pping: TC-BPF use BTF map if iproute has libbpf

Copy setup from traffic-pacing-edt to use BTF-defined map if configure
detects that iproute2 has libbpf support, otherwise fall back on
bpf_elf_map. Also fix a minor bug with setting default value for SEC
in bpf_egress_loader.sh.

Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>

pping/Makefile

@@ -1,10 +1,34 @@
 # SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
 
 USER_TARGETS   := pping
-BPF_TARGETS  := pping_kern_xdp pping_kern_tc
+TC_BPF_TARGETS := pping_kern_tc
+BPF_TARGETS    := pping_kern_xdp
+BPF_TARGETS    += $(TC_BPF_TARGETS)
 
-LDFLAGS = -pthread
+LDFLAGS    += -pthread
+EXTRA_DEPS += config.mk
 
 LIB_DIR = ../lib
 
 include $(LIB_DIR)/common.mk
+include config.mk
+
+all: config.mk
+
+config.mk: configure
+	@sh configure
+
+ifndef HAVE_TC_LIBBPF
+# If the iproute2 'tc' tool doesn't understand BTF debug info
+# use llvm-strip to remove this debug info from object file
+#
+# *BUT* cannot strip everything as it removes ELF elems needed for
+#  creating maps
+#
+.PHONY: strip_tc_obj
+strip_tc_obj: ${TC_BPF_TARGETS:=.o}
+	$(Q) echo "TC don't support libbpf - strip BTF info"
+	$(Q) llvm-strip --no-strip-all --remove-section .BTF $?
+
+all: strip_tc_obj
+endif

pping/bpf_egress_loader.sh

@@ -3,6 +3,9 @@
 # Author: Jesper Dangaaard Brouer <netoptimizer@brouer.com>
 # License: GPLv2
 #
+# Extended by Simon Sundberg <simon.sundberg@kau.se> to add support
+# of optional section (--sec) option
+#
 basedir=`dirname $0`
 source ${basedir}/functions.sh
 
@@ -16,13 +19,13 @@ export TC=/sbin/tc
 # This can be changed via --file or --obj
 if [[ -z ${BPF_OBJ} ]]; then
     # Fallback default
-    BPF_OBJ=pping.bpf.o
+    BPF_OBJ=pping_kern_tc.o
 fi
 
 # This can be changed via --sec
-if [[ -z ${BPF_OBJ} ]]; then
+if [[ -z ${SEC} ]]; then
     # Fallback default
-    SEC=egress
+    SEC=pping_egress
 fi
 
 info "Applying TC-BPF egress setup on device: $DEV with object file: $BPF_OBJ"
@@ -57,7 +60,6 @@ function tc_egress_bpf_attach()
     local section=${3:-$SEC}
     shift 3
 
-    # TODO: Handle selecting program 'sec' - Simon Sundberg added section option 2021-01-08
     call_tc filter add dev "$device" pref 2  handle 2 \
 	    egress bpf da obj "$objfile" sec "$section"
 }

pping/configure

@@ -0,0 +1,29 @@
+#!/bin/bash
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# This is not an autoconf generated configure
+#
+
+# Output file which is input to Makefile
+CONFIG=config.mk
+
+# Assume tc is in $PATH
+TC=tc
+
+check_tc_libbpf()
+{
+    tc_version=$($TC -V)
+    if echo $tc_version | grep -q libbpf; then
+	libbpf_version=${tc_version##*libbpf }
+	echo "HAVE_TC_LIBBPF:=y" >> $CONFIG
+	echo "BPF_CFLAGS += -DHAVE_TC_LIBBPF" >> $CONFIG
+	echo "yes ($libbpf_version)"
+    else
+	echo "no"
+    fi
+}
+
+echo "# Generated config" > $CONFIG
+echo "Detecting available features on system"
+
+echo -n " - libbpf support in tc tool: "
+check_tc_libbpf

pping/pping_kern_tc.c

@@ -16,6 +16,16 @@
 
 char _license[] SEC("license") = "GPL";
 
+#ifdef HAVE_TC_LIBBPF /* detected by configure script in config.mk */
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(struct ts_key));
+	__uint(value_size, sizeof(struct ts_timestamp));
+	__uint(max_entries, 16384);
+	__uint(pinning, LIBBPF_PIN_BY_NAME);
+} ts_start SEC(".maps");
+
+#else
 struct bpf_elf_map SEC("maps") ts_start = {
 	.type = BPF_MAP_TYPE_HASH,
 	.size_key = sizeof(struct ts_key),
@@ -23,6 +33,7 @@ struct bpf_elf_map SEC("maps") ts_start = {
 	.max_elem = 16384,
 	.pinning = PIN_GLOBAL_NS,
 };
+#endif
 
 // TC-BFP for parsing TSVAL from egress traffic and add to map
 SEC("pping_egress")