jump_label.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Copyright (C) 2025 Chen Miao
 4 *
 5 * Based on arch/arm/kernel/jump_label.c
 6 */
 7#include <linux/jump_label.h>
 8#include <linux/kernel.h>
 9#include <linux/memory.h>
10#include <asm/bug.h>
11#include <asm/cacheflush.h>
12#include <asm/text-patching.h>
13
14bool arch_jump_label_transform_queue(struct jump_entry *entry,
15				     enum jump_label_type type)
16{
17	void *addr = (void *)jump_entry_code(entry);
18	u32 insn;
19
20	if (type == JUMP_LABEL_JMP) {
21		long offset;
22
23		offset = jump_entry_target(entry) - jump_entry_code(entry);
24		/*
25		 * The actual maximum range of the l.j instruction's offset is -134,217,728
26		 * ~ 134,217,724 (sign 26-bit imm).
27		 * For the original jump range, we need to right-shift N by 2 to obtain the
28		 * instruction's offset.
29		 */
30		WARN_ON_ONCE(offset < -134217728 || offset > 134217724);
31
32		/* 26bit imm mask */
33		offset = (offset >> 2) & 0x03ffffff;
34
35		insn = offset;
36	} else {
37		insn = OPENRISC_INSN_NOP;
38	}
39
40	if (early_boot_irqs_disabled)
41		copy_to_kernel_nofault(addr, &insn, sizeof(insn));
42	else
43		patch_insn_write(addr, insn);
44
45	return true;
46}
47
48void arch_jump_label_transform_apply(void)
49{
50	kick_all_cpus_sync();
51}