1/*  Kernel module help for x86.
2    Copyright (C) 2001 Rusty Russell.
3
4    This program is free software; you can redistribute it and/or modify
5    it under the terms of the GNU General Public License as published by
6    the Free Software Foundation; either version 2 of the License, or
7    (at your option) any later version.
8
9    This program is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12    GNU General Public License for more details.
13
14    You should have received a copy of the GNU General Public License
15    along with this program; if not, write to the Free Software
16    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17*/
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/moduleloader.h>
22#include <linux/elf.h>
23#include <linux/vmalloc.h>
24#include <linux/fs.h>
25#include <linux/string.h>
26#include <linux/kernel.h>
27#include <linux/kasan.h>
28#include <linux/bug.h>
29#include <linux/mm.h>
30#include <linux/gfp.h>
31#include <linux/jump_label.h>
32#include <linux/random.h>
33
34#include <asm/page.h>
35#include <asm/pgtable.h>
36#include <asm/setup.h>
37
38#if 0
39#define DEBUGP(fmt, ...)				\
40	printk(KERN_DEBUG fmt, ##__VA_ARGS__)
41#else
42#define DEBUGP(fmt, ...)				\
43do {							\
44	if (0)						\
45		printk(KERN_DEBUG fmt, ##__VA_ARGS__);	\
46} while (0)
47#endif
48
49#ifdef CONFIG_RANDOMIZE_BASE
50static unsigned long module_load_offset;
51
52/* Mutex protects the module_load_offset. */
53static DEFINE_MUTEX(module_kaslr_mutex);
54
55static unsigned long int get_module_load_offset(void)
56{
57	if (kaslr_enabled()) {
58		mutex_lock(&module_kaslr_mutex);
59		/*
60		 * Calculate the module_load_offset the first time this
61		 * code is called. Once calculated it stays the same until
62		 * reboot.
63		 */
64		if (module_load_offset == 0)
65			module_load_offset =
66				(get_random_int() % 1024 + 1) * PAGE_SIZE;
67		mutex_unlock(&module_kaslr_mutex);
68	}
69	return module_load_offset;
70}
71#else
72static unsigned long int get_module_load_offset(void)
73{
74	return 0;
75}
76#endif
77
78void *module_alloc(unsigned long size)
79{
80	void *p;
81
82	if (PAGE_ALIGN(size) > MODULES_LEN)
83		return NULL;
84
85	p = __vmalloc_node_range(size, MODULE_ALIGN,
86				    MODULES_VADDR + get_module_load_offset(),
87				    MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
88				    PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
89				    __builtin_return_address(0));
90	if (p && (kasan_module_alloc(p, size) < 0)) {
91		vfree(p);
92		return NULL;
93	}
94
95	return p;
96}
97
98#ifdef CONFIG_X86_32
99int apply_relocate(Elf32_Shdr *sechdrs,
100		   const char *strtab,
101		   unsigned int symindex,
102		   unsigned int relsec,
103		   struct module *me)
104{
105	unsigned int i;
106	Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
107	Elf32_Sym *sym;
108	uint32_t *location;
109
110	DEBUGP("Applying relocate section %u to %u\n",
111	       relsec, sechdrs[relsec].sh_info);
112	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
113		/* This is where to make the change */
114		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
115			+ rel[i].r_offset;
116		/* This is the symbol it is referring to.  Note that all
117		   undefined symbols have been resolved.  */
118		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
119			+ ELF32_R_SYM(rel[i].r_info);
120
121		switch (ELF32_R_TYPE(rel[i].r_info)) {
122		case R_386_32:
123			/* We add the value into the location given */
124			*location += sym->st_value;
125			break;
126		case R_386_PC32:
127			/* Add the value, subtract its position */
128			*location += sym->st_value - (uint32_t)location;
129			break;
130		default:
131			pr_err("%s: Unknown relocation: %u\n",
132			       me->name, ELF32_R_TYPE(rel[i].r_info));
133			return -ENOEXEC;
134		}
135	}
136	return 0;
137}
138#else /*X86_64*/
139int apply_relocate_add(Elf64_Shdr *sechdrs,
140		   const char *strtab,
141		   unsigned int symindex,
142		   unsigned int relsec,
143		   struct module *me)
144{
145	unsigned int i;
146	Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
147	Elf64_Sym *sym;
148	void *loc;
149	u64 val;
150
151	DEBUGP("Applying relocate section %u to %u\n",
152	       relsec, sechdrs[relsec].sh_info);
153	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
154		/* This is where to make the change */
155		loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
156			+ rel[i].r_offset;
157
158		/* This is the symbol it is referring to.  Note that all
159		   undefined symbols have been resolved.  */
160		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
161			+ ELF64_R_SYM(rel[i].r_info);
162
163		DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
164		       (int)ELF64_R_TYPE(rel[i].r_info),
165		       sym->st_value, rel[i].r_addend, (u64)loc);
166
167		val = sym->st_value + rel[i].r_addend;
168
169		switch (ELF64_R_TYPE(rel[i].r_info)) {
170		case R_X86_64_NONE:
171			break;
172		case R_X86_64_64:
173			*(u64 *)loc = val;
174			break;
175		case R_X86_64_32:
176			*(u32 *)loc = val;
177			if (val != *(u32 *)loc)
178				goto overflow;
179			break;
180		case R_X86_64_32S:
181			*(s32 *)loc = val;
182			if ((s64)val != *(s32 *)loc)
183				goto overflow;
184			break;
185		case R_X86_64_PC32:
186			val -= (u64)loc;
187			*(u32 *)loc = val;
188#if 0
189			if ((s64)val != *(s32 *)loc)
190				goto overflow;
191#endif
192			break;
193		default:
194			pr_err("%s: Unknown rela relocation: %llu\n",
195			       me->name, ELF64_R_TYPE(rel[i].r_info));
196			return -ENOEXEC;
197		}
198	}
199	return 0;
200
201overflow:
202	pr_err("overflow in relocation type %d val %Lx\n",
203	       (int)ELF64_R_TYPE(rel[i].r_info), val);
204	pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
205	       me->name);
206	return -ENOEXEC;
207}
208#endif
209
210int module_finalize(const Elf_Ehdr *hdr,
211		    const Elf_Shdr *sechdrs,
212		    struct module *me)
213{
214	const Elf_Shdr *s, *text = NULL, *alt = NULL, *locks = NULL,
215		*para = NULL;
216	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
217
218	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
219		if (!strcmp(".text", secstrings + s->sh_name))
220			text = s;
221		if (!strcmp(".altinstructions", secstrings + s->sh_name))
222			alt = s;
223		if (!strcmp(".smp_locks", secstrings + s->sh_name))
224			locks = s;
225		if (!strcmp(".parainstructions", secstrings + s->sh_name))
226			para = s;
227	}
228
229	if (alt) {
230		/* patch .altinstructions */
231		void *aseg = (void *)alt->sh_addr;
232		apply_alternatives(aseg, aseg + alt->sh_size);
233	}
234	if (locks && text) {
235		void *lseg = (void *)locks->sh_addr;
236		void *tseg = (void *)text->sh_addr;
237		alternatives_smp_module_add(me, me->name,
238					    lseg, lseg + locks->sh_size,
239					    tseg, tseg + text->sh_size);
240	}
241
242	if (para) {
243		void *pseg = (void *)para->sh_addr;
244		apply_paravirt(pseg, pseg + para->sh_size);
245	}
246
247	/* make jump label nops */
248	jump_label_apply_nops(me);
249
250	return 0;
251}
252
253void module_arch_cleanup(struct module *mod)
254{
255	alternatives_smp_module_del(mod);
256}
257