1 // SPDX-License-Identifier: GPL-2.0-or-later 1
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 (diffe
24 addend) */
25 static unsigned int count_relocs(const Elf32_R
26 {
27 unsigned int i, r_info, r_addend, _cou
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, o
34 if (ELF32_R_TYPE(rela[i].r_inf
35 (r_info != ELF32_R_SYM(rel
36 r_addend != rela[i].r_add
37 _count_relocs++;
38 r_info = ELF32_R_SYM(r
39 r_addend = rela[i].r_a
40 }
41
42 #ifdef CONFIG_DYNAMIC_FTRACE
43 _count_relocs++; /* add one for
44 #endif
45 return _count_relocs;
46 }
47
48 static int relacmp(const void *_x, const void
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 oppos
56 * make the comparison cheaper/faster.
57 * the counting algorithms' performanc
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
72 non-init sections */
73 static unsigned long get_plt_size(const Elf32_
74 const Elf32_
75 const char *
76 int is_init)
77 {
78 unsigned long ret = 0;
79 unsigned i;
80
81 /* Everything marked ALLOC (this inclu
82 symbols) */
83 for (i = 1; i < hdr->e_shnum; i++) {
84 /* If it's called *.init*, and
85 not interested */
86 if ((strstr(secstrings + sechd
87 != is_init)
88 continue;
89
90 /* We don't want to look at de
91 if (strstr(secstrings + sechdr
92 continue;
93
94 if (sechdrs[i].sh_type == SHT_
95 pr_debug("Found reloca
96 pr_debug("Ptr: %p. Nu
97 (void *)hdr + s
98 sechdrs[i].sh_s
99
100 /* Sort the relocation
101 * addend key. This is
102 * algorithm but it wi
103 * count_relocs() to l
104 */
105 sort((void *)hdr + sec
106 sechdrs[i].sh_siz
107 sizeof(Elf32_Rela
108
109 ret += count_relocs((v
110 +
111 s
112 /
113 * sizeof(struc
114 }
115 }
116
117 return ret;
118 }
119
120 int module_frob_arch_sections(Elf32_Ehdr *hdr,
121 Elf32_Shdr *sech
122 char *secstrings
123 struct module *m
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 + sechdr
130 me->arch.init_plt_sect
131 else if (strcmp(secstrings + s
132 me->arch.core_plt_sect
133 }
134 if (!me->arch.core_plt_section || !me-
135 pr_err("Module doesn't contain
136 return -ENOEXEC;
137 }
138
139 /* Override their sizes */
140 sechdrs[me->arch.core_plt_section].sh_
141 = get_plt_size(hdr, sechdrs, s
142 sechdrs[me->arch.init_plt_section].sh_
143 = get_plt_size(hdr, sechdrs, s
144 return 0;
145 }
146
147 static inline int entry_matches(struct ppc_plt
148 {
149 if (entry->jump[0] != PPC_RAW_LIS(_R12
150 return 0;
151 if (entry->jump[1] != PPC_RAW_ADDI(_R1
152 return 0;
153 return 1;
154 }
155
156 /* Set up a trampoline in the PLT to bounce us
157 static uint32_t do_plt_call(void *location,
158 Elf32_Addr val,
159 const Elf32_Shdr *
160 struct module *mod
161 {
162 struct ppc_plt_entry *entry;
163
164 pr_debug("Doing plt for call to 0x%x a
165 /* Init, or core PLT? */
166 if (within_module_core((unsigned long)
167 entry = (void *)sechdrs[mod->a
168 else
169 entry = (void *)sechdrs[mod->a
170
171 /* Find this entry, or if that fails,
172 while (entry->jump[0]) {
173 if (entry_matches(entry, val))
174 entry++;
175 }
176
177 if (patch_instruction(&entry->jump[0],
178 return 0;
179 if (patch_instruction(&entry->jump[1],
180 return 0;
181 if (patch_instruction(&entry->jump[2],
182 return 0;
183 if (patch_instruction(&entry->jump[3],
184 return 0;
185
186 pr_debug("Initialized plt for 0x%x at
187 return (uint32_t)entry;
188 }
189
190 static int patch_location_16(uint32_t *loc, u1
191 {
192 loc = PTR_ALIGN_DOWN(loc, sizeof(u32))
193 return patch_instruction(loc, ppc_inst
194 }
195
196 int 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[rel
204 Elf32_Sym *sym;
205 uint32_t *location;
206 uint32_t value;
207
208 pr_debug("Applying ADD relocate sectio
209 sechdrs[relsec].sh_info);
210 for (i = 0; i < sechdrs[relsec].sh_siz
211 /* This is where to make the c
212 location = (void *)sechdrs[sec
213 + rela[i].r_offset;
214 /* This is the symbol it is re
215 undefined symbols have been
216 sym = (Elf32_Sym *)sechdrs[sym
217 + ELF32_R_SYM(rela[i].
