1/* SPDX-License-Identifier: GPL-2.0 */
2/* Copyright (C) 2017 Andes Technology Corporation */
3
4#ifndef _ASM_RISCV_MODULE_H
5#define _ASM_RISCV_MODULE_H
6
7#include <asm-generic/module.h>
8
9struct module;
10unsigned long module_emit_got_entry(struct module *mod, unsigned long val);
11unsigned long module_emit_plt_entry(struct module *mod, unsigned long val);
12
13#ifdef CONFIG_MODULE_SECTIONS
14struct mod_section {
15	Elf_Shdr *shdr;
16	int num_entries;
17	int max_entries;
18};
19
20struct mod_arch_specific {
21	struct mod_section got;
22	struct mod_section plt;
23	struct mod_section got_plt;
24};
25
26struct got_entry {
27	unsigned long symbol_addr;	/* the real variable address */
28};
29
30static inline struct got_entry emit_got_entry(unsigned long val)
31{
32	return (struct got_entry) {val};
33}
34
35static inline struct got_entry *get_got_entry(unsigned long val,
36					      const struct mod_section *sec)
37{
38	struct got_entry *got = (struct got_entry *)(sec->shdr->sh_addr);
39	int i;
40	for (i = 0; i < sec->num_entries; i++) {
41		if (got[i].symbol_addr == val)
42			return &got[i];
43	}
44	return NULL;
45}
46
47struct plt_entry {
48	/*
49	 * Trampoline code to real target address. The return address
50	 * should be the original (pc+4) before entring plt entry.
51	 */
52	u32 insn_auipc;		/* auipc t0, 0x0                       */
53	u32 insn_ld;		/* ld    t1, 0x10(t0)                  */
54	u32 insn_jr;		/* jr    t1                            */
55};
56
57#define OPC_AUIPC  0x0017
58#define OPC_LD     0x3003
59#define OPC_JALR   0x0067
60#define REG_T0     0x5
61#define REG_T1     0x6
62
63static inline struct plt_entry emit_plt_entry(unsigned long val,
64					      unsigned long plt,
65					      unsigned long got_plt)
66{
67	/*
68	 * U-Type encoding:
69	 * +------------+----------+----------+
70	 * | imm[31:12] | rd[11:7] | opc[6:0] |
71	 * +------------+----------+----------+
72	 *
73	 * I-Type encoding:
74	 * +------------+------------+--------+----------+----------+
75	 * | imm[31:20] | rs1[19:15] | funct3 | rd[11:7] | opc[6:0] |
76	 * +------------+------------+--------+----------+----------+
77	 *
78	 */
79	unsigned long offset = got_plt - plt;
80	u32 hi20 = (offset + 0x800) & 0xfffff000;
81	u32 lo12 = (offset - hi20);
82	return (struct plt_entry) {
83		OPC_AUIPC | (REG_T0 << 7) | hi20,
84		OPC_LD | (lo12 << 20) | (REG_T0 << 15) | (REG_T1 << 7),
85		OPC_JALR | (REG_T1 << 15)
86	};
87}
88
89static inline int get_got_plt_idx(unsigned long val, const struct mod_section *sec)
90{
91	struct got_entry *got_plt = (struct got_entry *)sec->shdr->sh_addr;
92	int i;
93	for (i = 0; i < sec->num_entries; i++) {
94		if (got_plt[i].symbol_addr == val)
95			return i;
96	}
97	return -1;
98}
99
100static inline struct plt_entry *get_plt_entry(unsigned long val,
101					      const struct mod_section *sec_plt,
102					      const struct mod_section *sec_got_plt)
103{
104	struct plt_entry *plt = (struct plt_entry *)sec_plt->shdr->sh_addr;
105	int got_plt_idx = get_got_plt_idx(val, sec_got_plt);
106	if (got_plt_idx >= 0)
107		return plt + got_plt_idx;
108	else
109		return NULL;
110}
111
112#endif /* CONFIG_MODULE_SECTIONS */
113
114#endif /* _ASM_RISCV_MODULE_H */
115