1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Kernel module help for x86.
3 Copyright (C) 2001 Rusty Russell.
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/moduleloader.h>
10 #include <linux/elf.h>
11 #include <linux/vmalloc.h>
13 #include <linux/string.h>
14 #include <linux/kernel.h>
15 #include <linux/kasan.h>
16 #include <linux/bug.h>
18 #include <linux/gfp.h>
19 #include <linux/jump_label.h>
20 #include <linux/random.h>
21 #include <linux/memory.h>
23 #include <asm/text-patching.h>
25 #include <asm/setup.h>
26 #include <asm/unwind.h>
29 #define DEBUGP(fmt, ...) \
30 printk(KERN_DEBUG fmt, ##__VA_ARGS__)
32 #define DEBUGP(fmt, ...) \
35 printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
39 #ifdef CONFIG_RANDOMIZE_BASE
40 static unsigned long module_load_offset;
42 /* Mutex protects the module_load_offset. */
43 static DEFINE_MUTEX(module_kaslr_mutex);
45 static unsigned long int get_module_load_offset(void)
47 if (kaslr_enabled()) {
48 mutex_lock(&module_kaslr_mutex);
50 * Calculate the module_load_offset the first time this
51 * code is called. Once calculated it stays the same until
54 if (module_load_offset == 0)
56 get_random_u32_inclusive(1, 1024) * PAGE_SIZE;
57 mutex_unlock(&module_kaslr_mutex);
59 return module_load_offset;
62 static unsigned long int get_module_load_offset(void)
68 void *module_alloc(unsigned long size)
70 gfp_t gfp_mask = GFP_KERNEL;
73 if (PAGE_ALIGN(size) > MODULES_LEN)
76 p = __vmalloc_node_range(size, MODULE_ALIGN,
77 MODULES_VADDR + get_module_load_offset(),
78 MODULES_END, gfp_mask, PAGE_KERNEL,
79 VM_FLUSH_RESET_PERMS | VM_DEFER_KMEMLEAK,
80 NUMA_NO_NODE, __builtin_return_address(0));
82 if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
91 int apply_relocate(Elf32_Shdr *sechdrs,
93 unsigned int symindex,
98 Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;
102 DEBUGP("Applying relocate section %u to %u\n",
103 relsec, sechdrs[relsec].sh_info);
104 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
105 /* This is where to make the change */
106 location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
108 /* This is the symbol it is referring to. Note that all
109 undefined symbols have been resolved. */
110 sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
111 + ELF32_R_SYM(rel[i].r_info);
113 switch (ELF32_R_TYPE(rel[i].r_info)) {
115 /* We add the value into the location given */
116 *location += sym->st_value;
120 /* Add the value, subtract its position */
121 *location += sym->st_value - (uint32_t)location;
124 pr_err("%s: Unknown relocation: %u\n",
125 me->name, ELF32_R_TYPE(rel[i].r_info));
132 static int __write_relocate_add(Elf64_Shdr *sechdrs,
134 unsigned int symindex,
137 void *(*write)(void *dest, const void *src, size_t len),
141 Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;
147 DEBUGP("%s relocate section %u to %u\n",
148 apply ? "Applying" : "Clearing",
149 relsec, sechdrs[relsec].sh_info);
150 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
153 /* This is where to make the change */
154 loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
157 /* This is the symbol it is referring to. Note that all
158 undefined symbols have been resolved. */
159 sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
160 + ELF64_R_SYM(rel[i].r_info);
162 DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",
163 (int)ELF64_R_TYPE(rel[i].r_info),
164 sym->st_value, rel[i].r_addend, (u64)loc);
166 val = sym->st_value + rel[i].r_addend;
168 switch (ELF64_R_TYPE(rel[i].r_info)) {
170 continue; /* nothing to write */
175 if (val != *(u32 *)&val)
180 if ((s64)val != *(s32 *)&val)
194 pr_err("%s: Unknown rela relocation: %llu\n",
195 me->name, ELF64_R_TYPE(rel[i].r_info));
