1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * |
4 | * Copyright (C) 2001 Rusty Russell. |
5 | * Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org) |
6 | * Copyright (C) 2005 Thiemo Seufer |
7 | */ |
8 | |
9 | #undef DEBUG |
10 | |
11 | #include <linux/extable.h> |
12 | #include <linux/moduleloader.h> |
13 | #include <linux/elf.h> |
14 | #include <linux/mm.h> |
15 | #include <linux/numa.h> |
16 | #include <linux/vmalloc.h> |
17 | #include <linux/slab.h> |
18 | #include <linux/fs.h> |
19 | #include <linux/string.h> |
20 | #include <linux/kernel.h> |
21 | #include <linux/spinlock.h> |
22 | #include <linux/jump_label.h> |
23 | #include <asm/jump_label.h> |
24 | |
25 | struct mips_hi16 { |
26 | struct mips_hi16 *next; |
27 | Elf_Addr *addr; |
28 | Elf_Addr value; |
29 | }; |
30 | |
31 | static LIST_HEAD(dbe_list); |
32 | static DEFINE_SPINLOCK(dbe_lock); |
33 | |
34 | #ifdef MODULE_START |
35 | void *module_alloc(unsigned long size) |
36 | { |
37 | return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END, |
38 | GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, |
39 | __builtin_return_address(0)); |
40 | } |
41 | #endif |
42 | |
43 | static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v) |
44 | { |
45 | *location = base + v; |
46 | } |
47 | |
48 | static int apply_r_mips_26(struct module *me, u32 *location, u32 base, |
49 | Elf_Addr v) |
50 | { |
51 | if (v % 4) { |
52 | pr_err("module %s: dangerous R_MIPS_26 relocation\n" , |
53 | me->name); |
54 | return -ENOEXEC; |
55 | } |
56 | |
57 | if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) { |
58 | pr_err("module %s: relocation overflow\n" , |
59 | me->name); |
60 | return -ENOEXEC; |
61 | } |
62 | |
63 | *location = (*location & ~0x03ffffff) | |
64 | ((base + (v >> 2)) & 0x03ffffff); |
65 | |
66 | return 0; |
67 | } |
68 | |
69 | static int apply_r_mips_hi16(struct module *me, u32 *location, Elf_Addr v, |
70 | bool rela) |
71 | { |
72 | struct mips_hi16 *n; |
73 | |
74 | if (rela) { |
75 | *location = (*location & 0xffff0000) | |
76 | ((((long long) v + 0x8000LL) >> 16) & 0xffff); |
77 | return 0; |
78 | } |
79 | |
80 | /* |
81 | * We cannot relocate this one now because we don't know the value of |
82 | * the carry we need to add. Save the information, and let LO16 do the |
83 | * actual relocation. |
84 | */ |
85 | n = kmalloc(size: sizeof *n, GFP_KERNEL); |
86 | if (!n) |
87 | return -ENOMEM; |
88 | |
89 | n->addr = (Elf_Addr *)location; |
90 | n->value = v; |
91 | n->next = me->arch.r_mips_hi16_list; |
92 | me->arch.r_mips_hi16_list = n; |
93 | |
94 | return 0; |
95 | } |
96 | |
97 | static void free_relocation_chain(struct mips_hi16 *l) |
98 | { |
99 | struct mips_hi16 *next; |
100 | |
101 | while (l) { |
102 | next = l->next; |
103 | kfree(objp: l); |
104 | l = next; |
105 | } |
106 | } |
107 | |
108 | static int apply_r_mips_lo16(struct module *me, u32 *location, |
109 | u32 base, Elf_Addr v, bool rela) |
110 | { |
111 | unsigned long insnlo = base; |
112 | struct mips_hi16 *l; |
113 | Elf_Addr val, vallo; |
114 | |
115 | if (rela) { |
116 | *location = (*location & 0xffff0000) | (v & 0xffff); |
117 | return 0; |
118 | } |
119 | |
120 | /* Sign extend the addend we extract from the lo insn. */ |
121 | vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000; |
122 | |
123 | if (me->arch.r_mips_hi16_list != NULL) { |
124 | l = me->arch.r_mips_hi16_list; |
125 | while (l != NULL) { |
126 | struct mips_hi16 *next; |
127 | unsigned long insn; |
128 | |
129 | /* |
130 | * The value for the HI16 had best be the same. |
131 | */ |
132 | if (v != l->value) |
133 | goto out_danger; |
134 | |
135 | /* |
136 | * Do the HI16 relocation. Note that we actually don't |
137 | * need to know anything about the LO16 itself, except |
138 | * where to find the low 16 bits of the addend needed |
139 | * by the LO16. |
140 | */ |
141 | insn = *l->addr; |
142 | val = ((insn & 0xffff) << 16) + vallo; |
143 | val += v; |
144 | |
145 | /* |
146 | * Account for the sign extension that will happen in |
147 | * the low bits. |
148 | */ |
149 | val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff; |
150 | |
151 | insn = (insn & ~0xffff) | val; |
152 | *l->addr = insn; |
153 | |
154 | next = l->next; |
155 | kfree(objp: l); |
156 | l = next; |
157 | } |
158 | |
159 | me->arch.r_mips_hi16_list = NULL; |
160 | } |
161 | |
162 | /* |
163 | * Ok, we're done with the HI16 relocs. Now deal with the LO16. |
164 | */ |
165 | val = v + vallo; |
166 | insnlo = (insnlo & ~0xffff) | (val & 0xffff); |
167 | *location = insnlo; |
168 | |
169 | return 0; |
170 | |
171 | out_danger: |
172 | free_relocation_chain(l); |
173 | me->arch.r_mips_hi16_list = NULL; |
174 | |
175 | pr_err("module %s: dangerous R_MIPS_LO16 relocation\n" , me->name); |
176 | |
177 | return -ENOEXEC; |
178 | } |
179 | |
180 | static int apply_r_mips_pc(struct module *me, u32 *location, u32 base, |
181 | Elf_Addr v, unsigned int bits) |
182 | { |
183 | unsigned long mask = GENMASK(bits - 1, 0); |
184 | unsigned long se_bits; |
185 | long offset; |
186 | |
187 | if (v % 4) { |
188 | pr_err("module %s: dangerous R_MIPS_PC%u relocation\n" , |
189 | me->name, bits); |
190 | return -ENOEXEC; |
191 | } |
192 | |
193 | /* retrieve & sign extend implicit addend if any */ |
194 | offset = base & mask; |
195 | offset |= (offset & BIT(bits - 1)) ? ~mask : 0; |
196 | |
197 | offset += ((long)v - (long)location) >> 2; |
198 | |
199 | /* check the sign bit onwards are identical - ie. we didn't overflow */ |
200 | se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0; |
201 | if ((offset & ~mask) != (se_bits & ~mask)) { |
202 | pr_err("module %s: relocation overflow\n" , me->name); |
203 | return -ENOEXEC; |
204 | } |
205 | |
206 | *location = (*location & ~mask) | (offset & mask); |
207 | |
208 | return 0; |
209 | } |
210 | |
211 | static int apply_r_mips_pc16(struct module *me, u32 *location, u32 base, |
212 | Elf_Addr v) |
213 | { |
214 | return apply_r_mips_pc(me, location, base, v, bits: 16); |
215 | } |
216 | |
217 | static int apply_r_mips_pc21(struct module *me, u32 *location, u32 base, |
218 | Elf_Addr v) |
219 | { |
220 | return apply_r_mips_pc(me, location, base, v, bits: 21); |
221 | } |
222 | |
223 | static int apply_r_mips_pc26(struct module *me, u32 *location, u32 base, |
224 | Elf_Addr v) |
225 | { |
226 | return apply_r_mips_pc(me, location, base, v, bits: 26); |
227 | } |
228 | |
229 | static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela) |
230 | { |
231 | if (WARN_ON(!rela)) |
232 | return -EINVAL; |
233 | |
234 | *(Elf_Addr *)location = v; |
235 | |
236 | return 0; |
237 | } |
238 | |
239 | static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela) |
240 | { |
241 | if (WARN_ON(!rela)) |
242 | return -EINVAL; |
243 | |
244 | *location = (*location & 0xffff0000) | |
245 | ((((long long)v + 0x80008000LL) >> 32) & 0xffff); |
246 | |
247 | return 0; |
248 | } |
249 | |
250 | static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela) |
251 | { |
252 | if (WARN_ON(!rela)) |
253 | return -EINVAL; |
254 | |
