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1/* Kernel module help for Alpha.
2 Copyright (C) 2002 Richard Henderson.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17*/
18#include <linux/moduleloader.h>
19#include <linux/elf.h>
20#include <linux/vmalloc.h>
21#include <linux/fs.h>
22#include <linux/string.h>
23#include <linux/kernel.h>
24#include <linux/slab.h>
25
26#if 0
27#define DEBUGP printk
28#else
29#define DEBUGP(fmt...)
30#endif
31
32/* Allocate the GOT at the end of the core sections. */
33
34struct got_entry {
35 struct got_entry *next;
36 Elf64_Sxword r_addend;
37 int got_offset;
38};
39
40static inline void
41process_reloc_for_got(Elf64_Rela *rela,
42 struct got_entry *chains, Elf64_Xword *poffset)
43{
44 unsigned long r_sym = ELF64_R_SYM (rela->r_info);
45 unsigned long r_type = ELF64_R_TYPE (rela->r_info);
46 Elf64_Sxword r_addend = rela->r_addend;
47 struct got_entry *g;
48
49 if (r_type != R_ALPHA_LITERAL)
50 return;
51
52 for (g = chains + r_sym; g ; g = g->next)
53 if (g->r_addend == r_addend) {
54 if (g->got_offset == 0) {
55 g->got_offset = *poffset;
56 *poffset += 8;
57 }
58 goto found_entry;
59 }
60
61 g = kmalloc (sizeof (*g), GFP_KERNEL);
62 g->next = chains[r_sym].next;
63 g->r_addend = r_addend;
64 g->got_offset = *poffset;
65 *poffset += 8;
66 chains[r_sym].next = g;
67
68 found_entry:
69 /* Trick: most of the ELF64_R_TYPE field is unused. There are
70 42 valid relocation types, and a 32-bit field. Co-opt the
71 bits above 256 to store the got offset for this reloc. */
72 rela->r_info |= g->got_offset << 8;
73}
74
75int
76module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
77 char *secstrings, struct module *me)
78{
79 struct got_entry *chains;
80 Elf64_Rela *rela;
81 Elf64_Shdr *esechdrs, *symtab, *s, *got;
82 unsigned long nsyms, nrela, i;
83
84 esechdrs = sechdrs + hdr->e_shnum;
85 symtab = got = NULL;
86
87 /* Find out how large the symbol table is. Allocate one got_entry
88 head per symbol. Normally this will be enough, but not always.
89 We'll chain different offsets for the symbol down each head. */
90 for (s = sechdrs; s < esechdrs; ++s)
91 if (s->sh_type == SHT_SYMTAB)
92 symtab = s;
93 else if (!strcmp(".got", secstrings + s->sh_name)) {
94 got = s;
95 me->arch.gotsecindex = s - sechdrs;
96 }
97
98 if (!symtab) {
99 printk(KERN_ERR "module %s: no symbol table\n", me->name);
100 return -ENOEXEC;
101 }
102 if (!got) {
103 printk(KERN_ERR "module %s: no got section\n", me->name);
104 return -ENOEXEC;
105 }
106
107 nsyms = symtab->sh_size / sizeof(Elf64_Sym);
108 chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);
109 if (!chains) {
110 printk(KERN_ERR
111 "module %s: no memory for symbol chain buffer\n",
112 me->name);
113 return -ENOMEM;
114 }
115
116 got->sh_size = 0;
117 got->sh_addralign = 8;
118 got->sh_type = SHT_NOBITS;
119
120 /* Examine all LITERAL relocations to find out what GOT entries
121 are required. This sizes the GOT section as well. */
122 for (s = sechdrs; s < esechdrs; ++s)
123 if (s->sh_type == SHT_RELA) {
124 nrela = s->sh_size / sizeof(Elf64_Rela);
125 rela = (void *)hdr + s->sh_offset;
126 for (i = 0; i < nrela; ++i)
127 process_reloc_for_got(rela+i, chains,
128 &got->sh_size);
129 }
130
131 /* Free the memory we allocated. */
132 for (i = 0; i < nsyms; ++i) {
133 struct got_entry *g, *n;
134 for (g = chains[i].next; g ; g = n) {
135 n = g->next;
136 kfree(g);
137 }
138 }
139 kfree(chains);
140
141 return 0;
142}
143
144int
145apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
146 unsigned int symindex, unsigned int relsec,
147 struct module *me)
148{
149 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
150 unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
151 Elf64_Sym *symtab, *sym;
152 void *base, *location;
153 unsigned long got, gp;
154
155 DEBUGP("Applying relocate section %u to %u\n", relsec,
156 sechdrs[relsec].sh_info);
157
158 base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
159 symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;
160
161 /* The small sections were sorted to the end of the segment.
