samples/bpf: like LLC also verify and allow redefining CLANG command

Users are likely to manually compile both LLVM 'llc' and 'clang'
tools.  Thus, also allow redefining CLANG and verify command exist.

Makefile implementation wise, the target that verify the command have
been generalized.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index dd63521832d8f44479f46e4e5f1caac1ef4066ea..66897e61232cbfdd3129c6bd8331af8eca229d1e 100644 (file)
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -81,9 +81,10 @@ HOSTLOADLIBES_spintest += -lelf
 HOSTLOADLIBES_map_perf_test += -lelf -lrt
 HOSTLOADLIBES_test_overhead += -lelf -lrt
 
-# Allows pointing LLC to a LLVM backend with bpf support, redefine on cmdline:
-#  make samples/bpf/ LLC=~/git/llvm/build/bin/llc
+# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
+#  make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
 LLC ?= llc
+CLANG ?= clang
 
 # Trick to allow make to be run from this directory
 all:
@@ -93,16 +94,18 @@ clean:
        $(MAKE) -C ../../ M=$$PWD clean
        @rm -f *~
 
-# Verify LLVM compiler is available and bpf target is supported
-.PHONY: verify_cmd_llc verify_target_bpf
+# Verify LLVM compiler tools are available and bpf target is supported by llc
+.PHONY: verify_cmds verify_target_bpf $(CLANG) $(LLC)
 
-verify_cmd_llc:
-       @if ! (which "${LLC}" > /dev/null 2>&1); then \
-               echo "*** ERROR: Cannot find LLVM tool 'llc' (${LLC})" ;\
-               exit 1; \
-       else true; fi
+verify_cmds: $(CLANG) $(LLC)
+       @for TOOL in $^ ; do \
+               if ! (which -- "$${TOOL}" > /dev/null 2>&1); then \
+                       echo "*** ERROR: Cannot find LLVM tool $${TOOL}" ;\
+                       exit 1; \
+               else true; fi; \
+       done
 
-verify_target_bpf: verify_cmd_llc
+verify_target_bpf: verify_cmds
        @if ! (${LLC} -march=bpf -mattr=help > /dev/null 2>&1); then \
                echo "*** ERROR: LLVM (${LLC}) does not support 'bpf' target" ;\
                echo "   NOTICE: LLVM version >= 3.7.1 required" ;\
@@ -115,6 +118,6 @@ $(src)/*.c: verify_target_bpf
 # But, there is no easy way to fix it, so just exclude it since it is
 # useless for BPF samples.
 $(obj)/%.o: $(src)/%.c
-       clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
+       $(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \
                -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
                -O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@

diff --git a/samples/bpf/README.rst b/samples/bpf/README.rst
index e36687d900c862a602640f3002b19ede642fdb34..a43eae3f05518765a7a7a8b38410753d2ef494d0 100644 (file)
--- a/samples/bpf/README.rst
+++ b/samples/bpf/README.rst
@@ -60,7 +60,7 @@ Quick sniplet for manually compiling LLVM and clang
  $ cmake .. -DLLVM_TARGETS_TO_BUILD="BPF;X86"
  $ make -j $(getconf _NPROCESSORS_ONLN)
 
-It is also possible to point make to the newly compiled 'llc' command
-via redefining LLC on the make command line::
+It is also possible to point make to the newly compiled 'llc' or
+'clang' command via redefining LLC or CLANG on the make command line::
 
- make samples/bpf/ LLC=~/git/llvm/build/bin/llc
+ make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang