* perf tools: Options being passed to clang when building the BPF part of skels @ 2023-08-22 12:33 Arnaldo Carvalho de Melo 2023-08-22 18:58 ` Guilherme Amadio 0 siblings, 1 reply; 3+ messages in thread From: Arnaldo Carvalho de Melo @ 2023-08-22 12:33 UTC (permalink / raw) To: Ian Rogers Cc: Adrian Hunter, Jiri Olsa, amadio, Namhyung Kim, Guilherme Amadio, Linux Kernel Mailing List Hi, On gentoo I'm noticing this: clang-16clang-16: : clang-16error: : error: clang-16clang-16: clang-16clang-16clang-16: clang-16error: clang-16: : ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]: : : clang-16error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]error: error: : error: error: error: error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] And while just doing: diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index a5dd1ba..7726b57 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -1101,7 +1101,7 @@ else endif $(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT) - $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ + $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror -Wno-option-ignored $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@ $(SKEL_OUT)/%.skel.h: $(SKEL_TMP_OUT)/%.bpf.o | $(BPFTOOL) "Fixes" it, I'm curious as where is that we're setting up the options that are being passed to clang at: tools/perf/Makefile.perf $(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT) $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@ Perhaps it is plain just using CFLAGS? I.e. maybe the native build CFLAGS is being passed to the BPF target clang calls? Ideas? - Arnaldo ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: perf tools: Options being passed to clang when building the BPF part of skels 2023-08-22 12:33 perf tools: Options being passed to clang when building the BPF part of skels Arnaldo Carvalho de Melo @ 2023-08-22 18:58 ` Guilherme Amadio 2023-08-22 19:43 ` Arnaldo Carvalho de Melo 0 siblings, 1 reply; 3+ messages in thread From: Guilherme Amadio @ 2023-08-22 18:58 UTC (permalink / raw) To: Arnaldo Carvalho de Melo Cc: Ian Rogers, Adrian Hunter, Jiri Olsa, amadio, Namhyung Kim, Linux Kernel Mailing List Hi Arnaldo, On Tue, Aug 22, 2023 at 09:33:16AM -0300, Arnaldo Carvalho de Melo wrote: > Hi, > > On gentoo I'm noticing this: > > clang-16clang-16: : clang-16error: : error: clang-16clang-16: clang-16clang-16clang-16: clang-16error: clang-16: : ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]: : : clang-16error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]error: error: : > error: > error: error: error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] > > ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] > > ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] > > And while just doing: > > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > index a5dd1ba..7726b57 100644 > --- a/tools/perf/Makefile.perf > +++ b/tools/perf/Makefile.perf > @@ -1101,7 +1101,7 @@ else > endif > > $(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT) > - $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > + $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror -Wno-option-ignored $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@ > > $(SKEL_OUT)/%.skel.h: $(SKEL_TMP_OUT)/%.bpf.o | $(BPFTOOL) > > > "Fixes" it, I'm curious as where is that we're setting up the options > that are being passed to clang at: > > tools/perf/Makefile.perf > > $(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT) > $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@ > > Perhaps it is plain just using CFLAGS? I.e. maybe the native build > CFLAGS is being passed to the BPF target clang calls? > > Ideas? In the patches I sent previously, I had a commit to address this. In summary, the extra flags you see are hardening flags added by default. Have also a look at /usr/include/gentoo/fortify.h. I suppose other distributions may add such flags as well. It's a pity the hardening flags are added indiscriminately to all target architectures, but just making the compiler not error out should be enough to work around the issue. In my patch, I put -Werror under the control of the WERROR build option and disabled it when configuring perf in the ebuild. Since other warnings may be triggered in the future, having an easy way to disable -Werror when building the package would be nice to have, otherwise when a new compiler comes out users may hit