[RFC PATCH 08/13] bpf tools: Add API for fetching ubpf_vm

[Wang Nan <wangnan0@huawei.com>]

Introduce bpf_program__vm and bpf_program__nth_vm for fetching ubpf
program instance.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
---
 tools/lib/bpf/libbpf.c | 38 ++++++++++++++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.h |  2 ++
 2 files changed, 40 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e4a1e77..4045a7e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1375,6 +1375,11 @@ int bpf_program__fd(struct bpf_program *prog)
 	return bpf_program__nth_fd(prog, 0);
 }
 
+struct ubpf_vm *bpf_program__vm(struct bpf_program *prog)
+{
+	return bpf_program__nth_vm(prog, 0);
+}
+
 int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
 			  bpf_program_prep_t prep)
 {
@@ -1429,6 +1434,32 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)
 }
 
 #ifdef HAVE_UBPF_SUPPORT
+struct ubpf_vm *bpf_program__nth_vm(struct bpf_program *prog, int n)
+{
+	struct ubpf_vm *vm;
+
+	if (prog->engine != ENGINE_UBPF) {
+		pr_warning("Can't get ubpf_vm from program %s: engine not UBPF or not loaded\n",
+			   prog->section_name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (n >= prog->instances.nr || n < 0) {
+		pr_warning("Can't get the %dth vm from program %s: only %d instances\n",
+			   n, prog->section_name, prog->instances.nr);
+		return ERR_PTR(-EINVAL);
+	}
+
+	vm = prog->instances.array[n].vm;
+	if (!vm) {
+		pr_warning("%dth instance of program '%s' is invalid\n",
+			   n, prog->section_name);
+		return ERR_PTR(-ENOENT);
+	}
+
+	return vm;
+}
+
 int bpf_program__set_ubpf(struct bpf_program *prog)
 {
 	if (prog->engine != ENGINE_UNKNOWN) {
@@ -1454,6 +1485,13 @@ bool bpf_program__is_ubpf(struct bpf_program *prog __maybe_unused)
 {
 	return false;
 }
+
+struct ubpf_vm *
+bpf_program__nth_vm(struct bpf_program *prog __maybe_unused,
+		    int n __maybe_unused)
+{
+	return ERR_PTR(-LIBBPF_ERRNO__NOUBPF);
+}
 #endif
 
 int bpf_map__get_fd(struct bpf_map *map)
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8e69c6f..41c35fd 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -92,6 +92,7 @@ int bpf_program__set_ubpf(struct bpf_program *prog);
 bool bpf_program__is_ubpf(struct bpf_program *prog);
 
 int bpf_program__fd(struct bpf_program *prog);
+struct ubpf_vm *bpf_program__vm(struct bpf_program *prog);
 
 struct bpf_insn;
 
@@ -162,6 +163,7 @@ int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,
 			  bpf_program_prep_t prep);
 
 int bpf_program__nth_fd(struct bpf_program *prog, int n);
+struct ubpf_vm *bpf_program__nth_vm(struct bpf_program *prog, int n);
 
 /*
  * We don't need __attribute__((packed)) now since it is
-- 
1.8.3.4