200 if (memcmp(loc, &zero, size)) {
201 pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
202 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
205 write(loc, &val, size);
207 if (memcmp(loc, &val, size)) {
208 pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
209 (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
212 write(loc, &zero, size);
218 pr_err("overflow in relocation type %d val %Lx\n",
219 (int)ELF64_R_TYPE(rel[i].r_info), val);
220 pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
225 static int write_relocate_add(Elf64_Shdr *sechdrs,
227 unsigned int symindex,
233 bool early = me->state == MODULE_STATE_UNFORMED;
234 void *(*write)(void *, const void *, size_t) = memcpy;
238 mutex_lock(&text_mutex);
241 ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,
246 mutex_unlock(&text_mutex);
252 int apply_relocate_add(Elf64_Shdr *sechdrs,
254 unsigned int symindex,
258 return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);
261 #ifdef CONFIG_LIVEPATCH
262 void clear_relocate_add(Elf64_Shdr *sechdrs,
264 unsigned int symindex,
268 write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);
274 int module_finalize(const Elf_Ehdr *hdr,
275 const Elf_Shdr *sechdrs,
278 const Elf_Shdr *s, *alt = NULL, *locks = NULL,
279 *para = NULL, *orc = NULL, *orc_ip = NULL,
280 *retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,
281 *calls = NULL, *cfi = NULL;
282 char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
284 for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
285 if (!strcmp(".altinstructions", secstrings + s->sh_name))
287 if (!strcmp(".smp_locks", secstrings + s->sh_name))
289 if (!strcmp(".parainstructions", secstrings + s->sh_name))
291 if (!strcmp(".orc_unwind", secstrings + s->sh_name))
293 if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))
295 if (!strcmp(".retpoline_sites", secstrings + s->sh_name))
297 if (!strcmp(".return_sites", secstrings + s->sh_name))
299 if (!strcmp(".call_sites", secstrings + s->sh_name))
301 if (!strcmp(".cfi_sites", secstrings + s->sh_name))
303 if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))
308 * See alternative_instructions() for the ordering rules between the
309 * various patching types.
312 void *pseg = (void *)para->sh_addr;
313 apply_paravirt(pseg, pseg + para->sh_size);
315 if (retpolines || cfi) {
316 void *rseg = NULL, *cseg = NULL;
317 unsigned int rsize = 0, csize = 0;
320 rseg = (void *)retpolines->sh_addr;
321 rsize = retpolines->sh_size;
325 cseg = (void *)cfi->sh_addr;
326 csize = cfi->sh_size;
329 apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize);
332 void *rseg = (void *)retpolines->sh_addr;
333 apply_retpolines(rseg, rseg + retpolines->sh_size);
336 void *rseg = (void *)returns->sh_addr;
337 apply_returns(rseg, rseg + returns->sh_size);
340 /* patch .altinstructions */
341 void *aseg = (void *)alt->sh_addr;
342 apply_alternatives(aseg, aseg + alt->sh_size);
345 struct callthunk_sites cs = {};
348 cs.call_start = (void *)calls->sh_addr;
349 cs.call_end = (void *)calls->sh_addr + calls->sh_size;
353 cs.pv_start = (void *)para->sh_addr;
354 cs.pv_end = (void *)para->sh_addr + para->sh_size;
357 callthunks_patch_module_calls(&cs, me);
360 void *iseg = (void *)ibt_endbr->sh_addr;
361 apply_ibt_endbr(iseg, iseg + ibt_endbr->sh_size);
364 void *lseg = (void *)locks->sh_addr;
365 void *text = me->core_layout.base;
366 void *text_end = text + me->core_layout.text_size;
367 alternatives_smp_module_add(me, me->name,
368 lseg, lseg + locks->sh_size,
373 unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
374 (void *)orc->sh_addr, orc->sh_size);
379 void module_arch_cleanup(struct module *mod)
381 alternatives_smp_module_del(mod);