On 1/13/23 3:13 PM, Quentin Monnet wrote:
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>
LGTM, thanks Holger! Looks like this patch is against GH mirror (https://github.com/libbpf/bpftool).
Manually applied it to the upstream tree:
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=878625e1c7a10dfbb1fdaaaae2c4d2a58fbce627
Thanks,
Daniel
