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
37void *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
57bool 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
64bool 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#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
72/*
73 * This implements the partitioning algorithm for group relocations as
74 * documented in the ARM AArch32 ELF psABI (IHI 0044).
75 *
76 * A single PC-relative symbol reference is divided in up to 3 add or subtract
77 * operations, where the final one could be incorporated into a load/store
78 * instruction with immediate offset. E.g.,
79 *
80 *   ADD	Rd, PC, #...		or	ADD	Rd, PC, #...
81 *   ADD	Rd, Rd, #...			ADD	Rd, Rd, #...
82 *   LDR	Rd, [Rd, #...]			ADD	Rd, Rd, #...
83 *
84 * The latter has a guaranteed range of only 16 MiB (3x8 == 24 bits), so it is
85 * of limited use in the kernel. However, the ADD/ADD/LDR combo has a range of
86 * -/+ 256 MiB, (2x8 + 12 == 28 bits), which means it has sufficient range for
87 * any in-kernel symbol reference (unless module PLTs are being used).
88 *
89 * The main advantage of this approach over the typical pattern using a literal
90 * load is that literal loads may miss in the D-cache, and generally lead to
91 * lower cache efficiency for variables that are referenced often from many
92 * different places in the code.
93 */
94static u32 get_group_rem(u32 group, u32 *offset)
95{
96	u32 val = *offset;
97	u32 shift;
98	do {
99		shift = val ? (31 - __fls(val)) & ~1 : 32;
100		*offset = val;
101		if (!val)
102			break;
103		val &= 0xffffff >> shift;
104	} while (group--);
105	return shift;
106}
107#endif
108
109int
110apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
111	       unsigned int relindex, struct module *module)
112{
113	Elf32_Shdr *symsec = sechdrs + symindex;
114	Elf32_Shdr *relsec = sechdrs + relindex;
115	Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
116	Elf32_Rel *rel = (void *)relsec->sh_addr;
117	unsigned int i;
118
119	for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++, rel++) {
120		unsigned long loc;
121		Elf32_Sym *sym;
122		const char *symname;
123#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
124		u32 shift, group = 1;
125#endif
126		s32 offset;
127		u32 tmp;
128#ifdef CONFIG_THUMB2_KERNEL
129		u32 upper, lower, sign, j1, j2;
130#endif
131
132		offset = ELF32_R_SYM(rel->r_info);
133		if (offset < 0 || offset > (symsec->sh_size / sizeof(Elf32_Sym))) {
134			pr_err("%s: section %u reloc %u: bad relocation sym offset\n",
135				module->name, relindex, i);
136			return -ENOEXEC;
137		}
138
139		sym = ((Elf32_Sym *)symsec->sh_addr) + offset;
140		symname = strtab + sym->st_name;
141
142		if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(u32)) {
143			pr_err("%s: section %u reloc %u sym '%s': out of bounds relocation, offset %d size %u\n",
144			       module->name, relindex, i, symname,
145			       rel->r_offset, dstsec->sh_size);
146			return -ENOEXEC;
147		}
148
149		loc = dstsec->sh_addr + rel->r_offset;
150
151		switch (ELF32_R_TYPE(rel->r_info)) {
152		case R_ARM_NONE:
153			/* ignore */
154			break;
155
156		case R_ARM_ABS32:
157		case R_ARM_TARGET1:
158			*(u32 *)loc += sym->st_value;
159			break;
160
161		case R_ARM_PC24:
162		case R_ARM_CALL:
163		case R_ARM_JUMP24:
164			if (sym->st_value & 3) {
165				pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (ARM -> Thumb)\n",
166				       module->name, relindex, i, symname);
167				return -ENOEXEC;
168			}
169
170			offset = __mem_to_opcode_arm(*(u32 *)loc);
171			offset = (offset & 0x00ffffff) << 2;
172			offset = sign_extend32(offset, 25);
173
174			offset += sym->st_value - loc;
175
176			/*
177			 * Route through a PLT entry if 'offset' exceeds the
178			 * supported range. Note that 'offset + loc + 8'
179			 * contains the absolute jump target, i.e.,
180			 * @sym + addend, corrected for the +8 PC bias.
