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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Clang Control Flow Integrity (CFI) support.
*
* Copyright (C) 2022 Google LLC
*/
#ifndef _LINUX_CFI_H
#define _LINUX_CFI_H
#include <linux/bug.h>
#include <linux/module.h>
#include <asm/cfi.h>
#ifdef CONFIG_CFI_CLANG
extern bool cfi_warn;
enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr,
unsigned long *target, u32 type);
static inline enum bug_trap_type report_cfi_failure_noaddr(struct pt_regs *regs,
unsigned long addr)
{
return report_cfi_failure(regs, addr, NULL, 0);
}
#ifndef cfi_get_offset
/*
* Returns the CFI prefix offset. By default, the compiler emits only
* a 4-byte CFI type hash before the function. If an architecture
* uses -fpatchable-function-entry=N,M where M>0 to change the prefix
* offset, they must override this function.
*/
static inline int cfi_get_offset(void)
{
return 4;
}
#endif
#ifndef cfi_get_func_hash
static inline u32 cfi_get_func_hash(void *func)
{
u32 hash;
if (get_kernel_nofault(hash, func - cfi_get_offset()))
return 0;
return hash;
}
#endif
/* CFI type hashes for BPF function types */
extern u32 cfi_bpf_hash;
extern u32 cfi_bpf_subprog_hash;
#else /* CONFIG_CFI_CLANG */
static inline int cfi_get_offset(void) { return 0; }
static inline u32 cfi_get_func_hash(void *func) { return 0; }
#define cfi_bpf_hash 0U
#define cfi_bpf_subprog_hash 0U
#endif /* CONFIG_CFI_CLANG */
#ifdef CONFIG_ARCH_USES_CFI_TRAPS
bool is_cfi_trap(unsigned long addr);
#else
static inline bool is_cfi_trap(unsigned long addr) { return false; }
#endif
#ifdef CONFIG_MODULES
#ifdef CONFIG_ARCH_USES_CFI_TRAPS
void module_cfi_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
struct module *mod);
#else
static inline void module_cfi_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *mod) {}
#endif /* CONFIG_ARCH_USES_CFI_TRAPS */
#endif /* CONFIG_MODULES */
#ifndef CFI_NOSEAL
#define CFI_NOSEAL(x)
#endif
#endif /* _LINUX_CFI_H */
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