[PATCH bpf-next] selftests/bpf: Cross-compile bpftool

Subsystems: bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest

STALE1311d

8 messages, 4 authors, 2023-02-14 · open the first message on its own page

[PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Björn Töpel <bjorn@kernel.org>
Date: 2023-02-10 08:43:40

From: Björn Töpel <redacted>

When the BPF selftests are cross-compiled, only the a host version of
bpftool is built. This version of bpftool is used to generate various
intermediates, e.g., skeletons.

The test runners are also using bpftool. The Makefile will symlink
bpftool from the selftest/bpf root, where the test runners will look
for the tool:

  | ...
  | $(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
  |    $(OUTPUT)/$(if $2,$2/)bpftool

There are two issues for cross-compilation builds:

 1. There is no native (cross-compilation target) build of bpftool
 2. The bootstrap variant of bpftool is never cross-compiled (by
    design)

Make sure that a native/cross-compiled version of bpftool is built,
and if CROSS_COMPILE is set, symlink to the native/non-bootstrap
version.

Signed-off-by: Björn Töpel <redacted>
---
 tools/testing/selftests/bpf/Makefile | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index b2eb3201b85a..b706750f71e2 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile

@@ -157,8 +157,9 @@ $(notdir $(TEST_GEN_PROGS)						\
 	 $(TEST_CUSTOM_PROGS)): %: $(OUTPUT)/% ;
 
 # sort removes libbpf duplicates when not cross-building
-MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf	       \
-	       $(HOST_BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/resolve_btfids      \
+MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf	\
+	       $(BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/bpftool		\
+	       $(HOST_BUILD_DIR)/resolve_btfids				\
 	       $(RUNQSLOWER_OUTPUT) $(INCLUDE_DIR))
 $(MAKE_DIRS):
 	$(call msg,MKDIR,,$@)

@@ -208,6 +209,14 @@ $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(wildcard bpf_testmod/Makefile bpf_tes
 	$(Q)cp bpf_testmod/bpf_testmod.ko $@
 
 DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
+ifneq ($(CROSS_COMPILE),)
+CROSS_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
+TRUNNER_BPFTOOL := $(CROSS_BPFTOOL)
+USE_BOOTSTRAP := ""
+else
+TRUNNER_BPFTOOL := $(DEFAULT_BPFTOOL)
+USE_BOOTSTRAP := "bootstrap"
+endif
 
 $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL) $(RUNQSLOWER_OUTPUT)
 	$(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower	       \

@@ -255,6 +264,18 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/			       \
 		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install-bin
 
+ifneq ($(CROSS_COMPILE),)
+$(CROSS_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)	\
+		    $(BPFOBJ) | $(BUILD_DIR)/bpftool
+	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)				\
+		    ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE)			\
+		    EXTRA_CFLAGS='-g -O0'					\
+		    OUTPUT=$(BUILD_DIR)/bpftool/				\
+		    LIBBPF_OUTPUT=$(BUILD_DIR)/libbpf/				\
+		    LIBBPF_DESTDIR=$(SCRATCH_DIR)/				\
+		    prefix= DESTDIR=$(SCRATCH_DIR)/ install-bin
+endif
+
 all: docs
 
 docs:

@@ -518,11 +539,12 @@ endif
 $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS)			\
 			     $(TRUNNER_EXTRA_OBJS) $$(BPFOBJ)		\
 			     $(RESOLVE_BTFIDS)				\
+			     $(TRUNNER_BPFTOOL)				\
 			     | $(TRUNNER_BINARY)-extras
 	$$(call msg,BINARY,,$$@)
 	$(Q)$$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) -o $$@
 	$(Q)$(RESOLVE_BTFIDS) --btf $(TRUNNER_OUTPUT)/btf_data.bpf.o $$@
-	$(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
+	$(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/$(USE_BOOTSTRAP)/bpftool \
 		   $(OUTPUT)/$(if $2,$2/)bpftool
 
 endef

base-commit: 06744f24696e1e7598412c3df61a538b57ebec22
-- 
2.37.2

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Björn Töpel <bjorn@kernel.org>
Date: 2023-02-13 14:30:58

Björn Töpel [off-list ref] writes:

From: Björn Töpel <redacted>

When the BPF selftests are cross-compiled, only the a host version of
bpftool is built. This version of bpftool is used to generate various
intermediates, e.g., skeletons.

