xref: /openbmc/linux/arch/arm/kernel/module.c (revision e5bd61e8)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/kernel/module.c
4  *
5  *  Copyright (C) 2002 Russell King.
6  *  Modified for nommu by Hyok S. Choi
7  *
8  * Module allocation method suggested by Andi Kleen.
9  */
10 #include <linux/module.h>
11 #include <linux/moduleloader.h>
12 #include <linux/kernel.h>
13 #include <linux/mm.h>
14 #include <linux/elf.h>
15 #include <linux/vmalloc.h>
16 #include <linux/fs.h>
17 #include <linux/string.h>
18 #include <linux/gfp.h>
19 
20 #include <asm/sections.h>
21 #include <asm/smp_plat.h>
22 #include <asm/unwind.h>
23 #include <asm/opcodes.h>
24 
25 #ifdef CONFIG_XIP_KERNEL
26 /*
27  * The XIP kernel text is mapped in the module area for modules and
28  * some other stuff to work without any indirect relocations.
29  * MODULES_VADDR is redefined here and not in asm/memory.h to avoid
30  * recompiling the whole kernel when CONFIG_XIP_KERNEL is turned on/off.
31  */
32 #undef MODULES_VADDR
33 #define MODULES_VADDR	(((unsigned long)_exiprom + ~PMD_MASK) & PMD_MASK)
34 #endif
35 
36 #ifdef CONFIG_MMU
37 void *module_alloc(unsigned long size)
38 {
39 	gfp_t gfp_mask = GFP_KERNEL;
40 	void *p;
41 
42 	/* Silence the initial allocation */
43 	if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS))
44 		gfp_mask |= __GFP_NOWARN;
45 
46 	p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
47 				gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
48 				__builtin_return_address(0));
49 	if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p)
50 		return p;
51 	return __vmalloc_node_range(size, 1,  VMALLOC_START, VMALLOC_END,
52 				GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
53 				__builtin_return_address(0));
54 }
55 #endif
56 
57 bool module_init_section(const char *name)
58 {
59 	return strstarts(name, ".init") ||
60 		strstarts(name, ".ARM.extab.init") ||
61 		strstarts(name, ".ARM.exidx.init");
62 }
63 
64 bool module_exit_section(const char *name)
65 {
66 	return strstarts(name, ".exit") ||
67 		strstarts(name, ".ARM.extab.exit") ||
68 		strstarts(name, ".ARM.exidx.exit");
69 }
70 
71 int
72 apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
73 	       unsigned int relindex, struct module *module)
74 {
75 	Elf32_Shdr *symsec = sechdrs + symindex;
76 	Elf32_Shdr *relsec = sechdrs + relindex;
77 	Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
78 	Elf32_Rel *rel = (void *)relsec->sh_addr;
79 	unsigned int i;
80 
81 	for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
82 		unsigned long loc;
83 		Elf32_Sym *sym;
84 		const char *symname;
85 		s32 offset;
86 		u32 tmp;
87 #ifdef CONFIG_THUMB2_KERNEL
88 		u32 upper, lower, sign, j1, j2;
89 #endif
90 
91 		offset = ELF32_R_SYM(rel->r_info);
92 		if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
93 			pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
94 				module->name, relindex, i);
95 			return -ENOEXEC;
96 		}
97 
98 		sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
99 		symname = strtab + sym->st_name;
100 
101 		if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
102 			pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
103 			       module->name, relindex, i, symname,
104 			       rel->r_offset, dstsec->sh_size);
105 			return -ENOEXEC;
106 		}
107 
108 		loc = dstsec->sh_addr + rel->r_offset;
109 
110 		switch (ELF32_R_TYPE(rel->r_info)) {
111 		case R_ARM_NONE:
112 			/* ignore */
113 			break;
114 
115 		case R_ARM_ABS32:
116 		case R_ARM_TARGET1:
117 			*(u32 *)loc += sym->st_value;
118 			break;
119 
120 		case R_ARM_PC24:
121 		case R_ARM_CALL:
122 		case R_ARM_JUMP24:
123 			if (sym->st_value & 3) {
124 				pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
125 				       module->name, relindex, i, symname);
126 				return -ENOEXEC;
127 			}
128 
129 			offset = __mem_to_opcode_arm(*(u32 *)loc);
130 			offset = (offset & 0x00ffffff) << 2;
131 			if (offset & 0x02000000)
132 				offset -= 0x04000000;
133 
134 			offset += sym->st_value - loc;
135 
136 			/*
137 			 * Route through a PLT entry if 'offset' exceeds the
138 			 * supported range. Note that 'offset + loc + 8'
139 			 * contains the absolute jump target, i.e.,
140 			 * @sym + addend, corrected for the +8 PC bias.
