Merge tag 'mips_fixes_5.2_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips...
[linux-2.6-microblaze.git] / arch / powerpc / kernel / module_32.c
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) */
24 static 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
47 static 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
70 static 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 */
87 static 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
134 int 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
161 static inline int entry_matches(struct ppc_plt_entry *entry, Elf32_Addr val)
162 {
163         if (entry->jump[0] == 0x3d800000 + ((val + 0x8000) >> 16)
164             && entry->jump[1] == 0x398c0000 + (val & 0xffff))
165                 return 1;
166         return 0;
167 }
168
169 /* Set up a trampoline in the PLT to bounce us to the distant function */
170 static uint32_t do_plt_call(void *location,
171                             Elf32_Addr val,
172                             const Elf32_Shdr *sechdrs,
173                             struct module *mod)
174 {
175         struct ppc_plt_entry *entry;
176
177         pr_debug("Doing plt for call to 0x%x at 0x%x\n", val, (unsigned int)location);
178         /* Init, or core PLT? */
179         if (location >= mod->core_layout.base
180             && location < mod->core_layout.base + mod->core_layout.size)
181                 entry = (void *)sechdrs[mod->arch.core_plt_section].sh_addr;
182         else
183                 entry = (void *)sechdrs[mod->arch.init_plt_section].sh_addr;
184
185         /* Find this entry, or if that fails, the next avail. entry */
186         while (entry->jump[0]) {
187                 if (entry_matches(entry, val)) return (uint32_t)entry;
188                 entry++;
189         }
190
191         entry->jump[0] = 0x3d800000+((val+0x8000)>>16); /* lis r12,sym@ha */
192         entry->jump[1] = 0x398c0000 + (val&0xffff);     /* addi r12,r12,sym@l*/
193         entry->jump[2] = 0x7d8903a6;                    /* mtctr r12 */
194         entry->jump[3] = 0x4e800420;                    /* bctr */
195
196         pr_debug("Initialized plt for 0x%x at %p\n", val, entry);
197         return (uint32_t)entry;
198 }
199
200 int apply_relocate_add(Elf32_Shdr *sechdrs,
201                        const char *strtab,
202                        unsigned int symindex,
203                        unsigned int relsec,
204                        struct module *module)
205 {
206         unsigned int i;
207         Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
208         Elf32_Sym *sym;
209         uint32_t *location;
210         uint32_t value;
211
212         pr_debug("Applying ADD relocate section %u to %u\n", relsec,
213                sechdrs[relsec].sh_info);
214         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
215                 /* This is where to make the change */
216                 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
217                         + rela[i].r_offset;
218                 /* This is the symbol it is referring to.  Note that all
219                    undefined symbols have been resolved.  */
220                 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
221                         + ELF32_R_SYM(rela[i].r_info);
222                 /* `Everything is relative'. */
223                 value = sym->st_value + rela[i].r_addend;
224
225                 switch (ELF32_R_TYPE(rela[i].r_info)) {
226                 case R_PPC_ADDR32:
227                         /* Simply set it */
228                         *(uint32_t *)location = value;
229                         break;
230
231                 case R_PPC_ADDR16_LO:
232                         /* Low half of the symbol */
233                         *(uint16_t *)location = value;
234                         break;
235
236                 case R_PPC_ADDR16_HI:
237                         /* Higher half of the symbol */
238                         *(uint16_t *)location = (value >> 16);
239                         break;
240
241                 case R_PPC_ADDR16_HA:
242                         /* Sign-adjusted lower 16 bits: PPC ELF ABI says:
243                            (((x >> 16) + ((x & 0x8000) ? 1 : 0))) & 0xFFFF.
244                            This is the same, only sane.
245                          */
246                         *(uint16_t *)location = (value + 0x8000) >> 16;
247                         break;
248
249                 case R_PPC_REL24:
250                         if ((int)(value - (uint32_t)location) < -0x02000000
251                             || (int)(value - (uint32_t)location) >= 0x02000000)
252                                 value = do_plt_call(location, value,
253                                                     sechdrs, module);
254
255                         /* Only replace bits 2 through 26 */
256                         pr_debug("REL24 value = %08X. location = %08X\n",
257                                value, (uint32_t)location);
258                         pr_debug("Location before: %08X.\n",
259                                *(uint32_t *)location);
260                         *(uint32_t *)location
261                                 = (*(uint32_t *)location & ~0x03fffffc)
262                                 | ((value - (uint32_t)location)
263                                    & 0x03fffffc);
264                         pr_debug("Location after: %08X.\n",
265                                *(uint32_t *)location);
266                         pr_debug("ie. jump to %08X+%08X = %08X\n",
267                                *(uint32_t *)location & 0x03fffffc,
268                                (uint32_t)location,
269                                (*(uint32_t *)location & 0x03fffffc)
270                                + (uint32_t)location);
271                         break;
272
273                 case R_PPC_REL32:
274                         /* 32-bit relative jump. */
275                         *(uint32_t *)location = value - (uint32_t)location;
276                         break;
277
278                 default:
279                         pr_err("%s: unknown ADD relocation: %u\n",
280                                module->name,
281                                ELF32_R_TYPE(rela[i].r_info));
282                         return -ENOEXEC;
283                 }
284         }
285
286         return 0;
287 }
288
289 #ifdef CONFIG_DYNAMIC_FTRACE
290 int module_finalize_ftrace(struct module *module, const Elf_Shdr *sechdrs)
291 {
292         module->arch.tramp = do_plt_call(module->core_layout.base,
293                                          (unsigned long)ftrace_caller,
294                                          sechdrs, module);
295         if (!module->arch.tramp)
296                 return -ENOENT;
297
298         return 0;
299 }
300 #endif