255 | *location = (*location & 0xffff0000) | |
256 | ((((long long)v + 0x800080008000LL) >> 48) & 0xffff); |
257 | |
258 | return 0; |
259 | } |
260 | |
261 | /** |
262 | * reloc_handler() - Apply a particular relocation to a module |
263 | * @type: type of the relocation to apply |
264 | * @me: the module to apply the reloc to |
265 | * @location: the address at which the reloc is to be applied |
266 | * @base: the existing value at location for REL-style; 0 for RELA-style |
267 | * @v: the value of the reloc, with addend for RELA-style |
268 | * @rela: indication of is this a RELA (true) or REL (false) relocation |
269 | * |
270 | * Each implemented relocation function applies a particular type of |
271 | * relocation to the module @me. Relocs that may be found in either REL or RELA |
272 | * variants can be handled by making use of the @base & @v parameters which are |
273 | * set to values which abstract the difference away from the particular reloc |
274 | * implementations. |
275 | * |
276 | * Return: 0 upon success, else -ERRNO |
277 | */ |
278 | static int reloc_handler(u32 type, struct module *me, u32 *location, u32 base, |
279 | Elf_Addr v, bool rela) |
280 | { |
281 | switch (type) { |
282 | case R_MIPS_NONE: |
283 | break; |
284 | case R_MIPS_32: |
285 | apply_r_mips_32(location, base, v); |
286 | break; |
287 | case R_MIPS_26: |
288 | return apply_r_mips_26(me, location, base, v); |
289 | case R_MIPS_HI16: |
290 | return apply_r_mips_hi16(me, location, v, rela); |
291 | case R_MIPS_LO16: |
292 | return apply_r_mips_lo16(me, location, base, v, rela); |
293 | case R_MIPS_PC16: |
294 | return apply_r_mips_pc16(me, location, base, v); |
295 | case R_MIPS_PC21_S2: |
296 | return apply_r_mips_pc21(me, location, base, v); |
297 | case R_MIPS_PC26_S2: |
298 | return apply_r_mips_pc26(me, location, base, v); |
299 | case R_MIPS_64: |
300 | return apply_r_mips_64(location, v, rela); |
301 | case R_MIPS_HIGHER: |
302 | return apply_r_mips_higher(location, v, rela); |
303 | case R_MIPS_HIGHEST: |
304 | return apply_r_mips_highest(location, v, rela); |
305 | default: |
306 | pr_err("%s: Unknown relocation type %u\n" , me->name, type); |
307 | return -EINVAL; |
308 | } |
309 | |
310 | return 0; |
311 | } |
312 | |
313 | static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab, |
314 | unsigned int symindex, unsigned int relsec, |
315 | struct module *me, bool rela) |
316 | { |
317 | union { |
318 | Elf_Mips_Rel *rel; |
319 | Elf_Mips_Rela *rela; |
320 | } r; |
321 | Elf_Sym *sym; |
322 | u32 *location, base; |
323 | unsigned int i, type; |
324 | Elf_Addr v; |
325 | int err = 0; |
326 | size_t reloc_sz; |
327 | |
328 | pr_debug("Applying relocate section %u to %u\n" , relsec, |
329 | sechdrs[relsec].sh_info); |
330 | |
331 | r.rel = (void *)sechdrs[relsec].sh_addr; |
332 | reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel); |
333 | me->arch.r_mips_hi16_list = NULL; |
334 | for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) { |
335 | /* This is where to make the change */ |
336 | location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr |
337 | + r.rel->r_offset; |
338 | /* This is the symbol it is referring to */ |
339 | sym = (Elf_Sym *)sechdrs[symindex].sh_addr |
340 | + ELF_MIPS_R_SYM(*r.rel); |
341 | if (sym->st_value >= -MAX_ERRNO) { |
342 | /* Ignore unresolved weak symbol */ |
343 | if (ELF_ST_BIND(sym->st_info) == STB_WEAK) |
344 | continue; |
345 | pr_warn("%s: Unknown symbol %s\n" , |
346 | me->name, strtab + sym->st_name); |
347 | err = -ENOENT; |
