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1/* Kernel module help for PPC.
2 Copyright (C) 2001 Rusty Russell.
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
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/module.h>
22#include <linux/moduleloader.h>
23#include <linux/elf.h>
24#include <linux/vmalloc.h>
25#include <linux/fs.h>
26#include <linux/string.h>
27#include <linux/kernel.h>
28#include <linux/ftrace.h>
29#include <linux/cache.h>
30#include <linux/bug.h>
31#include <linux/sort.h>
32#include <asm/setup.h>
33
34/* Count how many different relocations (different symbol, different
35 addend) */
36static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
37{
38 unsigned int i, r_info, r_addend, _count_relocs;
39
40 _count_relocs = 0;
41 r_info = 0;
42 r_addend = 0;
43 for (i = 0; i < num; i++)
44 /* Only count 24-bit relocs, others don't need stubs */
45 if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
46 (r_info != ELF32_R_SYM(rela[i].r_info) ||
47 r_addend != rela[i].r_addend)) {
48 _count_relocs++;
49 r_info = ELF32_R_SYM(rela[i].r_info);
50 r_addend = rela[i].r_addend;
51 }
52
53#ifdef CONFIG_DYNAMIC_FTRACE
54 _count_relocs++; /* add one for ftrace_caller */
55#endif
56 return _count_relocs;
57}
58
59static int relacmp(const void *_x, const void *_y)
60{
61 const Elf32_Rela *x, *y;
62
63 y = (Elf32_Rela *)_x;
64 x = (Elf32_Rela *)_y;
65
66 /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
67 * make the comparison cheaper/faster. It won't affect the sorting or
68 * the counting algorithms' performance
69 */
70 if (x->r_info < y->r_info)
71 return -1;
72 else if (x->r_info > y->r_info)
73 return 1;
74 else if (x->r_addend < y->r_addend)
75 return -1;
76 else if (x->r_addend > y->r_addend)
77 return 1;
78 else
79 return 0;
80}
81
82static void relaswap(void *_x, void *_y, int size)
83{
84 uint32_t *x, *y, tmp;
85 int i;
86
87 y = (uint32_t *)_x;
88 x = (uint32_t *)_y;
89
90 for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) {
91 tmp = x[i];
92 x[i] = y[i];
93 y[i] = tmp;
94 }
95}
96
97/* Get the potential trampolines size required of the init and
98 non-init sections */
99static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
100 const Elf32_Shdr *sechdrs,
101 const char *secstrings,
102 int is_init)
103{
104 unsigned long ret = 0;
105 unsigned i;
106
107 /* Everything marked ALLOC (this includes the exported
108 symbols) */
109 for (i = 1; i < hdr->e_shnum; i++) {
110 /* If it's called *.init*, and we're not init, we're
111 not interested */
112 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != 0)
113 != is_init)
114 continue;
115
116 /* We don't want to look at debug sections. */
117 if (strstr(secstrings + sechdrs[i].sh_name, ".debug") != 0)
118 continue;
119
120 if (sechdrs[i].sh_type == SHT_RELA) {
121 pr_debug("Found relocations in section %u\n", i);
122 pr_debug("Ptr: %p. Number: %u\n",
123 (void *)hdr + sechdrs[i].sh_offset,
124 sechdrs[i].sh_size / sizeof(Elf32_Rela));
125
126 /* Sort the relocation information based on a symbol and
127 * addend key. This is a stable O(n*log n) complexity
128 * alogrithm but it will reduce the complexity of
129 * count_relocs() to linear complexity O(n)
130 */
131 sort((void *)hdr + sechdrs[i].sh_offset,
132 sechdrs[i].sh_size / sizeof(Elf32_Rela),
133 sizeof(Elf32_Rela), relacmp, relaswap);
134
135 ret += count_relocs((void *)hdr
136 + sechdrs[i].sh_offset,
137 sechdrs[i].sh_size
138 / sizeof(Elf32_Rela))
139 * sizeof(struct ppc_plt_entry);
