From 1ce53adf13a54375d2a5c7cdbe341b2558389615 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Thu, 29 Jul 2010 01:47:53 +0200 Subject: [PATCH] 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 Signed-off-by: Anders Kaseorg Acked-by: Sam Ravnborg Cc: Rusty Russell Cc: Andi Kleen Signed-off-by: Michal Marek --- scripts/mod/file2alias.c | 6 +-- scripts/mod/modpost.c | 102 +++++++++++++++++++++++++++++---------- scripts/mod/modpost.h | 43 +++++++++++++++++ 3 files changed, 122 insertions(+), 29 deletions(-) diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c index 220213e603db..33f436328f9a 100644 --- a/scripts/mod/file2alias.c +++ b/scripts/mod/file2alias.c @@ -839,16 +839,16 @@ void handle_moddevtable(struct module *mod, struct elf_info *info, char *zeros = NULL; /* We're looking for a section relative symbol */ - if (!sym->st_shndx || sym->st_shndx >= info->hdr->e_shnum) + if (!sym->st_shndx || get_secindex(info, sym) >= info->num_sections) return; /* Handle all-NULL symbols allocated into .bss */ - if (info->sechdrs[sym->st_shndx].sh_type & SHT_NOBITS) { + if (info->sechdrs[get_secindex(info, sym)].sh_type & SHT_NOBITS) { zeros = calloc(1, sym->st_size); symval = zeros; } else { symval = (void *)info->hdr - + info->sechdrs[sym->st_shndx].sh_offset + + info->sechdrs[get_secindex(info, sym)].sh_offset + sym->st_value; } diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 3318692e4e76..7249ab44f44c 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -253,7 +253,7 @@ static enum export export_no(const char *s) return export_unknown; } -static enum export export_from_sec(struct elf_info *elf, Elf_Section sec) +static enum export export_from_sec(struct elf_info *elf, unsigned int sec) { if (sec == elf->export_sec) return export_plain; @@ -373,6 +373,8 @@ static int parse_elf(struct elf_info *info, const char *filename) Elf_Ehdr *hdr; Elf_Shdr *sechdrs; Elf_Sym *sym; + const char *secstrings; + unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U; hdr = grab_file(filename, &info->size); if (!hdr) { @@ -417,8 +419,27 @@ static int parse_elf(struct elf_info *info, const char *filename) return 0; } + if (hdr->e_shnum == 0) { + /* + * There are more than 64k sections, + * read count from .sh_size. + * note: it doesn't need shndx2secindex() + */ + info->num_sections = TO_NATIVE(sechdrs[0].sh_size); + } + else { + info->num_sections = hdr->e_shnum; + } + if (hdr->e_shstrndx == SHN_XINDEX) { + info->secindex_strings = + shndx2secindex(TO_NATIVE(sechdrs[0].sh_link)); + } + else { + info->secindex_strings = hdr->e_shstrndx; + } + /* Fix endianness in section headers */ - for (i = 0; i < hdr->e_shnum; i++) { + for (i = 0; i < info->num_sections; i++) { sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name); sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type); sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags); @@ -431,9 +452,8 @@ static int parse_elf(struct elf_info *info, const char *filename) sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize); } /* Find symbol table. */ - for (i = 1; i < hdr->e_shnum; i++) { - const char *secstrings - = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; + secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset; + for (i = 1; i < info->num_sections; i++) { const char *secname; int nobits = sechdrs[i].sh_type == SHT_NOBITS; @@ -461,14 +481,26 @@ static int parse_elf(struct elf_info *info, const char *filename) else if (strcmp(secname, "__ksymtab_gpl_future") == 