xref: /openbmc/linux/arch/arm/kernel/module.c (revision b6dcefde)
1 /*
2  *  linux/arch/arm/kernel/module.c
3  *
4  *  Copyright (C) 2002 Russell King.
5  *  Modified for nommu by Hyok S. Choi
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * Module allocation method suggested by Andi Kleen.
12  */
13 #include <linux/module.h>
14 #include <linux/moduleloader.h>
15 #include <linux/kernel.h>
16 #include <linux/mm.h>
17 #include <linux/elf.h>
18 #include <linux/vmalloc.h>
19 #include <linux/slab.h>
20 #include <linux/fs.h>
21 #include <linux/string.h>
22 
23 #include <asm/pgtable.h>
24 #include <asm/sections.h>
25 #include <asm/unwind.h>
26 
27 #ifdef CONFIG_XIP_KERNEL
28 /*
29  * The XIP kernel text is mapped in the module area for modules and
30  * some other stuff to work without any indirect relocations.
31  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
32  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
33  */
34 #undef MODULES_VADDR
35 #define MODULES_VADDR	(((unsigned long)_etext + ~PGDIR_MASK) & PGDIR_MASK)
36 #endif
37 
38 #ifdef CONFIG_MMU
39 void *module_alloc(unsigned long size)
40 {
41 	struct vm_struct *area;
42 
43 	size = PAGE_ALIGN(size);
44 	if (!size)
45 		return NULL;
46 
47 	area = __get_vm_area(size, VM_ALLOC, MODULES_VADDR, MODULES_END);
48 	if (!area)
49 		return NULL;
50 
51 	return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
52 }
53 #else /* CONFIG_MMU */
54 void *module_alloc(unsigned long size)
55 {
56 	return size == 0 ? NULL : vmalloc(size);
57 }
58 #endif /* !CONFIG_MMU */
59 
60 void module_free(struct module *module, void *region)
61 {
62 	vfree(region);
63 }
64 
65 int module_frob_arch_sections(Elf_Ehdr *hdr,
66 			      Elf_Shdr *sechdrs,
67 			      char *secstrings,
68 			      struct module *mod)
69 {
70 #ifdef CONFIG_ARM_UNWIND
71 	Elf_Shdr *s, *sechdrs_end = sechdrs + hdr->e_shnum;
72 
73 	for (s = sechdrs; s < sechdrs_end; s++) {
74 		if (strcmp(".ARM.exidx.init.text", secstrings + s->sh_name) == 0)
75 			mod->arch.unw_sec_init = s;
76 		else if (strcmp(".ARM.exidx.devinit.text", secstrings + s->sh_name) == 0)
77 			mod->arch.unw_sec_devinit = s;
78 		else if (strcmp(".ARM.exidx", secstrings + s->sh_name) == 0)
79 			mod->arch.unw_sec_core = s;
80 		else if (strcmp(".init.text", secstrings + s->sh_name) == 0)
81 			mod->arch.sec_init_text = s;
82 		else if (strcmp(".devinit.text", secstrings + s->sh_name) == 0)
83 			mod->arch.sec_devinit_text = s;
84 		else if (strcmp(".text", secstrings + s->sh_name) == 0)
85 			mod->arch.sec_core_text = s;
86 	}
87 #endif
88 	return 0;
89 }
90 
91 int
92 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
93 	       unsigned int relindex, struct module *module)
94 {
95 	Elf32_Shdr *symsec = sechdrs + symindex;
96 	Elf32_Shdr *relsec = sechdrs + relindex;
97 	Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
98 	Elf32_Rel *rel = (void *)relsec->sh_addr;
99 	unsigned int i;
100 
101 	for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
102 		unsigned long loc;
103 		Elf32_Sym *sym;
104 		s32 offset;
105 		u32 upper, lower, sign, j1, j2;
