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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4 */
5
6#include <linux/elf.h>
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/moduleloader.h>
10#include <linux/ftrace.h>
11
12Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
13{
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);
17
18 if (got)
19 return (Elf_Addr)got;
20
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);
24
25 got_sec->num_entries++;
26 if (got_sec->num_entries > got_sec->max_entries) {
27 /*
28 * This may happen when the module contains a GOT_HI20 without
29 * a paired GOT_LO12. Such a module is broken, reject it.
30 */
31 pr_err("%s: module contains bad GOT relocation\n", mod->name);
32 return 0;
33 }
34
35 return (Elf_Addr)&got[i];
36}
37
38Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
39{
40 int nr;
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;
45
46 if (plt)
47 return (Elf_Addr)plt;
48
49 nr = plt_sec->num_entries;
50
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);
56
57 plt_sec->num_entries++;
58 plt_idx_sec->num_entries++;
59 BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
60
61 return (Elf_Addr)&plt[nr];
62}
63
64static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
65{
66 return x->r_info == y->r_info && x->r_addend == y->r_addend;
67}
68
69static bool duplicate_rela(const Elf_Rela *rela, int idx)
70{
71 int i;
72
73 for (i = 0; i < idx; i++) {
74 if (is_rela_equal(&rela[i], &rela[idx]))
75 return true;
76 }
77
78 return false;
79}
80
81static void count_max_entries(Elf_Rela *relas, int num,
82 unsigned int *plts, unsigned int *gots)
83{
84 unsigned int i, type;
85
86 for (i = 0; i < num; i++) {
87 type = ELF_R_TYPE(relas[i].r_info);
88 switch (type) {
89 case R_LARCH_SOP_PUSH_PLT_PCREL:
90 case R_LARCH_B26:
91 if (!duplicate_rela(relas, i))
92 (*plts)++;
93 break;
94 case R_LARCH_GOT_PC_HI20:
95 if (!duplicate_rela(relas, i))
96 (*gots)++;
97 break;
98 default:
99 break; /* Do nothing. */
100 }
101 }
102}
103
104int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
105 char *secstrings, struct module *mod)
106{
107 unsigned int i, num_plts = 0, num_gots = 0;
108 Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;
109
110 /*
111 * Find the empty .plt sections.
112 */
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"))
121 tramp = sechdrs + i;
122 }
123
124 if (!mod->arch.got.shndx) {
125 pr_err("%s: module GOT section(s) missing\n", mod->name);
126 return -ENOEXEC;
127 }
128 if (!mod->arch.plt.shndx) {
129 pr_err("%s: module PLT section(s) missing\n", mod->name);
130 return -ENOEXEC;
131 }
132 if (!mod->arch.plt_idx.shndx) {
133 pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
134 return -ENOEXEC;
135 }
136
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;
142
143 if (sechdrs[i].sh_type != SHT_RELA)
144 continue;
145
146 /* ignore relocations that operate on non-exec sections */
147 if (!(dst_sec->sh_flags & SHF_EXECINSTR))
148 continue;
149
150 count_max_entries(relas, num_rela, &num_plts, &num_gots);
151 }
152
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;
160
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;
168
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;
176
177 if (tramp) {
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);
182 }
183
184 return 0;
185}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4 */
5
6#include <linux/elf.h>
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/ftrace.h>
10
11Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
12{
13 struct mod_section *got_sec = &mod->arch.got;
14 int i = got_sec->num_entries;
15 struct got_entry *got = get_got_entry(val, sechdrs, got_sec);
16
17 if (got)
18 return (Elf_Addr)got;
19
20 /* There is no GOT entry for val yet, create a new one. */
21 got = (struct got_entry *)sechdrs[got_sec->shndx].sh_addr;
22 got[i] = emit_got_entry(val);
23
24 got_sec->num_entries++;
25 if (got_sec->num_entries > got_sec->max_entries) {
26 /*
27 * This may happen when the module contains a GOT_HI20 without
28 * a paired GOT_LO12. Such a module is broken, reject it.
