1
2
3
4
5
6
7
8#include <linux/elf.h>
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/moduleloader.h>
12
13unsigned 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
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
32unsigned 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
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
58static 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
63static 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
73static void count_max_entries(Elf_Rela *relas, int num,
74 unsigned int *plts, unsigned int *gots)
75{
76 unsigned int type, i;
77
78 for (i = 0; i < num; i++) {
79 type = ELF_RISCV_R_TYPE(relas[i].r_info);
80 if (type == R_RISCV_CALL_PLT) {
81 if (!duplicate_rela(relas, i))
82 (*plts)++;
83 } else if (type == R_RISCV_GOT_HI20) {
84 if (!duplicate_rela(relas, i))
85 (*gots)++;
86 }
87 }
88}
89
90int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
91 char *secstrings, struct module *mod)
92{
93 unsigned int num_plts = 0;
94 unsigned int num_gots = 0;
95 int i;
96
97
98
99
100 for (i = 0; i < ehdr->e_shnum; i++) {
101 if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
102 mod->arch.plt.shdr = sechdrs + i;
103 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
104 mod->arch.got.shdr = sechdrs + i;
105 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt"))
106 mod->arch.got_plt.shdr = sechdrs + i;
107 }
108
109 if (!mod->arch.plt.shdr) {
110 pr_err("%s: module PLT section(s) missing\n", mod->name);
111 return -ENOEXEC;
112 }
113 if (!mod->arch.got.shdr) {
114 pr_err("%s: module GOT section(s) missing\n", mod->name);
115 return -ENOEXEC;
116 }
117 if (!mod->arch.got_plt.shdr) {
118 pr_err("%s: module GOT.PLT section(s) missing\n", mod->name);
119 return -ENOEXEC;
120 }
121
122
123 for (i = 0; i < ehdr->e_shnum; i++) {
124 Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
125 int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
126 Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
127
128 if (sechdrs[i].sh_type != SHT_RELA)
129 continue;
130
131
132 if (!(dst_sec->sh_flags & SHF_EXECINSTR))
133 continue;
134
135 count_max_entries(relas, num_rela, &num_plts, &num_gots);
136 }
137
138 mod->arch.plt.shdr->sh_type = SHT_NOBITS;
139 mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
140 mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES;
141 mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
142 mod->arch.plt.num_entries = 0;
143 mod->arch.plt.max_entries = num_plts;
144
145 mod->arch.got.shdr->sh_type = SHT_NOBITS;
146 mod->arch.got.shdr->sh_flags = SHF_ALLOC;
147 mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES;
148 mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry);
149 mod->arch.got.num_entries = 0;
150 mod->arch.got.max_entries = num_gots;
151
152 mod->arch.got_plt.shdr->sh_type = SHT_NOBITS;
153 mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC;
154 mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES;
155 mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry);
156 mod->arch.got_plt.num_entries = 0;
157 mod->arch.got_plt.max_entries = num_plts;
158 return 0;
159}
160