181			 */
182			if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
183			    (offset <= (s32)0xfe000000 ||
184			     offset >= (s32)0x02000000))
185				offset = get_module_plt(module, loc,
186							offset + loc + 8)
187					 - loc - 8;
188
189			if (offset <= (s32)0xfe000000 ||
190			    offset >= (s32)0x02000000) {
191				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
192				       module->name, relindex, i, symname,
193				       ELF32_R_TYPE(rel->r_info), loc,
194				       sym->st_value);
195				return -ENOEXEC;
196			}
197
198			offset >>= 2;
199			offset &= 0x00ffffff;
200
201			*(u32 *)loc &= __opcode_to_mem_arm(0xff000000);
202			*(u32 *)loc |= __opcode_to_mem_arm(offset);
203			break;
204
205	       case R_ARM_V4BX:
206		       /* Preserve Rm and the condition code. Alter
207			* other bits to re-code instruction as
208			* MOV PC,Rm.
209			*/
210		       *(u32 *)loc &= __opcode_to_mem_arm(0xf000000f);
211		       *(u32 *)loc |= __opcode_to_mem_arm(0x01a0f000);
212		       break;
213
214		case R_ARM_PREL31:
215			offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
216			offset += sym->st_value - loc;
217			if (offset >= 0x40000000 || offset < -0x40000000) {
218				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
219				       module->name, relindex, i, symname,
220				       ELF32_R_TYPE(rel->r_info), loc,
221				       sym->st_value);
222				return -ENOEXEC;
223			}
224			*(u32 *)loc &= 0x80000000;
225			*(u32 *)loc |= offset & 0x7fffffff;
226			break;
227
228		case R_ARM_REL32:
229			*(u32 *)loc += sym->st_value - loc;
230			break;
231
232		case R_ARM_MOVW_ABS_NC:
233		case R_ARM_MOVT_ABS:
234		case R_ARM_MOVW_PREL_NC:
235		case R_ARM_MOVT_PREL:
236			offset = tmp = __mem_to_opcode_arm(*(u32 *)loc);
237			offset = ((offset & 0xf0000) >> 4) | (offset & 0xfff);
238			offset = sign_extend32(offset, 15);
239
240			offset += sym->st_value;
241			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL ||
242			    ELF32_R_TYPE(rel->r_info) == R_ARM_MOVW_PREL_NC)
243				offset -= loc;
244			if (ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_ABS ||
245			    ELF32_R_TYPE(rel->r_info) == R_ARM_MOVT_PREL)
246				offset >>= 16;
247
248			tmp &= 0xfff0f000;
249			tmp |= ((offset & 0xf000) << 4) |
250				(offset & 0x0fff);
251
252			*(u32 *)loc = __opcode_to_mem_arm(tmp);
253			break;
254
255#ifdef CONFIG_ARM_HAS_GROUP_RELOCS
256		case R_ARM_ALU_PC_G0_NC:
257			group = 0;
258			fallthrough;
259		case R_ARM_ALU_PC_G1_NC:
260			tmp = __mem_to_opcode_arm(*(u32 *)loc);
261			offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7);
262			if (tmp & BIT(22))
263				offset = -offset;
264			offset += sym->st_value - loc;
265			if (offset < 0) {
266				offset = -offset;
267				tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode
268			} else {
269				tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode
270			}
271
272			shift = get_group_rem(group, &offset);
273			if (shift < 24) {
274				offset >>= 24 - shift;
275				offset |= (shift + 8) << 7;
276			}
277			*(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
278			break;
279
280		case R_ARM_LDR_PC_G2:
281			tmp = __mem_to_opcode_arm(*(u32 *)loc);
282			offset = tmp & 0xfff;
283			if (~tmp & BIT(23))		// U bit cleared?
284				offset = -offset;
285			offset += sym->st_value - loc;
286			if (offset < 0) {
287				offset = -offset;
288				tmp &= ~BIT(23);	// clear U bit
289			} else {
290				tmp |= BIT(23);		// set U bit
291			}
292			get_group_rem(2, &offset);
293
294			if (offset > 0xfff) {
295				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
296				       module->name, relindex, i, symname,
297				       ELF32_R_TYPE(rel->r_info), loc,
298				       sym->st_value);
299				return -ENOEXEC;
300			}
301			*(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset);
302			break;
303#endif
304#ifdef CONFIG_THUMB2_KERNEL
305		case R_ARM_THM_CALL:
306		case R_ARM_THM_JUMP24:
307			/*
308			 * For function symbols, only Thumb addresses are
309			 * allowed (no interworking).