build failures, since we are a source based distribution. Best regards, -Guilherme ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: perf tools: Options being passed to clang when building the BPF part of skels 2023-08-22 18:58 ` Guilherme Amadio @ 2023-08-22 19:43 ` Arnaldo Carvalho de Melo 0 siblings, 0 replies; 3+ messages in thread From: Arnaldo Carvalho de Melo @ 2023-08-22 19:43 UTC (permalink / raw) To: Guilherme Amadio Cc: Ian Rogers, Adrian Hunter, Jiri Olsa, Namhyung Kim, Linux Kernel Mailing List Em Tue, Aug 22, 2023 at 08:58:09PM +0200, Guilherme Amadio escreveu: > On Tue, Aug 22, 2023 at 09:33:16AM -0300, Arnaldo Carvalho de Melo wrote: > > On gentoo I'm noticing this: > > clang-16clang-16: : clang-16error: : error: clang-16clang-16: clang-16clang-16clang-16: clang-16error: clang-16: : ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]: : : clang-16error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]error: error: : > > error: > > error: error: error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]error: ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] > > > > ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored]ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] > > ignoring '-fstack-protector-strong' option as it is not currently supported for target 'bpf' [-Werror,-Woption-ignored] > > And while just doing: > > > > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > > index a5dd1ba..7726b57 100644 > > --- a/tools/perf/Makefile.perf > > +++ b/tools/perf/Makefile.perf > > @@ -1101,7 +1101,7 @@ else > > endif > > $(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT) > > - $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > > + $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror -Wno-option-ignored $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > > -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@ > > $(SKEL_OUT)/%.skel.h: $(SKEL_TMP_OUT)/%.bpf.o | $(BPFTOOL) > > "Fixes" it, I'm curious as where is that we're setting up the options > > that are being passed to clang at: > > tools/perf/Makefile.perf > > $(SKEL_TMP_OUT)/%.bpf.o: util/bpf_skel/%.bpf.c $(LIBBPF) $(SKEL_OUT)/vmlinux.h | $(SKEL_TMP_OUT) > > $(QUIET_CLANG)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(BPF_INCLUDE) $(TOOLS_UAPI_INCLUDE) \ > > -c $(filter util/bpf_skel/%.bpf.c,$^) -o $@ > > Perhaps it is plain just using CFLAGS? I.e. maybe the native build > > CFLAGS is being passed to the BPF target clang calls? > > Ideas? > In the patches I sent previously, I had a commit to address this. In I tried the one that introduced CLANG_OPTIONS and checked WERROR= to set Werror, read more further down this message. I think we need to have it but for this problem I want to have finer grained control on what goes into the CFLAGS for CLANG _when building BPF bytecode_. > summary, the extra flags you see are hardening flags added by default. > Have also a look at /usr/include/gentoo/fortify.h. I suppose other > distributions may add such flags as well. It's a pity the hardening > flags are added indiscriminately to all target architectures, but just Oh, I see, so we need to overcome that in the perf Makefiles by _removing_ those unsupported options for the BPF target, something like what is done in tools/perf/util/setup.py, because some of the options may not be supported for one version of clang but be supported in a newer one :-\ > making the compiler not error out should be enough to work around the > issue. In my patch, I put -Werror under the control of the WERROR build > option and disabled it when configuring perf in the ebuild. Since other Right, so it is the one I saw. > warnings may be triggered in the future, having an easy way to disable > -Werror when building the package would be nice to have, otherwise when Right, I'll apply that patch, I tested it, it just didn't some the problem at hand, i.e. after applying it one has to use WERROR=0. - Arnaldo > a new compiler comes out users may hit build failures, since we are a > source based distribution. > > Best regards, > -Guilherme ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-08-22 19:43 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2023-08-22 12:33 perf tools: Options being passed to clang when building the BPF part of skels Arnaldo Carvalho de Melo 2023-08-22 18:58 ` Guilherme Amadio 2023-08-22 19:43 ` Arnaldo Carvalho de Melo
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