modpost: support objects with more than 64k sections
This patch makes modpost able to process object files with more than 64k sections. Needed for huge kernel builds (allyesconfig, for example) with -ffunction-sections. 64k sections handling is covered, for example, by this document: "IA-64 gABI Proposal 74: Section Indexes" http://www.codesourcery.com/public/cxx-abi/abi/prop-74-sindex.html Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com> Signed-off-by: Anders Kaseorg <andersk@mit.edu> Acked-by: Sam Ravnborg <sam@ravnborg.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Michal Marek <mmarek@suse.cz>
This commit is contained in:
Denys Vlasenko
Michal Marek
parent
4696e2958b
commit
1ce53adf13
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@ -839,16 +839,16 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
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char *zeros = NULL;
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/* We're looking for a section relative symbol */
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if (!sym->st_shndx || sym->st_shndx >= info->hdr->e_shnum)
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if (!sym->st_shndx || get_secindex(info, sym) >= info->num_sections)
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return;
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/* Handle all-NULL symbols allocated into .bss */
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if (info->sechdrs[sym->st_shndx].sh_type & SHT_NOBITS) {
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if (info->sechdrs[get_secindex(info, sym)].sh_type & SHT_NOBITS) {
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zeros = calloc(1, sym->st_size);
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symval = zeros;
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} else {
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symval = (void *)info->hdr
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+ info->sechdrs[sym->st_shndx].sh_offset
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+ info->sechdrs[get_secindex(info, sym)].sh_offset
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+ sym->st_value;
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}
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@ -253,7 +253,7 @@ static enum export export_no(const char *s)
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return export_unknown;
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}
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static enum export export_from_sec(struct elf_info *elf, Elf_Section sec)
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static enum export export_from_sec(struct elf_info *elf, unsigned int sec)
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{
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if (sec == elf->export_sec)
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return export_plain;
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@ -373,6 +373,8 @@ static int parse_elf(struct elf_info *info, const char *filename)
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Elf_Ehdr *hdr;
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Elf_Shdr *sechdrs;
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Elf_Sym *sym;
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const char *secstrings;
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unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U;
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hdr = grab_file(filename, &info->size);
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if (!hdr) {
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@ -417,8 +419,27 @@ static int parse_elf(struct elf_info *info, const char *filename)
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return 0;
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}
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if (hdr->e_shnum == 0) {
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/*
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* There are more than 64k sections,
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* read count from .sh_size.
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* note: it doesn't need shndx2secindex()
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*/
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info->num_sections = TO_NATIVE(sechdrs[0].sh_size);
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}
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else {
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info->num_sections = hdr->e_shnum;
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}
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if (hdr->e_shstrndx == SHN_XINDEX) {
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info->secindex_strings =
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shndx2secindex(TO_NATIVE(sechdrs[0].sh_link));
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}
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else {
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info->secindex_strings = hdr->e_shstrndx;
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}
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/* Fix endianness in section headers */
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for (i = 0; i < hdr->e_shnum; i++) {
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for (i = 0; i < info->num_sections; i++) {
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sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name);
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sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type);
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sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags);
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@ -431,9 +452,8 @@ static int parse_elf(struct elf_info *info, const char *filename)
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sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize);
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}
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/* Find symbol table. */
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for (i = 1; i < hdr->e_shnum; i++) {
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const char *secstrings
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= (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
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secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset;
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for (i = 1; i < info->num_sections; i++) {
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const char *secname;
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int nobits = sechdrs[i].sh_type == SHT_NOBITS;
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@ -461,14 +481,26 @@ static int parse_elf(struct elf_info *info, const char *filename)
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else if (strcmp(secname, "__ksymtab_gpl_future") == 0)
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info->export_gpl_future_sec = i;
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if (sechdrs[i].sh_type != SHT_SYMTAB)
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continue;
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if (sechdrs[i].sh_type == SHT_SYMTAB) {
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unsigned int sh_link_idx;
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symtab_idx = i;
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info->symtab_start = (void *)hdr +
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sechdrs[i].sh_offset;
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info->symtab_stop = (void *)hdr +
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sechdrs[i].sh_offset + sechdrs[i].sh_size;
