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Mon, 16 Jan 2023 02:30:16 -0800 (PST) Received: from [192.168.178.32] ([51.155.200.13]) by smtp.gmail.com with ESMTPSA id q6-20020a05600c46c600b003d1f3e9df3csm40561236wmo.7.2023.01.16.02.30.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Jan 2023 02:30:16 -0800 (PST) Message-ID: Date: Mon, 16 Jan 2023 10:30:15 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH] tools: bpf: Disable stack protector Content-Language: en-GB To: Peter Foley , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Nathan Chancellor , Nick Desaulniers , Tom Rix Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev References: <20230114-bpf-v1-1-f836695a8b62@pefoley.com> From: Quentin Monnet In-Reply-To: <20230114-bpf-v1-1-f836695a8b62@pefoley.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2023-01-14 18:00 UTC-0500 ~ Peter Foley > Avoid build errors on distros that force the stack protector on by > default. > e.g. > CLANG /home/peter/linux/work/tools/bpf/bpftool/pid_iter.bpf.o > skeleton/pid_iter.bpf.c:53:5: error: A call to built-in function '__stack_chk_fail' is not supported. > int iter(struct bpf_iter__task_file *ctx) > ^ > 1 error generated. > > Signed-off-by: Peter Foley > --- > tools/bpf/bpftool/Makefile | 1 + > tools/bpf/runqslower/Makefile | 5 +++-- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile > index f610e184ce02a..36ac0002e386f 100644 > --- a/tools/bpf/bpftool/Makefile > +++ b/tools/bpf/bpftool/Makefile > @@ -215,6 +215,7 @@ $(OUTPUT)%.bpf.o: skeleton/%.bpf.c $(OUTPUT)vmlinux.h $(LIBBPF_BOOTSTRAP) > -I$(or $(OUTPUT),.) \ > -I$(srctree)/tools/include/uapi/ \ > -I$(LIBBPF_BOOTSTRAP_INCLUDE) \ > + -fno-stack-protector \ > -g -O2 -Wall -target bpf -c $< -o $@ > $(Q)$(LLVM_STRIP) -g $@ > For bpftool, a similar patch was already submitted and merged to the bpf-next tree last Friday: 878625e1c7a1 ("bpftool: Always disable stack protection for BPF objects"). > diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile > index 8b3d87b82b7a2..f7313cc966a04 100644 > --- a/tools/bpf/runqslower/Makefile > +++ b/tools/bpf/runqslower/Makefile > @@ -60,8 +60,9 @@ $(OUTPUT)/%.skel.h: $(OUTPUT)/%.bpf.o | $(BPFTOOL) > $(QUIET_GEN)$(BPFTOOL) gen skeleton $< > $@ > > $(OUTPUT)/%.bpf.o: %.bpf.c $(BPFOBJ) | $(OUTPUT) > - $(QUIET_GEN)$(CLANG) -g -O2 -target bpf $(INCLUDES) \ > - -c $(filter %.c,$^) -o $@ && \ > + $(QUIET_GEN)$(CLANG) -g -O2 -target bpf $(INCLUDES) \ > + -fno-stack-protector \ > + -c $(filter %.c,$^) -o $@ && \ > $(LLVM_STRIP) -g $@ > > $(OUTPUT)/%.o: %.c | $(OUTPUT) This one looks good, thanks! I note a few more places in the repository where we compile to BPF using clang. Given that there have been patches to add -fno-stack-protector at several locations already, have you checked if any of these also need the flag, by any chance, so we could fix this once and for all? $ git grep -l 'target bpf ' | egrep -v '(Documentation|bpftool)' kernel/bpf/preload/iterators/Makefile samples/bpf/Makefile samples/bpf/test_lwt_bpf.sh tools/bpf/runqslower/Makefile tools/build/feature/Makefile tools/perf/Makefile.perf tools/perf/util/llvm-utils.c tools/testing/selftests/bpf/Makefile tools/testing/selftests/net/bpf/Makefile tools/testing/selftests/tc-testing/Makefile