106 
107 		offset = ELF32_R_SYM(rel->r_info);
108 		if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
109 			printk(KERN_ERR "%s: bad relocation, section %d reloc %d\n",
110 				module->name, relindex, i);
111 			return -ENOEXEC;
112 		}
113 
114 		sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
115 
116 		if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
117 			printk(KERN_ERR "%s: out of bounds relocation, "
118 				"section %d reloc %d offset %d size %d\n",
119 				module->name, relindex, i, rel->r_offset,
120 				dstsec->sh_size);
121 			return -ENOEXEC;
122 		}
123 
124 		loc = dstsec->sh_addr + rel->r_offset;
125 
126 		switch (ELF32_R_TYPE(rel->r_info)) {
127 		case R_ARM_NONE:
128 			/* ignore */
129 			break;
130 
131 		case R_ARM_ABS32:
132 			*(u32 *)loc += sym->st_value;
133 			break;
134 
135 		case R_ARM_PC24:
136 		case R_ARM_CALL:
137 		case R_ARM_JUMP24:
138 			offset = (*(u32 *)loc & 0x00ffffff) << 2;
139 			if (offset & 0x02000000)
140 				offset -= 0x04000000;
141 
142 			offset += sym->st_value - loc;
143 			if (offset & 3 ||
144 			    offset <= (s32)0xfe000000 ||
145 			    offset >= (s32)0x02000000) {
146 				printk(KERN_ERR
147 				       "%s: relocation out of range, section "
148 				       "%d reloc %d sym '%s'\n", module->name,
149 				       relindex, i, strtab + sym->st_name);
150 				return -ENOEXEC;
151 			}
152 
153 			offset >>= 2;
154 
155 			*(u32 *)loc &= 0xff000000;
156 			*(u32 *)loc |= offset & 0x00ffffff;
157 			break;
158 
159 	       case R_ARM_V4BX:
160 		       /* Preserve Rm and the condition code. Alter
161 			* other bits to re-code instruction as
162 			* MOV PC,Rm.
163 			*/
164 		       *(u32 *)loc &= 0xf000000f;
165 		       *(u32 *)loc |= 0x01a0f000;
166 		       break;
167 
168 		case R_ARM_PREL31:
169 			offset = *(u32 *)loc + sym->st_value - loc;
170 			*(u32 *)loc = offset & 0x7fffffff;
171 			break;
172 
173 		case R_ARM_MOVW_ABS_NC:
174 		case R_ARM_MOVT_ABS:
175 			offset = *(u32 *)loc;
176 			offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
177 			offset = (offset ^ 0x8000) - 0x8000;
178 
179 			offset += sym->st_value;
180 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
181 				offset >>= 16;
182 
183 			*(u32 *)loc &= 0xfff0f000;
184 			*(u32 *)loc |= ((offset & 0xf000) << 4) |
185 					(offset & 0x0fff);
186 			break;
187 
188 		case R_ARM_THM_CALL:
189 		case R_ARM_THM_JUMP24:
190 			upper = *(u16 *)loc;
191 			lower = *(u16 *)(loc + 2);
192 
193 			/*
194 			 * 25 bit signed address range (Thumb-2 BL and B.W
195 			 * instructions):
196 			 *   S:I1:I2:imm10:imm11:0
197 			 * where:
198 			 *   S     = upper[10]   = offset[24]
199 			 *   I1    = ~(J1 ^ S)   = offset[23]
200 			 *   I2    = ~(J2 ^ S)   = offset[22]
201 			 *   imm10 = upper[9:0]  = offset[21:12]
202 			 *   imm11 = lower[10:0] = offset[11:1]
203 			 *   J1    = lower[13]
204 			 *   J2    = lower[11]
205 			 */
206 			sign = (upper >> 10) & 1;
207 			j1 = (lower >> 13) & 1;
208 			j2 = (lower >> 11) & 1;
209 			offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