The test runners are also using bpftool. The Makefile will symlink
bpftool from the selftest/bpf root, where the test runners will look
for the tool:

  | ...
  | $(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
  |    $(OUTPUT)/$(if $2,$2/)bpftool

There are two issues for cross-compilation builds:

 1. There is no native (cross-compilation target) build of bpftool
 2. The bootstrap variant of bpftool is never cross-compiled (by
    design)

Make sure that a native/cross-compiled version of bpftool is built,
and if CROSS_COMPILE is set, symlink to the native/non-bootstrap
version.

...and the grand master plan is to add BPF CI support for riscv64, where
this patch a prerequisite to [1]. I would suspect that other platforms
might benefit from cross-compilation builds as well.

[1] https://github.com/kernel-patches/vmtest/pull/194

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Quentin Monnet <hidden>
Date: 2023-02-13 20:53:39

2023-02-10 09:43 UTC+0100 ~ Björn Töpel [off-list ref]

quoted hunk

From: Björn Töpel <redacted>

When the BPF selftests are cross-compiled, only the a host version of
bpftool is built. This version of bpftool is used to generate various
intermediates, e.g., skeletons.

The test runners are also using bpftool. The Makefile will symlink
bpftool from the selftest/bpf root, where the test runners will look
for the tool:

  | ...
  | $(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
  |    $(OUTPUT)/$(if $2,$2/)bpftool

There are two issues for cross-compilation builds:

 1. There is no native (cross-compilation target) build of bpftool
 2. The bootstrap variant of bpftool is never cross-compiled (by
    design)

Make sure that a native/cross-compiled version of bpftool is built,
and if CROSS_COMPILE is set, symlink to the native/non-bootstrap
version.

Signed-off-by: Björn Töpel <redacted>
---
 tools/testing/selftests/bpf/Makefile | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index b2eb3201b85a..b706750f71e2 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile

@@ -157,8 +157,9 @@ $(notdir $(TEST_GEN_PROGS)						\
 	 $(TEST_CUSTOM_PROGS)): %: $(OUTPUT)/% ;
 
 # sort removes libbpf duplicates when not cross-building
-MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf	       \
-	       $(HOST_BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/resolve_btfids      \
+MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf	\
+	       $(BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/bpftool		\
+	       $(HOST_BUILD_DIR)/resolve_btfids				\
 	       $(RUNQSLOWER_OUTPUT) $(INCLUDE_DIR))
 $(MAKE_DIRS):
 	$(call msg,MKDIR,,$@)

@@ -208,6 +209,14 @@ $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(wildcard bpf_testmod/Makefile bpf_tes
 	$(Q)cp bpf_testmod/bpf_testmod.ko $@
 
 DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
+ifneq ($(CROSS_COMPILE),)
+CROSS_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
+TRUNNER_BPFTOOL := $(CROSS_BPFTOOL)
+USE_BOOTSTRAP := ""
+else
+TRUNNER_BPFTOOL := $(DEFAULT_BPFTOOL)
+USE_BOOTSTRAP := "bootstrap"
+endif
 
 $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL) $(RUNQSLOWER_OUTPUT)
 	$(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower	       \

@@ -255,6 +264,18 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/			       \
 		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install-bin
 
+ifneq ($(CROSS_COMPILE),)
+$(CROSS_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)	\
+		    $(BPFOBJ) | $(BUILD_DIR)/bpftool
+	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)				\
+		    ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE)			\
+		    EXTRA_CFLAGS='-g -O0'					\
+		    OUTPUT=$(BUILD_DIR)/bpftool/				\
+		    LIBBPF_OUTPUT=$(BUILD_DIR)/libbpf/				\
+		    LIBBPF_DESTDIR=$(SCRATCH_DIR)/				\
+		    prefix= DESTDIR=$(SCRATCH_DIR)/ install-bin
+endif
+
 all: docs
 
 docs:

@@ -518,11 +539,12 @@ endif
 $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TEST_OBJS)			\
 			     $(TRUNNER_EXTRA_OBJS) $$(BPFOBJ)		\
 			     $(RESOLVE_BTFIDS)				\
+			     $(TRUNNER_BPFTOOL)				\
 			     | $(TRUNNER_BINARY)-extras
 	$$(call msg,BINARY,,$$@)
 	$(Q)$$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) -o $$@
 	$(Q)$(RESOLVE_BTFIDS) --btf $(TRUNNER_OUTPUT)/btf_data.bpf.o $$@
-	$(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
+	$(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/$(USE_BOOTSTRAP)/bpftool \

Nit: You'll have a double slash in this path when USE_BOOSTRAP is empty
(.../tools/build/bpftool//bpftool), but it probably doesn't matter much.

