1 // SPDX-License-Identifier: GPL-2.0+
3 * Kernel module help for s390.
6 * Copyright IBM Corp. 2002, 2003
7 * Author(s): Arnd Bergmann (arndb@de.ibm.com)
8 * Martin Schwidefsky (schwidefsky@de.ibm.com)
10 * based on i386 version
11 * Copyright (C) 2001 Rusty Russell.
13 #include <linux/module.h>
14 #include <linux/elf.h>
15 #include <linux/vmalloc.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 <asm/alternative.h>
25 #include <asm/nospec-branch.h>
26 #include <asm/facility.h>
27 #include <asm/ftrace.lds.h>
28 #include <asm/set_memory.h>
33 #define DEBUGP(fmt , ...)
36 #define PLT_ENTRY_SIZE 22
38 void *module_alloc(unsigned long size)
40 gfp_t gfp_mask = GFP_KERNEL;
43 if (PAGE_ALIGN(size) > MODULES_LEN)
45 p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,
46 gfp_mask, PAGE_KERNEL_EXEC, VM_DEFER_KMEMLEAK, NUMA_NO_NODE,
47 __builtin_return_address(0));
48 if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
55 #ifdef CONFIG_FUNCTION_TRACER
56 void module_arch_cleanup(struct module *mod)
58 module_memfree(mod->arch.trampolines_start);
62 void module_arch_freeing_init(struct module *mod)
64 if (is_livepatch_module(mod) &&
65 mod->state == MODULE_STATE_LIVE)
68 vfree(mod->arch.syminfo);
69 mod->arch.syminfo = NULL;
72 static void check_rela(Elf_Rela *rela, struct module *me)
74 struct mod_arch_syminfo *info;
76 info = me->arch.syminfo + ELF_R_SYM (rela->r_info);
77 switch (ELF_R_TYPE (rela->r_info)) {
78 case R_390_GOT12: /* 12 bit GOT offset. */
79 case R_390_GOT16: /* 16 bit GOT offset. */
80 case R_390_GOT20: /* 20 bit GOT offset. */
81 case R_390_GOT32: /* 32 bit GOT offset. */
82 case R_390_GOT64: /* 64 bit GOT offset. */
83 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
84 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
85 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
86 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
87 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
88 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
89 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
90 if (info->got_offset == -1UL) {
91 info->got_offset = me->arch.got_size;
92 me->arch.got_size += sizeof(void*);
95 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
96 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
97 case R_390_PLT32: /* 32 bit PC relative PLT address. */
98 case R_390_PLT64: /* 64 bit PC relative PLT address. */
99 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
100 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
101 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
102 if (info->plt_offset == -1UL) {
103 info->plt_offset = me->arch.plt_size;
104 me->arch.plt_size += PLT_ENTRY_SIZE;
111 /* Only needed if we want to support loading of
112 modules linked with -shared. */
118 * Account for GOT and PLT relocations. We can't add sections for
119 * got and plt but we can increase the core module size.
121 int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
122 char *secstrings, struct module *me)
129 struct module_memory *mod_mem;
131 /* Find symbol table and string table. */
133 for (i = 0; i < hdr->e_shnum; i++)
134 switch (sechdrs[i].sh_type) {
136 symtab = sechdrs + i;
140 printk(KERN_ERR "module %s: no symbol table\n", me->name);
144 /* Allocate one syminfo structure per symbol. */
145 me->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
146 me->arch.syminfo = vmalloc(array_size(sizeof(struct mod_arch_syminfo),
148 if (!me->arch.syminfo)
150 symbols = (void *) hdr + symtab->sh_offset;
151 strings = (void *) hdr + sechdrs[symtab->sh_link].sh_offset;
152 for (i = 0; i < me->arch.nsyms; i++) {
153 if (symbols[i].st_shndx == SHN_UNDEF &&
154 strcmp(strings + symbols[i].st_name,
155 "_GLOBAL_OFFSET_TABLE_") == 0)
156 /* "Define" it as absolute. */
157 symbols[i].st_shndx = SHN_ABS;
158 me->arch.syminfo[i].got_offset = -1UL;
159 me->arch.syminfo[i].plt_offset = -1UL;
160 me->arch.syminfo[i].got_initialized = 0;
