netdev - [PATCH bpf-next v3 10/13] tools/bpf: do not use pahole if clang/llvm can generate BTF sections

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Message-ID: <20181017233101.1072913-1-yhs@fb.com>
Date:   Wed, 17 Oct 2018 16:30:58 -0700
From:   Yonghong Song <yhs@...com>
To:     <ast@...com>, <kafai@...com>, <daniel@...earbox.net>,
        <netdev@...r.kernel.org>
CC:     <kernel-team@...com>
Subject: [PATCH bpf-next v3 10/13] tools/bpf: do not use pahole if clang/llvm can generate BTF sections

Add additional checks in tools/testing/selftests/bpf and
samples/bpf such that if clang/llvm compiler can generate
BTF sections, do not use pahole.

Signed-off-by: Yonghong Song <yhs@...com>
---
 samples/bpf/Makefile                 | 8 ++++++++
 tools/testing/selftests/bpf/Makefile | 8 ++++++++
 2 files changed, 16 insertions(+)

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index be0a961450bc..870fe7ee2b69 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -208,12 +208,20 @@ endif
 BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
 BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
 BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')
+BTF_LLVM_PROBE := $(shell echo "int main() { return 0; }" | \
+			  clang -target bpf -O2 -g -c -x c - -o ./llvm_btf_verify.o; \
+			  readelf -S ./llvm_btf_verify.o | grep BTF; \
+			  /bin/rm -f ./llvm_btf_verify.o)
 
+ifneq ($(BTF_LLVM_PROBE),)
+	EXTRA_CFLAGS += -g
+else
 ifneq ($(and $(BTF_LLC_PROBE),$(BTF_PAHOLE_PROBE),$(BTF_OBJCOPY_PROBE)),)
 	EXTRA_CFLAGS += -g
 	LLC_FLAGS += -mattr=dwarfris
 	DWARF2BTF = y
 endif
+endif
 
 # Trick to allow make to be run from this directory
 all:
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index d99dd6fc3fbe..8d5612724db8 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -121,7 +121,14 @@ $(OUTPUT)/test_xdp_noinline.o: CLANG_FLAGS += -fno-inline
 BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
 BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
 BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')
+BTF_LLVM_PROBE := $(shell echo "int main() { return 0; }" | \
+			  clang -target bpf -O2 -g -c -x c - -o ./llvm_btf_verify.o; \
+			  readelf -S ./llvm_btf_verify.o | grep BTF; \
+			  /bin/rm -f ./llvm_btf_verify.o)
 
+ifneq ($(BTF_LLVM_PROBE),)
+	CLANG_FLAGS += -g
+else
 ifneq ($(BTF_LLC_PROBE),)
 ifneq ($(BTF_PAHOLE_PROBE),)
 ifneq ($(BTF_OBJCOPY_PROBE),)
@@ -131,6 +138,7 @@ ifneq ($(BTF_OBJCOPY_PROBE),)
 endif
 endif
 endif
+endif
 
 $(OUTPUT)/%.o: %.c
 	$(CLANG) $(CLANG_FLAGS) \
-- 
2.17.1