162 The following should definitely cover them. */
163 gp = (u64)me->core_layout.base + me->core_layout.size - 0x8000;
164 got = sechdrs[me->arch.gotsecindex].sh_addr;
165
166 for (i = 0; i < n; i++) {
167 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
168 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
169 unsigned long r_got_offset = r_type >> 8;
170 unsigned long value, hi, lo;
171 r_type &= 0xff;
172
173 /* This is where to make the change. */
174 location = base + rela[i].r_offset;
175
176 /* This is the symbol it is referring to. Note that all
177 unresolved symbols have been resolved. */
178 sym = symtab + r_sym;
179 value = sym->st_value + rela[i].r_addend;
180
181 switch (r_type) {
182 case R_ALPHA_NONE:
183 break;
184 case R_ALPHA_REFLONG:
185 *(u32 *)location = value;
186 break;
187 case R_ALPHA_REFQUAD:
188 /* BUG() can produce misaligned relocations. */
189 ((u32 *)location)[0] = value;
190 ((u32 *)location)[1] = value >> 32;
191 break;
192 case R_ALPHA_GPREL32:
193 value -= gp;
194 if ((int)value != value)
195 goto reloc_overflow;
196 *(u32 *)location = value;
197 break;
198 case R_ALPHA_LITERAL:
199 hi = got + r_got_offset;
200 lo = hi - gp;
201 if ((short)lo != lo)
202 goto reloc_overflow;
203 *(u16 *)location = lo;
204 *(u64 *)hi = value;
205 break;
206 case R_ALPHA_LITUSE:
207 break;
208 case R_ALPHA_GPDISP:
209 value = gp - (u64)location;
210 lo = (short)value;
211 hi = (int)(value - lo);
212 if (hi + lo != value)
213 goto reloc_overflow;
214 *(u16 *)location = hi >> 16;
215 *(u16 *)(location + rela[i].r_addend) = lo;
216 break;
217 case R_ALPHA_BRSGP:
218 /* BRSGP is only allowed to bind to local symbols.
219 If the section is undef, this means that the
220 value was resolved from somewhere else. */
221 if (sym->st_shndx == SHN_UNDEF)
222 goto reloc_overflow;
223 if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
224 STO_ALPHA_STD_GPLOAD)
225 /* Omit the prologue. */
226 value += 8;
227 /* FALLTHRU */
228 case R_ALPHA_BRADDR:
229 value -= (u64)location + 4;
230 if (value & 3)
231 goto reloc_overflow;
232 value = (long)value >> 2;
233 if (value + (1<<21) >= 1<<22)
234 goto reloc_overflow;
235 value &= 0x1fffff;
236 value |= *(u32 *)location & ~0x1fffff;
237 *(u32 *)location = value;
238 break;
239 case R_ALPHA_HINT:
240 break;
241 case R_ALPHA_SREL32:
242 value -= (u64)location;
243 if ((int)value != value)
244 goto reloc_overflow;
245 *(u32 *)location = value;
246 break;
247 case R_ALPHA_SREL64:
248 value -= (u64)location;
249 *(u64 *)location = value;
250 break;
251 case R_ALPHA_GPRELHIGH:
252 value = (long)(value - gp + 0x8000) >> 16;
253 if ((short) value != value)
254 goto reloc_overflow;
255 *(u16 *)location = value;
256 break;
257 case R_ALPHA_GPRELLOW:
258 value -= gp;
259 *(u16 *)location = value;
260 break;
261 case R_ALPHA_GPREL16:
262 value -= gp;
263 if ((short) value != value)
264 goto reloc_overflow;
265 *(u16 *)location = value;
266 break;
267 default:
268 printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
269 me->name, r_type);
270 return -ENOEXEC;
271 reloc_overflow:
272 if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
273 printk(KERN_ERR
274 "module %s: Relocation (type %lu) overflow vs section %d\n",
275 me->name, r_type, sym->st_shndx);
276 else
277 printk(KERN_ERR
278 "module %s: Relocation (type %lu) overflow vs %s\n",
279 me->name, r_type, strtab + sym->st_name);
280 return -ENOEXEC;
281 }
282 }
283
284 return 0;
285}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Kernel module help for Alpha.