161 me->arch.syminfo[i].plt_initialized = 0;
164 /* Search for got/plt relocations. */
165 me->arch.got_size = me->arch.plt_size = 0;
166 for (i = 0; i < hdr->e_shnum; i++) {
167 if (sechdrs[i].sh_type != SHT_RELA)
169 nrela = sechdrs[i].sh_size / sizeof(Elf_Rela);
170 rela = (void *) hdr + sechdrs[i].sh_offset;
171 for (j = 0; j < nrela; j++)
172 check_rela(rela + j, me);
175 /* Increase core size by size of got & plt and set start
176 offsets for got and plt. */
177 mod_mem = &me->mem[MOD_TEXT];
178 mod_mem->size = ALIGN(mod_mem->size, 4);
179 me->arch.got_offset = mod_mem->size;
180 mod_mem->size += me->arch.got_size;
181 me->arch.plt_offset = mod_mem->size;
182 if (me->arch.plt_size) {
183 if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
184 me->arch.plt_size += PLT_ENTRY_SIZE;
185 mod_mem->size += me->arch.plt_size;
190 static int apply_rela_bits(Elf_Addr loc, Elf_Addr val,
191 int sign, int bits, int shift,
192 void *(*write)(void *dest, const void *src, size_t len))
196 void *dest = (void *)loc;
198 if (val & ((1UL << shift) - 1))
201 val = (Elf_Addr)(((long) val) >> shift);
202 min = -(1L << (bits - 1));
203 max = (1L << (bits - 1)) - 1;
204 if ((long) val < min || (long) val > max)
208 umax = ((1UL << (bits - 1)) << 1) - 1;
209 if ((unsigned long) val > umax)
214 unsigned char tmp = val;
215 write(dest, &tmp, 1);
216 } else if (bits == 12) {
217 unsigned short tmp = (val & 0xfff) |
218 (*(unsigned short *) loc & 0xf000);
219 write(dest, &tmp, 2);
220 } else if (bits == 16) {
221 unsigned short tmp = val;
222 write(dest, &tmp, 2);
223 } else if (bits == 20) {
224 unsigned int tmp = (val & 0xfff) << 16 |
225 (val & 0xff000) >> 4 | (*(unsigned int *) loc & 0xf00000ff);
226 write(dest, &tmp, 4);
227 } else if (bits == 32) {
228 unsigned int tmp = val;
229 write(dest, &tmp, 4);
230 } else if (bits == 64) {
231 unsigned long tmp = val;
232 write(dest, &tmp, 8);
237 static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
238 const char *strtab, struct module *me,
239 void *(*write)(void *dest, const void *src, size_t len))
241 struct mod_arch_syminfo *info;
246 /* This is where to make the change */
247 loc = base + rela->r_offset;
248 /* This is the symbol it is referring to. Note that all
249 undefined symbols have been resolved. */
250 r_sym = ELF_R_SYM(rela->r_info);
251 r_type = ELF_R_TYPE(rela->r_info);
252 info = me->arch.syminfo + r_sym;
253 val = symtab[r_sym].st_value;
256 case R_390_NONE: /* No relocation. */
259 case R_390_8: /* Direct 8 bit. */
260 case R_390_12: /* Direct 12 bit. */
261 case R_390_16: /* Direct 16 bit. */
262 case R_390_20: /* Direct 20 bit. */
263 case R_390_32: /* Direct 32 bit. */
264 case R_390_64: /* Direct 64 bit. */
265 val += rela->r_addend;
266 if (r_type == R_390_8)
267 rc = apply_rela_bits(loc, val, 0, 8, 0, write);
268 else if (r_type == R_390_12)
269 rc = apply_rela_bits(loc, val, 0, 12, 0, write);
270 else if (r_type == R_390_16)
271 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
272 else if (r_type == R_390_20)
273 rc = apply_rela_bits(loc, val, 1, 20, 0, write);
274 else if (r_type == R_390_32)
275 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
276 else if (r_type == R_390_64)
277 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
279 case R_390_PC16: /* PC relative 16 bit. */
280 case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
281 case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
282 case R_390_PC32: /* PC relative 32 bit. */
283 case R_390_PC64: /* PC relative 64 bit. */
284 val += rela->r_addend - loc;
285 if (r_type == R_390_PC16)
286 rc = apply_rela_bits(loc, val, 1, 16, 0, write);
287 else if (r_type == R_390_PC16DBL)
288 rc = apply_rela_bits(loc, val, 1, 16, 1, write);
289 else if (r_type == R_390_PC32DBL)
290 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
291 else if (r_type == R_390_PC32)
292 rc = apply_rela_bits(loc, val, 1, 32, 0, write);
293 else if (r_type == R_390_PC64)