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sh_link_idx = shndx2secindex(sechdrs[i].sh_link);
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info->strtab = (void *)hdr +
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sechdrs[sh_link_idx].sh_offset;
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}
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info->symtab_start = (void *)hdr + sechdrs[i].sh_offset;
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info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset
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+ sechdrs[i].sh_size;
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info->strtab = (void *)hdr +
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sechdrs[sechdrs[i].sh_link].sh_offset;
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/* 32bit section no. table? ("more than 64k sections") */
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if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) {
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symtab_shndx_idx = i;
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info->symtab_shndx_start = (void *)hdr +
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sechdrs[i].sh_offset;
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info->symtab_shndx_stop = (void *)hdr +
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sechdrs[i].sh_offset + sechdrs[i].sh_size;
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}
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}
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if (!info->symtab_start)
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fatal("%s has no symtab?\n", filename);
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@ -480,6 +512,21 @@ static int parse_elf(struct elf_info *info, const char *filename)
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sym->st_value = TO_NATIVE(sym->st_value);
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sym->st_size = TO_NATIVE(sym->st_size);
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}
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if (symtab_shndx_idx != ~0U) {
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Elf32_Word *p;
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if (symtab_idx !=
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shndx2secindex(sechdrs[symtab_shndx_idx].sh_link))
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fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n",
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filename,
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shndx2secindex(sechdrs[symtab_shndx_idx].sh_link),
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symtab_idx);
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/* Fix endianness */
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for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop;
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p++)
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*p = TO_NATIVE(*p);
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}
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return 1;
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}
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@ -514,7 +561,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
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Elf_Sym *sym, const char *symname)
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{
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unsigned int crc;
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enum export export = export_from_sec(info, sym->st_shndx);
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enum export export = export_from_sec(info, get_secindex(info, sym));
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switch (sym->st_shndx) {
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case SHN_COMMON:
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@ -656,19 +703,19 @@ static const char *sym_name(struct elf_info *elf, Elf_Sym *sym)
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return "(unknown)";
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}
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static const char *sec_name(struct elf_info *elf, int shndx)
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static const char *sec_name(struct elf_info *elf, int secindex)
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{
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Elf_Shdr *sechdrs = elf->sechdrs;
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return (void *)elf->hdr +
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elf->sechdrs[elf->hdr->e_shstrndx].sh_offset +
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sechdrs[shndx].sh_name;
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elf->sechdrs[elf->secindex_strings].sh_offset +
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sechdrs[secindex].sh_name;
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}
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static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
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{
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return (void *)elf->hdr +
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elf->sechdrs[elf->hdr->e_shstrndx].sh_offset +
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sechdr->sh_name;
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elf->sechdrs[elf->secindex_strings].sh_offset +
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sechdr->sh_name;
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}
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/* if sym is empty or point to a string
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@ -1047,11 +1094,14 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr,
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Elf_Sym *near = NULL;
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Elf64_Sword distance = 20;
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Elf64_Sword d;
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unsigned int relsym_secindex;
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if (relsym->st_name != 0)
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return relsym;
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relsym_secindex = get_secindex(elf, relsym);
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for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
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if (sym->st_shndx != relsym->st_shndx)
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if (get_secindex(elf, sym) != relsym_secindex)
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continue;
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if (ELF_ST_TYPE(sym->st_info) == STT_SECTION)
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continue;
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@ -1113,9 +1163,9 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
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for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) {
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const char *symsec;
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if (sym->st_shndx >= SHN_LORESERVE)
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if (is_shndx_special(sym->st_shndx))
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continue;
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symsec = sec_name(elf, sym->st_shndx);
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symsec = sec_name(elf, get_secindex(elf, sym));
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if (strcmp(symsec, sec) != 0)
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continue;
