1fcdfe9d2SHuacai Chen // SPDX-License-Identifier: GPL-2.0
2fcdfe9d2SHuacai Chen /*
3fcdfe9d2SHuacai Chen * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4fcdfe9d2SHuacai Chen */
5fcdfe9d2SHuacai Chen
6fcdfe9d2SHuacai Chen #include <linux/elf.h>
7fcdfe9d2SHuacai Chen #include <linux/kernel.h>
8fcdfe9d2SHuacai Chen #include <linux/module.h>
9*c718a0baSBibo Mao #include <linux/moduleloader.h>
1028ac0a9eSQing Zhang #include <linux/ftrace.h>
11fcdfe9d2SHuacai Chen
module_emit_got_entry(struct module * mod,Elf_Shdr * sechdrs,Elf_Addr val)129151dde4SHuacai Chen Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
1359b3d4a9SXi Ruoyao {
1459b3d4a9SXi Ruoyao struct mod_section *got_sec = &mod->arch.got;
1559b3d4a9SXi Ruoyao int i = got_sec->num_entries;
169151dde4SHuacai Chen struct got_entry *got = get_got_entry(val, sechdrs, got_sec);
1759b3d4a9SXi Ruoyao
1859b3d4a9SXi Ruoyao if (got)
1959b3d4a9SXi Ruoyao return (Elf_Addr)got;
2059b3d4a9SXi Ruoyao
2159b3d4a9SXi Ruoyao /* There is no GOT entry for val yet, create a new one. */
229151dde4SHuacai Chen got = (struct got_entry *)sechdrs[got_sec->shndx].sh_addr;
2359b3d4a9SXi Ruoyao got[i] = emit_got_entry(val);
2459b3d4a9SXi Ruoyao
2559b3d4a9SXi Ruoyao got_sec->num_entries++;
2659b3d4a9SXi Ruoyao if (got_sec->num_entries > got_sec->max_entries) {
2759b3d4a9SXi Ruoyao /*
2859b3d4a9SXi Ruoyao * This may happen when the module contains a GOT_HI20 without
2959b3d4a9SXi Ruoyao * a paired GOT_LO12. Such a module is broken, reject it.
3059b3d4a9SXi Ruoyao */
3159b3d4a9SXi Ruoyao pr_err("%s: module contains bad GOT relocation\n", mod->name);
3259b3d4a9SXi Ruoyao return 0;
3359b3d4a9SXi Ruoyao }
3459b3d4a9SXi Ruoyao
3559b3d4a9SXi Ruoyao return (Elf_Addr)&got[i];
3659b3d4a9SXi Ruoyao }
3759b3d4a9SXi Ruoyao
module_emit_plt_entry(struct module * mod,Elf_Shdr * sechdrs,Elf_Addr val)389151dde4SHuacai Chen Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
39fcdfe9d2SHuacai Chen {
40fcdfe9d2SHuacai Chen int nr;
41fcdfe9d2SHuacai Chen struct mod_section *plt_sec = &mod->arch.plt;
42fcdfe9d2SHuacai Chen struct mod_section *plt_idx_sec = &mod->arch.plt_idx;
439151dde4SHuacai Chen struct plt_entry *plt = get_plt_entry(val, sechdrs, plt_sec, plt_idx_sec);
44fcdfe9d2SHuacai Chen struct plt_idx_entry *plt_idx;
45fcdfe9d2SHuacai Chen
46fcdfe9d2SHuacai Chen if (plt)
47fcdfe9d2SHuacai Chen return (Elf_Addr)plt;
48fcdfe9d2SHuacai Chen
49fcdfe9d2SHuacai Chen nr = plt_sec->num_entries;
50fcdfe9d2SHuacai Chen
51fcdfe9d2SHuacai Chen /* There is no duplicate entry, create a new one */
529151dde4SHuacai Chen plt = (struct plt_entry *)sechdrs[plt_sec->shndx].sh_addr;
53fcdfe9d2SHuacai Chen plt[nr] = emit_plt_entry(val);
549151dde4SHuacai Chen plt_idx = (struct plt_idx_entry *)sechdrs[plt_idx_sec->shndx].sh_addr;