294 rc = apply_rela_bits(loc, val, 1, 64, 0, write);
296 case R_390_GOT12: /* 12 bit GOT offset. */
297 case R_390_GOT16: /* 16 bit GOT offset. */
298 case R_390_GOT20: /* 20 bit GOT offset. */
299 case R_390_GOT32: /* 32 bit GOT offset. */
300 case R_390_GOT64: /* 64 bit GOT offset. */
301 case R_390_GOTENT: /* 32 bit PC rel. to GOT entry shifted by 1. */
302 case R_390_GOTPLT12: /* 12 bit offset to jump slot. */
303 case R_390_GOTPLT20: /* 20 bit offset to jump slot. */
304 case R_390_GOTPLT16: /* 16 bit offset to jump slot. */
305 case R_390_GOTPLT32: /* 32 bit offset to jump slot. */
306 case R_390_GOTPLT64: /* 64 bit offset to jump slot. */
307 case R_390_GOTPLTENT: /* 32 bit rel. offset to jump slot >> 1. */
308 if (info->got_initialized == 0) {
309 Elf_Addr *gotent = me->mem[MOD_TEXT].base +
310 me->arch.got_offset +
313 write(gotent, &val, sizeof(*gotent));
314 info->got_initialized = 1;
316 val = info->got_offset + rela->r_addend;
317 if (r_type == R_390_GOT12 ||
318 r_type == R_390_GOTPLT12)
319 rc = apply_rela_bits(loc, val, 0, 12, 0, write);
320 else if (r_type == R_390_GOT16 ||
321 r_type == R_390_GOTPLT16)
322 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
323 else if (r_type == R_390_GOT20 ||
324 r_type == R_390_GOTPLT20)
325 rc = apply_rela_bits(loc, val, 1, 20, 0, write);
326 else if (r_type == R_390_GOT32 ||
327 r_type == R_390_GOTPLT32)
328 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
329 else if (r_type == R_390_GOT64 ||
330 r_type == R_390_GOTPLT64)
331 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
332 else if (r_type == R_390_GOTENT ||
333 r_type == R_390_GOTPLTENT) {
334 val += (Elf_Addr) me->mem[MOD_TEXT].base - loc;
335 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
338 case R_390_PLT16DBL: /* 16 bit PC rel. PLT shifted by 1. */
339 case R_390_PLT32DBL: /* 32 bit PC rel. PLT shifted by 1. */
340 case R_390_PLT32: /* 32 bit PC relative PLT address. */
341 case R_390_PLT64: /* 64 bit PC relative PLT address. */
342 case R_390_PLTOFF16: /* 16 bit offset from GOT to PLT. */
343 case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
344 case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
345 if (info->plt_initialized == 0) {
346 unsigned char insn[PLT_ENTRY_SIZE];
350 plt_base = me->mem[MOD_TEXT].base + me->arch.plt_offset;
351 ip = plt_base + info->plt_offset;
352 *(int *)insn = 0x0d10e310; /* basr 1,0 */
353 *(int *)&insn[4] = 0x100c0004; /* lg 1,12(1) */
354 if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
357 jump_r1 = plt_base + me->arch.plt_size -
359 /* brcl 0xf,__jump_r1 */
360 *(short *)&insn[8] = 0xc0f4;
361 *(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
363 *(int *)&insn[8] = 0x07f10000; /* br %r1 */
365 *(long *)&insn[14] = val;
367 write(ip, insn, sizeof(insn));
368 info->plt_initialized = 1;
370 if (r_type == R_390_PLTOFF16 ||
371 r_type == R_390_PLTOFF32 ||
372 r_type == R_390_PLTOFF64)
373 val = me->arch.plt_offset - me->arch.got_offset +
374 info->plt_offset + rela->r_addend;
376 if (!((r_type == R_390_PLT16DBL &&
377 val - loc + 0xffffUL < 0x1ffffeUL) ||
378 (r_type == R_390_PLT32DBL &&
379 val - loc + 0xffffffffULL < 0x1fffffffeULL)))
380 val = (Elf_Addr) me->mem[MOD_TEXT].base +
381 me->arch.plt_offset +
383 val += rela->r_addend - loc;
385 if (r_type == R_390_PLT16DBL)
386 rc = apply_rela_bits(loc, val, 1, 16, 1, write);
387 else if (r_type == R_390_PLTOFF16)
388 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
389 else if (r_type == R_390_PLT32DBL)
390 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
391 else if (r_type == R_390_PLT32 ||
392 r_type == R_390_PLTOFF32)
393 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
394 else if (r_type == R_390_PLT64 ||
395 r_type == R_390_PLTOFF64)
396 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
398 case R_390_GOTOFF16: /* 16 bit offset to GOT. */
399 case R_390_GOTOFF32: /* 32 bit offset to GOT. */
