diff options
Diffstat (limited to 'arch/loongarch/kernel/module-sections.c')
| -rw-r--r-- | arch/loongarch/kernel/module-sections.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c new file mode 100644 index 000000000000..d296a70b758f --- /dev/null +++ b/arch/loongarch/kernel/module-sections.c @@ -0,0 +1,170 @@ +// 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> + +Elf_Addr module_emit_got_entry(struct module *mod, 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, got_sec); + + if (got) + return (Elf_Addr)got; + + /* There is no GOT entry for val yet, create a new one. */ + got = (struct got_entry *)got_sec->shdr->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_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, 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 *)plt_sec->shdr->sh_addr; + plt[nr] = emit_plt_entry(val); + plt_idx = (struct plt_idx_entry *)plt_idx_sec->shdr->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; + + /* + * Find the empty .plt sections. + */ + for (i = 0; i < ehdr->e_shnum; i++) { + if (!strcmp(secstrings + sechdrs[i].sh_name, ".got")) + mod->arch.got.shdr = sechdrs + i; + else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) + mod->arch.plt.shdr = sechdrs + i; + else if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt.idx")) + mod->arch.plt_idx.shdr = sechdrs + i; + } + + if (!mod->arch.got.shdr) { + pr_err("%s: module GOT section(s) missing\n", mod->name); + return -ENOEXEC; + } + if (!mod->arch.plt.shdr) { + pr_err("%s: module PLT section(s) missing\n", mod->name); + return -ENOEXEC; + } + if (!mod->arch.plt_idx.shdr) { + 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); + } + + 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.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.plt_idx.shdr->sh_type = SHT_NOBITS; + mod->arch.plt_idx.shdr->sh_flags = SHF_ALLOC; + mod->arch.plt_idx.shdr->sh_addralign = L1_CACHE_BYTES; + mod->arch.plt_idx.shdr->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; + + return 0; +} |