arch/arm64/include/asm/asm-extable.h

Source file repositories/reference/linux-study-clean/arch/arm64/include/asm/asm-extable.h

File Facts

System
Linux kernel
Corpus path
arch/arm64/include/asm/asm-extable.h
Extension
.h
Size
3933 bytes
Lines
138
Domain
Architecture Layer
Bucket
arch/arm64
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.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef __ASM_ASM_EXTABLE_H
#define __ASM_ASM_EXTABLE_H

#include <linux/bits.h>
#include <asm/gpr-num.h>

#define EX_TYPE_NONE			0
#define EX_TYPE_BPF			1
#define EX_TYPE_UACCESS_ERR_ZERO	2
#define EX_TYPE_KACCESS_ERR_ZERO	3
#define EX_TYPE_UACCESS_CPY		4
#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD	5

/* Data fields for EX_TYPE_UACCESS_ERR_ZERO */
#define EX_DATA_REG_ERR_SHIFT	0
#define EX_DATA_REG_ERR		GENMASK(4, 0)
#define EX_DATA_REG_ZERO_SHIFT	5
#define EX_DATA_REG_ZERO	GENMASK(9, 5)

/* Data fields for EX_TYPE_LOAD_UNALIGNED_ZEROPAD */
#define EX_DATA_REG_DATA_SHIFT	0
#define EX_DATA_REG_DATA	GENMASK(4, 0)
#define EX_DATA_REG_ADDR_SHIFT	5
#define EX_DATA_REG_ADDR	GENMASK(9, 5)

/* Data fields for EX_TYPE_UACCESS_CPY */
#define EX_DATA_UACCESS_WRITE	BIT(0)

#ifdef __ASSEMBLER__

#define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
	.pushsection	__ex_table, "a";		\
	.align		2;				\
	.long		((insn) - .);			\
	.long		((fixup) - .);			\
	.short		(type);				\
	.short		(data);				\
	.popsection;

#define EX_DATA_REG(reg, gpr)	\
	(.L__gpr_num_##gpr << EX_DATA_REG_##reg##_SHIFT)

#define _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero)		\
	__ASM_EXTABLE_RAW(insn, fixup, 					\
			  EX_TYPE_UACCESS_ERR_ZERO,			\
			  (						\
			    EX_DATA_REG(ERR, err) |			\
			    EX_DATA_REG(ZERO, zero)			\
			  ))

#define _ASM_EXTABLE_UACCESS_ERR(insn, fixup, err)			\
	_ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, wzr)

#define _ASM_EXTABLE_UACCESS(insn, fixup)				\
	_ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, wzr, wzr)

/*
 * Create an exception table entry for uaccess `insn`, which will branch to `fixup`
 * when an unhandled fault is taken.
 */
	.macro          _asm_extable_uaccess, insn, fixup
	_ASM_EXTABLE_UACCESS(\insn, \fixup)
	.endm

/*
 * Create an exception table entry for `insn` if `fixup` is provided. Otherwise
 * do nothing.
 */
	.macro		_cond_uaccess_extable, insn, fixup
	.ifnc			\fixup,
	_asm_extable_uaccess	\insn, \fixup
	.endif
	.endm

	.macro		_asm_extable_uaccess_cpy, insn, fixup, uaccess_is_write
	__ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_UACCESS_CPY, \uaccess_is_write)
	.endm

#else /* __ASSEMBLER__ */

#include <linux/stringify.h>

#define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
	".pushsection	__ex_table, \"a\"\n"		\
	".align		2\n"				\
	".long		((" insn ") - .)\n"		\
	".long		((" fixup ") - .)\n"		\
	".short		(" type ")\n"			\
	".short		(" data ")\n"			\
	".popsection\n"

Annotation

Implementation Notes