1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (c) 2010 Cavium Networks, Inc.
7 */
8
9#include <linux/jump_label.h>
10#include <linux/kernel.h>
11#include <linux/memory.h>
12#include <linux/mutex.h>
13#include <linux/types.h>
14#include <linux/cpu.h>
15
16#include <asm/cacheflush.h>
17#include <asm/inst.h>
18
19#ifdef HAVE_JUMP_LABEL
20
21/*
22 * Define parameters for the standard MIPS and the microMIPS jump
23 * instruction encoding respectively:
24 *
25 * - the ISA bit of the target, either 0 or 1 respectively,
26 *
27 * - the amount the jump target address is shifted right to fit in the
28 *   immediate field of the machine instruction, either 2 or 1,
29 *
30 * - the mask determining the size of the jump region relative to the
31 *   delay-slot instruction, either 256MB or 128MB,
32 *
33 * - the jump target alignment, either 4 or 2 bytes.
34 */
35#define J_ISA_BIT	IS_ENABLED(CONFIG_CPU_MICROMIPS)
36#define J_RANGE_SHIFT	(2 - J_ISA_BIT)
37#define J_RANGE_MASK	((1ul << (26 + J_RANGE_SHIFT)) - 1)
38#define J_ALIGN_MASK	((1ul << J_RANGE_SHIFT) - 1)
39
40void arch_jump_label_transform(struct jump_entry *e,
41			       enum jump_label_type type)
42{
43	union mips_instruction *insn_p;
44	union mips_instruction insn;
45
46	insn_p = (union mips_instruction *)msk_isa16_mode(e->code);
47
48	/* Jump only works within an aligned region its delay slot is in. */
49	BUG_ON((e->target & ~J_RANGE_MASK) != ((e->code + 4) & ~J_RANGE_MASK));
50
51	/* Target must have the right alignment and ISA must be preserved. */
52	BUG_ON((e->target & J_ALIGN_MASK) != J_ISA_BIT);
53
54	if (type == JUMP_LABEL_JMP) {
55		insn.j_format.opcode = J_ISA_BIT ? mm_j32_op : j_op;
56		insn.j_format.target = e->target >> J_RANGE_SHIFT;
57	} else {
58		insn.word = 0; /* nop */
59	}
60
61	get_online_cpus();
62	mutex_lock(&text_mutex);
63	if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) {
64		insn_p->halfword[0] = insn.word >> 16;
65		insn_p->halfword[1] = insn.word;
66	} else
67		*insn_p = insn;
68
69	flush_icache_range((unsigned long)insn_p,
70			   (unsigned long)insn_p + sizeof(*insn_p));
71
72	mutex_unlock(&text_mutex);
73	put_online_cpus();
74}
75
76#endif /* HAVE_JUMP_LABEL */
77