55fcdfe9d2SHuacai Chen plt_idx[nr] = emit_plt_idx_entry(val);
56fcdfe9d2SHuacai Chen
57fcdfe9d2SHuacai Chen plt_sec->num_entries++;
58fcdfe9d2SHuacai Chen plt_idx_sec->num_entries++;
59fcdfe9d2SHuacai Chen BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
60fcdfe9d2SHuacai Chen
61fcdfe9d2SHuacai Chen return (Elf_Addr)&plt[nr];
62fcdfe9d2SHuacai Chen }
63fcdfe9d2SHuacai Chen
is_rela_equal(const Elf_Rela * x,const Elf_Rela * y)64fcdfe9d2SHuacai Chen static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
65fcdfe9d2SHuacai Chen {
66fcdfe9d2SHuacai Chen return x->r_info == y->r_info && x->r_addend == y->r_addend;
67fcdfe9d2SHuacai Chen }
68fcdfe9d2SHuacai Chen
duplicate_rela(const Elf_Rela * rela,int idx)69fcdfe9d2SHuacai Chen static bool duplicate_rela(const Elf_Rela *rela, int idx)
70fcdfe9d2SHuacai Chen {
71fcdfe9d2SHuacai Chen int i;
72fcdfe9d2SHuacai Chen
73fcdfe9d2SHuacai Chen for (i = 0; i < idx; i++) {
74fcdfe9d2SHuacai Chen if (is_rela_equal(&rela[i], &rela[idx]))
75fcdfe9d2SHuacai Chen return true;
76fcdfe9d2SHuacai Chen }
77fcdfe9d2SHuacai Chen
78fcdfe9d2SHuacai Chen return false;
79fcdfe9d2SHuacai Chen }
80fcdfe9d2SHuacai Chen
count_max_entries(Elf_Rela * relas,int num,unsigned int * plts,unsigned int * gots)8159b3d4a9SXi Ruoyao static void count_max_entries(Elf_Rela *relas, int num,
8259b3d4a9SXi Ruoyao unsigned int *plts, unsigned int *gots)
83fcdfe9d2SHuacai Chen {
84fcdfe9d2SHuacai Chen unsigned int i, type;
85fcdfe9d2SHuacai Chen
86fcdfe9d2SHuacai Chen for (i = 0; i < num; i++) {
87fcdfe9d2SHuacai Chen type = ELF_R_TYPE(relas[i].r_info);
889bd1e380SXi Ruoyao switch (type) {
899bd1e380SXi Ruoyao case R_LARCH_SOP_PUSH_PLT_PCREL:
909bd1e380SXi Ruoyao case R_LARCH_B26:
91fcdfe9d2SHuacai Chen if (!duplicate_rela(relas, i))
92fcdfe9d2SHuacai Chen (*plts)++;
939bd1e380SXi Ruoyao break;
9459b3d4a9SXi Ruoyao case R_LARCH_GOT_PC_HI20:
9559b3d4a9SXi Ruoyao if (!duplicate_rela(relas, i))
9659b3d4a9SXi Ruoyao (*gots)++;
9759b3d4a9SXi Ruoyao break;
989bd1e380SXi Ruoyao default:
999bd1e380SXi Ruoyao break; /* Do nothing. */
100fcdfe9d2SHuacai Chen }
101fcdfe9d2SHuacai Chen }
102fcdfe9d2SHuacai Chen }
103fcdfe9d2SHuacai Chen
module_frob_arch_sections(Elf_Ehdr * ehdr,Elf_Shdr * sechdrs,char * secstrings,struct module * mod)104fcdfe9d2SHuacai Chen int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
105fcdfe9d2SHuacai Chen char *secstrings, struct module *mod)
106fcdfe9d2SHuacai Chen {
10759b3d4a9SXi Ruoyao unsigned int i, num_plts = 0, num_gots = 0;
10828ac0a9eSQing Zhang Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;
109fcdfe9d2SHuacai Chen
110fcdfe9d2SHuacai Chen /*
111fcdfe9d2SHuacai Chen * Find the empty .plt sections.
