2023-01-13 14:49 UTC+0100 ~ Holger Hoffstätte <holger@xxxxxxxxxxxxxxxxxxxxxx> > > When the clang toolchain has stack protection enabled in order to be > consistent > with gcc - which just happens to be the case on Gentoo - the bpftool build > fails: > > clang \ > -I. \ > -I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/include/uapi/ \ > -I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/bpf/bpftool/bootstrap/libbpf/include \ > -g -O2 -Wall -target bpf -c skeleton/pid_iter.bpf.c -o pid_iter.bpf.o > clang \ > -I. \ > -I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/include/uapi/ \ > -I/tmp/portage/dev-util/bpftool-6.0.12/work/linux-6.0/tools/bpf/bpftool/bootstrap/libbpf/include \ > -g -O2 -Wall -target bpf -c skeleton/profiler.bpf.c -o profiler.bpf.o > skeleton/profiler.bpf.c:40:14: error: A call to built-in function > '__stack_chk_fail' is not supported. > int BPF_PROG(fentry_XXX) > ^ > skeleton/profiler.bpf.c:94:14: error: A call to built-in function > '__stack_chk_fail' is not supported. > int BPF_PROG(fexit_XXX) > ^ > 2 errors generated. > > Since stack-protector makes no sense for the BPF bits just unconditionally > disable it. > > Bug: https://bugs.gentoo.org/890638 > Signed-off-by: Holger Hoffstätte <holger@xxxxxxxxxxxxxxxxxxxxxx> > > --snip-- > > diff a/src/Makefile b/src/Makefile > --- a/src/Makefile > +++ b/src/Makefile > @@ -205,7 +205,7 @@ $(OUTPUT)%.bpf.o: skeleton/%.bpf.c > $(OUTPUT)vmlinux.h $(LIBBPF_BOOTSTRAP) > -I$(or $(OUTPUT),.) \ > -I$(srctree)/include/uapi/ \ > -I$(LIBBPF_BOOTSTRAP_INCLUDE) \ > - -g -O2 -Wall -target bpf -c $< -o $@ > + -g -O2 -Wall -fno-stack-protector -target bpf -c $< -o $@ > $(Q)$(LLVM_STRIP) -g $@ > > $(OUTPUT)%.skel.h: $(OUTPUT)%.bpf.o $(BPFTOOL_BOOTSTRAP) Right, I understand we don't want it when compiling the BPF program from the skeleton. Looks good, thank you! Acked-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