210 				((~(j2 ^ sign) & 1) << 22) |
211 				((upper & 0x03ff) << 12) |
212 				((lower & 0x07ff) << 1);
213 			if (offset & 0x01000000)
214 				offset -= 0x02000000;
215 			offset += sym->st_value - loc;
216 
217 			/* only Thumb addresses allowed (no interworking) */
218 			if (!(offset & 1) ||
219 			    offset <= (s32)0xff000000 ||
220 			    offset >= (s32)0x01000000) {
221 				printk(KERN_ERR
222 				       "%s: relocation out of range, section "
223 				       "%d reloc %d sym '%s'\n", module->name,
224 				       relindex, i, strtab + sym->st_name);
225 				return -ENOEXEC;
226 			}
227 
228 			sign = (offset >> 24) & 1;
229 			j1 = sign ^ (~(offset >> 23) & 1);
230 			j2 = sign ^ (~(offset >> 22) & 1);
231 			*(u16 *)loc = (u16)((upper & 0xf800) | (sign << 10) |
232 					    ((offset >> 12) & 0x03ff));
233 			*(u16 *)(loc + 2) = (u16)((lower & 0xd000) |
234 						  (j1 << 13) | (j2 << 11) |
235 						  ((offset >> 1) & 0x07ff));
236 			upper = *(u16 *)loc;
237 			lower = *(u16 *)(loc + 2);
238 			break;
239 
240 		default:
241 			printk(KERN_ERR "%s: unknown relocation: %u\n",
242 			       module->name, ELF32_R_TYPE(rel->r_info));
243 			return -ENOEXEC;
244 		}
245 	}
246 	return 0;
247 }
248 
249 int
250 apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
251 		   unsigned int symindex, unsigned int relsec, struct module *module)
252 {
253 	printk(KERN_ERR "module %s: ADD RELOCATION unsupported\n",
254 	       module->name);
255 	return -ENOEXEC;
256 }
257 
258 #ifdef CONFIG_ARM_UNWIND
259 static void register_unwind_tables(struct module *mod)
260 {
261 	if (mod->arch.unw_sec_init && mod->arch.sec_init_text)
262 		mod->arch.unwind_init =
263 			unwind_table_add(mod->arch.unw_sec_init->sh_addr,
264 					 mod->arch.unw_sec_init->sh_size,
265 					 mod->arch.sec_init_text->sh_addr,
266 					 mod->arch.sec_init_text->sh_size);
267 	if (mod->arch.unw_sec_devinit && mod->arch.sec_devinit_text)
268 		mod->arch.unwind_devinit =
269 			unwind_table_add(mod->arch.unw_sec_devinit->sh_addr,
270 					 mod->arch.unw_sec_devinit->sh_size,
271 					 mod->arch.sec_devinit_text->sh_addr,
272 					 mod->arch.sec_devinit_text->sh_size);
273 	if (mod->arch.unw_sec_core && mod->arch.sec_core_text)
274 		mod->arch.unwind_core =
275 			unwind_table_add(mod->arch.unw_sec_core->sh_addr,
276 					 mod->arch.unw_sec_core->sh_size,
277 					 mod->arch.sec_core_text->sh_addr,
278 					 mod->arch.sec_core_text->sh_size);
279 }
280 
281 static void unregister_unwind_tables(struct module *mod)
282 {
283 	unwind_table_del(mod->arch.unwind_init);
284 	unwind_table_del(mod->arch.unwind_devinit);
285 	unwind_table_del(mod->arch.unwind_core);
286 }
287 #else
288 static inline void register_unwind_tables(struct module *mod) { }
289 static inline void unregister_unwind_tables(struct module *mod) { }
290 #endif
291 
292 int
293 module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
294 		struct module *module)
295 {
296 	register_unwind_tables(module);
297 	return 0;
298 }
299 
300 void
301 module_arch_cleanup(struct module *mod)
302 {
303 	unregister_unwind_tables(mod);
304 }
305