aboutsummaryrefslogtreecommitdiffstats
path: root/arch/alpha/kernel/module.c
blob: 026ba9af6d6ae3e70a9ea71f6af4c014620176c7 (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
/*  Kernel module help for Alpha.
    Copyright (C) 2002 Richard Henderson.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/moduleloader.h>
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/slab.h>

#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt...)
#endif

void *
module_alloc(unsigned long size)
{
	if (size == 0)
		return NULL;
	return vmalloc(size);
}

void
module_free(struct module *mod, void *module_region)
{
	vfree(module_region);
}

/* Allocate the GOT at the end of the core sections.  */

struct got_entry {
	struct got_entry *next;
	Elf64_Sxword r_addend;
	int got_offset;
};

static inline void
process_reloc_for_got(Elf64_Rela *rela,
		      struct got_entry *chains, Elf64_Xword *poffset)
{
	unsigned long r_sym = ELF64_R_SYM (rela->r_info);
	unsigned long r_type = ELF64_R_TYPE (rela->r_info);
	Elf64_Sxword r_addend = rela->r_addend;
	struct got_entry *g;

	if (r_type != R_ALPHA_LITERAL)
		return;

	for (g = chains + r_sym; g ; g = g->next)
		if (g->r_addend == r_addend) {
			if (g->got_offset == 0) {
				g->got_offset = *poffset;
				*poffset += 8;
			}
			goto found_entry;
		}

	g = kmalloc (sizeof (*g), GFP_KERNEL);
	g->next = chains[r_sym].next;
	g->r_addend = r_addend;
	g->got_offset = *poffset;
	*poffset += 8;
	chains[r_sym].next = g;

 found_entry:
	/* Trick: most of the ELF64_R_TYPE field is unused.  There are
	   42 valid relocation types, and a 32-bit field.  Co-opt the
	   bits above 256 to store the got offset for this reloc.  */
	rela->r_info |= g->got_offset << 8;
}

int
module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
			  char *secstrings, struct module *me)
{
	struct got_entry *chains;
	Elf64_Rela *rela;
	Elf64_Shdr *esechdrs, *symtab, *s, *got;
	unsigned long nsyms, nrela, i;

	esechdrs = sechdrs + hdr->e_shnum;
	symtab = got = NULL;

	/* Find out how large the symbol table is.  Allocate one got_entry
	   head per symbol.  Normally this will be enough, but not always.
	   We'll chain different offsets for the symbol down each head.  */
	for (s = sechdrs; s < esechdrs; ++s)
		if (s->sh_type == SHT_SYMTAB)
			symtab = s;
		else if (!strcmp(".got", secstrings + s->sh_name)) {
			got = s;
			me->arch.gotsecindex = s - sechdrs;
		}

	if (!symtab) {
		printk(KERN_ERR "module %s: no symbol table\n", me->name);
		return -ENOEXEC;
	}
	if (!got) {
		printk(KERN_ERR "module %s: no got section\n", me->name);
		return -ENOEXEC;
	}

	nsyms = symtab->sh_size / sizeof(Elf64_Sym);
	chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);

	got->sh_size = 0;
	got->sh_addralign = 8;
	got->sh_type = SHT_NOBITS;

	/* Examine all LITERAL relocations to find out what GOT entries
	   are required.  This sizes the GOT section as well.  */
	for (s = sechdrs; s < esechdrs; ++s)
		if (s->sh_type == SHT_RELA) {
			nrela = s->sh_size / sizeof(Elf64_Rela);
			rela = (void *)hdr + s->sh_offset;
			for (i = 0; i < nrela; ++i)
				process_reloc_for_got(rela+i, chains,
						      &got->sh_size);
		}

	/* Free the memory we allocated.  */
	for (i = 0; i < nsyms; ++i) {
		struct got_entry *g, *n;
		for (g = chains[i].next; g ; g = n) {
			n = g->next;
			kfree(g);
		}
	}
	kfree(chains);

	return 0;
}

int
apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex,
	       unsigned int relsec, struct module *me)
{
	printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name);
	return -ENOEXEC;
}

int
apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
		   unsigned int symindex, unsigned int relsec,
		   struct module *me)
{
	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
	unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
	Elf64_Sym *symtab, *sym;
	void *base, *location;
	unsigned long got, gp;