140 }
141 }
142
143 return ret;
144}
145
146int module_frob_arch_sections(Elf32_Ehdr *hdr,
147 Elf32_Shdr *sechdrs,
148 char *secstrings,
149 struct module *me)
150{
151 unsigned int i;
152
153 /* Find .plt and .init.plt sections */
154 for (i = 0; i < hdr->e_shnum; i++) {
155 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
156 me->arch.init_plt_section = i;
157 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
158 me->arch.core_plt_section = i;
159 }
160 if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
161 pr_err("Module doesn't contain .plt or .init.plt sections.\n");
162 return -ENOEXEC;
163 }
164
165 /* Override their sizes */
166 sechdrs[me->arch.core_plt_section].sh_size
167 = get_plt_size(hdr, sechdrs, secstrings, 0);
168 sechdrs[me->arch.init_plt_section].sh_size
169 = get_plt_size(hdr, sechdrs, secstrings, 1);
170 return 0;
171}
172
173static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
174{
175 if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16)
176 && entry->jump[1] == 0x398c0000 + (val & 0xffff))
177 return 1;
178 return 0;
179}
180
181/* Set up a trampoline in the PLT to bounce us to the distant function */
182static uint32_t do_plt_call(void *location,
183 Elf32_Addr val,
184 const Elf32_Shdr *sechdrs,
185 struct module *mod)
186{
187 struct ppc_plt_entry *entry;
188
189 pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
190 /* Init, or core PLT? */
191 if (location >= mod->core_layout.base
192 && location < mod->core_layout.base + mod->core_layout.size)
193 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
194 else
195 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
196
197 /* Find this entry, or if that fails, the next avail. entry */
198 while (entry->jump[0]) {
199 if (entry_matches(entry, val)) return (uint32_t)entry;
200 entry++;
201 }
202
203 entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */
204 entry->jump[1] = 0x398c0000 + (val&0xffff); /* addi r12,r12,sym@l*/
205 entry->jump[2] = 0x7d8903a6; /* mtctr r12 */
206 entry->jump[3] = 0x4e800420; /* bctr */
207
208 pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
209 return (uint32_t)entry;
210}
211
212int apply_relocate_add(Elf32_Shdr *sechdrs,
213 const char *strtab,
214 unsigned int symindex,
215 unsigned int relsec,
216 struct module *module)
217{
218 unsigned int i;
219 Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
220 Elf32_Sym *sym;
221 uint32_t *location;
222 uint32_t value;
223
224 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
225 sechdrs[relsec].sh_info);
226 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
227 /* This is where to make the change */
228 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
229 + rela[i].r_offset;
230 /* This is the symbol it is referring to. Note that all
231 undefined symbols have been resolved. */
232 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
233 + ELF32_R_SYM(rela[i].r_info);
234 /* `Everything is relative'. */
235 value = sym->st_value + rela[i].r_addend;
236
237 switch (ELF32_R_TYPE(rela[i].r_info)) {
238 case R_PPC_ADDR32:
239 /* Simply set it */
240 *(uint32_t *)location = value;
241 break;
242
243 case R_PPC_ADDR16_LO:
244 /* Low half of the symbol */
245 *(uint16_t *)location = value;
246 break;
247
248 case R_PPC_ADDR16_HI:
249 /* Higher half of the symbol */
250 *(uint16_t *)location = (value >> 16);
251 break;
252
253 case R_PPC_ADDR16_HA:
254 /* Sign-adjusted lower 16 bits: PPC ELF ABI says:
255 (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
256 This is the same, only sane.
257 */
258 *(uint16_t *)location = (value + 0x8000) >> 16;
259 break;
260
261 case R_PPC_REL24:
262 if ((int)(value - (uint32_t)location) < -0x02000000
263 || (int)(value - (uint32_t)location) >= 0x02000000)
264 value = do_plt_call(location, value,
265 sechdrs, module);
266
267 /* Only replace bits 2 through 26 */
268 pr_debug("REL24 value = %08X. location = %08X\n",
269 value, (uint32_t)location);
270 pr_debug("Location before: %08X.\n",
271 *(uint32_t *)location);
272 *(uint32_t *)location
273 = (*(uint32_t *)location & ~0x03fffffc)
274 | ((value - (uint32_t)location)
275 & 0x03fffffc);
276 pr_debug("Location after: %08X.\n",
277 *(uint32_t *)location);
278 pr_debug("ie. jump to %08X+%08X = %08X\n",
279 *(uint32_t *)location & 0x03fffffc,
280 (uint32_t)location,
281 (*(uint32_t *)location & 0x03fffffc)
282 + (uint32_t)location);
283 break;
284
285 case R_PPC_REL32:
286 /* 32-bit relative jump. */
287 *(uint32_t *)location = value - (uint32_t)location;
288 break;
289
290 default:
291 pr_err("%s: unknown ADD relocation: %u\n",
292 module->name,
293 ELF32_R_TYPE(rela[i].r_info));
294 return -ENOEXEC;
295 }
296 }
297
298 return 0;
299}
300
301#ifdef CONFIG_DYNAMIC_FTRACE
302int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
303{
304 module->arch.tramp = do_plt_call(module->core_layout.base,
305 (unsigned long)ftrace_caller,
306 sechdrs, module);
307 if (!module->arch.tramp)
308 return -ENOENT;
309
310 return 0;
311}
312#endif
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Kernel module help for PPC.
3 Copyright (C) 2001 Rusty Russell.
4
5*/
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/module.h>
10#include <linux/moduleloader.h>
11#include <linux/elf.h>
12#include <linux/vmalloc.h>
13#include <linux/fs.h>
14#include <linux/string.h>
15#include <linux/kernel.h>
16#include <linux/ftrace.h>
17#include <linux/cache.h>
18#include <linux/bug.h>
19#include <linux/sort.h>
20#include <asm/setup.h>
21#include <asm/code-patching.h>
22
23/* Count how many different relocations (different symbol, different
24 addend) */
25static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
26{
27 unsigned int i, r_info, r_addend, _count_relocs;
28
29 _count_relocs = 0;
30 r_info = 0;
31 r_addend = 0;
32 for (i = 0; i < num; i++)
33 /* Only count 24-bit relocs, others don't need stubs */
34 if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
35 (r_info != ELF32_R_SYM(rela[i].r_info) ||
36 r_addend != rela[i].r_addend)) {
37 _count_relocs++;
38 r_info = ELF32_R_SYM(rela[i].r_info);
39 r_addend = rela[i].r_addend;
40 }
41
42#ifdef CONFIG_DYNAMIC_FTRACE
43 _count_relocs++; /* add one for ftrace_caller */
44#endif
45 return _count_relocs;
46}
47
48static int relacmp(const void *_x, const void *_y)
49{
50 const Elf32_Rela *x, *y;
51
52 y = (Elf32_Rela *)_x;
53 x = (Elf32_Rela *)_y;
54
55 /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
56 * make the comparison cheaper/faster. It won't affect the sorting or
57 * the counting algorithms' performance
58 */
59 if (x->r_info < y->r_info)
60 return -1;
61 else if (x->r_info > y->r_info)
62 return 1;
63 else if (x->r_addend < y->r_addend)
64 return -1;
65 else if (x->r_addend > y->r_addend)
66 return 1;
67 else
68 return 0;
69}
70
71/* Get the potential trampolines size required of the init and
72 non-init sections */
73static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
74 const Elf32_Shdr *sechdrs,
75 const char *secstrings,
76 int is_init)
77{
78 unsigned long ret = 0;
79 unsigned i;
80
81 /* Everything marked ALLOC (this includes the exported
82 symbols) */
83 for (i = 1; i < hdr->e_shnum; i++) {
84 /* If it's called *.init*, and we're not init, we're
85 not interested */
86 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL)
