// SPDX-License-Identifier: GPL-2.0/* * Clang Control Flow Integrity (CFI) error handling. * * Copyright (C) 2022 Google LLC */ #include <linux/cfi.h> enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr,				      unsigned long *target, u32 type){	if (target)		pr_err("CFI failure at %pS (target: %pS; expected type: 0x%08x)\n",		       (void *)addr, (void *)*target, type);	else		pr_err("CFI failure at %pS (no target information)\n",		       (void *)addr); 	if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) {		__warn(NULL, 0, (void *)addr, 0, regs, NULL);		return BUG_TRAP_TYPE_WARN;	} 	return BUG_TRAP_TYPE_BUG;} #ifdef CONFIG_ARCH_USES_CFI_TRAPSstatic inline unsigned long trap_address(s32 *p){	return (unsigned long)((long)p + (long)*p);} static bool is_trap(unsigned long addr, s32 *start, s32 *end){	s32 *p; 	for (p = start; p < end; ++p) {		if (trap_address(p) == addr)			return true;	} 	return false;} #ifdef CONFIG_MODULES/* Populates `kcfi_trap(_end)?` fields in `struct module`. */void module_cfi_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,			 struct module *mod){	char *secstrings;	unsigned int i; 	mod->kcfi_traps = NULL;	mod->kcfi_traps_end = NULL; 	secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 	for (i = 1; i < hdr->e_shnum; i++) {		if (strcmp(secstrings + sechdrs[i].sh_name, "__kcfi_traps"))			continue; 		mod->kcfi_traps = (s32 *)sechdrs[i].sh_addr;		mod->kcfi_traps_end = (s32 *)(sechdrs[i].sh_addr + sechdrs[i].sh_size);		break;	}} static bool is_module_cfi_trap(unsigned long addr){	struct module *mod;	bool found = false; 	rcu_read_lock_sched_notrace(); 	mod = __module_address(addr);	if (mod)		found = is_trap(addr, mod->kcfi_traps, mod->kcfi_traps_end); 	rcu_read_unlock_sched_notrace(); 	return found;}#else /* CONFIG_MODULES */static inline bool is_module_cfi_trap(unsigned long addr){	return false;}#endif /* CONFIG_MODULES */ extern s32 __start___kcfi_traps[];extern s32 __stop___kcfi_traps[]; bool is_cfi_trap(unsigned long addr){	if (is_trap(addr, __start___kcfi_traps, __stop___kcfi_traps))		return true; 	return is_module_cfi_trap(addr);}#endif /* CONFIG_ARCH_USES_CFI_TRAPS */