 		   $(OUTPUT)/$(if $2,$2/)bpftool
 
 endef

base-commit: 06744f24696e1e7598412c3df61a538b57ebec22

The changes look good to me, thanks!

Acked-by: Quentin Monnet <redacted>

Jean-Philippe, I know you do some cross-compiling with bpftool, how does
this look from your side?

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Zachary Leaf <hidden>
Date: 2023-02-14 08:57:47

Hi Bjorn,

Thanks for the patch, I've tested it and it works for me.

I have a minor suggestion but otherwise happy to see this getting fixed.

On 10/02/2023 08:43, Björn Töpel wrote:

quoted hunk

From: Björn Töpel <redacted>

When the BPF selftests are cross-compiled, only the a host version of
bpftool is built. This version of bpftool is used to generate various
intermediates, e.g., skeletons.

The test runners are also using bpftool. The Makefile will symlink
bpftool from the selftest/bpf root, where the test runners will look
for the tool:

  | ...
  | $(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
  |    $(OUTPUT)/$(if $2,$2/)bpftool

There are two issues for cross-compilation builds:

 1. There is no native (cross-compilation target) build of bpftool
 2. The bootstrap variant of bpftool is never cross-compiled (by
    design)

Make sure that a native/cross-compiled version of bpftool is built,
and if CROSS_COMPILE is set, symlink to the native/non-bootstrap
version.

Signed-off-by: Björn Töpel <redacted>
---
 tools/testing/selftests/bpf/Makefile | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index b2eb3201b85a..b706750f71e2 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile

@@ -157,8 +157,9 @@ $(notdir $(TEST_GEN_PROGS)						\
 	 $(TEST_CUSTOM_PROGS)): %: $(OUTPUT)/% ;
 
 # sort removes libbpf duplicates when not cross-building
-MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf	       \
-	       $(HOST_BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/resolve_btfids      \
+MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf	\
+	       $(BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/bpftool		\
+	       $(HOST_BUILD_DIR)/resolve_btfids				\
 	       $(RUNQSLOWER_OUTPUT) $(INCLUDE_DIR))
 $(MAKE_DIRS):
 	$(call msg,MKDIR,,$@)

@@ -208,6 +209,14 @@ $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(wildcard bpf_testmod/Makefile bpf_tes
 	$(Q)cp bpf_testmod/bpf_testmod.ko $@
 
 DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
+ifneq ($(CROSS_COMPILE),)
+CROSS_BPFTOOL := $(SCRATCH_DIR)/sbin/bpftool
+TRUNNER_BPFTOOL := $(CROSS_BPFTOOL)
+USE_BOOTSTRAP := ""
+else
+TRUNNER_BPFTOOL := $(DEFAULT_BPFTOOL)
+USE_BOOTSTRAP := "bootstrap"
+endif
 
 $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL) $(RUNQSLOWER_OUTPUT)
 	$(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/runqslower	       \

...


-TEST_GEN_PROGS_EXTENDED += $(DEFAULT_BPFTOOL)
+TEST_GEN_PROGS_EXTENDED += $(TRUNNER_BPFTOOL)

Ensure the target arch bpftool is copied into the kselftest_bpf_install
dir by selftests/lib.mk instead of always the default/host version.

Thanks,
Zach

quoted hunk

@@ -255,6 +264,18 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/			       \
 		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install-bin
 
+ifneq ($(CROSS_COMPILE),)
+$(CROSS_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)	\
+		    $(BPFOBJ) | $(BUILD_DIR)/bpftool
+	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)				\
+		    ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE)			\
+		    EXTRA_CFLAGS='-g -O0'					\
+		    OUTPUT=$(BUILD_DIR)/bpftool/				\
+		    LIBBPF_OUTPUT=$(BUILD_DIR)/libbpf/				\
+		    LIBBPF_DESTDIR=$(SCRATCH_DIR)/				\
+		    prefix= DESTDIR=$(SCRATCH_DIR)/ install-bin
+endif
+
 all: docs
 
 docs:
@@ -518,11 +539,12 @@ endif
 $(OUTPUT)/$(TRUNNER_BINARY): $(TRUNNER_TESAT_OBJS)			\
 			     $(TRUNNER_EXTRA_OBJS) $$(BPFOBJ)		\
 			     $(RESOLVE_BTFIDS)		related to		\
+			     $(TRUNNER_BPFTOOL)				\
 			     | $(TRUNNER_BINARY)-extras
 	$$(call msg,BINARY,,$$@)
 	$(Q)$$(CC) $$(CFLAGS) $$(filter %.a %.o,$$^) $$(LDLIBS) -o $$@
 	$(Q)$(RESOLVE_BTFIDS) --btf $(TRUNNER_OUTPUT)/btf_data.bpf.o $$@
-	$(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
+	$(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/$(USE_BOOTSTRAP)/bpftool \>  		   $(OUTPUT)/$(if $2,$2/)bpftool
 
 endef

base-commit: 06744f24696e1e7598412c3df61a538b57ebec22

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Zachary Leaf <hidden>
Date: 2023-02-14 09:17:51

