xref: /openbmc/linux/arch/arm/kernel/module.c (revision 92a2c6b2)
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/fs.h>
20 #include <linux/string.h>
21 #include <linux/gfp.h>
22 
23 #include <asm/pgtable.h>
24 #include <asm/sections.h>
25 #include <asm/smp_plat.h>
26 #include <asm/unwind.h>
27 #include <asm/opcodes.h>
28 
29 #ifdef CONFIG_XIP_KERNEL
30 /*
31  * The XIP kernel text is mapped in the module area for modules and
32  * some other stuff to work without any indirect relocations.
33  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
34  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
35  */
36 #undef MODULES_VADDR
37 #define MODULES_VADDR	(((unsigned long)_etext + ~PMD_MASK) & PMD_MASK)
38 #endif
39 
40 #ifdef CONFIG_MMU
41 void *module_alloc(unsigned long size)
42 {
43 	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
44 				GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
45 				__builtin_return_address(0));
46 }
47 #endif
48 
49 int
50 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
51 	       unsigned int relindex, struct module *module)
52 {
53 	Elf32_Shdr *symsec = sechdrs + symindex;
54 	Elf32_Shdr *relsec = sechdrs + relindex;
55 	Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
56 	Elf32_Rel *rel = (void *)relsec->sh_addr;
57 	unsigned int i;
58 
59 	for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
60 		unsigned long loc;
61 		Elf32_Sym *sym;
62 		const char *symname;
63 		s32 offset;
64 		u32 tmp;
65 #ifdef CONFIG_THUMB2_KERNEL
66 		u32 upper, lower, sign, j1, j2;
67 #endif
68 
69 		offset = ELF32_R_SYM(rel->r_info);
70 		if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
71 			pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
72 				module->name, relindex, i);
73 			return -ENOEXEC;
74 		}
75 
76 		sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
77 		symname = strtab + sym->st_name;
78 
79 		if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
80 			pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
81 			       module->name, relindex, i, symname,
82 			       rel->r_offset, dstsec->sh_size);
83 			return -ENOEXEC;
84 		}
85 
86 		loc = dstsec->sh_addr + rel->r_offset;
87 
88 		switch (ELF32_R_TYPE(rel->r_info)) {
89 		case R_ARM_NONE:
90 			/* ignore */
91 			break;
92 
93 		case R_ARM_ABS32:
94 		case R_ARM_TARGET1:
95 			*(u32 *)loc += sym->st_value;
96 			break;
97 
98 		case R_ARM_PC24:
99 		case R_ARM_CALL:
100 		case R_ARM_JUMP24:
101 			offset = __mem_to_opcode_arm(*(u32 *)loc);
102 			offset = (offset & 0x00ffffff) << 2;
103 			if (offset & 0x02000000)
104 				offset -= 0x04000000;
105 
106 			offset += sym->st_value - loc;
107 			if (offset & 3 ||
108 			    offset <= (s32)0xfe000000 ||
109 			    offset >= (s32)0x02000000) {
110 				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
111 				       module->name, relindex, i, symname,
112 				       ELF32_R_TYPE(rel->r_info), loc,
113 				       sym->st_value);
114 				return -ENOEXEC;
115 			}
116 
117 			offset >>= 2;
118 			offset &= 0x00ffffff;
119 
120 			*(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
121 			*(u32 *)loc |= __opcode_to_mem_arm(offset);
122 			break;
123 
124 	       case R_ARM_V4BX:
125 		       /* Preserve Rm and the condition code. Alter
126 			* other bits to re-code instruction as
127 			* MOV PC,Rm.
