arch/loongarch/kernel/module-sections.c

Source file repositories/reference/linux-study-clean/arch/loongarch/kernel/module-sections.c

File Facts

System
Linux kernel
Corpus path
arch/loongarch/kernel/module-sections.c
Extension
.c
Size
5229 bytes
Lines
187
Domain
Architecture Layer
Bucket
arch/loongarch
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

switch (ELF_R_TYPE(relas[i].r_info)) {
		case R_LARCH_SOP_PUSH_PLT_PCREL:
		case R_LARCH_B26:
			(*plts)++;
			break;
		case R_LARCH_GOT_PC_HI20:
		case R_LARCH_GOT_PCADD_HI20:
			(*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;

Annotation

Implementation Notes