summaryrefslogtreecommitdiffstats
path: root/arch/mips/kernel/module.c
blob: 7b2fbaa9cac579cf27c071efaf515c0f4e225cd3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 *  Copyright (C) 2001 Rusty Russell.
 *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
 *  Copyright (C) 2005 Thiemo Seufer
 */

#undef DEBUG

#include <linux/extable.h>
#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/mm.h>
#include <linux/numa.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/jump_label.h>
#include <asm/jump_label.h>

struct mips_hi16 {
	struct mips_hi16 *next;
	Elf_Addr *addr;
	Elf_Addr value;
};

static LIST_HEAD(dbe_list);
static DEFINE_SPINLOCK(dbe_lock);

#ifdef MODULE_START
void *module_alloc(unsigned long size)
{
	return __vmalloc_node_range(size, 1, MODULE_START, MODULE_END,
				GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE,
				__builtin_return_address(0));
}
#endif

static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v)
{
	*location = base + v;
}

static int apply_r_mips_26(struct module *me, u32 *location, u32 base,
			   Elf_Addr v)
{
	if (v % 4) {
		pr_err("module %s: dangerous R_MIPS_26 relocation\n",
		       me->name);
		return -ENOEXEC;
	}

	if ((v & 0xf0000000) != (((unsigned long)location + 4) & 0xf0000000)) {
		pr_err("module %s: relocation overflow\n",
		       me->name);
		return -ENOEXEC;
	}

	*location = (*location & ~0x03ffffff) |
		    ((base + (v >> 2)) & 0x03ffffff);

	return 0;
}

static int apply_r_mips_hi16(struct module *me, u32 *location, Elf_Addr v,
			     bool rela)
{
	struct mips_hi16 *n;

	if (rela) {
		*location = (*location & 0xffff0000) |
			    ((((long long) v + 0x8000LL) >> 16) & 0xffff);
		return 0;
	}

	/*
	 * We cannot relocate this one now because we don't know the value of
	 * the carry we need to add.  Save the information, and let LO16 do the
	 * actual relocation.
	 */
	n = kmalloc(sizeof *n, GFP_KERNEL);
	if (!n)
		return -ENOMEM;

	n->addr = (Elf_Addr *)location;
	n->value = v;
	n->next = me->arch.r_mips_hi16_list;
	me->arch.r_mips_hi16_list = n;

	return 0;
}

static void free_relocation_chain(struct mips_hi16 *l)
{
	struct mips_hi16 *next;

	while (l) {
		next = l->next;
		kfree(l);
		l = next;
	}
}

static int apply_r_mips_lo16(struct module *me, u32 *location,
			     u32 base, Elf_Addr v, bool rela)
{
	unsigned long insnlo = base;
	struct mips_hi16 *l;
	Elf_Addr val, vallo;

	if (rela) {
		*location = (*location & 0xffff0000) | (v & 0xffff);
		return 0;
	}

	/* Sign extend the addend we extract from the lo insn.	*/
	vallo = ((insnlo & 0xffff) ^ 0x8000) - 0x8000;

	if (me->arch.r_mips_hi16_list != NULL) {
		l = me->arch.r_mips_hi16_list;
		while (l != NULL) {
			struct mips_hi16 *next;
			unsigned long insn;

			/*
			 * The value for the HI16 had best be the same.
			 */
			if (v != l->value)
				goto out_danger;

			/*
			 * Do the HI16 relocation.  Note that we actually don't
			 * need to know anything about the LO16 itself, except
			 * where to find the low 16 bits of the addend needed
			 * by the LO16.
			 */
			insn = *l->addr;
			val = ((insn & 0xffff) << 16) + vallo;
			val += v;

			/*
			 * Account for the sign extension that will happen in
			 * the low bits.
			 */
			val = ((val >> 16) + ((val & 0x8000) != 0)) & 0xffff;

			insn = (insn & ~0xffff) | val;
			*l->addr = insn;

			next = l->next;
			kfree(l);
			l = next;
		}

		me->arch.r_mips_hi16_list = NULL;
	}

	/*
	 * Ok, we're done with the HI16 relocs.	 Now deal with the LO16.
	 */
	val = v + vallo;
	insnlo = (insnlo & ~0xffff) | (val & 0xffff);
	*location = insnlo;

	return 0;

out_danger:
	free_relocation_chain(l);
	me->arch.r_mips_hi16_list = NULL;

	pr_err("module %s: dangerous R_MIPS_LO16 relocation\n", me->name);

	return -ENOEXEC;
}

static int apply_r_mips_pc(struct module *me, u32 *location, u32 base,
			   Elf_Addr v, unsigned int bits)
{
	unsigned long mask = GENMASK(bits - 1, 0);
	unsigned long se_bits;
	long offset;

	if (v % 4) {
		pr_err("module %s: dangerous R_MIPS_PC%u relocation\n",
		       me->name, bits);
		return -ENOEXEC;
	}