29 */
30 pr_err("%s: module contains bad GOT relocation\n", mod->name);
31 return 0;
32 }
33
34 return (Elf_Addr)&got[i];
35}
36
37Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
38{
39 int nr;
40 struct mod_section *plt_sec = &mod->arch.plt;
41 struct mod_section *plt_idx_sec = &mod->arch.plt_idx;
42 struct plt_entry *plt = get_plt_entry(val, sechdrs, plt_sec, plt_idx_sec);
43 struct plt_idx_entry *plt_idx;
44
45 if (plt)
46 return (Elf_Addr)plt;
47
48 nr = plt_sec->num_entries;
49
50 /* There is no duplicate entry, create a new one */
51 plt = (struct plt_entry *)sechdrs[plt_sec->shndx].sh_addr;
52 plt[nr] = emit_plt_entry(val);
53 plt_idx = (struct plt_idx_entry *)sechdrs[plt_idx_sec->shndx].sh_addr;
54 plt_idx[nr] = emit_plt_idx_entry(val);
55
56 plt_sec->num_entries++;
57 plt_idx_sec->num_entries++;
58 BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
59
60 return (Elf_Addr)&plt[nr];
61}
62
63static int is_rela_equal(const Elf_Rela *x, const Elf_Rela *y)
64{
65 return x->r_info == y->r_info && x->r_addend == y->r_addend;
66}
67
68static bool duplicate_rela(const Elf_Rela *rela, int idx)
69{
70 int i;
71
72 for (i = 0; i < idx; i++) {
73 if (is_rela_equal(&rela[i], &rela[idx]))
74 return true;
75 }
76
77 return false;
78}
79
80static void count_max_entries(Elf_Rela *relas, int num,
81 unsigned int *plts, unsigned int *gots)
82{
83 unsigned int i, type;
84
85 for (i = 0; i < num; i++) {
86 type = ELF_R_TYPE(relas[i].r_info);
87 switch (type) {
88 case R_LARCH_SOP_PUSH_PLT_PCREL:
89 case R_LARCH_B26:
90 if (!duplicate_rela(relas, i))
91 (*plts)++;
92 break;
93 case R_LARCH_GOT_PC_HI20:
94 if (!duplicate_rela(relas, i))
95 (*gots)++;
96 break;
97 default:
98 break; /* Do nothing. */
99 }
100 }
101}
102
103int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
104 char *secstrings, struct module *mod)
105{
106 unsigned int i, num_plts = 0, num_gots = 0;
107 Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;
108
109 /*
110 * Find the empty .plt sections.
111 */
112 for (i = 0; i < ehdr->e_shnum; i++) {
113 if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
114 mod->arch.got.shndx = i;
115 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
116 mod->arch.plt.shndx = i;
117 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
118 mod->arch.plt_idx.shndx = i;
119 else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
120 tramp = sechdrs + i;
121 }
122
123 if (!mod->arch.got.shndx) {
124 pr_err("%s: module GOT section(s) missing\n", mod->name);
125 return -ENOEXEC;
126 }
127 if (!mod->arch.plt.shndx) {
128 pr_err("%s: module PLT section(s) missing\n", mod->name);
129 return -ENOEXEC;
130 }
131 if (!mod->arch.plt_idx.shndx) {
132 pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
133 return -ENOEXEC;
134 }
135
136 /* Calculate the maxinum number of entries */
137 for (i = 0; i < ehdr->e_shnum; i++) {
138 int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
139 Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
140 Elf_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
141
142 if (sechdrs[i].sh_type != SHT_RELA)
143 continue;
144
145 /* ignore relocations that operate on non-exec sections */
146 if (!(dst_sec->sh_flags & SHF_EXECINSTR))
147 continue;
148
149 count_max_entries(relas, num_rela, &num_plts, &num_gots);
150 }
151
152 got_sec = sechdrs + mod->arch.got.shndx;
153 got_sec->sh_type = SHT_NOBITS;
154 got_sec->sh_flags = SHF_ALLOC;
155 got_sec->sh_addralign = L1_CACHE_BYTES;
156 got_sec->sh_size = (num_gots + 1) * sizeof(struct got_entry);
157 mod->arch.got.num_entries = 0;
158 mod->arch.got.max_entries = num_gots;
159
160 plt_sec = sechdrs + mod->arch.plt.shndx;
161 plt_sec->sh_type = SHT_NOBITS;
162 plt_sec->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
163 plt_sec->sh_addralign = L1_CACHE_BYTES;
164 plt_sec->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
165 mod->arch.plt.num_entries = 0;
166 mod->arch.plt.max_entries = num_plts;
167
168 plt_idx_sec = sechdrs + mod->arch.plt_idx.shndx;
169 plt_idx_sec->sh_type = SHT_NOBITS;
170 plt_idx_sec->sh_flags = SHF_ALLOC;
171 plt_idx_sec->sh_addralign = L1_CACHE_BYTES;
172 plt_idx_sec->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry);
173 mod->arch.plt_idx.num_entries = 0;
174 mod->arch.plt_idx.max_entries = num_plts;
175
176 if (tramp) {
177 tramp->sh_type = SHT_NOBITS;
178 tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
179 tramp->sh_addralign = __alignof__(struct plt_entry);
180 tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
181 }
182
183 return 0;
184}