[RFC PATCH v1 3/3] bpftool: Prefer zlib-rs over zlib when available

[Ian Rogers <irogers@google.com>]

Add zlib-rs and zlib to FEATURE_TESTS and FEATURE_DISPLAY in
tools/bpf/bpftool/Makefile and use feature_rust_lib to configure
ZLIB_CFLAGS and ZLIB_LIBS when zlib-rs is detected, falling back to -lz.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/bpf/bpftool/.gitignore |  1 +
 tools/bpf/bpftool/Makefile   | 56 ++++++++++++++++++++++++++++++++----
 2 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/bpftool/.gitignore b/tools/bpf/bpftool/.gitignore
index a736f64dc5dc..ea2222373634 100644
--- a/tools/bpf/bpftool/.gitignore
+++ b/tools/bpf/bpftool/.gitignore
@@ -6,5 +6,6 @@ bpftool*.8
 FEATURE-DUMP.bpftool
 feature
 libbpf
+libz_rs
 /*.skel.h
 /vmlinux.h
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index b0f7168e7943..a193cf89a034 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 include ../../scripts/Makefile.include
+include ../../scripts/Makefile.arch
 
 ifeq ($(srctree),)
 srctree := $(patsubst %/,%,$(dir $(CURDIR)))
@@ -16,6 +17,8 @@ else
 endif
 BOOTSTRAP_OUTPUT := $(_OUTPUT)bootstrap/
 
+LIBZ_RS_OUTPUT := $(_OUTPUT)libz_rs/
+
 LIBBPF_OUTPUT := $(_OUTPUT)libbpf/
 LIBBPF_DESTDIR := $(LIBBPF_OUTPUT)
 LIBBPF_INCLUDE := $(LIBBPF_DESTDIR)include
@@ -38,7 +41,9 @@ $(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT) $(LIBBPF_BOOTSTRAP_OUTPUT) $(LIBBPF_HDRS_DI
 
 $(LIBBPF): $(wildcard $(BPF_DIR)/*.[ch] $(BPF_DIR)/Makefile) | $(LIBBPF_OUTPUT)
 	$(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) \
-		DESTDIR=$(LIBBPF_DESTDIR:/=) prefix= $(LIBBPF) install_headers
+		DESTDIR=$(LIBBPF_DESTDIR:/=) prefix= \
+		$(if $(ZLIB_CFLAGS),EXTRA_CFLAGS="$(or $(EXTRA_CFLAGS),-g -O2) $(ZLIB_CFLAGS)") \
+		$(LIBBPF) install_headers
 
 $(LIBBPF_INTERNAL_HDRS): $(LIBBPF_HDRS_DIR)/%.h: $(BPF_DIR)/%.h | $(LIBBPF_HDRS_DIR)
 	$(call QUIET_INSTALL, $@)
@@ -115,8 +120,20 @@ ifneq ($(SKIP_CRYPTO),1)
   CRYPTO_LIBS := -lcrypto
 endif
 
+ifneq ($(CROSS_COMPILE),)
+  ifneq ($(MAKECMDGOALS),bootstrap)
+    ifneq ($(RUST_TARGET_FLAGS_$(ARCH)),)
+      RUST_FLAGS += --target=$(RUST_TARGET_FLAGS_$(ARCH))
+    else
+      NO_ZLIB_RS := 1
+    endif
+  else
+    NO_ZLIB_RS := 1
+  endif
+endif
+
 ifeq ($(MAKECMDGOALS),bootstrap)
-FEATURE_TESTS := libelf-zstd
+FEATURE_TESTS := libelf-zstd $(if $(NO_ZLIB_RS),,zlib-rs) zlib
 FEATURE_DISPLAY :=
 else
 FEATURE_TESTS := clang-bpf-co-re
@@ -128,6 +145,10 @@ FEATURE_TESTS += libbfd-liberty-z
 FEATURE_TESTS += disassembler-four-args
 FEATURE_TESTS += disassembler-init-styled
 FEATURE_TESTS += libelf-zstd
+ifeq ($(NO_ZLIB_RS),)
+FEATURE_TESTS += zlib-rs
+endif
+FEATURE_TESTS += zlib
 
 FEATURE_DISPLAY := clang-bpf-co-re
 FEATURE_DISPLAY += llvm
@@ -135,6 +156,10 @@ FEATURE_DISPLAY += libcap
 FEATURE_DISPLAY += libbfd
 FEATURE_DISPLAY += libbfd-liberty
 FEATURE_DISPLAY += libbfd-liberty-z
+ifeq ($(NO_ZLIB_RS),)
+FEATURE_DISPLAY += zlib-rs
+endif
+FEATURE_DISPLAY += zlib
 endif
 
 check_feat := 1
@@ -153,8 +178,27 @@ include $(FEATURES_DUMP)
 endif
 endif
 
-LIBS = $(LIBBPF) -lelf $(CRYPTO_LIBS) -lz
-LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf $(CRYPTO_LIBS) -lz
+# Prefer zlib-rs over C zlib when detected. When cross-compiling, the host
+# bootstrap bpftool still links against the host's -lz.
+ifeq ($(feature-zlib-rs),1)
+  $(call feature_rust_lib,zlib-rs)
+  ZLIB_CFLAGS := $(FEATURE_CFLAGS-zlib-rs)
+  ZLIB_LIBS := $(FEATURE_LIBS-zlib-rs)
+  CFLAGS += $(ZLIB_CFLAGS)
+  ifeq ($(CROSS_COMPILE),)
+    HOST_CFLAGS += $(ZLIB_CFLAGS)
+    LIBBPF_BOOTSTRAP_CFLAGS += $(ZLIB_CFLAGS)
+    ZLIB_BOOTSTRAP_LIBS := $(ZLIB_LIBS)
+  else
+    ZLIB_BOOTSTRAP_LIBS := -lz
+  endif
+else
+  ZLIB_LIBS := -lz
+  ZLIB_BOOTSTRAP_LIBS := -lz
+endif
+
+LIBS = $(LIBBPF) -lelf $(CRYPTO_LIBS) $(ZLIB_LIBS)
+LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf $(CRYPTO_LIBS) $(ZLIB_BOOTSTRAP_LIBS)
 
 ifeq ($(feature-libelf-zstd),1)
 LIBS += -lzstd
@@ -200,7 +244,7 @@ else
   else ifeq ($(feature-libbfd-liberty),1)
     LIBS += -lbfd -ldl -lopcodes -liberty
   else ifeq ($(feature-libbfd-liberty-z),1)
-    LIBS += -lbfd -ldl -lopcodes -liberty -lz
+    LIBS += -lbfd -ldl -lopcodes -liberty $(ZLIB_LIBS)
   endif
 
   # If one of the above feature combinations is set, we support libbfd
@@ -304,7 +348,7 @@ clean: $(LIBBPF)-clean $(LIBBPF_BOOTSTRAP)-clean feature-detect-clean
 	$(call QUIET_CLEAN, bpftool)
 	$(Q)$(RM) -- $(OUTPUT)bpftool $(OUTPUT)*.o $(OUTPUT)*.d
 	$(Q)$(RM) -- $(OUTPUT)*.skel.h $(OUTPUT)vmlinux.h
-	$(Q)$(RM) -r -- $(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT)
+	$(Q)$(RM) -r -- $(LIBBPF_OUTPUT) $(BOOTSTRAP_OUTPUT) $(LIBZ_RS_OUTPUT)
 	$(call QUIET_CLEAN, core-gen)
 	$(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.bpftool
 	$(Q)$(RM) -r -- $(OUTPUT)feature/
-- 
2.56.0.313.g2479322e68-goog