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 #include <linux/elf.h> 9 10 struct module; 11 unsigned long module_emit_got_entry(struct module *mod, unsigned long val); 12 unsigned long module_emit_plt_entry(struct module *mod, unsigned long val); 13 14 #ifdef CONFIG_MODULE_SECTIONS 15 struct mod_section { 16 Elf_Shdr *shdr; 17 int num_entries; 18 int max_entries; 19 }; 20 21 struct mod_arch_specific { 22 struct mod_section got; 23 struct mod_section plt; 24 struct mod_section got_plt; 25 }; 26 27 struct got_entry { 28 unsigned long symbol_addr; /* the real variable address */ 29 }; 30 31 static inline struct got_entry emit_got_entry(unsigned long val) 32 { 33 return (struct got_entry) {val}; 34 } 35 36 static inline struct got_entry *get_got_entry(unsigned long val, 37 const struct mod_section *sec) 38 { 39 struct got_entry *got = (struct got_entry *)(sec->shdr->sh_addr); 40 int i; 41 for (i = 0; i < sec->num_entries; i++) { 42 if (got[i].symbol_addr == val) 43 return &got[i]; 44 } 45 return NULL; 46 } 47 48 struct plt_entry { 49 /* 50 * Trampoline code to real target address. The return address 51 * should be the original (pc+4) before entring plt entry. 52 */ 53 u32 insn_auipc; /* auipc t0, 0x0 */ 54 u32 insn_ld; /* ld t1, 0x10(t0) */ 55 u32 insn_jr; /* jr t1 */ 56 }; 57 58 #define OPC_AUIPC 0x0017 59 #define OPC_LD 0x3003 60 #define OPC_JALR 0x0067 61 #define REG_T0 0x5 62 #define REG_T1 0x6 63 64 static inline struct plt_entry emit_plt_entry(unsigned long val, 65 unsigned long plt, 66 unsigned long got_plt) 67 { 68 /* 69 * U-Type encoding: 70 * +------------+----------+----------+ 71 * | imm[31:12] | rd[11:7] | opc[6:0] | 72 * +------------+----------+----------+ 73 * 74 * I-Type encoding: 75 * +------------+------------+--------+----------+----------+ 76 * | imm[31:20] | rs1[19:15] | funct3 | rd[11:7] | opc[6:0] | 77 * +------------+------------+--------+----------+----------+ 78 * 79 */ 80 unsigned long offset = got_plt - plt; 81 u32 hi20 = (offset + 0x800) & 0xfffff000; 82 u32 lo12 = (offset - hi20); 83 return (struct plt_entry) { 84 OPC_AUIPC | (REG_T0 << 7) | hi20, 85 OPC_LD | (lo12 << 20) | (REG_T0 << 15) | (REG_T1 << 7), 86 OPC_JALR | (REG_T1 << 15) 87 }; 88 } 89 90 static inline int get_got_plt_idx(unsigned long val, const struct mod_section *sec) 91 { 92 struct got_entry *got_plt = (struct got_entry *)sec->shdr->sh_addr; 93 int i; 94 for (i = 0; i < sec->num_entries; i++) { 95 if (got_plt[i].symbol_addr == val) 96 return i; 97 } 98 return -1; 99 } 100 101 static inline struct plt_entry *get_plt_entry(unsigned long val, 102 const struct mod_section *sec_plt, 103 const struct mod_section *sec_got_plt) 104 { 105 struct plt_entry *plt = (struct plt_entry *)sec_plt->shdr->sh_addr; 106 int got_plt_idx = get_got_plt_idx(val, sec_got_plt); 107 if (got_plt_idx >= 0) 108 return plt + got_plt_idx; 109 else 110 return NULL; 111 } 112 113 #endif /* CONFIG_MODULE_SECTIONS */ 114 115 static inline const Elf_Shdr *find_section(const Elf_Ehdr *hdr, 116 const Elf_Shdr *sechdrs, 117 const char *name) 118 { 119 const Elf_Shdr *s, *se; 120 const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 121 122 for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) { 123 if (strcmp(name, secstrs + s->sh_name) == 0) 124 return s; 125 } 126 127 return NULL; 128 } 129 130 #endif /* _ASM_RISCV_MODULE_H */ 131