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if (!is_valid_name(elf, sym))
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@ -1311,7 +1361,7 @@ static void check_section_mismatch(const char *modname, struct elf_info *elf,
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const char *tosec;
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const struct sectioncheck *mismatch;
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tosec = sec_name(elf, sym->st_shndx);
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tosec = sec_name(elf, get_secindex(elf, sym));
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mismatch = section_mismatch(fromsec, tosec);
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if (mismatch) {
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Elf_Sym *to;
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@ -1339,7 +1389,7 @@ static unsigned int *reloc_location(struct elf_info *elf,
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Elf_Shdr *sechdr, Elf_Rela *r)
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{
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Elf_Shdr *sechdrs = elf->sechdrs;
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int section = sechdr->sh_info;
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int section = shndx2secindex(sechdr->sh_info);
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return (void *)elf->hdr + sechdrs[section].sh_offset +
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(r->r_offset - sechdrs[section].sh_addr);
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@ -1447,7 +1497,7 @@ static void section_rela(const char *modname, struct elf_info *elf,
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r.r_addend = TO_NATIVE(rela->r_addend);
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sym = elf->symtab_start + r_sym;
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/* Skip special sections */
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if (sym->st_shndx >= SHN_LORESERVE)
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if (is_shndx_special(sym->st_shndx))
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continue;
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check_section_mismatch(modname, elf, &r, sym, fromsec);
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}
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@ -1505,7 +1555,7 @@ static void section_rel(const char *modname, struct elf_info *elf,
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}
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sym = elf->symtab_start + r_sym;
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/* Skip special sections */
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if (sym->st_shndx >= SHN_LORESERVE)
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if (is_shndx_special(sym->st_shndx))
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continue;
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check_section_mismatch(modname, elf, &r, sym, fromsec);
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}
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@ -1530,7 +1580,7 @@ static void check_sec_ref(struct module *mod, const char *modname,
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Elf_Shdr *sechdrs = elf->sechdrs;
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/* Walk through all sections */
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for (i = 0; i < elf->hdr->e_shnum; i++) {
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for (i = 0; i < elf->num_sections; i++) {
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check_section(modname, elf, &elf->sechdrs[i]);
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/* We want to process only relocation sections and not .init */
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if (sechdrs[i].sh_type == SHT_RELA)
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@ -129,8 +129,51 @@ struct elf_info {
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const char *strtab;
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char *modinfo;
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unsigned int modinfo_len;
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/* support for 32bit section numbers */
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unsigned int num_sections; /* max_secindex + 1 */
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unsigned int secindex_strings;
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/* if Nth symbol table entry has .st_shndx = SHN_XINDEX,
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* take shndx from symtab_shndx_start[N] instead */
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Elf32_Word *symtab_shndx_start;
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Elf32_Word *symtab_shndx_stop;
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};
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static inline int is_shndx_special(unsigned int i)
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{
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return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
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}
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/* shndx is in [0..SHN_LORESERVE) U (SHN_HIRESERVE, 0xfffffff], thus:
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* shndx == 0 <=> sechdrs[0]
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* ......
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* shndx == SHN_LORESERVE-1 <=> sechdrs[SHN_LORESERVE-1]
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* shndx == SHN_HIRESERVE+1 <=> sechdrs[SHN_LORESERVE]
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* shndx == SHN_HIRESERVE+2 <=> sechdrs[SHN_LORESERVE+1]
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* ......
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* fyi: sym->st_shndx is uint16, SHN_LORESERVE = ff00, SHN_HIRESERVE = ffff,
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* so basically we map 0000..feff -> 0000..feff
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* ff00..ffff -> (you are a bad boy, dont do it)
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* 10000..xxxx -> ff00..(xxxx-0x100)
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*/
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static inline unsigned int shndx2secindex(unsigned int i)
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{
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if (i <= SHN_HIRESERVE)
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return i;
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return i - (SHN_HIRESERVE + 1 - SHN_LORESERVE);
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}
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/* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
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static inline unsigned int get_secindex(const struct elf_info *info,
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const Elf_Sym *sym)
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{
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if (sym->st_shndx != SHN_XINDEX)
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return sym->st_shndx;
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return shndx2secindex(info->symtab_shndx_start[sym -
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info->symtab_start]);
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}
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/* file2alias.c */
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extern unsigned int cross_build;
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void handle_moddevtable(struct module *mod, struct elf_info *info,
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