On 13/02/2023 14:30, Björn Töpel wrote:

Björn Töpel [off-list ref] writes:

quoted

From: Björn Töpel <redacted>

When the BPF selftests are cross-compiled, only the a host version of
bpftool is built. This version of bpftool is used to generate various
intermediates, e.g., skeletons.

The test runners are also using bpftool. The Makefile will symlink
bpftool from the selftest/bpf root, where the test runners will look
for the tool:

  | ...
  | $(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
  |    $(OUTPUT)/$(if $2,$2/)bpftool

There are two issues for cross-compilation builds:

 1. There is no native (cross-compilation target) build of bpftool
 2. The bootstrap variant of bpftool is never cross-compiled (by
    design)

Make sure that a native/cross-compiled version of bpftool is built,
and if CROSS_COMPILE is set, symlink to the native/non-bootstrap
version.

...and the grand master plan is to add BPF CI support for riscv64, where
this patch a prerequisite to [1]. I would suspect that other platforms
might benefit from cross-compilation builds as well.

Similar use case. There also seems to be a lot of issues building these
tests out of tree.

I have some potential fixes up to 6.1 but linux-next seems to have
introduced a few more issues on top.

[1] https://github.com/kernel-patches/vmtest/pull/194

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Björn Töpel <bjorn@kernel.org>
Date: 2023-02-14 09:41:13

Zachary Leaf [off-list ref] writes:

Hi Bjorn,

Thanks for the patch, I've tested it and it works for me.

Good!

I have a minor suggestion but otherwise happy to see this getting fixed.

...


-TEST_GEN_PROGS_EXTENDED += $(DEFAULT_BPFTOOL)
+TEST_GEN_PROGS_EXTENDED += $(TRUNNER_BPFTOOL)

Ensure the target arch bpftool is copied into the kselftest_bpf_install
dir by selftests/lib.mk instead of always the default/host version.

Good one. I'll spin a v2, and also fix Quentin's "double-slash".


Björn

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Björn Töpel <bjorn@kernel.org>
Date: 2023-02-14 09:44:40

Zachary Leaf [off-list ref] writes:

On 13/02/2023 14:30, Björn Töpel wrote:

quoted

Björn Töpel [off-list ref] writes:

quoted

From: Björn Töpel <redacted>

When the BPF selftests are cross-compiled, only the a host version of
bpftool is built. This version of bpftool is used to generate various
intermediates, e.g., skeletons.

The test runners are also using bpftool. The Makefile will symlink
bpftool from the selftest/bpf root, where the test runners will look
for the tool:

  | ...
  | $(Q)ln -sf $(if $2,..,.)/tools/build/bpftool/bootstrap/bpftool \
  |    $(OUTPUT)/$(if $2,$2/)bpftool

There are two issues for cross-compilation builds:

 1. There is no native (cross-compilation target) build of bpftool
 2. The bootstrap variant of bpftool is never cross-compiled (by
    design)

Make sure that a native/cross-compiled version of bpftool is built,
and if CROSS_COMPILE is set, symlink to the native/non-bootstrap
version.

...and the grand master plan is to add BPF CI support for riscv64, where
this patch a prerequisite to [1]. I would suspect that other platforms
might benefit from cross-compilation builds as well.

Similar use case. There also seems to be a lot of issues building these
tests out of tree.

I have some potential fixes up to 6.1 but linux-next seems to have
introduced a few more issues on top.

Ah, yes. FWIW, the BPF CI builds the selftests *in-tree*, so with this
patch (and my PRs) the BPF CI is capable of cross-compiling.


Björn

Re: [PATCH bpf-next] selftests/bpf: Cross-compile bpftool

From: Jean-Philippe Brucker <hidden>
Date: 2023-02-14 09:47:00

Hi Quentin,

On Mon, Feb 13, 2023 at 08:53:31PM +0000, Quentin Monnet wrote:

Jean-Philippe, I know you do some cross-compiling with bpftool, how does
this look from your side?

I don't have enough time for BPF at the moment unfortunately. Zachary is
looking at cross-compiling the selftests for arm64

Thanks,
Jean

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