Re: [Buildroot] [LTP] [PATCH 2/2] kvm: Fix undefined reference to __stack_chk_fail()

From: Petr Vorel <petr.vorel@gmail.com>
To: Joerg Vehlow <lkml@jv-coder.de>
Cc: "Yann E. MORIN" <yann.morin.1998@free.fr>,
	Martin Doucha <mdoucha@suse.cz>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Buildroot Mailing List <buildroot@buildroot.org>,
	Fabrice Fontaine <fontaine.fabrice@gmail.com>,
	ltp@lists.linux.it
Subject: Re: [Buildroot] [LTP] [PATCH 2/2] kvm: Fix undefined reference to __stack_chk_fail()
Date: Mon, 13 Jun 2022 23:31:15 +0200	[thread overview]
Message-ID: <Yqeso3ZYuZZatAfQ@pevik> (raw)
In-Reply-To: <024cf3d9-f9c1-80a4-8b06-799309912c7f@jv-coder.de>

Hi all,

> Hi,

> Am 6/9/2022 um 10:26 AM schrieb Martin Doucha:
> > On 06. 06. 22 20:43, Petr Vorel wrote:
> >> Some x86_64 buildroot toolchains (bootlin-x86-64-glibc,
> >> bootlin-x86-64-musl) try to link to __stack_chk_fail().
> >> -nostdlib is not enough, it requires also -fstack-protector.

> >> x86_64-buildroot-linux-gnu/bin/ld: /tmp/ccgBXEoR.o: in function `handle_page_fault':
> >> kvm_pagefault01.c:(.text+0x5d): undefined reference to `__stack_chk_fail'
> >> collect2: error: ld returned 1 exit status

> >> Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
> >> ---
> >>  testcases/kernel/kvm/Makefile | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)

> >> diff --git a/testcases/kernel/kvm/Makefile b/testcases/kernel/kvm/Makefile
> >> index 8d5193d8e..bce1a4eb5 100644
> >> --- a/testcases/kernel/kvm/Makefile
> >> +++ b/testcases/kernel/kvm/Makefile
> >> @@ -9,7 +9,7 @@ ASFLAGS =
> >>  CPPFLAGS += -I$(abs_srcdir)/include
> >>  GUEST_CPPFLAGS = $(CPPFLAGS) -DCOMPILE_PAYLOAD
> >>  GUEST_CFLAGS = -ffreestanding -O2 -Wall -fno-asynchronous-unwind-tables -mno-mmx -mno-sse
> >> -GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none
> >> +GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none -fstack-protector

> > We should use -fno-stack-protector here instead. Your patch probably
> > enables linking of libssp despite -nostdlib which we don't want. The GCC
> > stack protector may also break tests because bootstrap initializes stack
> > manually instead of letting GCC handle it.
> I can confirm, that adding -fno-stack-protector to GUEST_LDFLAGS fixes
> the linker error.

Thanks a lot for your input. Martin, thanks a lot for testing.
I also verified that -fno-stack-protector fix compilation, thus patchset merged.

Kind regards,
Petr

> >>  GUEST_LDLIBS =

> >>  FILTER_OUT_MAKE_TARGETS := lib_guest lib_host lib_x86

> Joerg
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