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