128 			*/
129 		       *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
130 		       *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
131 		       break;
132 
133 		case R_ARM_PREL31:
134 			offset = *(u32 *)loc + sym->st_value - loc;
135 			*(u32 *)loc = offset & 0x7fffffff;
136 			break;
137 
138 		case R_ARM_MOVW_ABS_NC:
139 		case R_ARM_MOVT_ABS:
140 			offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
141 			offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
142 			offset = (offset ^ 0x8000) - 0x8000;
143 
144 			offset += sym->st_value;
145 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS)
146 				offset >>= 16;
147 
148 			tmp &= 0xfff0f000;
149 			tmp |= ((offset & 0xf000) << 4) |
150 				(offset & 0x0fff);
151 
152 			*(u32 *)loc = __opcode_to_mem_arm(tmp);
153 			break;
154 
155 #ifdef CONFIG_THUMB2_KERNEL
156 		case R_ARM_THM_CALL:
157 		case R_ARM_THM_JUMP24:
158 			upper = __mem_to_opcode_thumb16(*(u16 *)loc);
159 			lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
160 
161 			/*
162 			 * 25 bit signed address range (Thumb-2 BL and B.W
163 			 * instructions):
164 			 *   S:I1:I2:imm10:imm11:0
165 			 * where:
166 			 *   S     = upper[10]   = offset[24]
167 			 *   I1    = ~(J1 ^ S)   = offset[23]
168 			 *   I2    = ~(J2 ^ S)   = offset[22]
169 			 *   imm10 = upper[9:0]  = offset[21:12]
170 			 *   imm11 = lower[10:0] = offset[11:1]
171 			 *   J1    = lower[13]
172 			 *   J2    = lower[11]
173 			 */
174 			sign = (upper >> 10) & 1;
175 			j1 = (lower >> 13) & 1;
176 			j2 = (lower >> 11) & 1;
177 			offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
178 				((~(j2 ^ sign) & 1) << 22) |
179 				((upper & 0x03ff) << 12) |
180 				((lower & 0x07ff) << 1);
181 			if (offset & 0x01000000)
182 				offset -= 0x02000000;
183 			offset += sym->st_value - loc;
184 
185 			/*
186 			 * For function symbols, only Thumb addresses are
187 			 * allowed (no interworking).
188 			 *
189 			 * For non-function symbols, the destination
190 			 * has no specific ARM/Thumb disposition, so
191 			 * the branch is resolved under the assumption
192 			 * that interworking is not required.
193 			 */
194 			if ((ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
195 				!(offset & 1)) ||
196 			    offset <= (s32)0xff000000 ||
197 			    offset >= (s32)0x01000000) {
198 				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
199 				       module->name, relindex, i, symname,
200 				       ELF32_R_TYPE(rel->r_info), loc,
201 				       sym->st_value);
202 				return -ENOEXEC;
203 			}
204 
205 			sign = (offset >> 24) & 1;
206 			j1 = sign ^ (~(offset >> 23) & 1);
207 			j2 = sign ^ (~(offset >> 22) & 1);
208 			upper = (u16)((upper & 0xf800) | (sign << 10) |
209 					    ((offset >> 12) & 0x03ff));
210 			lower = (u16)((lower & 0xd000) |
211 				      (j1 << 13) | (j2 << 11) |
212 				      ((offset >> 1) & 0x07ff));
213 
214 			*(u16 *)loc = __opcode_to_mem_thumb16(upper);
215 			*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
216 			break;
217 
218 		case R_ARM_THM_MOVW_ABS_NC:
219 		case R_ARM_THM_MOVT_ABS:
220 			upper = __mem_to_opcode_thumb16(*(u16 *)loc);
221 			lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
222 
223 			/*
224 			 * MOVT/MOVW instructions encoding in Thumb-2:
225 			 *
226 			 * i	= upper[10]
227 			 * imm4	= upper[3:0]
228 			 * imm3	= lower[14:12]
229 			 * imm8	= lower[7:0]
230 			 *
231 			 * imm16 = imm4:i:imm3:imm8
232 			 */
233 			offset = ((upper & 0x000f) << 12) |
234 				((upper & 0x0400) << 1) |
235 				((lower & 0x7000) >> 4) | (lower & 0x00ff);
236 			offset = (offset ^ 0x8000) - 0x8000;
237 			offset += sym->st_value;
238 
