[RFC bpf-next 4/5] iproute2: Allow compiling against libbpf

["Toke Høiland-Jørgensen" <toke@redhat.com>]

This adds a configure check for libbpf and renames functions to allow
lib/bpf.c to be compiled with it present. This makes it possible to
port functionality piecemeal to use libbpf.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 configure          | 16 ++++++++++++++++
 include/bpf_util.h |  6 +++---
 ip/ipvrf.c         |  4 ++--
 lib/bpf.c          | 33 +++++++++++++++++++--------------
 4 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/configure b/configure
index 45fcffb6..5a89ee9f 100755
--- a/configure
+++ b/configure
@@ -238,6 +238,19 @@ check_elf()
     fi
 }
 
+check_libbpf()
+{
+    if ${PKG_CONFIG} libbpf --exists; then
+	echo "HAVE_LIBBPF:=y" >>$CONFIG
+	echo "yes"
+
+	echo 'CFLAGS += -DHAVE_LIBBPF' `${PKG_CONFIG} libbpf --cflags` >> $CONFIG
+	echo 'LDLIBS += ' `${PKG_CONFIG} libbpf --libs` >>$CONFIG
+    else
+	echo "no"
+    fi
+}
+
 check_selinux()
 # SELinux is a compile time option in the ss utility
 {
@@ -386,6 +399,9 @@ check_selinux
 echo -n "ELF support: "
 check_elf
 
+echo -n "libbpf support: "
+check_libbpf
+
 echo -n "libmnl support: "
 check_mnl
 
diff --git a/include/bpf_util.h b/include/bpf_util.h
index 63db07ca..72d3a32c 100644
--- a/include/bpf_util.h
+++ b/include/bpf_util.h
@@ -274,9 +274,9 @@ int bpf_trace_pipe(void);
 
 void bpf_print_ops(struct rtattr *bpf_ops, __u16 len);
 
-int bpf_prog_load(enum bpf_prog_type type, const struct bpf_insn *insns,
-		  size_t size_insns, const char *license, char *log,
-		  size_t size_log);
+int bpf_prog_load_buf(enum bpf_prog_type type, const struct bpf_insn *insns,
+		      size_t size_insns, const char *license, char *log,
+		      size_t size_log);
 
 int bpf_prog_attach_fd(int prog_fd, int target_fd, enum bpf_attach_type type);
 int bpf_prog_detach_fd(int target_fd, enum bpf_attach_type type);
diff --git a/ip/ipvrf.c b/ip/ipvrf.c
index 43366f6e..1d1aae6f 100644
--- a/ip/ipvrf.c
+++ b/ip/ipvrf.c
@@ -256,8 +256,8 @@ static int prog_load(int idx)
 		BPF_EXIT_INSN(),
 	};
 
-	return bpf_prog_load(BPF_PROG_TYPE_CGROUP_SOCK, prog, sizeof(prog),
-			     "GPL", bpf_log_buf, sizeof(bpf_log_buf));
+	return bpf_prog_load_buf(BPF_PROG_TYPE_CGROUP_SOCK, prog, sizeof(prog),
+				 "GPL", bpf_log_buf, sizeof(bpf_log_buf));
 }
 
 static int vrf_configure_cgroup(const char *path, int ifindex)
diff --git a/lib/bpf.c b/lib/bpf.c
index 7d2a322f..c6e3bd0d 100644
--- a/lib/bpf.c
+++ b/lib/bpf.c
@@ -28,6 +28,11 @@
 #include <gelf.h>
 #endif
 
+#ifdef HAVE_LIBBPF
+#include <bpf/libbpf.h>
+#include <bpf/bpf.h>
+#endif
+
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/un.h>
@@ -795,7 +800,7 @@ out:
 	return mnt;
 }
 
