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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020-2022 Loongson Technology Corporation Limited
*/
#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/ftrace.h>
Elf_Addr module_emit_got_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
{
struct mod_section *got_sec = &mod->arch.got;
int i = got_sec->num_entries;
struct got_entry *got = get_got_entry(val, sechdrs, got_sec);
if (got)
return (Elf_Addr)got;
/* There is no GOT entry for val yet, create a new one. */
got = (struct got_entry *)sechdrs[got_sec->shndx].sh_addr;
got[i] = emit_got_entry(val);
got_sec->num_entries++;
if (got_sec->num_entries > got_sec->max_entries) {
/*
* This may happen when the module contains a GOT_HI20 without
* a paired GOT_LO12. Such a module is broken, reject it.
*/
pr_err("%s: module contains bad GOT relocation\n", mod->name);
return 0;
}
return (Elf_Addr)&got[i];
}
Elf_Addr module_emit_plt_entry(struct module *mod, Elf_Shdr *sechdrs, Elf_Addr val)
{
int nr;
struct mod_section *plt_sec = &mod->arch.plt;
struct mod_section *plt_idx_sec = &mod->arch.plt_idx;
struct plt_entry *plt = get_plt_entry(val, sechdrs, plt_sec, plt_idx_sec);
struct plt_idx_entry *plt_idx;
if (plt)
return (Elf_Addr)plt;
nr = plt_sec->num_entries;
/* There is no duplicate entry, create a new one */
plt = (struct plt_entry *)sechdrs[plt_sec->shndx].sh_addr;
plt[nr] = emit_plt_entry(val);
plt_idx = (struct plt_idx_entry *)sechdrs[plt_idx_sec->shndx].sh_addr;
plt_idx[nr] = emit_plt_idx_entry(val);
plt_sec->num_entries++;
plt_idx_sec->num_entries++;
BUG_ON(plt_sec->num_entries > plt_sec->max_entries);
return (Elf_Addr)&plt[nr];
}
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 i, type;
for (i = 0; i < num; i++) {
type = ELF_R_TYPE(relas[i].r_info);
switch (type) {
case R_LARCH_SOP_PUSH_PLT_PCREL:
case R_LARCH_B26:
if (!duplicate_rela(relas, i))
(*plts)++;
break;
case R_LARCH_GOT_PC_HI20:
if (!duplicate_rela(relas, i))
(*gots)++;
break;
default:
break; /* Do nothing. */
}
}
}
int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *mod)
{
unsigned int i, num_plts = 0, num_gots = 0;
Elf_Shdr *got_sec, *plt_sec, *plt_idx_sec, *tramp = NULL;
/*
* Find the empty .plt sections.
*/
for (i = 0; i < ehdr->e_shnum; i++) {
if (!strcmp(secstrings + sechdrs[i].sh_name, ".got"))
mod->arch.got.shndx = i;
else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt"))
mod->arch.plt.shndx = i;
else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx"))
mod->arch.plt_idx.shndx = i;
else if (!strcmp(secstrings + sechdrs[i].sh_name, ".ftrace_trampoline"))
tramp = sechdrs + i;
}
if (!mod->arch.got.shndx) {
pr_err("%s: module GOT section(s) missing\n", mod->name);
return -ENOEXEC;
}
if (!mod->arch.plt.shndx) {
pr_err("%s: module PLT section(s) missing\n", mod->name);
return -ENOEXEC;
}
if (!mod->arch.plt_idx.shndx) {
pr_err("%s: module PLT.IDX section(s) missing\n", mod->name);
return -ENOEXEC;
}
/* Calculate the maxinum number of entries */
for (i = 0; i < ehdr->e_shnum; i++) {
int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela);
Elf_Rela *relas = (void *)ehdr + sechdrs[i].sh_offset;
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);
}
got_sec = sechdrs + mod->arch.got.shndx;
got_sec->sh_type = SHT_NOBITS;
got_sec->sh_flags = SHF_ALLOC;
got_sec->sh_addralign = L1_CACHE_BYTES;
got_sec->sh_size = (num_gots + 1) * sizeof(struct got_entry);
mod->arch.got.num_entries = 0;
mod->arch.got.max_entries = num_gots;
plt_sec = sechdrs + mod->arch.plt.shndx;
plt_sec->sh_type = SHT_NOBITS;
plt_sec->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
plt_sec->sh_addralign = L1_CACHE_BYTES;
plt_sec->sh_size = (num_plts + 1) * sizeof(struct plt_entry);
mod->arch.plt.num_entries = 0;
mod->arch.plt.max_entries = num_plts;
plt_idx_sec = sechdrs + mod->arch.plt_idx.shndx;
plt_idx_sec->sh_type = SHT_NOBITS;
plt_idx_sec->sh_flags = SHF_ALLOC;
plt_idx_sec->sh_addralign = L1_CACHE_BYTES;
plt_idx_sec->sh_size = (num_plts + 1) * sizeof(struct plt_idx_entry);
mod->arch.plt_idx.num_entries = 0;
mod->arch.plt_idx.max_entries = num_plts;
if (tramp) {
tramp->sh_type = SHT_NOBITS;
tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
tramp->sh_addralign = __alignof__(struct plt_entry);
tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
}
return 0;
}
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