0) info->export_gpl_future_sec = i; - if (sechdrs[i].sh_type != SHT_SYMTAB) - continue; + if (sechdrs[i].sh_type == SHT_SYMTAB) { + unsigned int sh_link_idx; + symtab_idx = i; + info->symtab_start = (void *)hdr + + sechdrs[i].sh_offset; + info->symtab_stop = (void *)hdr + + sechdrs[i].sh_offset + sechdrs[i].sh_size; + sh_link_idx = shndx2secindex(sechdrs[i].sh_link); + info->strtab = (void *)hdr + + sechdrs[sh_link_idx].sh_offset; + } - info->symtab_start = (void *)hdr + sechdrs[i].sh_offset; - info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset - + sechdrs[i].sh_size; - info->strtab = (void *)hdr + - sechdrs[sechdrs[i].sh_link].sh_offset; + /* 32bit section no. table? ("more than 64k sections") */ + if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) { + symtab_shndx_idx = i; + info->symtab_shndx_start = (void *)hdr + + sechdrs[i].sh_offset; + info->symtab_shndx_stop = (void *)hdr + + sechdrs[i].sh_offset + sechdrs[i].sh_size; + } } if (!info->symtab_start) fatal("%s has no symtab?\n", filename); @@ -480,6 +512,21 @@ static int parse_elf(struct elf_info *info, const char *filename) sym->st_value = TO_NATIVE(sym->st_value); sym->st_size = TO_NATIVE(sym->st_size); } + + if (symtab_shndx_idx != ~0U) { + Elf32_Word *p; + if (symtab_idx != + shndx2secindex(sechdrs[symtab_shndx_idx].sh_link)) + fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n", + filename, + shndx2secindex(sechdrs[symtab_shndx_idx].sh_link), + symtab_idx); + /* Fix endianness */ + for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop; + p++) + *p = TO_NATIVE(*p); + } + return 1; } @@ -514,7 +561,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info, Elf_Sym *sym, const char *symname) { unsigned int crc; - enum export export = export_from_sec(info, sym->st_shndx); + enum export export = export_from_sec(info, get_secindex(info, sym)); switch (sym->st_shndx) { case SHN_COMMON: @@ -656,19 +703,19 @@ static const char *sym_name(struct elf_info *elf, Elf_Sym *sym) return "(unknown)"; } -static const char *sec_name(struct elf_info *elf, int shndx) +static const char *sec_name(struct elf_info *elf, int secindex) { Elf_Shdr *sechdrs = elf->sechdrs; return (void *)elf->hdr + - elf->sechdrs[elf->hdr->e_shstrndx].sh_offset + - sechdrs[shndx].sh_name; + elf->sechdrs[elf->secindex_strings].sh_offset + + sechdrs[secindex].sh_name; } static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr) { return (void *)elf->hdr + - elf->sechdrs[elf->hdr->e_shstrndx].sh_offset + - sechdr->sh_name; + elf->sechdrs[elf->secindex_strings].sh_offset + + sechdr->sh_name; } /* if sym is empty or point to a string @@ -1047,11 +1094,14 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr, Elf_Sym *near = NULL; Elf64_Sword distance = 20; Elf64_Sword d; + unsigned int relsym_secindex; if (relsym->st_name != 0) return relsym; + + relsym_secindex = get_secindex(elf, relsym); for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { - if (sym->st_shndx != relsym->st_shndx) + if (get_secindex(elf, sym) != relsym_secindex) continue; if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) continue; @@ -1113,9 +1163,9 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr, for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { const char *symsec; - if (sym->st_shndx >= SHN_LORESERVE) + if (is_shndx_special(sym->st_shndx)) continue; - symsec = sec_name(elf, sym->st_shndx); + symsec = sec_name(elf, get_secindex(elf, sym)); if (strcmp(symsec, sec) != 