1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited 4 */ 5 6 #include <linux/elf.h> 7 #include <linux/kernel.h> 8 #include <linux/module.h> 9 10 Elf_Addr module_emit_plt_entry(struct module *mod, unsigned long val) 11 { 12 int nr; 13 struct mod_section *plt_sec = &mod->arch.plt; 14 struct mod_section *plt_idx_sec = &mod->arch.plt_idx; 15 struct plt_entry *plt = get_plt_entry(val, plt_sec, plt_idx_sec); 16 struct plt_idx_entry *plt_idx; 17 18 if (plt) 19 return (Elf_Addr)plt; 20 21 nr = plt_sec->num_entries; 22 23 /* There is no duplicate entry, create a new one */ 24 plt = (struct plt_entry *)plt_sec->shdr->sh_addr; 25 plt[nr] = emit_plt_entry(val); 26 plt_idx = (struct plt_idx_entry *)plt_idx_sec->shdr->sh_addr; 27 plt_idx[nr] = emit_plt_idx_entry(val); 28 29 plt_sec->num_entries++; 30 plt_idx_sec->num_entries++; 31 BUG_ON(plt_sec->num_entries > plt_sec->max_entries); 32 33 return (Elf_Addr)&plt[nr]; 34 } 35 36 static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y) 37 { 38 return x->r_info == y->r_info && x->r_addend == y->r_addend; 39 } 40 41 static bool duplicate_rela(const Elf_Rela *rela, int idx) 42 { 43 int i; 44 45 for (i = 0; i < idx; i++) { 46 if (is_rela_equal(&rela[i], &rela[idx])) 47 return true; 48 } 49 50 return false; 51 } 52 53 static void count_max_entries(Elf_Rela *relas, int num, unsigned int *plts) 54 { 55 unsigned int i, type; 56 57 for (i = 0; i < num; i++) { 58 type = ELF_R_TYPE(relas[i].r_info); 59 if (type == R_LARCH_SOP_PUSH_PLT_PCREL) { 60 if (!duplicate_rela(relas, i)) 61 (*plts)++; 62 } 63 } 64 } 65 66 int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, 67 char *secstrings, struct module *mod) 68 { 69 unsigned int i, num_plts = 0; 70 71 /* 72 * Find the empty .plt sections. 73 */ 74 for (i = 0; i < ehdr->e_shnum; i++) { 75 if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) 76 mod->arch.plt.shdr = sechdrs + i; 77 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx")) 78 mod->arch.plt_idx.shdr = sechdrs + i; 79 } 80 81 if (!mod->arch.plt.shdr) { 82 pr_err("%s: module PLT section(s) missing\n", mod->name); 83 return -ENOEXEC; 84 } 85 if (!mod->arch.plt_idx.shdr) { 86 pr_err("%s: module PLT.IDX section(s) missing\n", mod->name); 87 return -ENOEXEC; 88 } 89 90 /* Calculate the maxinum number of entries */ 91 for (i = 0; i < ehdr->e_shnum; i++) { 92 int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela); 93 Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset; 94 Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info; 95 96 if (sechdrs[i].sh_type != SHT_RELA) 97 continue; 98 99 /* ignore relocations that operate on non-exec sections */ 100 if (!(dst_sec->sh_flags & SHF_EXECINSTR)) 101 continue; 102 103 count_max_entries(relas, num_rela, &num_plts); 104 } 105 106 mod->arch.plt.shdr->sh_type = SHT_NOBITS; 107 mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC; 108 mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES; 109 mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry); 110 mod->arch.plt.num_entries = 0; 111 mod->arch.plt.max_entries = num_plts; 112 113 mod->arch.plt_idx.shdr->sh_type = SHT_NOBITS; 114 mod->arch.plt_idx.shdr->sh_flags = SHF_ALLOC; 115 mod->arch.plt_idx.shdr->sh_addralign = L1_CACHE_BYTES; 116 mod->arch.plt_idx.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry); 117 mod->arch.plt_idx.num_entries = 0; 118 mod->arch.plt_idx.max_entries = num_plts; 119 120 return 0; 121 } 122