141 			 */
142 			if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
143 			    (offset <= (s32)0xfe000000 ||
144 			     offset >= (s32)0x02000000))
145 				offset = get_module_plt(module, loc,
146 							offset + loc + 8)
147 					 - loc - 8;
148 
149 			if (offset <= (s32)0xfe000000 ||
150 			    offset >= (s32)0x02000000) {
151 				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
152 				       module->name, relindex, i, symname,
153 				       ELF32_R_TYPE(rel->r_info), loc,
154 				       sym->st_value);
155 				return -ENOEXEC;
156 			}
157 
158 			offset >>= 2;
159 			offset &= 0x00ffffff;
160 
161 			*(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
162 			*(u32 *)loc |= __opcode_to_mem_arm(offset);
163 			break;
164 
165 	       case R_ARM_V4BX:
166 		       /* Preserve Rm and the condition code. Alter
167 			* other bits to re-code instruction as
168 			* MOV PC,Rm.
169 			*/
170 		       *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
171 		       *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
172 		       break;
173 
174 		case R_ARM_PREL31:
175 			offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
176 			offset += sym->st_value - loc;
177 			if (offset >= 0x40000000 || offset < -0x40000000) {
178 				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
179 				       module->name, relindex, i, symname,
180 				       ELF32_R_TYPE(rel->r_info), loc,
181 				       sym->st_value);
182 				return -ENOEXEC;
183 			}
184 			*(u32 *)loc &= 0x80000000;
185 			*(u32 *)loc |= offset & 0x7fffffff;
186 			break;
187 
188 		case R_ARM_REL32:
189 			*(u32 *)loc += sym->st_value - loc;
190 			break;
191 
192 		case R_ARM_MOVW_ABS_NC:
193 		case R_ARM_MOVT_ABS:
194 		case R_ARM_MOVW_PREL_NC:
195 		case R_ARM_MOVT_PREL:
196 			offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
197 			offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
198 			offset = (offset ^ 0x8000) - 0x8000;
199 
200 			offset += sym->st_value;
201 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL ||
202 			    ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC)
203 				offset -= loc;
204 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS ||
205 			    ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL)
206 				offset >>= 16;
207 
208 			tmp &= 0xfff0f000;
209 			tmp |= ((offset & 0xf000) << 4) |
210 				(offset & 0x0fff);
211 
212 			*(u32 *)loc = __opcode_to_mem_arm(tmp);
213 			break;
214 
215 #ifdef CONFIG_THUMB2_KERNEL
216 		case R_ARM_THM_CALL:
217 		case R_ARM_THM_JUMP24:
218 			/*
219 			 * For function symbols, only Thumb addresses are
220 			 * allowed (no interworking).
221 			 *
222 			 * For non-function symbols, the destination
223 			 * has no specific ARM/Thumb disposition, so
224 			 * the branch is resolved under the assumption
225 			 * that interworking is not required.