400 case R_390_GOTOFF64: /* 64 bit offset to GOT. */
401 val = val + rela->r_addend -
402 ((Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset);
403 if (r_type == R_390_GOTOFF16)
404 rc = apply_rela_bits(loc, val, 0, 16, 0, write);
405 else if (r_type == R_390_GOTOFF32)
406 rc = apply_rela_bits(loc, val, 0, 32, 0, write);
407 else if (r_type == R_390_GOTOFF64)
408 rc = apply_rela_bits(loc, val, 0, 64, 0, write);
410 case R_390_GOTPC: /* 32 bit PC relative offset to GOT. */
411 case R_390_GOTPCDBL: /* 32 bit PC rel. off. to GOT shifted by 1. */
412 val = (Elf_Addr) me->mem[MOD_TEXT].base + me->arch.got_offset +
413 rela->r_addend - loc;
414 if (r_type == R_390_GOTPC)
415 rc = apply_rela_bits(loc, val, 1, 32, 0, write);
416 else if (r_type == R_390_GOTPCDBL)
417 rc = apply_rela_bits(loc, val, 1, 32, 1, write);
420 case R_390_GLOB_DAT: /* Create GOT entry. */
421 case R_390_JMP_SLOT: /* Create PLT entry. */
422 case R_390_RELATIVE: /* Adjust by program base. */
423 /* Only needed if we want to support loading of
424 modules linked with -shared. */
427 printk(KERN_ERR "module %s: unknown relocation: %u\n",
432 printk(KERN_ERR "module %s: relocation error for symbol %s "
433 "(r_type %i, value 0x%lx)\n",
434 me->name, strtab + symtab[r_sym].st_name,
435 r_type, (unsigned long) val);
441 static int __apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
442 unsigned int symindex, unsigned int relsec,
444 void *(*write)(void *dest, const void *src, size_t len))
452 DEBUGP("Applying relocate section %u to %u\n",
453 relsec, sechdrs[relsec].sh_info);
454 base = sechdrs[sechdrs[relsec].sh_info].sh_addr;
455 symtab = (Elf_Sym *) sechdrs[symindex].sh_addr;
456 rela = (Elf_Rela *) sechdrs[relsec].sh_addr;
457 n = sechdrs[relsec].sh_size / sizeof(Elf_Rela);
459 for (i = 0; i < n; i++, rela++) {
460 rc = apply_rela(rela, base, symtab, strtab, me, write);
467 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
468 unsigned int symindex, unsigned int relsec,
471 bool early = me->state == MODULE_STATE_UNFORMED;
472 void *(*write)(void *, const void *, size_t) = memcpy;
475 write = s390_kernel_write;
477 return __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
481 #ifdef CONFIG_FUNCTION_TRACER
482 static int module_alloc_ftrace_hotpatch_trampolines(struct module *me,
489 size = FTRACE_HOTPATCH_TRAMPOLINES_SIZE(s->sh_size);
490 numpages = DIV_ROUND_UP(size, PAGE_SIZE);
491 start = module_alloc(numpages * PAGE_SIZE);
494 set_memory_ro((unsigned long)start, numpages);
497 me->arch.trampolines_start = (struct ftrace_hotpatch_trampoline *)start;
498 me->arch.trampolines_end = (struct ftrace_hotpatch_trampoline *)end;
499 me->arch.next_trampoline = me->arch.trampolines_start;
503 #endif /* CONFIG_FUNCTION_TRACER */
505 int module_finalize(const Elf_Ehdr *hdr,
506 const Elf_Shdr *sechdrs,
510 char *secstrings, *secname;
512 #ifdef CONFIG_FUNCTION_TRACER
516 if (IS_ENABLED(CONFIG_EXPOLINE) &&
517 !nospec_disable && me->arch.plt_size) {
520 ij = me->mem[MOD_TEXT].base + me->arch.plt_offset +
521 me->arch.plt_size - PLT_ENTRY_SIZE;
522 ij[0] = 0xc6000000; /* exrl %r0,.+10 */
523 ij[1] = 0x0005a7f4; /* j . */
524 ij[2] = 0x000007f1; /* br %r1 */
527 secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
528 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
529 aseg = (void *) s->sh_addr;
530 secname = secstrings + s->sh_name;
532 if (!strcmp(".altinstructions", secname))
533 /* patch .altinstructions */
534 apply_alternatives(aseg, aseg + s->sh_size);
536 if (IS_ENABLED(CONFIG_EXPOLINE) &&
537 (str_has_prefix(secname, ".s390_indirect")))
538 nospec_revert(aseg, aseg + s->sh_size);
540 if (IS_ENABLED(CONFIG_EXPOLINE) &&
541 (str_has_prefix(secname, ".s390_return")))
542 nospec_revert(aseg, aseg + s->sh_size);
544 #ifdef CONFIG_FUNCTION_TRACER
545 if (!strcmp(FTRACE_CALLSITE_SECTION, secname)) {
546 ret = module_alloc_ftrace_hotpatch_trampolines(me, s);
550 #endif /* CONFIG_FUNCTION_TRACER */