| Message ID | 20220606184320.8210-3-petr.vorel@gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | LTP compilation fixes for buildroot toolchains | expand |
Hi! > 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 I'm still puzzled on why does it try to link it. Why is stack protection turned on for the code. Does buildroot pass -fstack-protector to the CFLAGS? I guess that -nostdlib causes the libssp (which implements __stack_chk_fail() not to be linked by default, but the __stack_chk_fail() shouldn't be called unless unless the feature is enabled in the first place. Also does -fno-stack-protector passed in GUEST_CFLAGS make it disappear? > 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 = $(CPPFLAGS) -DCOMPILE_PAYLOAD > GUEST_CFLAGS = -ffreestanding -O2 -Wall -fno-asynchronous-unwind-tables -mno-mmx -mno-sse > -GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none > +GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none -fstack-protector > GUEST_LDLIBS = > > FILTER_OUT_MAKE_TARGETS := lib_guest lib_host lib_x86 > -- > 2.36.1 >
On 06. 06. 22 20:43, Petr Vorel wrote: > Some x86_64 buildroot toolchains (bootlin-x86-64-glibc, > bootlin-x86-64-musl) try to link to __stack_chk_fail(). > -nostdlib is not enough, it requires also -fstack-protector. > > x86_64-buildroot-linux-gnu/bin/ld: /tmp/ccgBXEoR.o: in function `handle_page_fault': > kvm_pagefault01.c:(.text+0x5d): undefined reference to `__stack_chk_fail' > collect2: error: ld returned 1 exit status > > Signed-off-by: Petr Vorel <petr.vorel@gmail.com> > --- > testcases/kernel/kvm/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/testcases/kernel/kvm/Makefile b/testcases/kernel/kvm/Makefile > index 8d5193d8e..bce1a4eb5 100644 > --- a/testcases/kernel/kvm/Makefile > +++ b/testcases/kernel/kvm/Makefile > @@ -9,7 +9,7 @@ ASFLAGS = > CPPFLAGS += -I$(abs_srcdir)/include > GUEST_CPPFLAGS = $(CPPFLAGS) -DCOMPILE_PAYLOAD > GUEST_CFLAGS = -ffreestanding -O2 -Wall -fno-asynchronous-unwind-tables -mno-mmx -mno-sse > -GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none > +GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none -fstack-protector We should use -fno-stack-protector here instead. Your patch probably enables linking of libssp despite -nostdlib which we don't want. The GCC stack protector may also break tests because bootstrap initializes stack manually instead of letting GCC handle it. > GUEST_LDLIBS = > > FILTER_OUT_MAKE_TARGETS := lib_guest lib_host lib_x86
On Thu, 9 Jun 2022 10:26:55 +0200 Martin Doucha <mdoucha@suse.cz> wrote: > > diff --git a/testcases/kernel/kvm/Makefile b/testcases/kernel/kvm/Makefile > > index 8d5193d8e..bce1a4eb5 100644 > > --- a/testcases/kernel/kvm/Makefile > > +++ b/testcases/kernel/kvm/Makefile > > @@ -9,7 +9,7 @@ ASFLAGS = > > CPPFLAGS += -I$(abs_srcdir)/include > > GUEST_CPPFLAGS = $(CPPFLAGS) -DCOMPILE_PAYLOAD > > GUEST_CFLAGS = -ffreestanding -O2 -Wall -fno-asynchronous-unwind-tables -mno-mmx -mno-sse > > -GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none > > +GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none -fstack-protector > > We should use -fno-stack-protector here instead. Your patch probably > enables linking of libssp despite -nostdlib which we don't want. The GCC > stack protector may also break tests because bootstrap initializes stack > manually instead of letting GCC handle it. I agree. Assuming -nostdlib means you're building freestanding code, then indeed, -fno-stack-protector is most likely what you want. Thomas