87 != is_init)
88 continue;
89
90 /* We don't want to look at debug sections. */
91 if (strstr(secstrings + sechdrs[i].sh_name, ".debug"))
92 continue;
93
94 if (sechdrs[i].sh_type == SHT_RELA) {
95 pr_debug("Found relocations in section %u\n", i);
96 pr_debug("Ptr: %p. Number: %u\n",
97 (void *)hdr + sechdrs[i].sh_offset,
98 sechdrs[i].sh_size / sizeof(Elf32_Rela));
99
100 /* Sort the relocation information based on a symbol and
101 * addend key. This is a stable O(n*log n) complexity
102 * algorithm but it will reduce the complexity of
103 * count_relocs() to linear complexity O(n)
104 */
105 sort((void *)hdr + sechdrs[i].sh_offset,
106 sechdrs[i].sh_size / sizeof(Elf32_Rela),
107 sizeof(Elf32_Rela), relacmp, NULL);
108
109 ret += count_relocs((void *)hdr
110 + sechdrs[i].sh_offset,
111 sechdrs[i].sh_size
112 / sizeof(Elf32_Rela))
113 * sizeof(struct ppc_plt_entry);
114 }
115 }
116
117 return ret;
118}
119
120int module_frob_arch_sections(Elf32_Ehdr *hdr,
121 Elf32_Shdr *sechdrs,
122 char *secstrings,
123 struct module *me)
124{
125 unsigned int i;
126
127 /* Find .plt and .init.plt sections */
128 for (i = 0; i < hdr->e_shnum; i++) {
129 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
130 me->arch.init_plt_section = i;
131 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
132 me->arch.core_plt_section = i;
133 }
134 if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
135 pr_err("Module doesn't contain .plt or .init.plt sections.\n");
136 return -ENOEXEC;
137 }
138
139 /* Override their sizes */
140 sechdrs[me->arch.core_plt_section].sh_size
141 = get_plt_size(hdr, sechdrs, secstrings, 0);
142 sechdrs[me->arch.init_plt_section].sh_size
143 = get_plt_size(hdr, sechdrs, secstrings, 1);
144 return 0;
145}
146
147static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
148{
149 if (entry->jump[0] != PPC_RAW_LIS(_R12, PPC_HA(val)))
150 return 0;
151 if (entry->jump[1] != PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))
152 return 0;
153 return 1;
154}
155
156/* Set up a trampoline in the PLT to bounce us to the distant function */
157static uint32_t do_plt_call(void *location,
158 Elf32_Addr val,
159 const Elf32_Shdr *sechdrs,
160 struct module *mod)
161{
162 struct ppc_plt_entry *entry;
163
164 pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
165 /* Init, or core PLT? */
166 if (within_module_core((unsigned long)location, mod))
167 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
168 else
169 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
170
171 /* Find this entry, or if that fails, the next avail. entry */
172 while (entry->jump[0]) {
173 if (entry_matches(entry, val)) return (uint32_t)entry;
174 entry++;
175 }
176
177 if (patch_instruction(&entry->jump[0], ppc_inst(PPC_RAW_LIS(_R12, PPC_HA(val)))))
178 return 0;
179 if (patch_instruction(&entry->jump[1], ppc_inst(PPC_RAW_ADDI(_R12, _R12, PPC_LO(val)))))
180 return 0;
181 if (patch_instruction(&entry->jump[2], ppc_inst(PPC_RAW_MTCTR(_R12))))
182 return 0;
183 if (patch_instruction(&entry->jump[3], ppc_inst(PPC_RAW_BCTR())))
184 return 0;
185
186 pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
187 return (uint32_t)entry;
188}
189
190static int patch_location_16(uint32_t *loc, u16 value)
191{
192 loc = PTR_ALIGN_DOWN(loc, sizeof(u32));
193 return patch_instruction(loc, ppc_inst((*loc & 0xffff0000) | value));
194}
195
196int apply_relocate_add(Elf32_Shdr *sechdrs,
197 const char *strtab,
198 unsigned int symindex,
199 unsigned int relsec,
200 struct module *module)
201{
202 unsigned int i;
203 Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
204 Elf32_Sym *sym;
205 uint32_t *location;
206 uint32_t value;
207
208 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
209 sechdrs[relsec].sh_info);
