improve portability

configure

@@ -56,9 +56,14 @@ check_toolchain()
     local emacs_version
     local clang_version
     local bpftool_version
+    local compiler=gcc
+
+    if ! command -v gcc >/dev/null 2>&1 && command -v clang >/dev/null 2>&1; then
+        compiler=clang
+    fi
 
     : ${PKG_CONFIG:=pkg-config}
-    : ${CC=gcc}
+    : ${CC=$compiler}
     : ${LD=ld}
     : ${OBJCOPY=objcopy}
     : ${CLANG=clang}
@@ -82,7 +87,7 @@ check_toolchain()
 
     ARCH_NAME=$($CC -print-multiarch 2>/dev/null)
 
-    clang_version=$($CLANG --version | grep -Po '(?<=clang version )[[:digit:]]+')
+    clang_version=$($CLANG --version | sed -nE 's/.*clang version ([[:digit:]]+).*/\1/p')
     if [ "$?" -ne "0" ]; then
         echo "*** ERROR: Couldn't execute '$CLANG --version'"
         exit 1
@@ -128,6 +133,13 @@ check_toolchain()
         done
     fi
 
+    case $(uname -m) in
+        aarch64) ARCH_EMULATION=aarch64linux ;;
+        armv7*) ARCH_EMULATION=armelf_linux_eabi ;;
+        i386) ARCH_EMULATION=elf_i386 ;;
+        *) ARCH_EMULATION=elf_x86_64 ;;
+    esac
+
     echo "PKG_CONFIG:=${PKG_CONFIG}" >>$CONFIG
     echo "CC:=${CC}" >>$CONFIG
     echo "LD:=${LD}" >>$CONFIG
@@ -139,6 +151,7 @@ check_toolchain()
     echo "ARCH_INCLUDES:=$ARCH_INCLUDES" >> $CONFIG
     echo "READELF:=${READELF}" >> $CONFIG
     echo "BPFTOOL:=${BPFTOOL}" >> $CONFIG
+    echo "ARCH_EMULATION:=${ARCH_EMULATION}" >> $CONFIG
     [ -n "$BPFTOOL" ] && echo "HAVE_FEATURES+=BPFTOOL" >>"$CONFIG"
 }
 

lib/libxdp/Makefile

@@ -131,7 +131,7 @@ $(TEMPLATED_SOURCES): %.c: %.c.in Makefile
 	$(QUIET_M4)$(M4) $(DEFINES) $< > $@ || ( ret=$$?; rm -f $@; exit $$ret )
 
 $(EMBEDDED_XDP_OBJS): %.embed.o: %.o
-	$(QUIET_GEN)$(LD) -r -b binary -o $@ -z noexecstack --format=binary $<
+	$(QUIET_GEN)$(LD) -r -b binary -o $@ -z noexecstack -m $(ARCH_EMULATION) --format=binary $<
 	$(Q)$(OBJCOPY)  --rename-section .data=.rodata,alloc,load,readonly,data,contents $@
 
 $(XDP_OBJS): %.o: %.c $(BPF_HEADERS) $(LIBMK)

lib/libxdp/libxdp.map

@@ -6,7 +6,6 @@ LIBXDP_1.0.0 {
 		xdp_multiprog__attach_mode;
 		xdp_multiprog__close;
 		xdp_multiprog__detach;
-		xdp_multiprog__dispatcher;
 		xdp_multiprog__get_from_ifindex;
 		xdp_multiprog__is_legacy;
 		xdp_multiprog__next_prog;

lib/libxdp/libxdp.mk

@@ -1,3 +1,3 @@
-LIBXDP_VERSION := $(shell sed -ne "/LIBXDP_[0-9\.]\+ {/ {s/LIBXDP_\([0-9\.]\+\) {/\1/;p}" $(LIB_DIR)/libxdp/libxdp.map | tail -n 1)
+LIBXDP_VERSION := $(shell sed -ne "/LIBXDP_[0-9\.]\+ {/ {s/LIBXDP_\([0-9\.]\+\) {/\1/;p;}" $(LIB_DIR)/libxdp/libxdp.map | tail -n 1)
 LIBXDP_MAJOR_VERSION := $(shell echo $(LIBXDP_VERSION) | sed 's/\..*//')
 

lib/libxdp/xdp-dispatcher.c.in

@@ -30,7 +30,7 @@ static volatile const struct xdp_dispatcher_config conf = {};
  */
 forloop(`i', `0', NUM_PROGS,
 `__attribute__ ((noinline))
-int format(`prog%d', i)(struct xdp_md *ctx) {
+int format_prog`'i`'(struct xdp_md *ctx) {
         volatile int ret = XDP_DISPATCHER_RETVAL;
 
         if (!ctx)
@@ -58,7 +58,7 @@ forloop(`i', `0', NUM_PROGS,
 `
         if (num_progs_enabled < incr(i))
                 goto out;
-        ret = format(`prog%d', i)(ctx);
+        ret = format_prog`'i`'(ctx);
         if (!((1U << ret) & conf.chain_call_actions[i]))
                 return ret;
 ')