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
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	/* 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
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	/* 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
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	 * Find the empty .got and .plt sections.
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	/* Calculate the maxinum number of entries */
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		/* ignore relocations that operate on non-exec sections */
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