Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759511AbXEVEkj (ORCPT ); Tue, 22 May 2007 00:40:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755363AbXEVEkc (ORCPT ); Tue, 22 May 2007 00:40:32 -0400 Received: from topsns2.toshiba-tops.co.jp ([202.230.225.126]:54360 "EHLO topsns2.toshiba-tops.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754993AbXEVEkb (ORCPT ); Tue, 22 May 2007 00:40:31 -0400 Date: Tue, 22 May 2007 13:40:15 +0900 (JST) Message-Id: <20070522.134015.65004318.nemoto@toshiba-tops.co.jp> To: ben.collins@ubuntu.com Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, sam@ravnborg.org, torvalds@linux-foundation.org, dwmw2@infradead.org, adobriyan@gmail.com Subject: Re: [RFC] Crash on modpost, addend_386_rel() From: Atsushi Nemoto In-Reply-To: <1179799287.7485.17.camel@cunning> References: <1179799287.7485.17.camel@cunning> X-Fingerprint: 6ACA 1623 39BD 9A94 9B1A B746 CA77 FE94 2874 D52F X-Pgp-Public-Key: http://wwwkeys.pgp.net/pks/lookup?op=get&search=0x2874D52F X-Mailer: Mew version 5.2 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6481 Lines: 187 On Mon, 21 May 2007 22:01:27 -0400, Ben Collins wrote: > Got this crash in modpost. Bisect blames this commit: > > commit f892b7d480eec809a5dfbd6e65742b3f3155e50e > Author: Atsushi Nemoto > Date: Thu May 17 01:14:38 2007 +0900 > kbuild: make better section mismatch reports on i386, arm and mips Sorry, the patch breaks CONFIG_RELOCATABLE=y build. Actually I had not tested with that configuration. Linus already have reverted the commmit on git tree due to this breakage. Unfortunately, fixing whole things in the _right_ way is somewhat out of my ELF understanding. Some help from ELF gurus are welcome! Anyway, here is a updated patch tested on i386 (RELOCATABLE=y/n), arm, and mips. On calculation of 'location', sh_addr should be subtracted (thank you for debugging, Linus). And this patch contains an another fix and an improvement of added_mips_rel (kbuild-fix-and-improve-mips-rel-handling.patch in mm tree). Subject: [PATCH] kbuild: make better section mismatch reports on i386, arm and mips (take 2) On i386, ARM and MIPS, warn_sec_mismatch() sometimes fails to show usefull symbol name. This is because empty 'refsym' due to 0 r_addend value. This patch is to adjust r_addend value, consulting with apply_relocate() routine in kernel code. Signed-off-by: Atsushi Nemoto --- diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 8e5610d..e0bd1cd 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -384,6 +384,8 @@ static int parse_elf(struct elf_info *info, const char *filename) sechdrs[i].sh_size = TO_NATIVE(sechdrs[i].sh_size); sechdrs[i].sh_link = TO_NATIVE(sechdrs[i].sh_link); sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name); + sechdrs[i].sh_info = TO_NATIVE(sechdrs[i].sh_info); + sechdrs[i].sh_addr = TO_NATIVE(sechdrs[i].sh_addr); } /* Find symbol table. */ for (i = 1; i < hdr->e_shnum; i++) { @@ -753,6 +755,8 @@ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf_Addr addr, for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { if (sym->st_shndx != relsym->st_shndx) continue; + if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) + continue; if (sym->st_value == addr) return sym; } @@ -895,6 +899,74 @@ static void warn_sec_mismatch(const char *modname, const char *fromsec, } } +static void addend_386_rel(struct elf_info *elf, int rsection, Elf_Rela *r) +{ + Elf_Shdr *sechdrs = elf->sechdrs; + unsigned int r_typ; + unsigned int *location; + int