112fcdfe9d2SHuacai Chen */
113fcdfe9d2SHuacai Chen for (i = 0; i < ehdr->e_shnum; i++) {
11459b3d4a9SXi Ruoyao if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
1159151dde4SHuacai Chen mod->arch.got.shndx = i;
11659b3d4a9SXi Ruoyao else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
1179151dde4SHuacai Chen mod->arch.plt.shndx = i;
118fcdfe9d2SHuacai Chen else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
1199151dde4SHuacai Chen mod->arch.plt_idx.shndx = i;
12028ac0a9eSQing Zhang else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
12128ac0a9eSQing Zhang tramp = sechdrs + i;
122fcdfe9d2SHuacai Chen }
123fcdfe9d2SHuacai Chen
1249151dde4SHuacai Chen if (!mod->arch.got.shndx) {
12559b3d4a9SXi Ruoyao pr_err("%s: module GOT section(s) missing\n", mod->name);
12659b3d4a9SXi Ruoyao return -ENOEXEC;
12759b3d4a9SXi Ruoyao }
1289151dde4SHuacai Chen if (!mod->arch.plt.shndx) {
129fcdfe9d2SHuacai Chen pr_err("%s: module PLT section(s) missing\n", mod->name);
130fcdfe9d2SHuacai Chen return -ENOEXEC;
131fcdfe9d2SHuacai Chen }
1329151dde4SHuacai Chen if (!mod->arch.plt_idx.shndx) {
133fcdfe9d2SHuacai Chen pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
134fcdfe9d2SHuacai Chen return -ENOEXEC;
135fcdfe9d2SHuacai Chen }
136fcdfe9d2SHuacai Chen
137fcdfe9d2SHuacai Chen /* Calculate the maxinum number of entries */
138fcdfe9d2SHuacai Chen for (i = 0; i < ehdr->e_shnum; i++) {
139fcdfe9d2SHuacai Chen int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
140fcdfe9d2SHuacai Chen Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
141fcdfe9d2SHuacai Chen Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
142fcdfe9d2SHuacai Chen
143fcdfe9d2SHuacai Chen if (sechdrs[i].sh_type != SHT_RELA)
144fcdfe9d2SHuacai Chen continue;
145fcdfe9d2SHuacai Chen
146fcdfe9d2SHuacai Chen /* ignore relocations that operate on non-exec sections */
147fcdfe9d2SHuacai Chen if (!(dst_sec->sh_flags & SHF_EXECINSTR))
148fcdfe9d2SHuacai Chen continue;
149fcdfe9d2SHuacai Chen
15059b3d4a9SXi Ruoyao count_max_entries(relas, num_rela, &num_plts, &num_gots);
151fcdfe9d2SHuacai Chen }
152fcdfe9d2SHuacai Chen
1539151dde4SHuacai Chen got_sec = sechdrs + mod->arch.got.shndx;
1549151dde4SHuacai Chen got_sec->sh_type = SHT_NOBITS;
1559151dde4SHuacai Chen got_sec->sh_flags = SHF_ALLOC;
1569151dde4SHuacai Chen got_sec->sh_addralign = L1_CACHE_BYTES;
1579151dde4SHuacai Chen got_sec->sh_size = (num_gots + 1) * sizeof(struct got_entry);
15859b3d4a9SXi Ruoyao mod->arch.got.num_entries = 0;
15959b3d4a9SXi Ruoyao mod->arch.got.max_entries = num_gots;
16059b3d4a9SXi Ruoyao
1619151dde4SHuacai Chen plt_sec = sechdrs + mod->arch.plt.shndx;
1629151dde4SHuacai Chen plt_sec->sh_type = SHT_NOBITS;
1639151dde4SHuacai Chen plt_sec->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
1649151dde4SHuacai Chen plt_sec->sh_addralign = L1_CACHE_BYTES;
1659151dde4SHuacai Chen plt_sec->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
166fcdfe9d2SHuacai Chen mod->arch.plt.num_entries = 0;
167fcdfe9d2SHuacai Chen mod->arch.plt.max_entries = num_plts;
168fcdfe9d2SHuacai Chen
1699151dde4SHuacai Chen plt_idx_sec = sechdrs + mod->arch.plt_idx.shndx;
1709151dde4SHuacai Chen plt_idx_sec->sh_type = SHT_NOBITS;
1719151dde4SHuacai Chen plt_idx_sec->sh_flags = SHF_ALLOC;
1729151dde4SHuacai Chen plt_idx_sec->sh_addralign = L1_CACHE_BYTES;
1739151dde4SHuacai Chen plt_idx_sec->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry);
174fcdfe9d2SHuacai Chen mod->arch.plt_idx.num_entries = 0;
175fcdfe9d2SHuacai Chen mod->arch.plt_idx.max_entries = num_plts;
176fcdfe9d2SHuacai Chen
17728ac0a9eSQing Zhang if (tramp) {
17828ac0a9eSQing Zhang tramp->sh_type = SHT_NOBITS;
17928ac0a9eSQing Zhang tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
18028ac0a9eSQing Zhang tramp->sh_addralign = __alignof__(struct plt_entry);
18128ac0a9eSQing Zhang tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
18228ac0a9eSQing Zhang }
18328ac0a9eSQing Zhang
184fcdfe9d2SHuacai Chen return 0;
185fcdfe9d2SHuacai Chen }
186