0) continue; if (!is_valid_name(elf, sym)) @@ -1311,7 +1361,7 @@ static void check_section_mismatch(const char *modname, struct elf_info *elf, const char *tosec; const struct sectioncheck *mismatch; - tosec = sec_name(elf, sym->st_shndx); + tosec = sec_name(elf, get_secindex(elf, sym)); mismatch = section_mismatch(fromsec, tosec); if (mismatch) { Elf_Sym *to; @@ -1339,7 +1389,7 @@ static unsigned int *reloc_location(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) { Elf_Shdr *sechdrs = elf->sechdrs; - int section = sechdr->sh_info; + int section = shndx2secindex(sechdr->sh_info); return (void *)elf->hdr + sechdrs[section].sh_offset + (r->r_offset - sechdrs[section].sh_addr); @@ -1447,7 +1497,7 @@ static void section_rela(const char *modname, struct elf_info *elf, r.r_addend = TO_NATIVE(rela->r_addend); sym = elf->symtab_start + r_sym; /* Skip special sections */ - if (sym->st_shndx >= SHN_LORESERVE) + if (is_shndx_special(sym->st_shndx)) continue; check_section_mismatch(modname, elf, &r, sym, fromsec); } @@ -1505,7 +1555,7 @@ static void section_rel(const char *modname, struct elf_info *elf, } sym = elf->symtab_start + r_sym; /* Skip special sections */ - if (sym->st_shndx >= SHN_LORESERVE) + if (is_shndx_special(sym->st_shndx)) continue; check_section_mismatch(modname, elf, &r, sym, fromsec); } @@ -1530,7 +1580,7 @@ static void check_sec_ref(struct module *mod, const char *modname, Elf_Shdr *sechdrs = elf->sechdrs; /* Walk through all sections */ - for (i = 0; i < elf->hdr->e_shnum; i++) { + for (i = 0; i < elf->num_sections; i++) { check_section(modname, elf, &elf->sechdrs[i]); /* We want to process only relocation sections and not .init */ if (sechdrs[i].sh_type == SHT_RELA) diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index be987a44f250..0388cfccac8d 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -129,8 +129,51 @@ struct elf_info { const char *strtab; char *modinfo; unsigned int modinfo_len; + + /* support for 32bit section numbers */ + + unsigned int num_sections; /* max_secindex + 1 */ + unsigned int secindex_strings; + /* if Nth symbol table entry has .st_shndx = SHN_XINDEX, + * take shndx from symtab_shndx_start[N] instead */ + Elf32_Word *symtab_shndx_start; + Elf32_Word *symtab_shndx_stop; }; +static inline int is_shndx_special(unsigned int i) +{ + return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE; +} + +/* shndx is in [0..SHN_LORESERVE) U (SHN_HIRESERVE, 0xfffffff], thus: + * shndx == 0 <=> sechdrs[0] + * ...... + * shndx == SHN_LORESERVE-1 <=> sechdrs[SHN_LORESERVE-1] + * shndx == SHN_HIRESERVE+1 <=> sechdrs[SHN_LORESERVE] + * shndx == SHN_HIRESERVE+2 <=> sechdrs[SHN_LORESERVE+1] + * ...... + * fyi: sym->st_shndx is uint16, SHN_LORESERVE = ff00, SHN_HIRESERVE = ffff, + * so basically we map 0000..feff -> 0000..feff + * ff00..ffff -> (you are a bad boy, dont do it) + * 10000..xxxx -> ff00..(xxxx-0x100) + */ +static inline unsigned int shndx2secindex(unsigned int i) +{ + if (i <= SHN_HIRESERVE) + return i; + return i - (SHN_HIRESERVE + 1 - SHN_LORESERVE); +} + +/* Accessor for sym->st_shndx, hides ugliness of "64k sections" */ +static inline unsigned int get_secindex(const struct elf_info *info, + const Elf_Sym *sym) +{ + if (sym->st_shndx != SHN_XINDEX) + return sym->st_shndx; + return shndx2secindex(info->symtab_shndx_start[sym - + info->symtab_start]); +} + /* file2alias.c */ extern unsigned int cross_build; void handle_moddevtable(struct module *mod, struct elf_info *info, -- 2.20.1