239 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS)
240 				offset >>= 16;
241 
242 			upper = (u16)((upper & 0xfbf0) |
243 				      ((offset & 0xf000) >> 12) |
244 				      ((offset & 0x0800) >> 1));
245 			lower = (u16)((lower & 0x8f00) |
246 				      ((offset & 0x0700) << 4) |
247 				      (offset & 0x00ff));
248 			*(u16 *)loc = __opcode_to_mem_thumb16(upper);
249 			*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
250 			break;
251 #endif
252 
253 		default:
254 			pr_err("%s: unknown relocation: %u\n",
255 			       module->name, ELF32_R_TYPE(rel->r_info));
256 			return -ENOEXEC;
257 		}
258 	}
259 	return 0;
260 }
261 
262 struct mod_unwind_map {
263 	const Elf_Shdr *unw_sec;
264 	const Elf_Shdr *txt_sec;
265 };
266 
267 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
268 	const Elf_Shdr *sechdrs, const char *name)
269 {
270 	const Elf_Shdr *s, *se;
271 	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
272 
273 	for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
274 		if (strcmp(name, secstrs + s->sh_name) == 0)
275 			return s;
276 
277 	return NULL;
278 }
279 
280 extern void fixup_pv_table(const void *, unsigned long);
281 extern void fixup_smp(const void *, unsigned long);
282 
283 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
284 		    struct module *mod)
285 {
286 	const Elf_Shdr *s = NULL;
287 #ifdef CONFIG_ARM_UNWIND
288 	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
289 	const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
290 	struct mod_unwind_map maps[ARM_SEC_MAX];
291 	int i;
292 
293 	memset(maps, 0, sizeof(maps));
294 
295 	for (s = sechdrs; s < sechdrs_end; s++) {
296 		const char *secname = secstrs + s->sh_name;
297 
298 		if (!(s->sh_flags & SHF_ALLOC))
299 			continue;
300 
301 		if (strcmp(".ARM.exidx.init.text", secname) == 0)
302 			maps[ARM_SEC_INIT].unw_sec = s;
303 		else if (strcmp(".ARM.exidx", secname) == 0)
304 			maps[ARM_SEC_CORE].unw_sec = s;
305 		else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
306 			maps[ARM_SEC_EXIT].unw_sec = s;
307 		else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
308 			maps[ARM_SEC_UNLIKELY].unw_sec = s;
309 		else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
310 			maps[ARM_SEC_HOT].unw_sec = s;
311 		else if (strcmp(".init.text", secname) == 0)
312 			maps[ARM_SEC_INIT].txt_sec = s;
313 		else if (strcmp(".text", secname) == 0)
314 			maps[ARM_SEC_CORE].txt_sec = s;
315 		else if (strcmp(".exit.text", secname) == 0)
316 			maps[ARM_SEC_EXIT].txt_sec = s;
317 		else if (strcmp(".text.unlikely", secname) == 0)
318 			maps[ARM_SEC_UNLIKELY].txt_sec = s;
319 		else if (strcmp(".text.hot", secname) == 0)
320 			maps[ARM_SEC_HOT].txt_sec = s;
321 	}
322 
323 	for (i = 0; i < ARM_SEC_MAX; i++)
324 		if (maps[i].unw_sec && maps[i].txt_sec)
325 			mod->arch.unwind[i] =
326 				unwind_table_add(maps[i].unw_sec->sh_addr,
327 					         maps[i].unw_sec->sh_size,
328 					         maps[i].txt_sec->sh_addr,
329 					         maps[i].txt_sec->sh_size);
330 #endif
331 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
332 	s = find_mod_section(hdr, sechdrs, ".pv_table");
333 	if (s)
334 		fixup_pv_table((void *)s->sh_addr, s->sh_size);
335 #endif
336 	s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
337 	if (s && !is_smp())
338 #ifdef CONFIG_SMP_ON_UP
339 		fixup_smp((void *)s->sh_addr, s->sh_size);
340 #else
341 		return -EINVAL;
342 #endif
343 	return 0;
344 }
345 
346 void
347 module_arch_cleanup(struct module *mod)
348 {
349 #ifdef CONFIG_ARM_UNWIND
350 	int i;
351 
352 	for (i = 0; i < ARM_SEC_MAX; i++)
353 		if (mod->arch.unwind[i])
354 			unwind_table_del(mod->arch.unwind[i]);
355 #endif
356 }
357