1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2020 Emil Renner Berthing
4 *
5 * Based on arch/arm64/kernel/jump_label.c
6 */
7#include <linux/jump_label.h>
8#include <linux/kernel.h>
9#include <linux/memory.h>
10#include <linux/mutex.h>
11#include <asm/bug.h>
12#include <asm/patch.h>
13
14#define RISCV_INSN_NOP 0x00000013U
15#define RISCV_INSN_JAL 0x0000006fU
16
17void arch_jump_label_transform(struct jump_entry *entry,
18			       enum jump_label_type type)
19{
20	void *addr = (void *)jump_entry_code(entry);
21	u32 insn;
22
23	if (type == JUMP_LABEL_JMP) {
24		long offset = jump_entry_target(entry) - jump_entry_code(entry);
25
26		if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
27			return;
28
29		insn = RISCV_INSN_JAL |
30			(((u32)offset & GENMASK(19, 12)) << (12 - 12)) |
31			(((u32)offset & GENMASK(11, 11)) << (20 - 11)) |
32			(((u32)offset & GENMASK(10,  1)) << (21 -  1)) |
33			(((u32)offset & GENMASK(20, 20)) << (31 - 20));
34	} else {
35		insn = RISCV_INSN_NOP;
36	}
37
38	mutex_lock(&text_mutex);
39	patch_text_nosync(addr, &insn, sizeof(insn));
40	mutex_unlock(&text_mutex);
41}
42