348 | goto out; |
349 | } |
350 | |
351 | type = ELF_MIPS_R_TYPE(*r.rel); |
352 | |
353 | if (rela) { |
354 | v = sym->st_value + r.rela->r_addend; |
355 | base = 0; |
356 | r.rela = &r.rela[1]; |
357 | } else { |
358 | v = sym->st_value; |
359 | base = *location; |
360 | r.rel = &r.rel[1]; |
361 | } |
362 | |
363 | err = reloc_handler(type, me, location, base, v, rela); |
364 | if (err) |
365 | goto out; |
366 | } |
367 | |
368 | out: |
369 | /* |
370 | * Normally the hi16 list should be deallocated at this point. A |
371 | * malformed binary however could contain a series of R_MIPS_HI16 |
372 | * relocations not followed by a R_MIPS_LO16 relocation, or if we hit |
373 | * an error processing a reloc we might have gotten here before |
374 | * reaching the R_MIPS_LO16. In either case, free up the list and |
375 | * return an error. |
376 | */ |
377 | if (me->arch.r_mips_hi16_list) { |
378 | free_relocation_chain(l: me->arch.r_mips_hi16_list); |
379 | me->arch.r_mips_hi16_list = NULL; |
380 | err = err ?: -ENOEXEC; |
381 | } |
382 | |
383 | return err; |
384 | } |
385 | |
386 | int apply_relocate(Elf_Shdr *sechdrs, const char *strtab, |
387 | unsigned int symindex, unsigned int relsec, |
388 | struct module *me) |
389 | { |
390 | return __apply_relocate(sechdrs, strtab, symindex, relsec, me, rela: false); |
391 | } |
392 | |
393 | #ifdef CONFIG_MODULES_USE_ELF_RELA |
394 | int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, |
395 | unsigned int symindex, unsigned int relsec, |
396 | struct module *me) |
397 | { |
398 | return __apply_relocate(sechdrs, strtab, symindex, relsec, me, rela: true); |
399 | } |
400 | #endif /* CONFIG_MODULES_USE_ELF_RELA */ |
401 | |
402 | /* Given an address, look for it in the module exception tables. */ |
403 | const struct exception_table_entry *search_module_dbetables(unsigned long addr) |
404 | { |
405 | unsigned long flags; |
406 | const struct exception_table_entry *e = NULL; |
407 | struct mod_arch_specific *dbe; |
408 | |
409 | spin_lock_irqsave(&dbe_lock, flags); |
410 | list_for_each_entry(dbe, &dbe_list, dbe_list) { |
411 | e = search_extable(base: dbe->dbe_start, |
412 | num: dbe->dbe_end - dbe->dbe_start, value: addr); |
413 | if (e) |
414 | break; |
415 | } |
416 | spin_unlock_irqrestore(lock: &dbe_lock, flags); |
417 | |
418 | /* Now, if we found one, we are running inside it now, hence |
419 | we cannot unload the module, hence no refcnt needed. */ |
420 | return e; |
421 | } |
422 | |
423 | /* Put in dbe list if necessary. */ |
424 | int module_finalize(const Elf_Ehdr *hdr, |
425 | const Elf_Shdr *sechdrs, |
426 | struct module *me) |
427 | { |
428 | const Elf_Shdr *s; |
429 | char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; |
430 | |
431 | if (IS_ENABLED(CONFIG_JUMP_LABEL)) |
432 | jump_label_apply_nops(me); |
433 | |
434 | INIT_LIST_HEAD(list: &me->arch.dbe_list); |
435 | for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) { |
436 | if (strcmp("__dbe_table" , secstrings + s->sh_name) != 0) |
437 | continue; |
438 | me->arch.dbe_start = (void *)s->sh_addr; |
439 | me->arch.dbe_end = (void *)s->sh_addr + s->sh_size; |
440 | spin_lock_irq(lock: &dbe_lock); |
441 | list_add(new: &me->arch.dbe_list, head: &dbe_list); |
442 | spin_unlock_irq(lock: &dbe_lock); |
443 | } |
444 | return 0; |
445 | } |
446 | |
447 | void module_arch_cleanup(struct module *mod) |
448 | { |
449 | spin_lock_irq(lock: &dbe_lock); |
450 | list_del(entry: &mod->arch.dbe_list); |
451 | spin_unlock_irq(lock: &dbe_lock); |
452 | } |
453 | |