226 			 */
227 			if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
228 			    !(sym->st_value & 1)) {
229 				pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
230 				       module->name, relindex, i, symname);
231 				return -ENOEXEC;
232 			}
233 
234 			upper = __mem_to_opcode_thumb16(*(u16 *)loc);
235 			lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
236 
237 			/*
238 			 * 25 bit signed address range (Thumb-2 BL and B.W
239 			 * instructions):
240 			 *   S:I1:I2:imm10:imm11:0
241 			 * where:
242 			 *   S     = upper[10]   = offset[24]
243 			 *   I1    = ~(J1 ^ S)   = offset[23]
244 			 *   I2    = ~(J2 ^ S)   = offset[22]
245 			 *   imm10 = upper[9:0]  = offset[21:12]
246 			 *   imm11 = lower[10:0] = offset[11:1]
247 			 *   J1    = lower[13]
248 			 *   J2    = lower[11]
249 			 */
250 			sign = (upper >> 10) & 1;
251 			j1 = (lower >> 13) & 1;
252 			j2 = (lower >> 11) & 1;
253 			offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
254 				((~(j2 ^ sign) & 1) << 22) |
255 				((upper & 0x03ff) << 12) |
256 				((lower & 0x07ff) << 1);
257 			if (offset & 0x01000000)
258 				offset -= 0x02000000;
259 			offset += sym->st_value - loc;
260 
261 			/*
262 			 * Route through a PLT entry if 'offset' exceeds the
263 			 * supported range.
264 			 */
265 			if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
266 			    (offset <= (s32)0xff000000 ||
267 			     offset >= (s32)0x01000000))
268 				offset = get_module_plt(module, loc,
269 							offset + loc + 4)
270 					 - loc - 4;
271 
272 			if (offset <= (s32)0xff000000 ||
273 			    offset >= (s32)0x01000000) {
274 				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
275 				       module->name, relindex, i, symname,
276 				       ELF32_R_TYPE(rel->r_info), loc,
277 				       sym->st_value);
278 				return -ENOEXEC;
279 			}
280 
281 			sign = (offset >> 24) & 1;
282 			j1 = sign ^ (~(offset >> 23) & 1);
283 			j2 = sign ^ (~(offset >> 22) & 1);
284 			upper = (u16)((upper & 0xf800) | (sign << 10) |
285 					    ((offset >> 12) & 0x03ff));
286 			lower = (u16)((lower & 0xd000) |
287 				      (j1 << 13) | (j2 << 11) |
288 				      ((offset >> 1) & 0x07ff));
289 
290 			*(u16 *)loc = __opcode_to_mem_thumb16(upper);
291 			*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
292 			break;
293 
294 		case R_ARM_THM_MOVW_ABS_NC:
295 		case R_ARM_THM_MOVT_ABS:
296 		case R_ARM_THM_MOVW_PREL_NC:
297 		case R_ARM_THM_MOVT_PREL:
298 			upper = __mem_to_opcode_thumb16(*(u16 *)loc);
299 			lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
300 
301 			/*
302 			 * MOVT/MOVW instructions encoding in Thumb-2:
303 			 *
304 			 * i	= upper[10]
305 			 * imm4	= upper[3:0]
306 			 * imm3	= lower[14:12]
307 			 * imm8	= lower[7:0]
308 			 *
309 			 * imm16 = imm4:i:imm3:imm8
310 			 */
311 			offset = ((upper & 0x000f) << 12) |
312 				((upper & 0x0400) << 1) |
313 				((lower & 0x7000) >> 4) | (lower & 0x00ff);
314 			offset = (offset ^ 0x8000) - 0x8000;
315 			offset += sym->st_value;
316 
317 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL ||
318 			    ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC)
319 				offset -= loc;
320 			if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS ||
321 			    ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL)
322 				offset >>= 16;
323 
324 			upper = (u16)((upper & 0xfbf0) |
325 				      ((offset & 0xf000) >> 12) |
326 				      ((offset & 0x0800) >> 1));
327 			lower = (u16)((lower & 0x8f00) |
328 				      ((offset & 0x0700) << 4) |
329 				      (offset & 0x00ff));
