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