From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757964AbbA0AiF (ORCPT ); Mon, 26 Jan 2015 19:38:05 -0500 Received: from ozlabs.org ([103.22.144.67]:40413 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757931AbbA0Ah5 (ORCPT ); Mon, 26 Jan 2015 19:37:57 -0500 From: Rusty Russell To: Rabin Vincent Cc: linux-kernel@vger.kernel.org, Rabin Vincent Subject: Re: [PATCH] module: set ksymtab/kcrctab* section addresses to 0x0 In-Reply-To: <1422305155-23136-1-git-send-email-rabin.vincent@axis.com> References: <1422305155-23136-1-git-send-email-rabin.vincent@axis.com> User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.3.1 (x86_64-pc-linux-gnu) Date: Tue, 27 Jan 2015 10:20:32 +1030 Message-ID: <87d261rtiv.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rabin Vincent writes: > These __ksymtab*/__kcrctab* sections currently have non-zero addresses. > Non-zero section addresses in a relocatable ELF confuse GDB and it ends > up not relocating all symbols when add-symbol-file is used on modules > which have exports. The kernel's module loader does not care about > these addresses, so let's just set them to zero. Hi Rabin, You're right, we don't use sh_addr. This should be safe, I've applied it for the next merge window. AFAICT this would have always been a problem; wonder if it should be CC:stable? I don't use gdb on modules so haven't got a good feel for how many people this would be hurting. Thanks, Rusty. > Before: > > $ readelf -S lib/notifier-error-inject.ko | grep 'Name\| __ksymtab_gpl' > [Nr] Name Type Addr Off Size ES Flg Lk Inf Al > [ 8] __ksymtab_gpl PROGBITS 0000000c 0001b4 000010 00 A 0 0 4 > > (gdb) add-symbol-file lib/notifier-error-inject.ko 0x500000 -s .bss 0x700000 > add symbol table from file "lib/notifier-error-inject.ko" at > .text_addr = 0x500000 > .bss_addr = 0x700000 > (gdb) p ¬ifier_err_inject_dir > $3 = (struct dentry **) 0x0 > > After: > > $ readelf -S lib/notifier-error-inject.ko | grep 'Name\| __ksymtab_gpl' > [Nr] Name Type Addr Off Size ES Flg Lk Inf Al > [ 8] __ksymtab_gpl PROGBITS 00000000 0001b4 000010 00 A 0 0 4 > > (gdb) add-symbol-file lib/notifier-error-inject.ko 0x500000 -s .bss 0x700000 > add symbol table from file "lib/notifier-error-inject.ko" at > .text_addr = 0x500000 > .bss_addr = 0x700000 > (gdb) p ¬ifier_err_inject_dir > $3 = (struct dentry **) 0x700000 > > Signed-off-by: Rabin Vincent > --- > scripts/module-common.lds | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/scripts/module-common.lds b/scripts/module-common.lds > index 0865b3e..bec15f9 100644 > --- a/scripts/module-common.lds > +++ b/scripts/module-common.lds > @@ -6,14 +6,14 @@ > SECTIONS { > /DISCARD/ : { *(.discard) } > > - __ksymtab : { *(SORT(___ksymtab+*)) } > - __ksymtab_gpl : { *(SORT(___ksymtab_gpl+*)) } > - __ksymtab_unused : { *(SORT(___ksymtab_unused+*)) } > - __ksymtab_unused_gpl : { *(SORT(___ksymtab_unused_gpl+*)) } > - __ksymtab_gpl_future : { *(SORT(___ksymtab_gpl_future+*)) } > - __kcrctab : { *(SORT(___kcrctab+*)) } > - __kcrctab_gpl : { *(SORT(___kcrctab_gpl+*)) } > - __kcrctab_unused : { *(SORT(___kcrctab_unused+*)) } > - __kcrctab_unused_gpl : { *(SORT(___kcrctab_unused_gpl+*)) } > - __kcrctab_gpl_future : { *(SORT(___kcrctab_gpl_future+*)) } > + __ksymtab 0 : { *(SORT(___ksymtab+*)) } > + __ksymtab_gpl 0 : { *(SORT(___ksymtab_gpl+*)) } > + __ksymtab_unused 0 : { *(SORT(___ksymtab_unused+*)) } > + __ksymtab_unused_gpl 0 : { *(SORT(___ksymtab_unused_gpl+*)) } > + __ksymtab_gpl_future 0 : { *(SORT(___ksymtab_gpl_future+*)) } > + __kcrctab 0 : { *(SORT(___kcrctab+*)) } > + __kcrctab_gpl 0 : { *(SORT(___kcrctab_gpl+*)) } > + __kcrctab_unused 0 : { *(SORT(___kcrctab_unused+*)) } > + __kcrctab_unused_gpl 0 : { *(SORT(___kcrctab_unused_gpl+*)) } > + __kcrctab_gpl_future 0 : { *(SORT(___kcrctab_gpl_future+*)) } > } > -- > 1.7.10.4 > > -- > 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/