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

	base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
	symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;

	/* The small sections were sorted to the end of the segment.
	   The following should definitely cover them.  */
	gp = (u64)me->module_core + me->core_size - 0x8000;
	got = sechdrs[me->arch.gotsecindex].sh_addr;

	for (i = 0; i < n; i++) {
		unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
		unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
		unsigned long r_got_offset = r_type >> 8;
		unsigned long value, hi, lo;
		r_type &= 0xff;

		/* This is where to make the change.  */
		location = base + rela[i].r_offset;

		/* This is the symbol it is referring to.  Note that all
		   unresolved symbols have been resolved.  */
		sym = symtab + r_sym;
		value = sym->st_value + rela[i].r_addend;

		switch (r_type) {
		case R_ALPHA_NONE:
			break;
		case R_ALPHA_REFQUAD:
			/* BUG() can produce misaligned relocations. */
			((u32 *)location)[0] = value;
			((u32 *)location)[1] = value >> 32;
			break;
		case R_ALPHA_GPREL32:
			value -= gp;
			if ((int)value != value)
				goto reloc_overflow;
			*(u32 *)location = value;
			break;
		case R_ALPHA_LITERAL:
			hi = got + r_got_offset;
			lo = hi - gp;
			if ((short)lo != lo)
				goto reloc_overflow;
			*(u16 *)location = lo;
			*(u64 *)hi = value;
			break;
		case R_ALPHA_LITUSE:
			break;
		case R_ALPHA_GPDISP:
			value = gp - (u64)location;
			lo = (short)value;
			hi = (int)(value - lo);
			if (hi + lo != value)
				goto reloc_overflow;
			*(u16 *)location = hi >> 16;
			*(u16 *)(location + rela[i].r_addend) = lo;
			break;
		case R_ALPHA_BRSGP:
			/* BRSGP is only allowed to bind to local symbols.
			   If the section is undef, this means that the
			   value was resolved from somewhere else.  */
			if (sym->st_shndx == SHN_UNDEF)
				goto reloc_overflow;
			if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
			    STO_ALPHA_STD_GPLOAD)
				/* Omit the prologue. */
				value += 8;
			/* FALLTHRU */
		case R_ALPHA_BRADDR:
			value -= (u64)location + 4;
			if (value & 3)
				goto reloc_overflow;
			value = (long)value >> 2;
			if (value + (1<<21) >= 1<<22)
				goto reloc_overflow;
			value &= 0x1fffff;
			value |= *(u32 *)location & ~0x1fffff;
			*(u32 *)location = value;
			break;
		case R_ALPHA_HINT:
			break;
		case R_ALPHA_SREL32:
			value -= (u64)location;
			if ((int)value != value)
				goto reloc_overflow;
			*(u32 *)location = value;
			break;
		case R_ALPHA_SREL64:
			value -= (u64)location;
			*(u64 *)location = value;
			break;
		case R_ALPHA_GPRELHIGH:
			value = (long)(value - gp + 0x8000) >> 16;
			if ((short) value != value)
				goto reloc_overflow;
			*(u16 *)location = value;
			break;
		case R_ALPHA_GPRELLOW:
			value -= gp;
			*(u16 *)location = value;
			break;
		case R_ALPHA_GPREL16:
			value -= gp;
			if ((short) value != value)
				goto reloc_overflow;
			*(u16 *)location = value;
			break;
		default:
			printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
			       me->name, r_type);
			return -ENOEXEC;
		reloc_overflow:
			if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
			  printk(KERN_ERR
			         "module %s: Relocation (type %lu) overflow vs section %d\n",
			         me->name, r_type, sym->st_shndx);
			else
			  printk(KERN_ERR
			         "module %s: Relocation (type %lu) overflow vs %s\n",
			         me->name, r_type, strtab + sym->st_name);
			return -ENOEXEC;
		}
	}

	return 0;
}

int
module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
		struct module *me)
{
	return 0;
}

void
module_arch_cleanup(struct module *mod)
{
}