310			 *
311			 * For non-function symbols, the destination
312			 * has no specific ARM/Thumb disposition, so
313			 * the branch is resolved under the assumption
314			 * that interworking is not required.
315			 */
316			if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
317			    !(sym->st_value & 1)) {
318				pr_err("%s: section %u reloc %u sym '%s': unsupported interworking call (Thumb -> ARM)\n",
319				       module->name, relindex, i, symname);
320				return -ENOEXEC;
321			}
322
323			upper = __mem_to_opcode_thumb16(*(u16 *)loc);
324			lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
325
326			/*
327			 * 25 bit signed address range (Thumb-2 BL and B.W
328			 * instructions):
329			 *   S:I1:I2:imm10:imm11:0
330			 * where:
331			 *   S     = upper[10]   = offset[24]
332			 *   I1    = ~(J1 ^ S)   = offset[23]
333			 *   I2    = ~(J2 ^ S)   = offset[22]
334			 *   imm10 = upper[9:0]  = offset[21:12]
335			 *   imm11 = lower[10:0] = offset[11:1]
336			 *   J1    = lower[13]
337			 *   J2    = lower[11]
338			 */
339			sign = (upper >> 10) & 1;
340			j1 = (lower >> 13) & 1;
341			j2 = (lower >> 11) & 1;
342			offset = (sign << 24) | ((~(j1 ^ sign) & 1) << 23) |
343				((~(j2 ^ sign) & 1) << 22) |
344				((upper & 0x03ff) << 12) |
345				((lower & 0x07ff) << 1);
346			offset = sign_extend32(offset, 24);
347			offset += sym->st_value - loc;
348
349			/*
350			 * Route through a PLT entry if 'offset' exceeds the
351			 * supported range.
352			 */
353			if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS) &&
354			    (offset <= (s32)0xff000000 ||
355			     offset >= (s32)0x01000000))
356				offset = get_module_plt(module, loc,
357							offset + loc + 4)
358					 - loc - 4;
359
360			if (offset <= (s32)0xff000000 ||
361			    offset >= (s32)0x01000000) {
362				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
363				       module->name, relindex, i, symname,
364				       ELF32_R_TYPE(rel->r_info), loc,
365				       sym->st_value);
366				return -ENOEXEC;
367			}
368
369			sign = (offset >> 24) & 1;
370			j1 = sign ^ (~(offset >> 23) & 1);
371			j2 = sign ^ (~(offset >> 22) & 1);
372			upper = (u16)((upper & 0xf800) | (sign << 10) |
373					    ((offset >> 12) & 0x03ff));
374			lower = (u16)((lower & 0xd000) |
375				      (j1 << 13) | (j2 << 11) |
376				      ((offset >> 1) & 0x07ff));
377
378			*(u16 *)loc = __opcode_to_mem_thumb16(upper);
379			*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
380			break;
381
382		case R_ARM_THM_MOVW_ABS_NC:
383		case R_ARM_THM_MOVT_ABS:
384		case R_ARM_THM_MOVW_PREL_NC:
385		case R_ARM_THM_MOVT_PREL:
386			upper = __mem_to_opcode_thumb16(*(u16 *)loc);
387			lower = __mem_to_opcode_thumb16(*(u16 *)(loc + 2));
388
389			/*
390			 * MOVT/MOVW instructions encoding in Thumb-2:
391			 *
392			 * i	= upper[10]
393			 * imm4	= upper[3:0]
394			 * imm3	= lower[14:12]
395			 * imm8	= lower[7:0]
396			 *
397			 * imm16 = imm4:i:imm3:imm8
398			 */
399			offset = ((upper & 0x000f) << 12) |
400				((upper & 0x0400) << 1) |
401				((lower & 0x7000) >> 4) | (lower & 0x00ff);
402			offset = sign_extend32(offset, 15);
403			offset += sym->st_value;
404
405			if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL ||
406			    ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVW_PREL_NC)
407				offset -= loc;
408			if (ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_ABS ||
409			    ELF32_R_TYPE(rel->r_info) == R_ARM_THM_MOVT_PREL)