section = sechdrs[rsection].sh_info; + + r_typ = ELF_R_TYPE(r->r_info); + location = (void *)elf->hdr + sechdrs[section].sh_offset + + (r->r_offset - sechdrs[section].sh_addr); + switch (r_typ) { + case R_386_32: + r->r_addend = TO_NATIVE(*location); + break; + case R_386_PC32: + r->r_addend = TO_NATIVE(*location) + 4; + break; + } +} + +static void addend_arm_rel(struct elf_info *elf, int rsection, Elf_Rela *r) +{ + Elf_Shdr *sechdrs = elf->sechdrs; + unsigned int r_typ; + unsigned int *location; + int section = sechdrs[rsection].sh_info; + + r_typ = ELF_R_TYPE(r->r_info); + location = (void *)elf->hdr + sechdrs[section].sh_offset + + (r->r_offset - sechdrs[section].sh_addr); + switch (r_typ) { + case R_ARM_ABS32: + r->r_addend = TO_NATIVE(*location); + break; + case R_ARM_PC24: + r->r_addend = ((TO_NATIVE(*location) & 0x00ffffff) << 2) + 8; + break; + } +} + +static int addend_mips_rel(struct elf_info *elf, int rsection, Elf_Rela *r) +{ + Elf_Shdr *sechdrs = elf->sechdrs; + unsigned int r_typ; + unsigned int *location; + int section = sechdrs[rsection].sh_info; + unsigned int inst; + + r_typ = ELF_R_TYPE(r->r_info); + if (r_typ == R_MIPS_HI16) + return 1; /* skip this */ + location = (void *)elf->hdr + sechdrs[section].sh_offset + + (r->r_offset - sechdrs[section].sh_addr); + inst = TO_NATIVE(*location); + switch (r_typ) { + case R_MIPS_LO16: + r->r_addend = inst & 0xffff; + break; + case R_MIPS_26: + r->r_addend = (inst & 0x03ffffff) << 2; + break; + case R_MIPS_32: + r->r_addend = inst; + break; + } + return 0; +} + /** * A module includes a number of sections that are discarded * either when loaded or when used as built-in. @@ -938,8 +1010,11 @@ static void check_sec_ref(struct module *mod, const char *modname, r.r_offset = TO_NATIVE(rela->r_offset); #if KERNEL_ELFCLASS == ELFCLASS64 if (hdr->e_machine == EM_MIPS) { + unsigned int r_typ; r_sym = ELF64_MIPS_R_SYM(rela->r_info); r_sym = TO_NATIVE(r_sym); + r_typ = ELF64_MIPS_R_TYPE(rela->r_info); + r.r_info = ELF64_R_INFO(r_sym, r_typ); } else { r.r_info = TO_NATIVE(rela->r_info); r_sym = ELF_R_SYM(r.r_info); @@ -972,8 +1047,11 @@ static void check_sec_ref(struct module *mod, const char *modname, r.r_offset = TO_NATIVE(rel->r_offset); #if KERNEL_ELFCLASS == ELFCLASS64 if (hdr->e_machine == EM_MIPS) { + unsigned int r_typ; r_sym = ELF64_MIPS_R_SYM(rel->r_info); r_sym = TO_NATIVE(r_sym); + r_typ = ELF64_MIPS_R_TYPE(rel->r_info); + r.r_info = ELF64_R_INFO(r_sym, r_typ); } else { r.r_info = TO_NATIVE(rel->r_info); r_sym = ELF_R_SYM(r.r_info); @@ -983,6 +1061,14 @@ static void check_sec_ref(struct module *mod, const char *modname, r_sym = ELF_R_SYM(r.r_info); #endif r.r_addend = 0; + if (hdr->e_machine == EM_386) + addend_386_rel(elf, i, &r); + else if (hdr->e_machine == EM_ARM) + addend_arm_rel(elf, i, &r); + else if (hdr->e_machine == EM_MIPS) { + if (addend_mips_rel(elf, i, &r)) + continue; + } sym = elf->symtab_start + r_sym; /* Skip special sections */ if (sym->st_shndx >= SHN_LORESERVE) diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index 0858caa..4156dd3 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -60,6 +60,9 @@ typedef union #define ELF64_MIPS_R_SYM(i) \ ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_sym) +#define ELF64_MIPS_R_TYPE(i) \ + ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_type1) + #if KERNEL_ELFDATA != HOST_ELFDATA static inline void __endian(const void *src, void *dest, unsigned int size) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/