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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// 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
22/* Count how many different relocations (different symbol, different
23 addend) */
24static unsigned int count_relocs(const Elf32_Rela *rela, unsigned int num)
25{
26 unsigned int i, r_info, r_addend, _count_relocs;
27
28 _count_relocs = 0;
29 r_info = 0;
30 r_addend = 0;
31 for (i = 0; i < num; i++)
32 /* Only count 24-bit relocs, others don't need stubs */
33 if (ELF32_R_TYPE(rela[i].r_info) == R_PPC_REL24 &&
34 (r_info != ELF32_R_SYM(rela[i].r_info) ||
35 r_addend != rela[i].r_addend)) {
36 _count_relocs++;
37 r_info = ELF32_R_SYM(rela[i].r_info);
38 r_addend = rela[i].r_addend;
39 }
40
41#ifdef CONFIG_DYNAMIC_FTRACE
42 _count_relocs++; /* add one for ftrace_caller */
43#endif
44 return _count_relocs;
45}
46
47static int relacmp(const void *_x, const void *_y)
48{
49 const Elf32_Rela *x, *y;
50
51 y = (Elf32_Rela *)_x;
52 x = (Elf32_Rela *)_y;
53
54 /* Compare the entire r_info (as opposed to ELF32_R_SYM(r_info) only) to
55 * make the comparison cheaper/faster. It won't affect the sorting or
56 * the counting algorithms' performance
57 */
58 if (x->r_info < y->r_info)
59 return -1;
60 else if (x->r_info > y->r_info)
61 return 1;
62 else if (x->r_addend < y->r_addend)
63 return -1;
64 else if (x->r_addend > y->r_addend)
65 return 1;
66 else
67 return 0;
68}
69
70static void relaswap(void *_x, void *_y, int size)
71{
72 uint32_t *x, *y, tmp;
73 int i;
74
75 y = (uint32_t *)_x;
76 x = (uint32_t *)_y;
77
78 for (i = 0; i < sizeof(Elf32_Rela) / sizeof(uint32_t); i++) {
79 tmp = x[i];
80 x[i] = y[i];
81 y[i] = tmp;
82 }
83}
84
85/* Get the potential trampolines size required of the init and
86 non-init sections */
87static unsigned long get_plt_size(const Elf32_Ehdr *hdr,
88 const Elf32_Shdr *sechdrs,
89 const char *secstrings,
90 int is_init)
91{
92 unsigned long ret = 0;
93 unsigned i;
94
95 /* Everything marked ALLOC (this includes the exported
96 symbols) */
97 for (i = 1; i < hdr->e_shnum; i++) {
98 /* If it's called *.init*, and we're not init, we're
99 not interested */
100 if ((strstr(secstrings + sechdrs[i].sh_name, ".init") != NULL)
101 != is_init)
102 continue;
103
104 /* We don't want to look at debug sections. */
105 if (strstr(secstrings + sechdrs[i].sh_name, ".debug"))
106 continue;
107
108 if (sechdrs[i].sh_type == SHT_RELA) {
109 pr_debug("Found relocations in section %u\n", i);
110 pr_debug("Ptr: %p. Number: %u\n",
111 (void *)hdr + sechdrs[i].sh_offset,
112 sechdrs[i].sh_size / sizeof(Elf32_Rela));
113
114 /* Sort the relocation information based on a symbol and
115 * addend key. This is a stable O(n*log n) complexity
116 * alogrithm but it will reduce the complexity of
117 * count_relocs() to linear complexity O(n)
118 */
119 sort((void *)hdr + sechdrs[i].sh_offset,
120 sechdrs[i].sh_size / sizeof(Elf32_Rela),
121 sizeof(Elf32_Rela), relacmp, relaswap);
122
123 ret += count_relocs((void *)hdr
124 + sechdrs[i].sh_offset,
125 sechdrs[i].sh_size
126 / sizeof(Elf32_Rela))
127 * sizeof(struct ppc_plt_entry);
128 }
129 }
130
131 return ret;
132}
133
134int module_frob_arch_sections(Elf32_Ehdr *hdr,
135 Elf32_Shdr *sechdrs,
136 char *secstrings,
137 struct module *me)
138{
139 unsigned int i;
140
141 /* Find .plt and .init.plt sections */
142 for (i = 0; i < hdr->e_shnum; i++) {
143 if (strcmp(secstrings + sechdrs[i].sh_name, ".init.plt") == 0)
144 me->arch.init_plt_section = i;
145 else if (strcmp(secstrings + sechdrs[i].sh_name, ".plt") == 0)
146 me->arch.core_plt_section = i;
147 }
148 if (!me->arch.core_plt_section || !me->arch.init_plt_section) {
149 pr_err("Module doesn't contain .plt or .init.plt sections.\n");
150 return -ENOEXEC;
151 }
152
153 /* Override their sizes */
154 sechdrs[me->arch.core_plt_section].sh_size
155 = get_plt_size(hdr, sechdrs, secstrings, 0);
156 sechdrs[me->arch.init_plt_section].sh_size
157 = get_plt_size(hdr, sechdrs, secstrings, 1);
158 return 0;
159}
160
161static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
162{
163 if (entry->jump[0] != (PPC_INST_ADDIS | __PPC_RT(R12) | PPC_HA(val)))
