jump_label.c

 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/cacheflush.h>
13#include <asm/text-patching.h>
14#include <asm/insn-def.h>
15
16#define RISCV_INSN_JAL 0x0000006fU
17
18bool arch_jump_label_transform_queue(struct jump_entry *entry,
19				     enum jump_label_type type)
20{
21	void *addr = (void *)jump_entry_code(entry);
22	u32 insn;
23
24	if (type == JUMP_LABEL_JMP) {
25		long offset = jump_entry_target(entry) - jump_entry_code(entry);
26
27		if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
28			return true;
29
30		insn = RISCV_INSN_JAL |
31			(((u32)offset & GENMASK(19, 12)) << (12 - 12)) |
32			(((u32)offset & GENMASK(11, 11)) << (20 - 11)) |
33			(((u32)offset & GENMASK(10,  1)) << (21 -  1)) |
34			(((u32)offset & GENMASK(20, 20)) << (31 - 20));
35	} else {
36		insn = RISCV_INSN_NOP4;
37	}
38
39	if (early_boot_irqs_disabled) {
40		riscv_patch_in_stop_machine = 1;
41		patch_insn_write(addr, &insn, sizeof(insn));
42		riscv_patch_in_stop_machine = 0;
43	} else {
44		mutex_lock(&text_mutex);
45		patch_insn_write(addr, &insn, sizeof(insn));
46		mutex_unlock(&text_mutex);
47	}
48
49	return true;
50}
51
52void arch_jump_label_transform_apply(void)
53{
54	flush_icache_all();
55}