218 /* `Everything is relative'. *
219 value = sym->st_value + rela[i
220
221 switch (ELF32_R_TYPE(rela[i].r
222 case R_PPC_ADDR32:
223 /* Simply set it */
224 *(uint32_t *)location
225 break;
226
227 case R_PPC_ADDR16_LO:
228 /* Low half of the sym
229 if (patch_location_16(
230 return -EFAULT
231 break;
232
233 case R_PPC_ADDR16_HI:
234 /* Higher half of the
235 if (patch_location_16(
236 return -EFAULT
237 break;
238
239 case R_PPC_ADDR16_HA:
240 if (patch_location_16(
241 return -EFAULT
242 break;
243
244 case R_PPC_REL24:
245 if ((int)(value - (uin
246 || (int)(value - (
247 value = do_plt
248
249 if (!value)
250 return
251 }
252
253 /* Only replace bits 2
254 pr_debug("REL24 value
255 value, (uint32_
256 pr_debug("Location bef
257 *(uint32_t *)lo
258 value = (*(uint32_t *)
259 PPC_LI(value -
260
261 if (patch_instruction(
262 return -EFAULT
263
264 pr_debug("Location aft
265 *(uint32_t *)lo
266 pr_debug("ie. jump to
267 *(uint32_t *)
268 (*(uint32_t *
269 break;
270
271 case R_PPC_REL32:
272 /* 32-bit relative jum
273 *(uint32_t *)location
274 break;
275
276 default:
277 pr_err("%s: unknown AD
278 module->name,
279 ELF32_R_TYPE(re
280 return -ENOEXEC;
281 }
282 }
283
284 return 0;
285 }
286
287 #ifdef CONFIG_DYNAMIC_FTRACE
288 notrace int module_trampoline_target(struct mo
289 unsigned
290 {
291 ppc_inst_t jmp[4];
292
293 /* Find where the trampoline jumps to
294 if (copy_inst_from_kernel_nofault(jmp,
295 return -EFAULT;
296 if (__copy_inst_from_kernel_nofault(jm
297 return -EFAULT;
298 if (__copy_inst_from_kernel_nofault(jm
299 return -EFAULT;
300 if (__copy_inst_from_kernel_nofault(jm
301 return -EFAULT;
302
303 /* verify that this is what we expect
304 if ((ppc_inst_val(jmp[0]) & 0xffff0000
305 return -EINVAL;
306 if ((ppc_inst_val(jmp[1]) & 0xffff0000
307 return -EINVAL;
308 if (ppc_inst_val(jmp[2]) != PPC_RAW_MT
309 return -EINVAL;
310 if (ppc_inst_val(jmp[3]) != PPC_RAW_BC
311 return -EINVAL;
312
313 addr = (ppc_inst_val(jmp[1]) & 0xffff)
314 if (addr & 0x8000)
315 addr -= 0x10000;
316
317 *target = addr;
318
319 return 0;
320 }
321
322 int module_finalize_ftrace(struct module *modu
323 {
324 module->arch.tramp = do_plt_call(modul
325 (unsi
326 sechd
327 if (!module->arch.tramp)
328 return -ENOENT;
329
330 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
331 module->arch.tramp_regs = do_plt_call(
332
333
334 if (!module->arch.tramp_regs)
335 return -ENOENT;
336 #endif
337
338 return 0;
339 }
340 #endif
341
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