aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/kernel/module.c
blob: 084dc8896986f321247fc590b9f348cb47872eff (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
/*
 *  linux/arch/arm/kernel/module.c
 *
 *  Copyright (C) 2002 Russell King.
 *  Modified for nommu by Hyok S. Choi
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Module allocation method suggested by Andi Kleen.
 */
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/gfp.h>

#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/smp_plat.h>
#include <asm/unwind.h>

#ifdef CONFIG_XIP_KERNEL
/*
 * The XIP kernel text is mapped in the module area for modules and
 * some other stuff to work without any indirect relocations.
 * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
 * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
 */
#undef MODULES_VADDR
#define MODULES_VADDR	(((unsigned long)_etext + ~PMD_MASK) & PMD_MASK)
#endif

#ifdef CONFIG_MMU
void *module_alloc(unsigned long size)
{
	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
				GFP_KERNEL, PAGE_KERNEL_EXEC, -1,
				__builtin_return_address(0));
}
#endif

int
apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
	       unsigned int relindex, struct module *module)
{
	Elf32_Shdr *symsec = sechdrs + symindex;
	Elf32_Shdr *relsec = sechdrs + relindex;
	Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
	Elf32_Rel *rel = (void *)relsec->sh_addr;
	unsigned int i;

	for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
		unsigned long loc;
		Elf32_Sym *sym;
		const char *symname;
		s32 offset;
#ifdef CONFIG_THUMB2_KERNEL
		u32 upper, lower, sign, j1, j2;
#endif

		offset = ELF32_R_SYM(rel->r_info);
		if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
			pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
				module->name, relindex, i);
			return -ENOEXEC;
		}

		sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
		symname = strtab + sym->st_name;

		if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
			pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
			       module->name, relindex, i, symname,
			       rel->r_offset, dstsec->sh_size);
			return -ENOEXEC;
		}

		loc = dstsec->sh_addr + rel->r_offset;

		switch (ELF32_R_TYPE(rel->r_info)) {
		case R_ARM_NONE:
			/* ignore */
			break;

		case R_ARM_ABS32:
			*(u32 *)loc += sym->st_value;
			break;

		case R_ARM_PC24:
		case R_ARM_CALL:
		case R_ARM_JUMP24:
			offset = (*(u32 *)loc & 0x00ffffff) << 2;
			if (offset & 0x02000000)
				offset -= 0x04000000;

			offset += sym->st_value - loc;
			if (offset & 3 ||
			    offset <= (s32)0xfe000000 ||
			    offset >= (s32)0x02000000) {
				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
				       module->name, relindex, i, symname,
				       ELF32_R_TYPE(rel->r_info), loc,
				       sym->st_value);
				return -ENOEXEC;
			}

			offset >>= 2;

			*(u32 *)loc &= 0xff000000;
			*(u32 *)loc |= offset & 0x00ffffff;
			break;

	       case R_ARM_V4BX:
		       /* Preserve Rm and the condition code. Alter
			* other bits to re-code instruction as
			* MOV PC,Rm.
			*/
		       *(u32 *)loc &= 0xf000000f;
		       *(u32 *)loc |= 0x01a0f000;
		       break;

		case R_ARM_PREL31:
			offset = *(u32 *)loc + sym->st_value - loc;
			*(u32 *)loc = offset & 0x7fffffff;
			break;

		case R_ARM_MOVW_ABS_NC:
		case R_ARM_MOVT_ABS:
			offset = *(u32 *)loc;
			offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
			offset = (offset ^ 0x8000) - 0x8000;

			offset += sym->st_value;
			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
				offset >>= 16;

			*(u32 *)loc &= 0xfff0f000;
			*(u32 *)loc |= ((offset & 0xf000) << 4) |
					(offset & 0x0fff);
			break;

#ifdef CONFIG_THUMB2_KERNEL
		case R_ARM_THM_CALL:
		case R_ARM_THM_JUMP24:
			upper = *(u16 *)loc;
			lower = *(u16 *)(loc + 2);

			/*
			 * 25 bit signed address range (Thumb-2 BL and B.W
			 * instructions):
			 *   S:I1:I2:imm10:imm11:0
			 * where:
			 *   S     = upper[10]   = offset[24]
			 *   I1    = ~(J1 ^ S)   = offset[23]
			 *   I2    = ~(J2 ^ S)   = offset[22]
			 *   imm10 = upper[9:0]  = offset[21:12]
			 *   imm11 = lower[10:0] = offset[11:1]
			 *   J1    = lower[13]
			 *   J2    = lower[11]
			 */
			sign = (upper >> 10) & 1;
			j1 = (lower >> 13) & 1;
			j2 = (lower >> 11) & 1;
			offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
				((~(j2 ^ sign) & 1) << 22) |
				((upper & 0x03ff) << 12) |
				((lower & 0x07ff) << 1);
			if (offset & 0x01000000)
				offset -= 0x02000000;
			offset += sym->st_value - loc;

