[PATCH 4/6] tools/build: Allow versioning LLVM readelf

[James Clark <james.clark@linaro.org>]

Documentation/kbuild/llvm.rst mentions that readelf is included in the
LLVM toolchain, but it's not currently included in this block.

Add it so that LLVM=... options also apply to readelf. Users in tools/
were Perf which was hardcoding it, and another was the BPF makefile.
Both already include Makefile.include so convert them to use the new
variable.

It also didn't have the cross compile prefix, so either readelf didn't
mind opening cross binaries, or it wasn't working for cross builds.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/lib/bpf/Makefile         | 8 ++++----
 tools/perf/Makefile.perf       | 1 -
 tools/scripts/Makefile.include | 2 ++
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 168140f8e646..180dca9c57c8 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -114,12 +114,12 @@ PC_FILE		:= $(addprefix $(OUTPUT),$(PC_FILE))
 
 TAGS_PROG := $(if $(shell which etags 2>/dev/null),etags,ctags)
 
-GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
+GLOBAL_SYM_COUNT = $(shell $(READELF) -s --wide $(BPF_IN_SHARED) | \
 			   cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' | \
 			   sed 's/\[.*\]//' | \
 			   awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}' | \
 			   sort -u | wc -l)
-VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
+VERSIONED_SYM_COUNT = $(shell $(READELF) --dyn-syms --wide $(OUTPUT)libbpf.so | \
 			      sed 's/\[.*\]//' | \
 			      awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}' | \
 			      grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
@@ -182,12 +182,12 @@ check_abi: $(OUTPUT)libbpf.so $(VERSION_SCRIPT)
 		     "versioned symbols in $^ ($(VERSIONED_SYM_COUNT))." \
 		     "Please make sure all LIBBPF_API symbols are"	 \
 		     "versioned in $(VERSION_SCRIPT)." >&2;		 \
-		readelf -s --wide $(BPF_IN_SHARED) |			 \
+		$(READELF) -s --wide $(BPF_IN_SHARED) |			 \
 		    cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' |	 \
 		    sed 's/\[.*\]//' |					 \
 		    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
 		    sort -u > $(OUTPUT)libbpf_global_syms.tmp;		 \
-		readelf --dyn-syms --wide $(OUTPUT)libbpf.so |		 \
+		$(READELF) --dyn-syms --wide $(OUTPUT)libbpf.so |		 \
 		    sed 's/\[.*\]//' |					 \
 		    awk '/GLOBAL/ && /DEFAULT/ && !/UND|ABS/ {print $$NF}'|  \
 		    grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 |		 \
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 0aba14f22a06..63276bf55856 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -215,7 +215,6 @@ FLEX    ?= flex
 BISON   ?= bison
 STRIP   = strip
 AWK     = awk
-READELF ?= readelf
 
 # include Makefile.config by default and rule out
 # non-config cases
diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index e81e5b479c56..380ad84ac51e 100644
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -73,6 +73,7 @@ ifneq ($(LLVM),)
   $(call allow-override,LLC,$(LLVM_PREFIX)llc$(LLVM_SUFFIX))
   $(call allow-override,LLVM_CONFIG,$(LLVM_PREFIX)llvm-config$(LLVM_SUFFIX))
   $(call allow-override,LLVM_OBJCOPY,$(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX))
+  $(call allow-override,READELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
 else
   # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
   $(call allow-override,CC,$(CROSS_COMPILE)gcc)
@@ -80,6 +81,7 @@ else
   $(call allow-override,LD,$(CROSS_COMPILE)ld)
   $(call allow-override,CXX,$(CROSS_COMPILE)g++)
   $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
+  $(call allow-override,READELF,$(CROSS_COMPILE)readelf)
 
   # Host versions aren't prefixed
   $(call allow-override,HOSTAR,ar)

-- 
2.34.1