164 return 0;
165 if (entry->jump[1] != (PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12) |
166 PPC_LO(val)))
167 return 0;
168 return 1;
169}
170
171/* Set up a trampoline in the PLT to bounce us to the distant function */
172static uint32_t do_plt_call(void *location,
173 Elf32_Addr val,
174 const Elf32_Shdr *sechdrs,
175 struct module *mod)
176{
177 struct ppc_plt_entry *entry;
178
179 pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
180 /* Init, or core PLT? */
181 if (location >= mod->core_layout.base
182 && location < mod->core_layout.base + mod->core_layout.size)
183 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
184 else
185 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
186
187 /* Find this entry, or if that fails, the next avail. entry */
188 while (entry->jump[0]) {
189 if (entry_matches(entry, val)) return (uint32_t)entry;
190 entry++;
191 }
192
193 /*
194 * lis r12, sym@ha
195 * addi r12, r12, sym@l
196 * mtctr r12
197 * bctr
198 */
199 entry->jump[0] = PPC_INST_ADDIS | __PPC_RT(R12) | PPC_HA(val);
200 entry->jump[1] = PPC_INST_ADDI | __PPC_RT(R12) | __PPC_RA(R12) | PPC_LO(val);
201 entry->jump[2] = PPC_INST_MTCTR | __PPC_RS(R12);
202 entry->jump[3] = PPC_INST_BCTR;
203
204 pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
205 return (uint32_t)entry;
206}
207
208int apply_relocate_add(Elf32_Shdr *sechdrs,
209 const char *strtab,
210 unsigned int symindex,
211 unsigned int relsec,
212 struct module *module)
213{
214 unsigned int i;
215 Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
216 Elf32_Sym *sym;
217 uint32_t *location;
218 uint32_t value;
219
220 pr_debug("Applying ADD relocate section %u to %u\n", relsec,
221 sechdrs[relsec].sh_info);
222 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
223 /* This is where to make the change */
224 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
225 + rela[i].r_offset;
226 /* This is the symbol it is referring to. Note that all
227 undefined symbols have been resolved. */
228 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
229 + ELF32_R_SYM(rela[i].r_info);
230 /* `Everything is relative'. */
231 value = sym->st_value + rela[i].r_addend;
232
233 switch (ELF32_R_TYPE(rela[i].r_info)) {
234 case R_PPC_ADDR32:
235 /* Simply set it */
236 *(uint32_t *)location = value;
237 break;
238
239 case R_PPC_ADDR16_LO:
240 /* Low half of the symbol */
241 *(uint16_t *)location = value;
242 break;
243
244 case R_PPC_ADDR16_HI:
245 /* Higher half of the symbol */
246 *(uint16_t *)location = (value >> 16);
247 break;
248
249 case R_PPC_ADDR16_HA:
250 /* Sign-adjusted lower 16 bits: PPC ELF ABI says:
251 (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
252 This is the same, only sane.
253 */
254 *(uint16_t *)location = (value + 0x8000) >> 16;
255 break;
256
257 case R_PPC_REL24:
258 if ((int)(value - (uint32_t)location) < -0x02000000
259 || (int)(value - (uint32_t)location) >= 0x02000000)
260 value = do_plt_call(location, value,
261 sechdrs, module);
262
263 /* Only replace bits 2 through 26 */
264 pr_debug("REL24 value = %08X. location = %08X\n",
265 value, (uint32_t)location);
266 pr_debug("Location before: %08X.\n",
267 *(uint32_t *)location);
268 *(uint32_t *)location
269 = (*(uint32_t *)location & ~0x03fffffc)
270 | ((value - (uint32_t)location)
271 & 0x03fffffc);
272 pr_debug("Location after: %08X.\n",
273 *(uint32_t *)location);
274 pr_debug("ie. jump to %08X+%08X = %08X\n",
275 *(uint32_t *)location & 0x03fffffc,
276 (uint32_t)location,
277 (*(uint32_t *)location & 0x03fffffc)
278 + (uint32_t)location);
279 break;
280
281 case R_PPC_REL32:
282 /* 32-bit relative jump. */
283 *(uint32_t *)location = value - (uint32_t)location;
284 break;
285
286 default:
287 pr_err("%s: unknown ADD relocation: %u\n",
288 module->name,
289 ELF32_R_TYPE(rela[i].r_info));
290 return -ENOEXEC;
291 }
292 }
293
294 return 0;
295}
296
297#ifdef CONFIG_DYNAMIC_FTRACE
298int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
299{
300 module->arch.tramp = do_plt_call(module->core_layout.base,
301 (unsigned long)ftrace_caller,
302 sechdrs, module);
303 if (!module->arch.tramp)
304 return -ENOENT;
305
306 return 0;
307}
308#endif