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* [PATCH bpf v2] samples: bpf: Fix vmlinux.h generation for XDP samples
@ 2021-09-28  5:46 Kumar Kartikeya Dwivedi
  2021-09-28 13:44 ` Toke Høiland-Jørgensen
  0 siblings, 1 reply; 3+ messages in thread
From: Kumar Kartikeya Dwivedi @ 2021-09-28  5:46 UTC (permalink / raw)
  To: bpf; +Cc: Toke Høiland-Jørgensen

Generate vmlinux.h only from the in-tree vmlinux, and remove enum
declarations that would cause a build failure in case of version
mismatches.

There are now two options when building the samples:
1. Compile the kernel to use in-tree vmlinux for vmlinux.h
2. Override VMLINUX_BTF for samples using something like this:
   make VMLINUX_BTF=/sys/kernel/btf/vmlinux -C samples/bpf

This change was tested with relative builds, e.g. cases like:
 * make O=build -C samples/bpf
 * make KBUILD_OUTPUT=build -C samples/bpf
 * make -C samples/bpf
 * cd samples/bpf && make

When a suitable VMLINUX_BTF is not found, the following message is
printed:
/home/kkd/src/linux/samples/bpf/Makefile:333: *** Cannot find a vmlinux
for VMLINUX_BTF at any of "  ./vmlinux", build the kernel or set
VMLINUX_BTF variable.  Stop.

Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Fixes: 384b6b3bbf0d (samples: bpf: Add vmlinux.h generation support)
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
v1->v2
Use abspath for VMLINUX_BTF_PATHS items (Andrii)
---
 samples/bpf/Makefile                     | 17 ++++++++---------
 samples/bpf/xdp_redirect_map_multi.bpf.c |  5 -----
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 4dc20be5fb96..5fd48a8d4f10 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -322,17 +322,11 @@ $(obj)/hbm_edt_kern.o: $(src)/hbm.h $(src)/hbm_kern.h

 -include $(BPF_SAMPLES_PATH)/Makefile.target

-VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)				\
-		     $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)	\
-		     ../../../../vmlinux				\
-		     /sys/kernel/btf/vmlinux				\
-		     /boot/vmlinux-$(shell uname -r)
+VMLINUX_BTF_PATHS ?= $(abspath $(if $(O),$(O)/vmlinux))				\
+		     $(abspath $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux))	\
+		     $(abspath ./vmlinux)
 VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))

-ifeq ($(VMLINUX_BTF),)
-$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)")
-endif
-
 $(obj)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL)
 ifeq ($(VMLINUX_H),)
 	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
@@ -340,6 +334,11 @@ else
 	$(Q)cp "$(VMLINUX_H)" $@
 endif

+ifeq ($(VMLINUX_BTF),)
+	$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)",\
+		build the kernel or set VMLINUX_BTF variable)
+endif
+
 clean-files += vmlinux.h

 # Get Clang's default includes on this system, as opposed to those seen by
diff --git a/samples/bpf/xdp_redirect_map_multi.bpf.c b/samples/bpf/xdp_redirect_map_multi.bpf.c
index 8f59d430cb64..bb0a5a3bfcf0 100644
--- a/samples/bpf/xdp_redirect_map_multi.bpf.c
+++ b/samples/bpf/xdp_redirect_map_multi.bpf.c
@@ -5,11 +5,6 @@
 #include "xdp_sample.bpf.h"
 #include "xdp_sample_shared.h"

-enum {
-	BPF_F_BROADCAST		= (1ULL << 3),
-	BPF_F_EXCLUDE_INGRESS	= (1ULL << 4),
-};
-
 struct {
 	__uint(type, BPF_MAP_TYPE_DEVMAP_HASH);
 	__uint(key_size, sizeof(int));
--
2.33.0


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2021-09-28  5:46 [PATCH bpf v2] samples: bpf: Fix vmlinux.h generation for XDP samples Kumar Kartikeya Dwivedi
2021-09-28 13:44 ` Toke Høiland-Jørgensen
2021-09-29  0:35   ` Andrii Nakryiko

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