			/*
			 * For function symbols, only Thumb addresses are
			 * allowed (no interworking).
			 *
			 * For non-function symbols, the destination
			 * has no specific ARM/Thumb disposition, so
			 * the branch is resolved under the assumption
			 * that interworking is not required.
			 */
			if ((ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
				!(offset & 1)) ||
			    offset <= (s32)0xff000000 ||
			    offset >= (s32)0x01000000) {
				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
				       module->name, relindex, i, symname,
				       ELF32_R_TYPE(rel->r_info), loc,
				       sym->st_value);
				return -ENOEXEC;
			}

			sign = (offset >> 24) & 1;
			j1 = sign ^ (~(offset >> 23) & 1);
			j2 = sign ^ (~(offset >> 22) & 1);
			*(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
					    ((offset >> 12) & 0x03ff));
			*(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
						  (j1 << 13) | (j2 << 11) |
						  ((offset >> 1) & 0x07ff));
			break;

		case R_ARM_THM_MOVW_ABS_NC:
		case R_ARM_THM_MOVT_ABS:
			upper = *(u16 *)loc;
			lower = *(u16 *)(loc + 2);

			/*
			 * MOVT/MOVW instructions encoding in Thumb-2:
			 *
			 * i	= upper[10]
			 * imm4	= upper[3:0]
			 * imm3	= lower[14:12]
			 * imm8	= lower[7:0]
			 *
			 * imm16 = imm4:i:imm3:imm8
			 */
			offset = ((upper & 0x000f) << 12) |
				((upper & 0x0400) << 1) |
				((lower & 0x7000) >> 4) | (lower & 0x00ff);
			offset = (offset ^ 0x8000) - 0x8000;
			offset += sym->st_value;

			if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
				offset >>= 16;

			*(u16 *)loc = (u16)((upper & 0xfbf0) |
					    ((offset & 0xf000) >> 12) |
					    ((offset & 0x0800) >> 1));
			*(u16 *)(loc + 2) = (u16)((lower & 0x8f00) |
						  ((offset & 0x0700) << 4) |
						  (offset & 0x00ff));
			break;
#endif

		default:
			printk(KERN_ERR "%s: unknown relocation: %u\n",
			       module->name, ELF32_R_TYPE(rel->r_info));
			return -ENOEXEC;
		}
	}
	return 0;
}

struct mod_unwind_map {
	const Elf_Shdr *unw_sec;
	const Elf_Shdr *txt_sec;
};

static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
	const Elf_Shdr *sechdrs, const char *name)
{
	const Elf_Shdr *s, *se;
	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

	for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
		if (strcmp(name, secstrs + s->sh_name) == 0)
			return s;

	return NULL;
}

extern void fixup_pv_table(const void *, unsigned long);
extern void fixup_smp(const void *, unsigned long);

int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
		    struct module *mod)
{
	const Elf_Shdr *s = NULL;
#ifdef CONFIG_ARM_UNWIND
	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
	const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
	struct mod_unwind_map maps[ARM_SEC_MAX];
	int i;

	memset(maps, 0, sizeof(maps));

	for (s = sechdrs; s < sechdrs_end; s++) {
		const char *secname = secstrs + s->sh_name;

		if (!(s->sh_flags & SHF_ALLOC))
			continue;

		if (strcmp(".ARM.exidx.init.text", secname) == 0)
			maps[ARM_SEC_INIT].unw_sec = s;
		else if (strcmp(".ARM.exidx", secname) == 0)
			maps[ARM_SEC_CORE].unw_sec = s;
		else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
			maps[ARM_SEC_EXIT].unw_sec = s;
		else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
			maps[ARM_SEC_UNLIKELY].unw_sec = s;
		else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
			maps[ARM_SEC_HOT].unw_sec = s;
		else if (strcmp(".init.text", secname) == 0)
			maps[ARM_SEC_INIT].txt_sec = s;
		else if (strcmp(".text", secname) == 0)
			maps[ARM_SEC_CORE].txt_sec = s;
		else if (strcmp(".exit.text", secname) == 0)
			maps[ARM_SEC_EXIT].txt_sec = s;
		else if (strcmp(".text.unlikely", secname) == 0)
			maps[ARM_SEC_UNLIKELY].txt_sec = s;
		else if (strcmp(".text.hot", secname) == 0)
			maps[ARM_SEC_HOT].txt_sec = s;
	}

	for (i = 0; i < ARM_SEC_MAX; i++)
		if (maps[i].unw_sec && maps[i].txt_sec)
			mod->arch.unwind[i] =
				unwind_table_add(maps[i].unw_sec->sh_addr,
					         maps[i].unw_sec->sh_size,
					         maps[i].txt_sec->sh_addr,
					         maps[i].txt_sec->sh_size);
#endif
#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
	s = find_mod_section(hdr, sechdrs, ".pv_table");
	if (s)
		fixup_pv_table((void *)s->sh_addr, s->sh_size);
#endif
	s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
	if (s && !is_smp())
#ifdef CONFIG_SMP_ON_UP
		fixup_smp((void *)s->sh_addr, s->sh_size);
#else
		return -EINVAL;
#endif
	return 0;
}

void
module_arch_cleanup(struct module *mod)
{
#ifdef CONFIG_ARM_UNWIND
	int i;

	for (i = 0; i < ARM_SEC_MAX; i++)
		if (mod->arch.unwind[i])
			unwind_table_del(mod->arch.unwind[i]);
#endif
}