// SPDX-License-Identifier: GPL-2.0-or-later/*  Kernel module help for x86.    Copyright (C) 2001 Rusty Russell. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/moduleloader.h>#include <linux/elf.h>#include <linux/vmalloc.h>#include <linux/fs.h>#include <linux/string.h>#include <linux/kernel.h>#include <linux/kasan.h>#include <linux/bug.h>#include <linux/mm.h>#include <linux/gfp.h>#include <linux/jump_label.h>#include <linux/random.h>#include <linux/memory.h> #include <asm/text-patching.h>#include <asm/page.h>#include <asm/setup.h>#include <asm/unwind.h> #if 0#define DEBUGP(fmt, ...)				\	printk(KERN_DEBUG fmt, ##__VA_ARGS__)#else#define DEBUGP(fmt, ...)				\do {							\	if (0)						\		printk(KERN_DEBUG fmt, ##__VA_ARGS__);	\} while (0)#endif #ifdef CONFIG_X86_32int apply_relocate(Elf32_Shdr *sechdrs,		   const char *strtab,		   unsigned int symindex,		   unsigned int relsec,		   struct module *me){	unsigned int i;	Elf32_Rel *rel = (void *)sechdrs[relsec].sh_addr;	Elf32_Sym *sym;	uint32_t *location; 	DEBUGP("Applying relocate section %u to %u\n",	       relsec, sechdrs[relsec].sh_info);	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {		/* This is where to make the change */		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr			+ rel[i].r_offset;		/* This is the symbol it is referring to.  Note that all		   undefined symbols have been resolved.  */		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr			+ ELF32_R_SYM(rel[i].r_info); 		switch (ELF32_R_TYPE(rel[i].r_info)) {		case R_386_32:			/* We add the value into the location given */			*location += sym->st_value;			break;		case R_386_PC32:		case R_386_PLT32:			/* Add the value, subtract its position */			*location += sym->st_value - (uint32_t)location;			break;		default:			pr_err("%s: Unknown relocation: %u\n",			       me->name, ELF32_R_TYPE(rel[i].r_info));			return -ENOEXEC;		}	}	return 0;}#else /*X86_64*/static int __write_relocate_add(Elf64_Shdr *sechdrs,		   const char *strtab,		   unsigned int symindex,		   unsigned int relsec,		   struct module *me,		   void *(*write)(void *dest, const void *src, size_t len),		   bool apply){	unsigned int i;	Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr;	Elf64_Sym *sym;	void *loc;	u64 val;	u64 zero = 0ULL; 	DEBUGP("%s relocate section %u to %u\n",	       apply ? "Applying" : "Clearing",	       relsec, sechdrs[relsec].sh_info); 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {		size_t size; 		/* This is where to make the change */		loc = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr			+ rel[i].r_offset; 		/* This is the symbol it is referring to.  Note that all		   undefined symbols have been resolved.  */		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr			+ ELF64_R_SYM(rel[i].r_info); 		DEBUGP("type %d st_value %Lx r_addend %Lx loc %Lx\n",		       (int)ELF64_R_TYPE(rel[i].r_info),		       sym->st_value, rel[i].r_addend, (u64)loc); 		val = sym->st_value + rel[i].r_addend; 		switch (ELF64_R_TYPE(rel[i].r_info)) {		case R_X86_64_NONE:			continue;  /* nothing to write */		case R_X86_64_64:			size = 8;			break;		case R_X86_64_32:			if (val != *(u32 *)&val)				goto overflow;			size = 4;			break;		case R_X86_64_32S:			if ((s64)val != *(s32 *)&val)				goto overflow;			size = 4;			break;		case R_X86_64_PC32:		case R_X86_64_PLT32:			val -= (u64)loc;			size = 4;			break;		case R_X86_64_PC64:			val -= (u64)loc;			size = 8;			break;		default:			pr_err("%s: Unknown rela relocation: %llu\n",			       me->name, ELF64_R_TYPE(rel[i].r_info));			return -ENOEXEC;		} 		if (apply) {			if (memcmp(loc, &zero, size)) {				pr_err("x86/modules: Invalid relocation target, existing value is nonzero for sec %u, idx %u, type %d, loc %lx, val %llx\n",				       relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),				       (unsigned long)loc, val);				return -ENOEXEC;			}			write(loc, &val, size);		} else {			if (memcmp(loc, &val, size)) {				pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for sec %u, idx %u, type %d, loc %lx, val %llx\n",					relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),					(unsigned long)loc, val);				return -ENOEXEC;			}			write(loc, &zero, size);		}	}	return 0; overflow:	pr_err("overflow in relocation type %d val %llx sec %u idx %d\n",	       (int)ELF64_R_TYPE(rel[i].r_info), val, relsec, i);	pr_err("`%s' likely not compiled with -mcmodel=kernel\n",	       me->name);	return -ENOEXEC;} static int write_relocate_add(Elf64_Shdr *sechdrs,			      const char *strtab,			      unsigned int symindex,			      unsigned int relsec,			      struct module *me,			      bool apply){	int ret;	bool early = me->state == MODULE_STATE_UNFORMED;	void *(*write)(void *, const void *, size_t) = memcpy; 	if (!early) {		write = text_poke;		mutex_lock(&text_mutex);	} 	ret = __write_relocate_add(sechdrs, strtab, symindex, relsec, me,				   write, apply); 	if (!early) {		smp_text_poke_sync_each_cpu();		mutex_unlock(&text_mutex);	} 	return ret;} int apply_relocate_add(Elf64_Shdr *sechdrs,		   const char *strtab,		   unsigned int symindex,		   unsigned int relsec,		   struct module *me){	return write_relocate_add(sechdrs, strtab, symindex, relsec, me, true);} #ifdef CONFIG_LIVEPATCHvoid clear_relocate_add(Elf64_Shdr *sechdrs,			const char *strtab,			unsigned int symindex,			unsigned int relsec,			struct module *me){	write_relocate_add(sechdrs, strtab, symindex, relsec, me, false);}#endif #endif int module_finalize(const Elf_Ehdr *hdr,		    const Elf_Shdr *sechdrs,		    struct module *me){	const Elf_Shdr *s, *alt = NULL,		*orc = NULL, *orc_ip = NULL,		*retpolines = NULL, *returns = NULL, *ibt_endbr = NULL,		*calls = NULL, *cfi = NULL;	char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 	for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {		if (!strcmp(".altinstructions", secstrings + s->sh_name))			alt = s;		if (!strcmp(".orc_unwind", secstrings + s->sh_name))			orc = s;		if (!strcmp(".orc_unwind_ip", secstrings + s->sh_name))			orc_ip = s;		if (!strcmp(".retpoline_sites", secstrings + s->sh_name))			retpolines = s;		if (!strcmp(".return_sites", secstrings + s->sh_name))			returns = s;		if (!strcmp(".call_sites", secstrings + s->sh_name))			calls = s;		if (!strcmp(".cfi_sites", secstrings + s->sh_name))			cfi = s;		if (!strcmp(".ibt_endbr_seal", secstrings + s->sh_name))			ibt_endbr = s;	} 	its_init_mod(me); 	if (retpolines || cfi) {		void *rseg = NULL, *cseg = NULL;		unsigned int rsize = 0, csize = 0; 		if (retpolines) {			rseg = (void *)retpolines->sh_addr;			rsize = retpolines->sh_size;		} 		if (cfi) {			cseg = (void *)cfi->sh_addr;			csize = cfi->sh_size;		} 		apply_fineibt(rseg, rseg + rsize, cseg, cseg + csize);	}	if (retpolines) {		void *rseg = (void *)retpolines->sh_addr;		apply_retpolines(rseg, rseg + retpolines->sh_size);	} 	its_fini_mod(me); 	if (returns) {		void *rseg = (void *)returns->sh_addr;		apply_returns(rseg, rseg + returns->sh_size);	}	if (calls) {		struct callthunk_sites cs = {}; 		cs.call_start = (void *)calls->sh_addr;		cs.call_end = (void *)calls->sh_addr + calls->sh_size; 		callthunks_patch_module_calls(&cs, me);	}	if (alt) {		/* patch .altinstructions */		void *aseg = (void *)alt->sh_addr;		apply_alternatives(aseg, aseg + alt->sh_size);	}	if (ibt_endbr) {		void *iseg = (void *)ibt_endbr->sh_addr;		apply_seal_endbr(iseg, iseg + ibt_endbr->sh_size);	} 	if (orc && orc_ip)		unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,				   (void *)orc->sh_addr, orc->sh_size); 	return 0;} void module_arch_cleanup(struct module *mod){	its_free_mod(mod);}