410				offset >>= 16;
411
412			upper = (u16)((upper & 0xfbf0) |
413				      ((offset & 0xf000) >> 12) |
414				      ((offset & 0x0800) >> 1));
415			lower = (u16)((lower & 0x8f00) |
416				      ((offset & 0x0700) << 4) |
417				      (offset & 0x00ff));
418			*(u16 *)loc = __opcode_to_mem_thumb16(upper);
419			*(u16 *)(loc + 2) = __opcode_to_mem_thumb16(lower);
420			break;
421#endif
422
423		default:
424			pr_err("%s: unknown relocation: %u\n",
425			       module->name, ELF32_R_TYPE(rel->r_info));
426			return -ENOEXEC;
427		}
428	}
429	return 0;
430}
431
432struct mod_unwind_map {
433	const Elf_Shdr *unw_sec;
434	const Elf_Shdr *txt_sec;
435};
436
437static const Elf_Shdr *find_mod_section(const Elf32_Ehdr *hdr,
438	const Elf_Shdr *sechdrs, const char *name)
439{
440	const Elf_Shdr *s, *se;
441	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
442
443	for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++)
444		if (strcmp(name, secstrs + s->sh_name) == 0)
445			return s;
446
447	return NULL;
448}
449
450extern void fixup_pv_table(const void *, unsigned long);
451extern void fixup_smp(const void *, unsigned long);
452
453int module_finalize(const Elf32_Ehdr *hdr, const Elf_Shdr *sechdrs,
454		    struct module *mod)
455{
456	const Elf_Shdr *s = NULL;
457#ifdef CONFIG_ARM_UNWIND
458	const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
459	const Elf_Shdr *sechdrs_end = sechdrs + hdr->e_shnum;
460	struct list_head *unwind_list = &mod->arch.unwind_list;
461
462	INIT_LIST_HEAD(unwind_list);
463	mod->arch.init_table = NULL;
464
465	for (s = sechdrs; s < sechdrs_end; s++) {
466		const char *secname = secstrs + s->sh_name;
467		const char *txtname;
468		const Elf_Shdr *txt_sec;
469
470		if (!(s->sh_flags & SHF_ALLOC) ||
471		    s->sh_type != ELF_SECTION_UNWIND)
472			continue;
473
474		if (!strcmp(".ARM.exidx", secname))
475			txtname = ".text";
476		else
477			txtname = secname + strlen(".ARM.exidx");
478		txt_sec = find_mod_section(hdr, sechdrs, txtname);
479
480		if (txt_sec) {
481			struct unwind_table *table =
482				unwind_table_add(s->sh_addr,
483						s->sh_size,
484						txt_sec->sh_addr,
485						txt_sec->sh_size);
486
487			list_add(&table->mod_list, unwind_list);
488
489			/* save init table for module_arch_freeing_init */
490			if (strcmp(".ARM.exidx.init.text", secname) == 0)
491				mod->arch.init_table = table;
492		}
493	}
494#endif
495#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
496	s = find_mod_section(hdr, sechdrs, ".pv_table");
497	if (s)
498		fixup_pv_table((void *)s->sh_addr, s->sh_size);
499#endif
500	s = find_mod_section(hdr, sechdrs, ".alt.smp.init");
501	if (s && !is_smp())
502#ifdef CONFIG_SMP_ON_UP
503		fixup_smp((void *)s->sh_addr, s->sh_size);
504#else
505		return -EINVAL;
506#endif
507	return 0;
508}
509
510void
511module_arch_cleanup(struct module *mod)
512{
513#ifdef CONFIG_ARM_UNWIND
514	struct unwind_table *tmp;
515	struct unwind_table *n;
516
517	list_for_each_entry_safe(tmp, n,
518			&mod->arch.unwind_list, mod_list) {
519		list_del(&tmp->mod_list);
520		unwind_table_del(tmp);
521	}
522	mod->arch.init_table = NULL;
523#endif
524}
525
526void __weak module_arch_freeing_init(struct module *mod)
527{
528#ifdef CONFIG_ARM_UNWIND
529	struct unwind_table *init = mod->arch.init_table;
530
531	if (init) {
532		mod->arch.init_table = NULL;
533		list_del(&init->mod_list);
534		unwind_table_del(init);
535	}
536#endif
537}
538