	/* retrieve & sign extend implicit addend if any */
	offset = base & mask;
	offset |= (offset & BIT(bits - 1)) ? ~mask : 0;

	offset += ((long)v - (long)location) >> 2;

	/* check the sign bit onwards are identical - ie. we didn't overflow */
	se_bits = (offset & BIT(bits - 1)) ? ~0ul : 0;
	if ((offset & ~mask) != (se_bits & ~mask)) {
		pr_err("module %s: relocation overflow\n", me->name);
		return -ENOEXEC;
	}

	*location = (*location & ~mask) | (offset & mask);

	return 0;
}

static int apply_r_mips_pc16(struct module *me, u32 *location, u32 base,
			     Elf_Addr v)
{
	return apply_r_mips_pc(me, location, base, v, 16);
}

static int apply_r_mips_pc21(struct module *me, u32 *location, u32 base,
			     Elf_Addr v)
{
	return apply_r_mips_pc(me, location, base, v, 21);
}

static int apply_r_mips_pc26(struct module *me, u32 *location, u32 base,
			     Elf_Addr v)
{
	return apply_r_mips_pc(me, location, base, v, 26);
}

static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela)
{
	if (WARN_ON(!rela))
		return -EINVAL;

	*(Elf_Addr *)location = v;

	return 0;
}

static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela)
{
	if (WARN_ON(!rela))
		return -EINVAL;

	*location = (*location & 0xffff0000) |
		    ((((long long)v + 0x80008000LL) >> 32) & 0xffff);

	return 0;
}

static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela)
{
	if (WARN_ON(!rela))
		return -EINVAL;

	*location = (*location & 0xffff0000) |
		    ((((long long)v + 0x800080008000LL) >> 48) & 0xffff);

	return 0;
}

/**
 * reloc_handler() - Apply a particular relocation to a module
 * @type: type of the relocation to apply
 * @me: the module to apply the reloc to
 * @location: the address at which the reloc is to be applied
 * @base: the existing value at location for REL-style; 0 for RELA-style
 * @v: the value of the reloc, with addend for RELA-style
 * @rela: indication of is this a RELA (true) or REL (false) relocation
 *
 * Each implemented relocation function applies a particular type of
 * relocation to the module @me. Relocs that may be found in either REL or RELA
 * variants can be handled by making use of the @base & @v parameters which are
 * set to values which abstract the difference away from the particular reloc
 * implementations.
 *
 * Return: 0 upon success, else -ERRNO
 */
static int reloc_handler(u32 type, struct module *me, u32 *location, u32 base,
			 Elf_Addr v, bool rela)
{
	switch (type) {
	case R_MIPS_NONE:
		break;
	case R_MIPS_32:
		apply_r_mips_32(location, base, v);
		break;
	case R_MIPS_26:
		return apply_r_mips_26(me, location, base, v);
	case R_MIPS_HI16:
		return apply_r_mips_hi16(me, location, v, rela);
	case R_MIPS_LO16:
		return apply_r_mips_lo16(me, location, base, v, rela);
	case R_MIPS_PC16:
		return apply_r_mips_pc16(me, location, base, v);
	case R_MIPS_PC21_S2:
		return apply_r_mips_pc21(me, location, base, v);
	case R_MIPS_PC26_S2:
		return apply_r_mips_pc26(me, location, base, v);
	case R_MIPS_64:
		return apply_r_mips_64(location, v, rela);
	case R_MIPS_HIGHER:
		return apply_r_mips_higher(location, v, rela);
	case R_MIPS_HIGHEST:
		return apply_r_mips_highest(location, v, rela);
	default:
		pr_err("%s: Unknown relocation type %u\n", me->name, type);
		return -EINVAL;
	}