-static int bpf_obj_get(const char *pathname, enum bpf_prog_type type)
+static int bpf_obj_get_path(const char *pathname, enum bpf_prog_type type)
 {
 	union bpf_attr attr = {};
 	char tmp[PATH_MAX];
@@ -814,7 +819,7 @@ static int bpf_obj_get(const char *pathname, enum bpf_prog_type type)
 
 static int bpf_obj_pinned(const char *pathname, enum bpf_prog_type type)
 {
-	int prog_fd = bpf_obj_get(pathname, type);
+	int prog_fd = bpf_obj_get_path(pathname, type);
 
 	if (prog_fd < 0)
 		fprintf(stderr, "Couldn\'t retrieve pinned program \'%s\': %s\n",
@@ -1036,7 +1041,7 @@ int bpf_graft_map(const char *map_path, uint32_t *key, int argc, char **argv)
 		}
 	}
 
-	map_fd = bpf_obj_get(map_path, cfg.type);
+	map_fd = bpf_obj_get_path(map_path, cfg.type);
 	if (map_fd < 0) {
 		fprintf(stderr, "Couldn\'t retrieve pinned map \'%s\': %s\n",
 			map_path, strerror(errno));
@@ -1105,9 +1110,9 @@ static int bpf_prog_load_dev(enum bpf_prog_type type,
 	return bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 }
 
-int bpf_prog_load(enum bpf_prog_type type, const struct bpf_insn *insns,
-		  size_t size_insns, const char *license, char *log,
-		  size_t size_log)
+int bpf_prog_load_buf(enum bpf_prog_type type, const struct bpf_insn *insns,
+		      size_t size_insns, const char *license, char *log,
+		      size_t size_log)
 {
 	return bpf_prog_load_dev(type, insns, size_insns, license, 0,
 				 log, size_log);
@@ -1284,7 +1289,7 @@ static int bpf_btf_load(void *btf, size_t size_btf,
 	return bpf(BPF_BTF_LOAD, &attr, sizeof(attr));
 }
 
-static int bpf_obj_pin(int fd, const char *pathname)
+static int bpf_obj_pin_fd(int fd, const char *pathname)
 {
 	union bpf_attr attr = {};
 
@@ -1433,7 +1438,7 @@ static int bpf_probe_pinned(const char *name, const struct bpf_elf_ctx *ctx,
 		return 0;
 
 	bpf_make_pathname(pathname, sizeof(pathname), name, ctx, pinning);
-	return bpf_obj_get(pathname, ctx->type);
+	return bpf_obj_get_path(pathname, ctx->type);
 }
 
 static int bpf_make_obj_path(const struct bpf_elf_ctx *ctx)
@@ -1501,7 +1506,7 @@ static int bpf_place_pinned(int fd, const char *name,
 		return ret;
 
 	bpf_make_pathname(pathname, sizeof(pathname), name, ctx, pinning);
-	return bpf_obj_pin(fd, pathname);
+	return bpf_obj_pin_fd(fd, pathname);
 }
 
 static void bpf_prog_report(int fd, const char *section,
@@ -1523,9 +1528,9 @@ static void bpf_prog_report(int fd, const char *section,
 	bpf_dump_error(ctx, "Verifier analysis:\n\n");
 }
 
-static int bpf_prog_attach(const char *section,
-			   const struct bpf_elf_prog *prog,
-			   struct bpf_elf_ctx *ctx)
+static int bpf_prog_attach_section(const char *section,
+				   const struct bpf_elf_prog *prog,
+				   struct bpf_elf_ctx *ctx)
 {
 	int tries = 0, fd;
 retry:
@@ -2347,7 +2352,7 @@ static int bpf_fetch_prog(struct bpf_elf_ctx *ctx, const char *section,
 		prog.insns_num = prog.size / sizeof(struct bpf_insn);
 		prog.insns     = data.sec_data->d_buf;
 
-		fd = bpf_prog_attach(section, &prog, ctx);
+		fd = bpf_prog_attach_section(section, &prog, ctx);
 		if (fd < 0)
 			return fd;
 
@@ -2513,7 +2518,7 @@ static int bpf_fetch_prog_relo(struct bpf_elf_ctx *ctx, const char *section,
 			goto out;
 		}
 
-		fd = bpf_prog_attach(section, prog, ctx);
+		fd = bpf_prog_attach_section(section, prog, ctx);
 		free(prog->insns);
 		if (fd < 0) {
 			*lderr = true;
-- 
2.22.1