3 Copyright (C) 2002 Richard Henderson.
4
5*/
6#include <linux/moduleloader.h>
7#include <linux/elf.h>
8#include <linux/vmalloc.h>
9#include <linux/fs.h>
10#include <linux/string.h>
11#include <linux/kernel.h>
12#include <linux/slab.h>
13
14#if 0
15#define DEBUGP printk
16#else
17#define DEBUGP(fmt...)
18#endif
19
20/* Allocate the GOT at the end of the core sections. */
21
22struct got_entry {
23 struct got_entry *next;
24 Elf64_Sxword r_addend;
25 int got_offset;
26};
27
28static inline void
29process_reloc_for_got(Elf64_Rela *rela,
30 struct got_entry *chains, Elf64_Xword *poffset)
31{
32 unsigned long r_sym = ELF64_R_SYM (rela->r_info);
33 unsigned long r_type = ELF64_R_TYPE (rela->r_info);
34 Elf64_Sxword r_addend = rela->r_addend;
35 struct got_entry *g;
36
37 if (r_type != R_ALPHA_LITERAL)
38 return;
39
40 for (g = chains + r_sym; g ; g = g->next)
41 if (g->r_addend == r_addend) {
42 if (g->got_offset == 0) {
43 g->got_offset = *poffset;
44 *poffset += 8;
45 }
46 goto found_entry;
47 }
48
49 g = kmalloc (sizeof (*g), GFP_KERNEL);
50 g->next = chains[r_sym].next;
51 g->r_addend = r_addend;
52 g->got_offset = *poffset;
53 *poffset += 8;
54 chains[r_sym].next = g;
55
56 found_entry:
57 /* Trick: most of the ELF64_R_TYPE field is unused. There are
58 42 valid relocation types, and a 32-bit field. Co-opt the
59 bits above 256 to store the got offset for this reloc. */
60 rela->r_info |= g->got_offset << 8;
61}
62
63int
64module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs,
65 char *secstrings, struct module *me)
66{
67 struct got_entry *chains;
68 Elf64_Rela *rela;
69 Elf64_Shdr *esechdrs, *symtab, *s, *got;
70 unsigned long nsyms, nrela, i;
71
72 esechdrs = sechdrs + hdr->e_shnum;
73 symtab = got = NULL;
74
75 /* Find out how large the symbol table is. Allocate one got_entry
76 head per symbol. Normally this will be enough, but not always.
77 We'll chain different offsets for the symbol down each head. */
78 for (s = sechdrs; s < esechdrs; ++s)
79 if (s->sh_type == SHT_SYMTAB)
80 symtab = s;
81 else if (!strcmp(".got", secstrings + s->sh_name)) {
82 got = s;
83 me->arch.gotsecindex = s - sechdrs;
84 }
85
86 if (!symtab) {
87 printk(KERN_ERR "module %s: no symbol table\n", me->name);
88 return -ENOEXEC;
89 }
90 if (!got) {
91 printk(KERN_ERR "module %s: no got section\n", me->name);
92 return -ENOEXEC;
93 }
94
95 nsyms = symtab->sh_size / sizeof(Elf64_Sym);
96 chains = kcalloc(nsyms, sizeof(struct got_entry), GFP_KERNEL);
97 if (!chains) {
98 printk(KERN_ERR
99 "module %s: no memory for symbol chain buffer\n",
100 me->name);
101 return -ENOMEM;
102 }
103
104 got->sh_size = 0;
105 got->sh_addralign = 8;
106 got->sh_type = SHT_NOBITS;
107
108 /* Examine all LITERAL relocations to find out what GOT entries
109 are required. This sizes the GOT section as well. */
110 for (s = sechdrs; s < esechdrs; ++s)
111 if (s->sh_type == SHT_RELA) {
112 nrela = s->sh_size / sizeof(Elf64_Rela);
113 rela = (void *)hdr + s->sh_offset;
114 for (i = 0; i < nrela; ++i)
115 process_reloc_for_got(rela+i, chains,
116 &got->sh_size);
117 }
118
119 /* Free the memory we allocated. */
120 for (i = 0; i < nsyms; ++i) {
121 struct got_entry *g, *n;
122 for (g = chains[i].next; g ; g = n) {
123 n = g->next;
124 kfree(g);
125 }
126 }
127 kfree(chains);
128
129 return 0;
130}
131
132int
133apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab,
134 unsigned int symindex, unsigned int relsec,
135 struct module *me)
136{
137 Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
138 unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela);
139 Elf64_Sym *symtab, *sym;
140 void *base, *location;
141 unsigned long got, gp;
142
143 DEBUGP("Applying relocate section %u to %u\n", relsec,
144 sechdrs[relsec].sh_info);
145
146 base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr;
147 symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr;
148
149 /* The small sections were sorted to the end of the segment.
