arch/x86/include/asm/cfi.h

File Facts

System

Linux kernel

Corpus path

arch/x86/include/asm/cfi.h

Extension

.h

Size

3075 bytes

Lines

169

Domain

Architecture Layer

Bucket

arch/x86

Inferred role

Architecture Layer: implementation source

Status

source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

• CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/bug.h
• asm/ibt.h

Detected Declarations

• struct pt_regs
• enum cfi_mode
• function cfi_get_offset
• function decode_fineibt_insn
• function handle_cfi_failure
• function cfi_get_func_arity

Annotated Snippet

#ifndef _ASM_X86_CFI_H
#define _ASM_X86_CFI_H

/*
 * Clang Control Flow Integrity (CFI) support.
 *
 * Copyright (C) 2022 Google LLC
 */
#include <linux/bug.h>
#include <asm/ibt.h>

/*
 * An overview of the various calling conventions...
 *
 * Traditional:
 *
 * foo:
 *   ... code here ...
 *   ret
 *
 * direct caller:
 *   call foo
 *
 * indirect caller:
 *   lea foo(%rip), %r11
 *   ...
 *   call *%r11
 *
 *
 * IBT:
 *
 * foo:
 *   endbr64
 *   ... code here ...
 *   ret
 *
 * direct caller:
 *   call foo / call foo+4
 *
 * indirect caller:
 *   lea foo(%rip), %r11
 *   ...
 *   call *%r11
 *
 *
 * kCFI:
 *
 * __cfi_foo:
 *   movl $0x12345678, %eax
 *				# 11 nops when CONFIG_CALL_PADDING
 * foo:
 *   endbr64			# when IBT
 *   ... code here ...
 *   ret
 *
 * direct call:
 *   call foo			# / call foo+4 when IBT
 *
 * indirect call:
 *   lea foo(%rip), %r11
 *   ...
 *   movl $(-0x12345678), %r10d
 *   addl -4(%r11), %r10d	# -15 when CONFIG_CALL_PADDING
 *   jz   1f
 *   ud2
 * 1:call *%r11
 *
 *
 * FineIBT (builds as kCFI + CALL_PADDING + IBT + RETPOLINE and runtime patches into):
 *
 * __cfi_foo:
 *   endbr64
 *   subl 0x12345678, %eax
 *   jne.32,pn foo+3
 * foo:
 *   nopl -42(%rax)		# was endbr64
 *   ... code here ...
 *   ret
 *
 * direct caller:
 *   call foo / call foo+4
 *
 * indirect caller:
 *   lea foo(%rip), %r11
 *   ...
 *   movl $0x12345678, %eax
 *   lea  -0x10(%r11), %r11
 *   nop5
 *   call *%r11
 *

Annotation

• Immediate include surface: `linux/bug.h`, `asm/ibt.h`.
• Detected declarations: `struct pt_regs`, `enum cfi_mode`, `function cfi_get_offset`, `function decode_fineibt_insn`, `function handle_cfi_failure`, `function cfi_get_func_arity`.
• Atlas domain: Architecture Layer / arch/x86.
• Implementation status: source implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.