210 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
211 /* This is where to make the change */
212 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
213 + rela[i].r_offset;
214 /* This is the symbol it is referring to. Note that all
215 undefined symbols have been resolved. */
216 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
217 + ELF32_R_SYM(rela[i].r_info);
218 /* `Everything is relative'. */
219 value = sym->st_value + rela[i].r_addend;
220
221 switch (ELF32_R_TYPE(rela[i].r_info)) {
222 case R_PPC_ADDR32:
223 /* Simply set it */
224 *(uint32_t *)location = value;
225 break;
226
227 case R_PPC_ADDR16_LO:
228 /* Low half of the symbol */
229 if (patch_location_16(location, PPC_LO(value)))
230 return -EFAULT;
231 break;
232
233 case R_PPC_ADDR16_HI:
234 /* Higher half of the symbol */
235 if (patch_location_16(location, PPC_HI(value)))
236 return -EFAULT;
237 break;
238
239 case R_PPC_ADDR16_HA:
240 if (patch_location_16(location, PPC_HA(value)))
241 return -EFAULT;
242 break;
243
244 case R_PPC_REL24:
245 if ((int)(value - (uint32_t)location) < -0x02000000
246 || (int)(value - (uint32_t)location) >= 0x02000000) {
247 value = do_plt_call(location, value,
248 sechdrs, module);
249 if (!value)
250 return -EFAULT;
251 }
252
253 /* Only replace bits 2 through 26 */
254 pr_debug("REL24 value = %08X. location = %08X\n",
255 value, (uint32_t)location);
256 pr_debug("Location before: %08X.\n",
257 *(uint32_t *)location);
258 value = (*(uint32_t *)location & ~PPC_LI_MASK) |
259 PPC_LI(value - (uint32_t)location);
260
261 if (patch_instruction(location, ppc_inst(value)))
262 return -EFAULT;
263
264 pr_debug("Location after: %08X.\n",
265 *(uint32_t *)location);
266 pr_debug("ie. jump to %08X+%08X = %08X\n",
267 *(uint32_t *)PPC_LI((uint32_t)location), (uint32_t)location,
268 (*(uint32_t *)PPC_LI((uint32_t)location)) + (uint32_t)location);
269 break;
270
271 case R_PPC_REL32:
272 /* 32-bit relative jump. */
273 *(uint32_t *)location = value - (uint32_t)location;
274 break;
275
276 default:
277 pr_err("%s: unknown ADD relocation: %u\n",
278 module->name,
279 ELF32_R_TYPE(rela[i].r_info));
280 return -ENOEXEC;
281 }
282 }
283
284 return 0;
285}
286
287#ifdef CONFIG_DYNAMIC_FTRACE
288notrace int module_trampoline_target(struct module *mod, unsigned long addr,
289 unsigned long *target)
290{
291 ppc_inst_t jmp[4];
292
293 /* Find where the trampoline jumps to */
294 if (copy_inst_from_kernel_nofault(jmp, (void *)addr))
295 return -EFAULT;
296 if (__copy_inst_from_kernel_nofault(jmp + 1, (void *)addr + 4))
297 return -EFAULT;
298 if (__copy_inst_from_kernel_nofault(jmp + 2, (void *)addr + 8))
299 return -EFAULT;
300 if (__copy_inst_from_kernel_nofault(jmp + 3, (void *)addr + 12))
301 return -EFAULT;
302
303 /* verify that this is what we expect it to be */
304 if ((ppc_inst_val(jmp[0]) & 0xffff0000) != PPC_RAW_LIS(_R12, 0))
305 return -EINVAL;
306 if ((ppc_inst_val(jmp[1]) & 0xffff0000) != PPC_RAW_ADDI(_R12, _R12, 0))
307 return -EINVAL;
308 if (ppc_inst_val(jmp[2]) != PPC_RAW_MTCTR(_R12))
309 return -EINVAL;
310 if (ppc_inst_val(jmp[3]) != PPC_RAW_BCTR())
311 return -EINVAL;
312
313 addr = (ppc_inst_val(jmp[1]) & 0xffff) | ((ppc_inst_val(jmp[0]) & 0xffff) << 16);
314 if (addr & 0x8000)
315 addr -= 0x10000;
316
317 *target = addr;
318
319 return 0;
320}
321
322int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
323{
324 module->arch.tramp = do_plt_call(module->mem[MOD_TEXT].base,
325 (unsigned long)ftrace_caller,
326 sechdrs, module);
327 if (!module->arch.tramp)
328 return -ENOENT;
329
330#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
331 module->arch.tramp_regs = do_plt_call(module->mem[MOD_TEXT].base,
332 (unsigned long)ftrace_regs_caller,
333 sechdrs, module);
334 if (!module->arch.tramp_regs)
335 return -ENOENT;
336#endif
337
338 return 0;
339}
340#endif