150 The following should definitely cover them. */
151 gp = (u64)me->core_layout.base + me->core_layout.size - 0x8000;
152 got = sechdrs[me->arch.gotsecindex].sh_addr;
153
154 for (i = 0; i < n; i++) {
155 unsigned long r_sym = ELF64_R_SYM (rela[i].r_info);
156 unsigned long r_type = ELF64_R_TYPE (rela[i].r_info);
157 unsigned long r_got_offset = r_type >> 8;
158 unsigned long value, hi, lo;
159 r_type &= 0xff;
160
161 /* This is where to make the change. */
162 location = base + rela[i].r_offset;
163
164 /* This is the symbol it is referring to. Note that all
165 unresolved symbols have been resolved. */
166 sym = symtab + r_sym;
167 value = sym->st_value + rela[i].r_addend;
168
169 switch (r_type) {
170 case R_ALPHA_NONE:
171 break;
172 case R_ALPHA_REFLONG:
173 *(u32 *)location = value;
174 break;
175 case R_ALPHA_REFQUAD:
176 /* BUG() can produce misaligned relocations. */
177 ((u32 *)location)[0] = value;
178 ((u32 *)location)[1] = value >> 32;
179 break;
180 case R_ALPHA_GPREL32:
181 value -= gp;
182 if ((int)value != value)
183 goto reloc_overflow;
184 *(u32 *)location = value;
185 break;
186 case R_ALPHA_LITERAL:
187 hi = got + r_got_offset;
188 lo = hi - gp;
189 if ((short)lo != lo)
190 goto reloc_overflow;
191 *(u16 *)location = lo;
192 *(u64 *)hi = value;
193 break;
194 case R_ALPHA_LITUSE:
195 break;
196 case R_ALPHA_GPDISP:
197 value = gp - (u64)location;
198 lo = (short)value;
199 hi = (int)(value - lo);
200 if (hi + lo != value)
201 goto reloc_overflow;
202 *(u16 *)location = hi >> 16;
203 *(u16 *)(location + rela[i].r_addend) = lo;
204 break;
205 case R_ALPHA_BRSGP:
206 /* BRSGP is only allowed to bind to local symbols.
207 If the section is undef, this means that the
208 value was resolved from somewhere else. */
209 if (sym->st_shndx == SHN_UNDEF)
210 goto reloc_overflow;
211 if ((sym->st_other & STO_ALPHA_STD_GPLOAD) ==
212 STO_ALPHA_STD_GPLOAD)
213 /* Omit the prologue. */
214 value += 8;
215 fallthrough;
216 case R_ALPHA_BRADDR:
217 value -= (u64)location + 4;
218 if (value & 3)
219 goto reloc_overflow;
220 value = (long)value >> 2;
221 if (value + (1<<21) >= 1<<22)
222 goto reloc_overflow;
223 value &= 0x1fffff;
224 value |= *(u32 *)location & ~0x1fffff;
225 *(u32 *)location = value;
226 break;
227 case R_ALPHA_HINT:
228 break;
229 case R_ALPHA_SREL32:
230 value -= (u64)location;
231 if ((int)value != value)
232 goto reloc_overflow;
233 *(u32 *)location = value;
234 break;
235 case R_ALPHA_SREL64:
236 value -= (u64)location;
237 *(u64 *)location = value;
238 break;
239 case R_ALPHA_GPRELHIGH:
240 value = (long)(value - gp + 0x8000) >> 16;
241 if ((short) value != value)
242 goto reloc_overflow;
243 *(u16 *)location = value;
244 break;
245 case R_ALPHA_GPRELLOW:
246 value -= gp;
247 *(u16 *)location = value;
248 break;
249 case R_ALPHA_GPREL16:
250 value -= gp;
251 if ((short) value != value)
252 goto reloc_overflow;
253 *(u16 *)location = value;
254 break;
255 default:
256 printk(KERN_ERR "module %s: Unknown relocation: %lu\n",
257 me->name, r_type);
258 return -ENOEXEC;
259 reloc_overflow:
260 if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION)
261 printk(KERN_ERR
262 "module %s: Relocation (type %lu) overflow vs section %d\n",
263 me->name, r_type, sym->st_shndx);
264 else
265 printk(KERN_ERR
266 "module %s: Relocation (type %lu) overflow vs %s\n",
267 me->name, r_type, strtab + sym->st_name);
268 return -ENOEXEC;
269 }
270 }
271
272 return 0;
273}