Messages in this thread Patch in this message | | | Subject | [PATCH 3/5] LoongArch: Support relocation against _GLOBAL_OFFSET_TABLE_ | From | Xi Ruoyao <> | Date | Thu, 28 Jul 2022 00:28:39 +0800 |
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With the stack-based relocations, the assembler emits three relocations to push the PC-relative offset of a GOT entry:
R_LARCH_SOP_PUSH_PCREL _GLOBAL_OFFSET_TABLE_ R_LARCH_SOP_PUSH_GPREL foo R_LARCH_SOP_ADD
"_GLOBAL_OFFSET_TABLE_" does not really exist in the symtab and the BFD linker handles it with special hack. Implement a similar hack for kernel so we will be able to really use R_LARCH_SOP_PUSH_GPREL relocation.
Signed-off-by: Xi Ruoyao <xry111@xry111.site> --- arch/loongarch/kernel/module-sections.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
diff --git a/arch/loongarch/kernel/module-sections.c b/arch/loongarch/kernel/module-sections.c index 509c0b86b1e9..73976addbf60 100644 --- a/arch/loongarch/kernel/module-sections.c +++ b/arch/loongarch/kernel/module-sections.c @@ -89,6 +89,9 @@ 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 *symtab = NULL; + Elf_Sym *symbols; + char *strings; /* * Find the empty .plt sections. @@ -100,6 +103,8 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, mod->arch.plt_idx.shdr = sechdrs + i; else if (!strcmp(secstrings + sechdrs[i].sh_name, ".got")) mod->arch.got.shdr = sechdrs + i; + else if (sechdrs[i].sh_type == SHT_SYMTAB) + symtab = sechdrs + i; } if (!mod->arch.plt.shdr) { @@ -115,6 +120,22 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, return -ENOEXEC; } + if (!symtab) { + pr_err("%s: module symbol table missing\n", mod->name); + return -ENOEXEC; + } + + symbols = (void *) ehdr + symtab->sh_offset; + strings = (void *) ehdr + sechdrs[symtab->sh_link].sh_offset; + + for (i = 0; i < symtab->sh_size / sizeof(Elf_Sym); i++) + if (symbols[i].st_shndx == SHN_UNDEF && + strcmp(strings + symbols[i].st_name, + "_GLOBAL_OFFSET_TABLE_") == 0) { + symbols[i].st_shndx = mod->arch.got.shdr - sechdrs; + symbols[i].st_value = 0; + } + /* Calculate the maxinum number of entries */ for (i = 0; i < ehdr->e_shnum; i++) { int num_rela = sechdrs[i].sh_size / sizeof(Elf_Rela); -- 2.37.0
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