	return 0;
}

static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
			    unsigned int symindex, unsigned int relsec,
			    struct module *me, bool rela)
{
	union {
		Elf_Mips_Rel *rel;
		Elf_Mips_Rela *rela;
	} r;
	Elf_Sym *sym;
	u32 *location, base;
	unsigned int i, type;
	Elf_Addr v;
	int err = 0;
	size_t reloc_sz;

	pr_debug("Applying relocate section %u to %u\n", relsec,
	       sechdrs[relsec].sh_info);

	r.rel = (void *)sechdrs[relsec].sh_addr;
	reloc_sz = rela ? sizeof(*r.rela) : sizeof(*r.rel);
	me->arch.r_mips_hi16_list = NULL;
	for (i = 0; i < sechdrs[relsec].sh_size / reloc_sz; i++) {
		/* This is where to make the change */
		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
			+ r.rel->r_offset;
		/* This is the symbol it is referring to */
		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
			+ ELF_MIPS_R_SYM(*r.rel);
		if (sym->st_value >= -MAX_ERRNO) {
			/* Ignore unresolved weak symbol */
			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
				continue;
			pr_warn("%s: Unknown symbol %s\n",
				me->name, strtab + sym->st_name);
			err = -ENOENT;
			goto out;
		}

		type = ELF_MIPS_R_TYPE(*r.rel);

		if (rela) {
			v = sym->st_value + r.rela->r_addend;
			base = 0;
			r.rela = &r.rela[1];
		} else {
			v = sym->st_value;
			base = *location;
			r.rel = &r.rel[1];
		}

		err = reloc_handler(type, me, location, base, v, rela);
		if (err)
			goto out;
	}

out:
	/*
	 * Normally the hi16 list should be deallocated at this point. A
	 * malformed binary however could contain a series of R_MIPS_HI16
	 * relocations not followed by a R_MIPS_LO16 relocation, or if we hit
	 * an error processing a reloc we might have gotten here before
	 * reaching the R_MIPS_LO16. In either case, free up the list and
	 * return an error.
	 */
	if (me->arch.r_mips_hi16_list) {
		free_relocation_chain(me->arch.r_mips_hi16_list);
		me->arch.r_mips_hi16_list = NULL;
		err = err ?: -ENOEXEC;
	}

	return err;
}

int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
		   unsigned int symindex, unsigned int relsec,
		   struct module *me)
{
	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, false);
}

#ifdef CONFIG_MODULES_USE_ELF_RELA
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
		       unsigned int symindex, unsigned int relsec,
		       struct module *me)
{
	return __apply_relocate(sechdrs, strtab, symindex, relsec, me, true);
}
#endif /* CONFIG_MODULES_USE_ELF_RELA */

/* Given an address, look for it in the module exception tables. */
const struct exception_table_entry *search_module_dbetables(unsigned long addr)
{
	unsigned long flags;
	const struct exception_table_entry *e = NULL;
	struct mod_arch_specific *dbe;

	spin_lock_irqsave(&dbe_lock, flags);
	list_for_each_entry(dbe, &dbe_list, dbe_list) {
		e = search_extable(dbe->dbe_start,
				   dbe->dbe_end - dbe->dbe_start, addr);
		if (e)
			break;
	}
	spin_unlock_irqrestore(&dbe_lock, flags);

	/* Now, if we found one, we are running inside it now, hence
	   we cannot unload the module, hence no refcnt needed. */
	return e;
}

/* Put in dbe list if necessary. */
int module_finalize(const Elf_Ehdr *hdr,
		    const Elf_Shdr *sechdrs,
		    struct module *me)
{
	const Elf_Shdr *s;
	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

	if (IS_ENABLED(CONFIG_JUMP_LABEL))
		jump_label_apply_nops(me);

	INIT_LIST_HEAD(&me->arch.dbe_list);
	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
		if (strcmp("__dbe_table", secstrings + s->sh_name) != 0)
			continue;
		me->arch.dbe_start = (void *)s->sh_addr;
		me->arch.dbe_end = (void *)s->sh_addr + s->sh_size;
		spin_lock_irq(&dbe_lock);
		list_add(&me->arch.dbe_list, &dbe_list);
		spin_unlock_irq(&dbe_lock);
	}
	return 0;
}

void module_arch_cleanup(struct module *mod)
{
	spin_lock_irq(&dbe_lock);
	list_del(&mod->arch.dbe_list);
	spin_unlock_irq(&dbe_lock);
}