4 files changed, 112 insertions, 1 deletions
diff --git a/tools/lib/bpf/Build b/tools/lib/bpf/Build
index 197b40f5b5c6..bfd9bfc82c3b 100644
--- a/tools/lib/bpf/Build
+++ b/tools/lib/bpf/Build
@@ -1 +1 @@
-libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o netlink.o bpf_prog_linfo.o
+libbpf-y := libbpf.o bpf.o nlattr.o btf.o libbpf_errno.o str_error.o netlink.o bpf_prog_linfo.o libbpf_probes.o
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 5f68d7b75215..8e63821109ab 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -355,6 +355,17 @@ LIBBPF_API const struct bpf_line_info *
 bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
 		      __u32 insn_off, __u32 nr_skip);
 
+/*
+ * Probe for supported system features
+ *
+ * Note that running many of these probes in a short amount of time can cause
+ * the kernel to reach the maximal size of lockable memory allowed for the
+ * user, causing subsequent probes to fail. In this case, the caller may want
+ * to adjust that limit with setrlimit().
+ */
+LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
+				    __u32 ifindex);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index cd02cd4e2cc3..c7ec3ffa24e9 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -124,3 +124,8 @@ LIBBPF_0.0.1 {
 	local:
 		*;
 };
+
+LIBBPF_0.0.2 {
+	global:
+		bpf_probe_prog_type;
+} LIBBPF_0.0.1;
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
new file mode 100644
index 000000000000..056c0c186f2a
--- /dev/null
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2019 Netronome Systems, Inc. */
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/utsname.h>
+
+#include <linux/filter.h>
+#include <linux/kernel.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+
+static int get_kernel_version(void)
+{
+	int version, subversion, patchlevel;
+	struct utsname utsn;
+
+	/* Return 0 on failure, and attempt to probe with empty kversion */
+	if (uname(&utsn))
+		return 0;
+
+	if (sscanf(utsn.release, "%d.%d.%d",
+		   &version, &subversion, &patchlevel) != 3)
+		return 0;
+
+	return (version << 16) + (subversion << 8) + patchlevel;
+}
+
+static void
+probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
+	   size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex)
+{
+	struct bpf_load_program_attr xattr = {};
+	int fd;
+
+	switch (prog_type) {
+	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
+		xattr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
+		break;
+	case BPF_PROG_TYPE_KPROBE:
+		xattr.kern_version = get_kernel_version();
+		break;
+	case BPF_PROG_TYPE_UNSPEC:
+	case BPF_PROG_TYPE_SOCKET_FILTER:
+	case BPF_PROG_TYPE_SCHED_CLS:
+	case BPF_PROG_TYPE_SCHED_ACT:
+	case BPF_PROG_TYPE_TRACEPOINT:
+	case BPF_PROG_TYPE_XDP:
+	case BPF_PROG_TYPE_PERF_EVENT:
+	case BPF_PROG_TYPE_CGROUP_SKB:
+	case BPF_PROG_TYPE_CGROUP_SOCK:
+	case BPF_PROG_TYPE_LWT_IN:
+	case BPF_PROG_TYPE_LWT_OUT:
+	case BPF_PROG_TYPE_LWT_XMIT:
+	case BPF_PROG_TYPE_SOCK_OPS:
+	case BPF_PROG_TYPE_SK_SKB:
+	case BPF_PROG_TYPE_CGROUP_DEVICE:
+	case BPF_PROG_TYPE_SK_MSG:
+	case BPF_PROG_TYPE_RAW_TRACEPOINT:
+	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
+	case BPF_PROG_TYPE_LIRC_MODE2:
+	case BPF_PROG_TYPE_SK_REUSEPORT:
+	case BPF_PROG_TYPE_FLOW_DISSECTOR:
+	default:
+		break;
+	}
+
+	xattr.prog_type = prog_type;
+	xattr.insns = insns;
+	xattr.insns_cnt = insns_cnt;
+	xattr.license = "GPL";
+	xattr.prog_ifindex = ifindex;
+
+	fd = bpf_load_program_xattr(&xattr, buf, buf_len);
+	if (fd >= 0)
+		close(fd);
+}
+
+bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
+{
+	struct bpf_insn insns[2] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN()
+	};
+
+	if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
+		/* nfp returns -EINVAL on exit(0) with TC offload */
+		insns[0].imm = 2;
+
+	errno = 0;
+	probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
+
+	return errno != EINVAL && errno != EOPNOTSUPP;
+}