1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2014-2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
*
* Copyright (C) 2018 Andes Technology Corporation <zong@andestech.com>
*/
#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/module.h>
unsigned long module_emit_got_entry(struct module *mod, unsigned long val)
{
struct mod_section *got_sec = &mod->arch.got;
int i = got_sec->num_entries;
struct got_entry *got = get_got_entry(val, got_sec);
if (got)
return (unsigned long)got;
/* There is no duplicate entry, create a new one */
got = (struct got_entry *)got_sec->shdr->sh_addr;
got[i] = emit_got_entry(val);
got_sec->num_entries++;
BUG_ON(got_sec->num_entries > got_sec->max_entries);
return (unsigned long)&got[i];
}
unsigned long module_emit_plt_entry(struct module *mod, unsigned long val)
{
struct mod_section *got_plt_sec = &mod->arch.got_plt;
struct got_entry *got_plt;
struct mod_section *plt_sec = &mod->arch.plt;
struct plt_entry *plt = get_plt_entry(val, plt_sec, got_plt_sec);
int i = plt_sec->num_entries;
if (plt)
return (unsigned long)plt;
/* There is no duplicate entry, create a new one */
got_plt = (struct got_entry *)got_plt_sec->shdr->sh_addr;
got_plt[i] = emit_got_entry(val);
plt = (struct plt_entry *)plt_sec->shdr->sh_addr;
plt[i] = emit_plt_entry(val,
(unsigned long)&plt[i],
(unsigned long)&got_plt[i]);
plt_sec->num_entries++;
got_plt_sec->num_entries++;
BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
return (unsigned long)&plt[i];
}
static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
{
return x->r_info == y->r_info && x->r_addend == y->r_addend;
}
static bool duplicate_rela(const Elf_Rela *rela, int idx)
{
int i;
for (i = 0; i < idx; i++) {
if (is_rela_equal(&rela[i], &rela[idx]))
return true;
}
return false;
}
static void count_max_entries(Elf_Rela *relas, int num,
unsigned int *plts, unsigned int *gots)
{
unsigned int type, i;
for (i = 0; i < num; i++) {
type = ELF_RISCV_R_TYPE(relas[i].r_info);
if (type == R_RISCV_CALL_PLT) {
if (!duplicate_rela(relas, i))
(*plts)++;
} else if (type == R_RISCV_GOT_HI20) {
if (!duplicate_rela(relas, i))
(*gots)++;
}
}
}
int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *mod)
{
unsigned int num_plts = 0;
unsigned int num_gots = 0;
int i;
/*
* Find the empty .got and .plt sections.
*/
for (i = 0; i < ehdr->e_shnum; i++) {
if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
mod->arch.plt.shdr = sechdrs + i;
else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
mod->arch.got.shdr = sechdrs + i;
else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt"))
mod->arch.got_plt.shdr = sechdrs + i;
}
if (!mod->arch.plt.shdr) {
pr_err("%s: module PLT section(s) missing\n", mod->name);
return -ENOEXEC;
}
if (!mod->arch.got.shdr) {
pr_err("%s: module GOT section(s) missing\n", mod->name);
return -ENOEXEC;
}
if (!mod->arch.got_plt.shdr) {
pr_err("%s: module GOT.PLT section(s) missing\n", mod->name);
return -ENOEXEC;
}
/* Calculate the maxinum number of entries */
for (i = 0; i < ehdr->e_shnum; i++) {
Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
if (sechdrs[i].sh_type != SHT_RELA)
continue;
/* ignore relocations that operate on non-exec sections */
if (!(dst_sec->sh_flags & SHF_EXECINSTR))
continue;
count_max_entries(relas, num_rela, &num_plts, &num_gots);
}
mod->arch.plt.shdr->sh_type = SHT_NOBITS;
mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES;
mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
mod->arch.plt.num_entries = 0;
mod->arch.plt.max_entries = num_plts;
mod->arch.got.shdr->sh_type = SHT_NOBITS;
mod->arch.got.shdr->sh_flags = SHF_ALLOC;
mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES;
mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry);
mod->arch.got.num_entries = 0;
mod->arch.got.max_entries = num_gots;
mod->arch.got_plt.shdr->sh_type = SHT_NOBITS;
mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC;
mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES;
mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry);
mod->arch.got_plt.num_entries = 0;
mod->arch.got_plt.max_entries = num_plts;
return 0;
}
|
