arch/openrisc/include/asm/jump_label.h

Source file repositories/reference/linux-study-clean/arch/openrisc/include/asm/jump_label.h

File Facts

System
Linux kernel
Corpus path
arch/openrisc/include/asm/jump_label.h
Extension
.h
Size
1905 bytes
Lines
73
Domain
Architecture Layer
Bucket
arch/openrisc
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_OPENRISC_JUMP_LABEL_H
#define __ASM_OPENRISC_JUMP_LABEL_H

#ifndef __ASSEMBLER__

#include <linux/types.h>
#include <asm/insn-def.h>

#define HAVE_JUMP_LABEL_BATCH

#define JUMP_LABEL_NOP_SIZE OPENRISC_INSN_SIZE

/**
 * JUMP_TABLE_ENTRY - Create a jump table entry
 * @key: Jump key identifier (typically a symbol address)
 * @label: Target label address
 *
 * This macro creates a jump table entry in the dedicated kernel section (__jump_table).
 * Each entry contains the following information:
 * 		Offset from current instruction to jump instruction (1b - .)
 * 		Offset from current instruction to target label (label - .)
 * 		Offset from current instruction to key identifier (key - .)
 */
#define JUMP_TABLE_ENTRY(key, label)			\
	".pushsection	__jump_table, \"aw\"	\n\t"	\
	".align 	4 			\n\t"	\
	".long 		1b - ., " label " - .	\n\t"	\
	".long 		" key " - . 		\n\t"	\
	".popsection				\n\t"

#define ARCH_STATIC_BRANCH_ASM(key, label)		\
	".align		4			\n\t"	\
	"1: l.nop				\n\t"	\
	"    l.nop				\n\t"	\
	JUMP_TABLE_ENTRY(key, label)

static __always_inline bool arch_static_branch(struct static_key *const key,
					       const bool branch)
{
	asm goto (ARCH_STATIC_BRANCH_ASM("%0", "%l[l_yes]")
		  ::"i"(&((char *)key)[branch])::l_yes);

	return false;
l_yes:
	return true;
}

#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label)		\
	".align		4			\n\t"	\
	"1: l.j	" label "			\n\t"	\
	"    l.nop				\n\t"	\
	JUMP_TABLE_ENTRY(key, label)

static __always_inline bool
arch_static_branch_jump(struct static_key *const key, const bool branch)
{
	asm goto (ARCH_STATIC_BRANCH_JUMP_ASM("%0", "%l[l_yes]")
		  ::"i"(&((char *)key)[branch])::l_yes);

	return false;
l_yes:
	return true;
}

#endif /* __ASSEMBLER__ */
#endif /* __ASM_OPENRISC_JUMP_LABEL_H */

Annotation

Implementation Notes