From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.cn.fujitsu.com ([183.91.158.132]:50399 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726310AbgCRKI4 (ORCPT ); Wed, 18 Mar 2020 06:08:56 -0400 Message-ID: <5E71F32E.20300@cn.fujitsu.com> Date: Wed, 18 Mar 2020 18:08:46 +0800 From: Xiao Yang MIME-Version: 1.0 Subject: Re: [PATCH] modpost: Get proper section index by get_secindex() instead of st_shndx References: <20200316122820.11032-1-yangx.jy@cn.fujitsu.com> <5E702236.8070109@cn.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Masahiro Yamada Cc: Michal Marek , Linux Kbuild mailing list , Linux Kernel Mailing List On 2020/3/18 17:49, Masahiro Yamada wrote: > On Tue, Mar 17, 2020 at 10:05 AM Xiao Yang wrote: >> >> On 2020/3/16 20:28, Xiao Yang wrote: > > Thanks for catching this bug. > > >>> (uint16_t) st_shndx is limited to 65535(i.e. SHN_XINDEX) so sym_get_data() gets >>> wrong section index by st_shndx if object file(e.g. vmlinux.o) has more than >> Hi, >> >> It seems better to say that sym_get_data() gets wrong section index by >> st_shndx if requested symbol contains extended section index that is >> more than 65535. > > > Sounds good to me. > > >> Thanks, >> Xiao Yang >>> 65535 sessions. In this case, we need to get proper section index by .symtab_shndx >>> section. >>> >>> Module.symvers generated by building kernel with "-ffunction-sections -fdata-sections" >>> shows the issue(i.e. cannot get 89902 by st_shndx): >>> ------------------------------------------------------------------- >>> [root@Fedora-30 linux]# file Module.symvers >>> Module.symvers: data >>> [root@Fedora-30 linux]# head -n1 Module.symvers >>> 0x5caf3011 ipv6_chk_custom_prefix ▒▒▒▒▒▒▒▒ vmlinux EXPORT_SYMBOL > > > Could you delete this dump? > I'd like to avoid garbling where possible. > Hi Masahiro, Sure, it is OK to delete it. > >>> ... >>> [root@Fedora-30 linux]# readelf -s -W vmlinux.o | grep __kstrtabns_ipv6_chk_custom_prefix >>> 199174: 0000000000032578 1 OBJECT LOCAL DEFAULT 89902 __kstrtabns_ipv6_chk_custom_prefix >>> [root@Fedora-30 linux]# readelf -S -W vmlinux.o | grep 89902 >>> [89902] __ksymtab_strings PROGBITS 0000000000000000 a94e00 0345a2 00 A 0 0 1 >>> ------------------------------------------------------------------- >>> >>> Fixes: afa0459daa7b ("modpost: add a helper to get data pointed by a symbol") > > Strictly speaking, this commit does not introduce any bug. > > The CRC bug for MODVERSIONS exists since > 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting > relative CRCs") > Will replace it with your suggested commit. > >>> Fixes: 5545322c86d9 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name") > > This commit hash is wrong. > The correct one is > > Fixes: e84f9fbbece1 ("modpost: refactor namespace_from_kstrtabns() to > not hard-code section name") > > Sorry for the wrong commit hash. Thanks a lot for your quick review. I will send v2 patch soon. Best Regards, Xiao Yang > > > >>> Signed-off-by: Xiao Yang >>> --- >>> scripts/mod/modpost.c | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c >>> index d9418c58a8c0..c1fec8cac257 100644 >>> --- a/scripts/mod/modpost.c >>> +++ b/scripts/mod/modpost.c >>> @@ -310,7 +310,8 @@ static const char *sec_name(struct elf_info *elf, int secindex) >>> >>> static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym) >>> { >>> - Elf_Shdr *sechdr =&info->sechdrs[sym->st_shndx]; >>> + unsigned int secindex = get_secindex(info, sym); >>> + Elf_Shdr *sechdr =&info->sechdrs[secindex]; >>> unsigned long offset; >>> >>> offset = sym->st_value; >> >> >> > > > -- > Best Regards > Masahiro Yamada > > > . >