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

Petr Vorel
2022-06-13T21:31:33Z

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