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
 12u64 module_emit_got_entry(struct module *mod, u64 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, got_sec);
 17
 18	if (got)
 19		return (u64)got;
 20
 21	/* There is no duplicate entry, create a new one */
 22	got = (struct got_entry *)got_sec->shdr->sh_addr;
 23	got[i] = emit_got_entry(val);
 24
 25	got_sec->num_entries++;
 26	BUG_ON(got_sec->num_entries > got_sec->max_entries);
 27
 28	return (u64)&got[i];
 29}
 30
 31u64 module_emit_plt_entry(struct module *mod, u64 val)
 32{
 33	struct mod_section *got_plt_sec = &mod->arch.got_plt;
 34	struct got_entry *got_plt;
 35	struct mod_section *plt_sec = &mod->arch.plt;
 36	struct plt_entry *plt = get_plt_entry(val, plt_sec, got_plt_sec);
 37	int i = plt_sec->num_entries;
 38
 39	if (plt)
 40		return (u64)plt;
 41
 42	/* There is no duplicate entry, create a new one */
 43	got_plt = (struct got_entry *)got_plt_sec->shdr->sh_addr;
 44	got_plt[i] = emit_got_entry(val);
 45	plt = (struct plt_entry *)plt_sec->shdr->sh_addr;
 46	plt[i] = emit_plt_entry(val, (u64)&plt[i], (u64)&got_plt[i]);
 47
 48	plt_sec->num_entries++;
 49	got_plt_sec->num_entries++;
 50	BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
 51
 52	return (u64)&plt[i];
 53}
 54
 55static int is_rela_equal(const Elf64_Rela *x, const Elf64_Rela *y)
 56{
 57	return x->r_info == y->r_info && x->r_addend == y->r_addend;
 58}
 59
 60static bool duplicate_rela(const Elf64_Rela *rela, int idx)
 61{
 62	int i;
 63	for (i = 0; i < idx; i++) {
 64		if (is_rela_equal(&rela[i], &rela[idx]))
 65			return true;
 66	}
 67	return false;
 68}
 69
 70static void count_max_entries(Elf64_Rela *relas, int num,
 71			      unsigned int *plts, unsigned int *gots)
 72{
 73	unsigned int type, i;
 74
 75	for (i = 0; i < num; i++) {
 76		type = ELF64_R_TYPE(relas[i].r_info);
 77		if (type == R_RISCV_CALL_PLT) {
 78			if (!duplicate_rela(relas, i))
 79				(*plts)++;
 80		} else if (type == R_RISCV_GOT_HI20) {
 81			if (!duplicate_rela(relas, i))
 82				(*gots)++;
 83		}
 84	}
 85}
 86
 87int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 88			      char *secstrings, struct module *mod)
 89{
 90	unsigned int num_plts = 0;
 91	unsigned int num_gots = 0;
 92	int i;
 93
 94	/*
 95	 * Find the empty .got and .plt sections.
 96	 */
 97	for (i = 0; i < ehdr->e_shnum; i++) {
 98		if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
 99			mod->arch.plt.shdr = sechdrs + i;
100		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
101			mod->arch.got.shdr = sechdrs + i;
102		else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got.plt"))
103			mod->arch.got_plt.shdr = sechdrs + i;
104	}
105
106	if (!mod->arch.plt.shdr) {
107		pr_err("%s: module PLT section(s) missing\n", mod->name);
108		return -ENOEXEC;
109	}
110	if (!mod->arch.got.shdr) {
111		pr_err("%s: module GOT section(s) missing\n", mod->name);
112		return -ENOEXEC;
113	}
114	if (!mod->arch.got_plt.shdr) {
115		pr_err("%s: module GOT.PLT section(s) missing\n", mod->name);
116		return -ENOEXEC;
117	}
118
119	/* Calculate the maxinum number of entries */
120	for (i = 0; i < ehdr->e_shnum; i++) {
121		Elf64_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
122		int num_rela = sechdrs[i].sh_size / sizeof(Elf64_Rela);
123		Elf64_Shdr *dst_sec = sechdrs + sechdrs[i].sh_info;
124
125		if (sechdrs[i].sh_type != SHT_RELA)
126			continue;
127
128		/* ignore relocations that operate on non-exec sections */
129		if (!(dst_sec->sh_flags & SHF_EXECINSTR))
130			continue;
131
132		count_max_entries(relas, num_rela, &num_plts, &num_gots);
133	}
134
135	mod->arch.plt.shdr->sh_type = SHT_NOBITS;
136	mod->arch.plt.shdr->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
137	mod->arch.plt.shdr->sh_addralign = L1_CACHE_BYTES;
138	mod->arch.plt.shdr->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
139	mod->arch.plt.num_entries = 0;
140	mod->arch.plt.max_entries = num_plts;
141
142	mod->arch.got.shdr->sh_type = SHT_NOBITS;
143	mod->arch.got.shdr->sh_flags = SHF_ALLOC;
144	mod->arch.got.shdr->sh_addralign = L1_CACHE_BYTES;
145	mod->arch.got.shdr->sh_size = (num_gots + 1) * sizeof(struct got_entry);
146	mod->arch.got.num_entries = 0;
147	mod->arch.got.max_entries = num_gots;
148
149	mod->arch.got_plt.shdr->sh_type = SHT_NOBITS;
150	mod->arch.got_plt.shdr->sh_flags = SHF_ALLOC;
151	mod->arch.got_plt.shdr->sh_addralign = L1_CACHE_BYTES;
152	mod->arch.got_plt.shdr->sh_size = (num_plts + 1) * sizeof(struct got_entry);
153	mod->arch.got_plt.num_entries = 0;
154	mod->arch.got_plt.max_entries = num_plts;
155	return 0;
156}