Hi, Am 6/9/2022 um 10:26 AM schrieb Martin Doucha: > On 06. 06. 22 20:43, Petr Vorel wrote: >> Some x86_64 buildroot toolchains (bootlin-x86-64-glibc, >> bootlin-x86-64-musl) try to link to __stack_chk_fail(). >> -nostdlib is not enough, it requires also -fstack-protector. >> >> x86_64-buildroot-linux-gnu/bin/ld: /tmp/ccgBXEoR.o: in function `handle_page_fault': >> kvm_pagefault01.c:(.text+0x5d): undefined reference to `__stack_chk_fail' >> collect2: error: ld returned 1 exit status >> >> Signed-off-by: Petr Vorel <petr.vorel@gmail.com> >> --- >> testcases/kernel/kvm/Makefile | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/testcases/kernel/kvm/Makefile b/testcases/kernel/kvm/Makefile >> index 8d5193d8e..bce1a4eb5 100644 >> --- a/testcases/kernel/kvm/Makefile >> +++ b/testcases/kernel/kvm/Makefile >> @@ -9,7 +9,7 @@ ASFLAGS = >> CPPFLAGS += -I$(abs_srcdir)/include >> GUEST_CPPFLAGS = $(CPPFLAGS) -DCOMPILE_PAYLOAD >> GUEST_CFLAGS = -ffreestanding -O2 -Wall -fno-asynchronous-unwind-tables -mno-mmx -mno-sse >> -GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none >> +GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none -fstack-protector > > We should use -fno-stack-protector here instead. Your patch probably > enables linking of libssp despite -nostdlib which we don't want. The GCC > stack protector may also break tests because bootstrap initializes stack > manually instead of letting GCC handle it. I can confirm, that adding -fno-stack-protector to GUEST_LDFLAGS fixes the linker error. > >> GUEST_LDLIBS = >> >> FILTER_OUT_MAKE_TARGETS := lib_guest lib_host lib_x86 > > Joerg
Hi all, > Hi, > Am 6/9/2022 um 10:26 AM schrieb Martin Doucha: > > On 06. 06. 22 20:43, Petr Vorel wrote: > >> Some x86_64 buildroot toolchains (bootlin-x86-64-glibc, > >> bootlin-x86-64-musl) try to link to __stack_chk_fail(). > >> -nostdlib is not enough, it requires also -fstack-protector. > >> x86_64-buildroot-linux-gnu/bin/ld: /tmp/ccgBXEoR.o: in function `handle_page_fault': > >> kvm_pagefault01.c:(.text+0x5d): undefined reference to `__stack_chk_fail' > >> collect2: error: ld returned 1 exit status > >> Signed-off-by: Petr Vorel <petr.vorel@gmail.com> > >> --- > >> testcases/kernel/kvm/Makefile | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> diff --git a/testcases/kernel/kvm/Makefile b/testcases/kernel/kvm/Makefile > >> index 8d5193d8e..bce1a4eb5 100644 > >> --- a/testcases/kernel/kvm/Makefile > >> +++ b/testcases/kernel/kvm/Makefile > >> @@ -9,7 +9,7 @@ ASFLAGS = > >> CPPFLAGS += -I$(abs_srcdir)/include > >> GUEST_CPPFLAGS = $(CPPFLAGS) -DCOMPILE_PAYLOAD > >> GUEST_CFLAGS = -ffreestanding -O2 -Wall -fno-asynchronous-unwind-tables -mno-mmx -mno-sse > >> -GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none > >> +GUEST_LDFLAGS = -nostdlib -Wl,--build-id=none -fstack-protector > > We should use -fno-stack-protector here instead. Your patch probably > > enables linking of libssp despite -nostdlib which we don't want. The GCC > > stack protector may also break tests because bootstrap initializes stack > > manually instead of letting GCC handle it. > I can confirm, that adding -fno-stack-protector to GUEST_LDFLAGS fixes > the linker error. Thanks a lot for your input. Martin, thanks a lot for testing. I also verified that -fno-stack-protector fix compilation, thus patchset merged. Kind regards, Petr > >> GUEST_LDLIBS = > >> FILTER_OUT_MAKE_TARGETS := lib_guest lib_host lib_x86 > Joerg
diff --git a/testcases/kernel/kvm/Makefile b/testcases/kernel/kvm/Makefile index 8d5193d8e..bce1a4eb5 100644 --- a/testcases/kernel/kvm/Makefile +++ b/testcases/kernel/kvm/Makefile @@ -9,7 +9,7 @@ ASFLAGS = CPPFLAGS += -I$(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 GUEST_LDLIBS = FILTER_OUT_MAKE_TARGETS := lib_guest lib_host lib_x86
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(-)