1 /* SPDX-License-Identifier: GPL-2.0 2 * 3 * Copyright (C) 2014-2017 Linaro Ltd. <ard.biesheuvel@linaro.org> 4 * 5 * Copyright (C) 2018 Andes Technology Corporation <zong@andestech.com> 6 */ 7 8 #include <linux/elf.h> 9 #include <linux/kernel.h> 10 #include <linux/module.h> 11 12 unsigned long module_emit_got_entry(struct module *mod, unsigned long val) 13 { 14 struct mod_section *got_sec = &mod->arch.got; 15 int i = got_sec->num_entries; 16 struct got_entry *got = get_got_entry(val, got_sec); 17 18 if (got) 19 return (unsigned long)got; 20 21 /* There is no duplicate entry, create a new one */ 22 got = (struct got_entry *)got_sec->shdr->sh_addr; 23 got[i] = emit_got_entry(val); 24 25 got_sec->num_entries++; 26 BUG_ON(got_sec->num_entries > got_sec->max_entries); 27 28 return (unsigned long)&got[i]; 29 } 30 31 unsigned long module_emit_plt_entry(struct module *mod, unsigned long val) 32 { 33 struct mod_section *got_plt_sec = &mod->arch.got_plt; 34 struct got_entry *got_plt; 35 struct mod_section *plt_sec = &mod->arch.plt; 36 struct plt_entry *plt = get_plt_entry(val, plt_sec, got_plt_sec); 37 int i = plt_sec->num_entries; 38 39 if (plt) 40 return (unsigned long)plt; 41 42 /* There is no duplicate entry, create a new one */ 43 got_plt = (struct got_entry *)got_plt_sec->shdr->sh_addr; 44 got_plt[i] = emit_got_entry(val); 45 plt = (struct plt_entry *)plt_sec->shdr->sh_addr; 46 plt[i] = emit_plt_entry(val, 47 (unsigned long)&plt[i], 48 (unsigned long)&got_plt[i]); 49 50 plt_sec->num_entries++; 51 got_plt_sec->num_entries++; 52 BUG_ON(plt_sec->num_entries > plt_sec->max_entries); 53 54 return (unsigned long)&plt[i]; 55 } 56 57 static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y) 58 { 59 return x->r_info == y->r_info && x->r_addend == y->r_addend; 60 } 61 62 static bool duplicate_rela(const Elf_Rela *rela, int idx) 63 { 64 int i; 65 for (i = 0; i < idx; i++) { 66 if (is_rela_equal(&rela[i], &rela[idx])) 67 return true; 68 } 69 return false; 70 } 71 72 static void count_max_entries(Elf_Rela *relas, int num, 73 unsigned int *plts, unsigned int *gots) 74 { 75 unsigned int type, i; 76 77 for (i = 0; i < num; i++) { 78 type = ELF_RISCV_R_TYPE(relas[i].r_info); 79 if (type == R_RISCV_CALL_PLT) { 80 if (!duplicate_rela(relas, i)) 81 (*plts)++; 82 } else if (type == R_RISCV_GOT_HI20) { 83 if (!duplicate_rela(relas, i)) 84 (*gots)++; 85 } 86 } 87 } 88 89 int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 90 char *secstrings, struct module *mod) 91 { 92 unsigned int num_plts = 0; 93 unsigned int num_gots = 0; 94 int i; 95 96 /* 97 * Find the empty .got and .plt sections. 98 */ 99 for (i = 0; i < ehdr->e_shnum; i++) { 100 if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) 101 mod->arch.plt.shdr = sechdrs + i; 102 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got")) 103 mod->arch.got.shdr = sechdrs + i; 104 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt")) 105 mod->arch.got_plt.shdr = sechdrs + i; 106 } 107 108 if (!mod->arch.plt.shdr) { 109 pr_err("%s: module PLT section(s) missing\n", mod->name); 110 return -ENOEXEC; 111 } 112 if (!mod->arch.got.shdr) { 113 pr_err("%s: module GOT section(s) missing\n", mod->name); 114 return -ENOEXEC; 115 } 116 if (!mod->arch.got_plt.shdr) { 117 pr_err("%s: module GOT.PLT section(s) missing\n", mod->name); 118 return -ENOEXEC; 119 } 120 121 /* Calculate the maxinum number of entries */ 122 for (i = 0; i < ehdr->e_shnum; i++) { 123 Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset; 124 int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela); 125 Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info; 126 127 if (sechdrs[i].sh_type != SHT_RELA) 128 continue; 129 130 /* ignore relocations that operate on non-exec sections */ 131 if (!(dst_sec->sh_flags & SHF_EXECINSTR)) 132 continue; 133 134 count_max_entries(relas, num_rela, &num_plts, &num_gots); 135 } 136 137 mod->arch.plt.shdr->sh_type = SHT_NOBITS; 138 mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC; 139 mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES; 140 mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry); 141 mod->arch.plt.num_entries = 0; 142 mod->arch.plt.max_entries = num_plts; 143 144 mod->arch.got.shdr->sh_type = SHT_NOBITS; 145 mod->arch.got.shdr->sh_flags = SHF_ALLOC; 146 mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES; 147 mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry); 148 mod->arch.got.num_entries = 0; 149 mod->arch.got.max_entries = num_gots; 150 151 mod->arch.got_plt.shdr->sh_type = SHT_NOBITS; 152 mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC; 153 mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES; 154 mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry); 155 mod->arch.got_plt.num_entries = 0; 156 mod->arch.got_plt.max_entries = num_plts; 157 return 0; 158 } 159