 struct module *me)
471 {
472 const Elf_Shdr *s;
473 char *secstrings, *secname;
474 void *aseg;
475
476 if (IS_ENABLED(CONFIG_EXPOLINE) &&
477 !nospec_disable && me->arch.plt_size) {
478 unsigned int *ij;
479
480 ij = me->core_layout.base + me->arch.plt_offset +
481 me->arch.plt_size - PLT_ENTRY_SIZE;
482 if (test_facility(35)) {
483 ij[0] = 0xc6000000; /* exrl %r0,.+10 */
484 ij[1] = 0x0005a7f4; /* j . */
485 ij[2] = 0x000007f1; /* br %r1 */
486 } else {
487 ij[0] = 0x44000000 | (unsigned int)
488 offsetof(struct lowcore, br_r1_trampoline);
489 ij[1] = 0xa7f40000; /* j . */
490 }
491 }
492
493 secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
494 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
495 aseg = (void *) s->sh_addr;
496 secname = secstrings + s->sh_name;
497
498 if (!strcmp(".altinstructions", secname))
499 /* patch .altinstructions */
500 apply_alternatives(aseg, aseg + s->sh_size);
501
502 if (IS_ENABLED(CONFIG_EXPOLINE) &&
503 (str_has_prefix(secname, ".s390_indirect")))
504 nospec_revert(aseg, aseg + s->sh_size);
505
506 if (IS_ENABLED(CONFIG_EXPOLINE) &&
507 (str_has_prefix(secname, ".s390_return")))
508 nospec_revert(aseg, aseg + s->sh_size);
509 }
510
511 jump_label_apply_nops(me);
512 return 0;
513 }
514