Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751935AbeADRcF (ORCPT + 1 other); Thu, 4 Jan 2018 12:32:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44832 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751246AbeADRcE (ORCPT ); Thu, 4 Jan 2018 12:32:04 -0500 Date: Thu, 4 Jan 2018 11:32:03 -0600 From: Josh Poimboeuf To: Markus Cc: Greg Kroah-Hartman , lkml , Ingo Molnar Subject: Re: objtool segfault with ORC unwinder enabled Message-ID: <20180104173203.zgy3g36wgaoeuii7@treble> References: <1537667.mbZVOcHbLR@markus> <2570840.NclWvBoOoG@markus> <20180104154613.rqpueangb3f4fpox@treble> <2752107.fJzmbfloTe@markus> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <2752107.fJzmbfloTe@markus> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 04 Jan 2018 17:32:04 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Thu, Jan 04, 2018 at 05:56:30PM +0100, Markus wrote: > On Thursday, 4 January 2018 16:46:13 CET Josh Poimboeuf wrote: > > On Wed, Jan 03, 2018 at 06:26:19PM +0100, Markus wrote: > > > > > > I'm unable to recreate. Can you attach one of the .o files (like > > > > > > the > > > > > > above irq.o)? > > > > > > > > > > Sure, see attached. (From vanilla linux-4.14.11.) > > > > > > > > There's something weird with the toolchain. The object file doesn't > > > > have an ELF section symbol for the .irqentry.text section. > > > > > > > > Are there any special KCFLAGS being added? Can you build the object > > > > with V=1 to show the full gcc command line? > > > > > > I have not added anything. There is no env variable set like $KCFLAGS or > > > $CFLAGS. (If that was the question.) > > > > > > I think you mean this line from output: > > > gcc -Wp,-MD,arch/x86/kernel/.irq.o.d -nostdinc -isystem > > > /usr/lib/gcc/x86_64- pc-linux-gnu/6.4.0/include -I./arch/x86/include > > > -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi > > > -I./arch/x86/include/generated/uapi -I./ include/uapi > > > -I./include/generated/uapi -include ./include/linux/kconfig.h - > > > D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict- > > > aliasing -fno-common -fshort-wchar -Werror-implicit-function-declaration > > > -Wno- format-security -std=gnu89 -fno-PIE -mno-sse -mno-mmx -mno-sse2 > > > -mno-3dnow - mno-avx -m64 -falign-jumps=1 -falign-loops=1 -mno-80387 > > > -mno-fp-ret-in-387 - mpreferred-stack-boundary=3 -mskip-rax-setup > > > -mtune=generic -mno-red-zone - mcmodel=kernel -funit-at-a-time > > > -DCONFIG_AS_CFI=1 - > > > DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 > > > -DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_SSSE3=1 -DCONFIG_AS_CRC32=1 > > > -DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 - DCONFIG_AS_AVX512=1 > > > -DCONFIG_AS_SHA1_NI=1 -DCONFIG_AS_SHA256_NI=1 -pipe -Wno- sign-compare > > > -fno-asynchronous-unwind-tables -fno-delete-null-pointer-checks - > > > Wno-frame-address -O2 --param=allow-store-data-races=0 -DCC_HAVE_ASM_GOTO > > > - Wframe-larger-than=2048 -fno-stack-protector > > > -Wno-unused-but-set-variable - Wno-unused-const-variable > > > -fomit-frame-pointer -fno-var-tracking-assignments - > > > Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fno- > > > stack-check -fconserve-stack -Werror=implicit-int > > > -Werror=strict-prototypes - Werror=date-time > > > -Werror=incompatible-pointer-types -Werror=designated-init - > > > Iarch/x86/kernel/../include/asm/trace -DKBUILD_BASENAME='"irq"' - > > > DKBUILD_MODNAME='"irq"' -c -o arch/x86/kernel/.tmp_irq.o > > > arch/x86/kernel/irq.c > > > > > > The next line is the objtool that segfaults. > > > > I don't see anything unusual there. Are there any Gentoo patches > > against either the kernel or GCC which would strip unused symbols? > > The kernel is the vanilla kernel. (4.14.11 and also 4.15-rc6) > Its not a gentoo specific gcc patch. (Then every gentoo user would be > affected?) > > But I enabled ld.gold as default linker like 5 years ago. Never had a problem > with this. > > Is ld.gold supposed to fail here? > > I switched back to ld.bfd and it seems to work. Ah, that explains it. With CONFIG_MODVERSIONS, the linker does some work after gcc, but before objtool. Can you try this patch? (Note this isn't the final patch, as this breaks the CONFIG_MODVERSIONS=n case.) diff --git a/scripts/Makefile.build b/scripts/Makefile.build index cb8997ed0149..3cf3cc6077ea 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -270,7 +270,7 @@ endif # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file cmd_objtool = $(if $(patsubst y%,, \ $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \ - $(__objtool_obj) $(objtool_args) "$(@)";) + $(__objtool_obj) $(objtool_args) "$(@D)/.tmp_$(@F)";) objtool_obj = $(if $(patsubst y%,, \ $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n), \ $(__objtool_obj)) @@ -286,16 +286,16 @@ objtool_dep = $(objtool_obj) \ define rule_cc_o_c $(call echo-cmd,checksrc) $(cmd_checksrc) \ $(call cmd_and_fixdep,cc_o_c) \ + $(call echo-cmd,objtool) $(cmd_objtool) \ $(cmd_modversions_c) \ $(cmd_checkdoc) \ - $(call echo-cmd,objtool) $(cmd_objtool) \ $(call echo-cmd,record_mcount) $(cmd_record_mcount) endef define rule_as_o_S $(call cmd_and_fixdep,as_o_S) \ - $(cmd_modversions_S) \ - $(call echo-cmd,objtool) $(cmd_objtool) + $(call echo-cmd,objtool) $(cmd_objtool) \ + $(cmd_modversions_S) endef # List module undefined symbols (or empty line if not enabled)