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From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
	<daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH v4 bpf-next 11/12] selftests/bpf: pass all BPF .o's through BPF static linker
Date: Thu, 18 Mar 2021 12:40:35 -0700	[thread overview]
Message-ID: <20210318194036.3521577-12-andrii@kernel.org> (raw)
In-Reply-To: <20210318194036.3521577-1-andrii@kernel.org>

Pass all individual BPF object files (generated from progs/*.c) through
`bpftool gen object` command to validate that BPF static linker doesn't
corrupt them.

As an additional sanity checks, validate that passing resulting object files
through linker again results in identical ELF files. Exact same ELF contents
can be guaranteed only after two passes, as after the first pass ELF sections
order changes, and thus .BTF.ext data sections order changes. That, in turn,
means that strings are added into the final BTF string sections in different
order, so .BTF strings data might not be exactly the same. But doing another
round of linking afterwards should result in the identical ELF file, which is
checked with additional `diff` command.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/testing/selftests/bpf/Makefile | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index dbca39f45382..3a7c02add70c 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -355,12 +355,13 @@ $(TRUNNER_BPF_OBJS): $(TRUNNER_OUTPUT)/%.o:				\
 	$$(call $(TRUNNER_BPF_BUILD_RULE),$$<,$$@,			\
 					  $(TRUNNER_BPF_CFLAGS))
 
-$(TRUNNER_BPF_SKELS): $(TRUNNER_OUTPUT)/%.skel.h:			\
-		      $(TRUNNER_OUTPUT)/%.o				\
-		      $(BPFTOOL)					\
-		      | $(TRUNNER_OUTPUT)
+$(TRUNNER_BPF_SKELS): %.skel.h: %.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
 	$$(call msg,GEN-SKEL,$(TRUNNER_BINARY),$$@)
-	$(Q)$$(BPFTOOL) gen skeleton $$< > $$@
+	$(Q)$$(BPFTOOL) gen object $$(<:.o=.linked.o) $$<
+	$(Q)$$(BPFTOOL) gen object $$(<:.o=.linked2.o) $$(<:.o=.linked.o)
+	$(Q)$$(BPFTOOL) gen object $$(<:.o=.linked3.o) $$(<:.o=.linked2.o)
+	$(Q)diff $$(<:.o=.linked2.o) $$(<:.o=.linked3.o)
+	$(Q)$$(BPFTOOL) gen skeleton $$(<:.o=.linked.o) name $$(notdir $$(<:.o=)) > $$@
 endif
 
 # ensure we set up tests.h header generation rule just once
-- 
2.30.2


  parent reply	other threads:[~2021-03-18 19:41 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18 19:40 [PATCH v4 bpf-next 00/12] BPF static linking Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 01/12] libbpf: expose btf_type_by_id() internally Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 02/12] libbpf: generalize BTF and BTF.ext type ID and strings iteration Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 03/12] libbpf: rename internal memory-management helpers Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 04/12] libbpf: extract internal set-of-strings datastructure APIs Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 05/12] libbpf: add generic BTF type shallow copy API Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 06/12] libbpf: add BPF static linker APIs Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 07/12] libbpf: add BPF static linker BTF and BTF.ext support Andrii Nakryiko
2021-03-19 16:23   ` Jiri Olsa
2021-03-19 18:39     ` Andrii Nakryiko
2021-03-19 18:58       ` Jiri Olsa
2021-03-28 12:03         ` Jiri Olsa
2021-03-28 18:29           ` Andrii Nakryiko
2021-03-29 11:16             ` Jiri Olsa
2021-03-18 19:40 ` [PATCH v4 bpf-next 08/12] bpftool: add ability to specify custom skeleton object name Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 09/12] bpftool: add `gen object` command to perform BPF static linking Andrii Nakryiko
2021-03-18 19:40 ` [PATCH v4 bpf-next 10/12] selftests/bpf: re-generate vmlinux.h and BPF skeletons if bpftool changed Andrii Nakryiko
2021-03-18 19:40 ` Andrii Nakryiko [this message]
2021-03-18 19:40 ` [PATCH v4 bpf-next 12/12] selftests/bpf: add multi-file statically linked BPF object file test Andrii Nakryiko
2021-03-18 23:29 ` [PATCH v4 bpf-next 00/12] BPF static linking Alexei Starovoitov

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