1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/moduleloader.h>
10 #include <linux/ftrace.h>
12 Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
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, sechdrs, got_sec);
21 /* There is no GOT entry for val yet, create a new one. */
22 got = (struct got_entry *)sechdrs[got_sec->shndx].sh_addr;
23 got[i] = emit_got_entry(val);
25 got_sec->num_entries++;
26 if (got_sec->num_entries > got_sec->max_entries) {
28 * This may happen when the module contains a GOT_HI20 without
29 * a paired GOT_LO12. Such a module is broken, reject it.
31 pr_err("%s: module contains bad GOT relocation\n", mod->name);
35 return (Elf_Addr)&got[i];
38 Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
41 struct mod_section *plt_sec = &mod->arch.plt;
42 struct mod_section *plt_idx_sec = &mod->arch.plt_idx;
43 struct plt_entry *plt = get_plt_entry(val, sechdrs, plt_sec, plt_idx_sec);
44 struct plt_idx_entry *plt_idx;
49 nr = plt_sec->num_entries;
51 /* There is no duplicate entry, create a new one */
52 plt = (struct plt_entry *)sechdrs[plt_sec->shndx].sh_addr;
53 plt[nr] = emit_plt_entry(val);
54 plt_idx = (struct plt_idx_entry *)sechdrs[plt_idx_sec->shndx].sh_addr;
55 plt_idx[nr] = emit_plt_idx_entry(val);
57 plt_sec->num_entries++;
58 plt_idx_sec->num_entries++;
59 BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
61 return (Elf_Addr)&plt[nr];
64 static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
66 return x->r_info == y->r_info && x->r_addend == y->r_addend;
69 static bool duplicate_rela(const Elf_Rela *rela, int idx)
73 for (i = 0; i < idx; i++) {
74 if (is_rela_equal(&rela[i], &rela[idx]))
81 static void count_max_entries(Elf_Rela *relas, int num,
82 unsigned int *plts, unsigned int *gots)
86 for (i = 0; i < num; i++) {
87 type = ELF_R_TYPE(relas[i].r_info);
89 case R_LARCH_SOP_PUSH_PLT_PCREL:
91 if (!duplicate_rela(relas, i))
94 case R_LARCH_GOT_PC_HI20:
95 if (!duplicate_rela(relas, i))
99 break; /* Do nothing. */
104 int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
105 char *secstrings, struct module *mod)
107 unsigned int i, num_plts = 0, num_gots = 0;
108 Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;
111 * Find the empty .plt sections.
113 for (i = 0; i < ehdr->e_shnum; i++) {
114 if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
115 mod->arch.got.shndx = i;
116 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
117 mod->arch.plt.shndx = i;
118 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
119 mod->arch.plt_idx.shndx = i;
120 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
124 if (!mod->arch.got.shndx) {
125 pr_err("%s: module GOT section(s) missing\n", mod->name);
128 if (!mod->arch.plt.shndx) {
129 pr_err("%s: module PLT section(s) missing\n", mod->name);
132 if (!mod->arch.plt_idx.shndx) {
133 pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
137 /* Calculate the maxinum number of entries */
138 for (i = 0; i < ehdr->e_shnum; i++) {
139 int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
140 Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
141 Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
143 if (sechdrs[i].sh_type != SHT_RELA)
146 /* ignore relocations that operate on non-exec sections */
147 if (!(dst_sec->sh_flags & SHF_EXECINSTR))
150 count_max_entries(relas, num_rela, &num_plts, &num_gots);
153 got_sec = sechdrs + mod->arch.got.shndx;
154 got_sec->sh_type = SHT_NOBITS;
155 got_sec->sh_flags = SHF_ALLOC;
156 got_sec->sh_addralign = L1_CACHE_BYTES;
157 got_sec->sh_size = (num_gots + 1) * sizeof(struct got_entry);
158 mod->arch.got.num_entries = 0;
159 mod->arch.got.max_entries = num_gots;
161 plt_sec = sechdrs + mod->arch.plt.shndx;
162 plt_sec->sh_type = SHT_NOBITS;
163 plt_sec->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
164 plt_sec->sh_addralign = L1_CACHE_BYTES;
165 plt_sec->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
166 mod->arch.plt.num_entries = 0;
167 mod->arch.plt.max_entries = num_plts;
169 plt_idx_sec = sechdrs + mod->arch.plt_idx.shndx;
170 plt_idx_sec->sh_type = SHT_NOBITS;
171 plt_idx_sec->sh_flags = SHF_ALLOC;
172 plt_idx_sec->sh_addralign = L1_CACHE_BYTES;
173 plt_idx_sec->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry);
174 mod->arch.plt_idx.num_entries = 0;
175 mod->arch.plt_idx.max_entries = num_plts;
178 tramp->sh_type = SHT_NOBITS;
179 tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
180 tramp->sh_addralign = __alignof__(struct plt_entry);
181 tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);