From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ste-pvt-msa2.bahnhof.se ([213.80.101.71]:14086 "EHLO ste-pvt-msa2.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726121AbfCXGh6 (ORCPT ); Sun, 24 Mar 2019 02:37:58 -0400 Date: Sun, 24 Mar 2019 07:30:19 +0100 From: Fredrik Noring Subject: Re: [PATCH] kbuild: modversions: Fix relative CRC byte order interpretion Message-ID: <20190324063019.GA2555@sx9> References: <20190323184618.GA4916@sx9> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190323184618.GA4916@sx9> Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Masahiro Yamada , Michal Marek , linux-kbuild@vger.kernel.org Cc: Ard Biesheuvel , "Maciej W. Rozycki" Masahiro, Michal -- > Fix commit 56067812d5b0 ("kbuild: modversions: add infrastructure for > emitting relative CRCs") where CRCs are interpreted in host byte order > rather than proper kernel byte order. > > For example, when loading BE modules compiled with a LE system, the > error "disagrees about version of symbol module_layout" is produced. > A message such as "Found checksum D7FA6856 vs module 5668FAD7" will be > given with debug enabled, which indicates an obvious endian problem. I realise that the description above is perhaps a bit too brief; although the error is triggered by loading modules, the precise location of the error is within __kcrctab within the kernel image. > The general solution is to use the macro TO_NATIVE, as is done in > similar cases throughout modpost.c. With this correction it has been > verified that BE modules compiled with a LE system load properly into > a BE kernel. One could note that it has also been tested with a LE kernel compiled with a LE system, in which case TO_NATIVE returns its value unmodified since the byte orders match. This is by far the common case. Would you like me to send an updated description? Fredrik > Signed-off-by: Fredrik Noring > Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs") > Cc: stable@vger.kernel.org > --- > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c > index 0b0d1080b1c5..f277e116e0eb 100644 > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -639,7 +639,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info, > info->sechdrs[sym->st_shndx].sh_offset - > (info->hdr->e_type != ET_REL ? > info->sechdrs[sym->st_shndx].sh_addr : 0); > - crc = *crcp; > + crc = TO_NATIVE(*crcp); > } > sym_update_crc(symname + strlen("__crc_"), mod, crc, > export);