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 #include <linux/moduleloader.h>
12
module_emit_got_entry(struct module * mod,unsigned long val)13 unsigned long module_emit_got_entry(struct module *mod, unsigned long val)
14 {
15 struct mod_section *got_sec = &mod->arch.got;
16 int i = got_sec->num_entries;
17 struct got_entry *got = get_got_entry(val, got_sec);
18
19 if (got)
20 return (unsigned long)got;
21
22 /* There is no duplicate entry, create a new one */
23 got = (struct got_entry *)got_sec->shdr->sh_addr;
24 got[i] = emit_got_entry(val);
25
26 got_sec->num_entries++;
27 BUG_ON(got_sec->num_entries > got_sec->max_entries);
28
29 return (unsigned long)&got[i];
30 }
31
module_emit_plt_entry(struct module * mod,unsigned long val)32 unsigned long module_emit_plt_entry(struct module *mod, unsigned long val)
33 {
34 struct mod_section *got_plt_sec = &mod->arch.got_plt;
35 struct got_entry *got_plt;
36 struct mod_section *plt_sec = &mod->arch.plt;
37 struct plt_entry *plt = get_plt_entry(val, plt_sec, got_plt_sec);
38 int i = plt_sec->num_entries;
39
40 if (plt)
41 return (unsigned long)plt;
42
43 /* There is no duplicate entry, create a new one */
44 got_plt = (struct got_entry *)got_plt_sec->shdr->sh_addr;
45 got_plt[i] = emit_got_entry(val);
46 plt = (struct plt_entry *)plt_sec->shdr->sh_addr;
47 plt[i] = emit_plt_entry(val,
48 (unsigned long)&plt[i],
49 (unsigned long)&got_plt[i]);
50
51 plt_sec->num_entries++;
52 got_plt_sec->num_entries++;
53 BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
54
55 return (unsigned long)&plt[i];
56 }
57
is_rela_equal(const Elf_Rela * x,const Elf_Rela * y)58 static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
59 {
60 return x->r_info == y->r_info && x->r_addend == y->r_addend;
61 }
62
duplicate_rela(const Elf_Rela * rela,int idx)63 static bool duplicate_rela(const Elf_Rela *rela, int idx)
64 {
65 int i;
66 for (i = 0; i < idx; i++) {
67 if (is_rela_equal(&rela[i], &rela[idx]))
68 return true;
69 }
70 return false;
71 }
72
count_max_entries(Elf_Rela * relas,int num,unsigned int * plts,unsigned int * gots)73 static void count_max_entries(Elf_Rela *relas, int num,
74 unsigned int *plts, unsigned int *gots)
75 {
76 for (int i = 0; i < num; i++) {
77 switch (ELF_R_TYPE(relas[i].r_info)) {
78 case R_RISCV_CALL_PLT:
79 case R_RISCV_PLT32:
80 if (!duplicate_rela(relas, i))
81 (*plts)++;
82 break;
83 case R_RISCV_GOT_HI20:
84 if (!duplicate_rela(relas, i))
85 (*gots)++;
86 break;
87 }
88 }
89 }
90
module_frob_arch_sections(Elf_Ehdr * ehdr,Elf_Shdr * sechdrs,char * secstrings,struct module * mod)91 int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
92 char *secstrings, struct module *mod)
93 {
94 unsigned int num_plts = 0;
95 unsigned int num_gots = 0;
96 int i;
97
98 /*
99 * Find the empty .got and .plt sections.
100 */
101 for (i = 0; i < ehdr->e_shnum; i++) {
102 if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
103 mod->arch.plt.shdr = sechdrs + i;
104 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
105 mod->arch.got.shdr = sechdrs + i;
106 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt"))
107 mod->arch.got_plt.shdr = sechdrs + i;
108 }
109
110 if (!mod->arch.plt.shdr) {
111 pr_err("%s: module PLT section(s) missing\n", mod->name);
112 return -ENOEXEC;
113 }
114 if (!mod->arch.got.shdr) {
115 pr_err("%s: module GOT section(s) missing\n", mod->name);
116 return -ENOEXEC;
117 }
118 if (!mod->arch.got_plt.shdr) {
119 pr_err("%s: module GOT.PLT section(s) missing\n", mod->name);
120 return -ENOEXEC;
121 }
122
123 /* Calculate the maxinum number of entries */
124 for (i = 0; i < ehdr->e_shnum; i++) {
125 Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
126 int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
127 Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
128
129 if (sechdrs[i].sh_type != SHT_RELA)
130 continue;
131
132 /* ignore relocations that operate on non-exec sections */
133 if (!(dst_sec->sh_flags & SHF_EXECINSTR))
134 continue;
135
136 count_max_entries(relas, num_rela, &num_plts, &num_gots);
137 }
138
139 mod->arch.plt.shdr->sh_type = SHT_NOBITS;
140 mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
141 mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES;
142 mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
143 mod->arch.plt.num_entries = 0;
144 mod->arch.plt.max_entries = num_plts;
145
146 mod->arch.got.shdr->sh_type = SHT_NOBITS;
147 mod->arch.got.shdr->sh_flags = SHF_ALLOC;
148 mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES;
149 mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry);
150 mod->arch.got.num_entries = 0;
151 mod->arch.got.max_entries = num_gots;
152
153 mod->arch.got_plt.shdr->sh_type = SHT_NOBITS;
154 mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC;
155 mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES;
156 mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry);
157 mod->arch.got_plt.num_entries = 0;
158 mod->arch.got_plt.max_entries = num_plts;
159 return 0;
160 }
161