330 			*(u16 *)loc = __opcode_to_mem_thumb16(upper);
331 			*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
332 			break;
333 #endif
334 
335 		default:
336 			pr_err("%s: unknown relocation: %u\n",
337 			       module->name, ELF32_R_TYPE(rel->r_info));
338 			return -ENOEXEC;
339 		}
340 	}
341 	return 0;
342 }
343 
344 struct mod_unwind_map {
345 	const Elf_Shdr *unw_sec;
346 	const Elf_Shdr *txt_sec;
347 };
348 
349 static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
350 	const Elf_Shdr *sechdrs, const char *name)
351 {
352 	const Elf_Shdr *s, *se;
353 	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
354 
355 	for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
356 		if (strcmp(name, secstrs + s->sh_name) == 0)
357 			return s;
358 
359 	return NULL;
360 }
361 
362 extern void fixup_pv_table(const void *, unsigned long);
363 extern void fixup_smp(const void *, unsigned long);
364 
365 int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
366 		    struct module *mod)
367 {
368 	const Elf_Shdr *s = NULL;
369 #ifdef CONFIG_ARM_UNWIND
370 	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
371 	const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
372 	struct mod_unwind_map maps[ARM_SEC_MAX];
373 	int i;
374 
375 	memset(maps, 0, sizeof(maps));
376 
377 	for (s = sechdrs; s < sechdrs_end; s++) {
378 		const char *secname = secstrs + s->sh_name;
379 
380 		if (!(s->sh_flags & SHF_ALLOC))
381 			continue;
382 
383 		if (strcmp(".ARM.exidx.init.text", secname) == 0)
384 			maps[ARM_SEC_INIT].unw_sec = s;
385 		else if (strcmp(".ARM.exidx", secname) == 0)
386 			maps[ARM_SEC_CORE].unw_sec = s;
387 		else if (strcmp(".ARM.exidx.exit.text", secname) == 0)
388 			maps[ARM_SEC_EXIT].unw_sec = s;
389 		else if (strcmp(".ARM.exidx.text.unlikely", secname) == 0)
390 			maps[ARM_SEC_UNLIKELY].unw_sec = s;
391 		else if (strcmp(".ARM.exidx.text.hot", secname) == 0)
392 			maps[ARM_SEC_HOT].unw_sec = s;
393 		else if (strcmp(".init.text", secname) == 0)
394 			maps[ARM_SEC_INIT].txt_sec = s;
395 		else if (strcmp(".text", secname) == 0)
396 			maps[ARM_SEC_CORE].txt_sec = s;
397 		else if (strcmp(".exit.text", secname) == 0)
398 			maps[ARM_SEC_EXIT].txt_sec = s;
399 		else if (strcmp(".text.unlikely", secname) == 0)
400 			maps[ARM_SEC_UNLIKELY].txt_sec = s;
401 		else if (strcmp(".text.hot", secname) == 0)
402 			maps[ARM_SEC_HOT].txt_sec = s;
403 	}
404 
405 	for (i = 0; i < ARM_SEC_MAX; i++)
406 		if (maps[i].unw_sec && maps[i].txt_sec)
407 			mod->arch.unwind[i] =
408 				unwind_table_add(maps[i].unw_sec->sh_addr,
409 					         maps[i].unw_sec->sh_size,
410 					         maps[i].txt_sec->sh_addr,
411 					         maps[i].txt_sec->sh_size);
412 #endif
413 #ifdef CONFIG_ARM_PATCH_PHYS_VIRT
414 	s = find_mod_section(hdr, sechdrs, ".pv_table");
415 	if (s)
416 		fixup_pv_table((void *)s->sh_addr, s->sh_size);
417 #endif
418 	s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
419 	if (s && !is_smp())
420 #ifdef CONFIG_SMP_ON_UP
421 		fixup_smp((void *)s->sh_addr, s->sh_size);
422 #else
423 		return -EINVAL;
424 #endif
425 	return 0;
426 }
427 
428 void
429 module_arch_cleanup(struct module *mod)
430 {
431 #ifdef CONFIG_ARM_UNWIND
432 	int i;
433 
434 	for (i = 0; i < ARM_SEC_MAX; i++) {
435 		unwind_table_del(mod->arch.unwind[i]);
436 		mod->arch.unwind[i] = NULL;
437 	}
438 #endif
439 }
440 
441 void __weak module_arch_freeing_init(struct module *mod)
442 {
443 #ifdef CONFIG_ARM_UNWIND
444 	unwind_table_del(mod->arch.unwind[ARM_SEC_INIT]);
445 	mod->arch.unwind[ARM_SEC_INIT] = NULL;
446 #endif
447 }
448