[RFC PATCH 06/13] bpf tools: Introduce ubpf_vm to program instance union

[Wang Nan <wangnan0@huawei.com>]

Add 'struct ubpf_vm *' into prog_instance union. Introduce if_engine()
macro to merge common code.

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 | 76 ++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 68 insertions(+), 8 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3755846..3a969fd 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -141,6 +141,9 @@ int libbpf_strerror(int err, char *buf, size_t size)
 
 union prog_instance {
 	int fd;
+#ifdef HAVE_UBPF_SUPPORT
+	struct ubpf_vm *vm;
+#endif
 };
 
 /*
@@ -176,6 +179,56 @@ struct bpf_program {
 	bpf_program_clear_priv_t clear_priv;
 };
 
+#ifdef HAVE_UBPF_SUPPORT
+# define __if_engine(p, d, k, u)	\
+	do {				\
+		switch (p->engine) {	\
+		default:		\
+		case ENGINE_UNKNOWN: {	\
+			d;		\
+		}			\
+		case ENGINE_KBPF: {	\
+			k; break;	\
+		}			\
+		case ENGINE_UBPF: {	\
+			u; break;	\
+		}			\
+		}			\
+	} while(0)
+
+/*
+ * ubpf_destroy() doesn't accept NULL input. This wrapper makes
+ * it similar to zclose.
+ */
+# define __ubpf_destroy(vm) do {	\
+	if (vm)				\
+		ubpf_destroy(vm);	\
+	(vm) = NULL;			\
+} while(0)
+
+#else
+# define __if_engine(p, d, k, u)	\
+	do { k; } while(0)
+#endif
+
+#define instan_fd(i) instances.array[i].fd
+#define instan_vm(i) instances.array[i].vm
+
+#define if_engine(p, k, u) __if_engine(p, do { } while(0), k, u)
+#define set_instance(p, i, k, u)		\
+	if_engine(p,				\
+		  p->instan_fd(i) = k,	\
+		  p->instan_vm(i) = u)
+
+static inline void init_instance_array(struct bpf_program *prog)
+{
+	size_t size = sizeof(prog->instances.array[0]) * prog->instances.nr;
+
+	if_engine(prog,
+		  memset(prog->instances.array, -1, size),
+		  memset(prog->instances.array, 0, size));
+}
+
 struct bpf_map {
 	int fd;
 	char *name;
@@ -239,7 +292,9 @@ static void bpf_program__unload(struct bpf_program *prog)
 	 */
 	if (prog->instances.nr > 0) {
 		for (i = 0; i < prog->instances.nr; i++)
-			zclose(prog->instances.array[i].fd);
+			if_engine(prog,
+				  zclose(prog->instan_fd(i)),
+				  __ubpf_destroy(prog->instan_vm(i)));
 	} else if (prog->instances.nr != -1) {
 		pr_warning("Internal error: instances.nr is %d\n",
 			   prog->instances.nr);
@@ -966,7 +1021,7 @@ bpf_program__load(struct bpf_program *prog,
 			return -ENOMEM;
 		}
 		prog->instances.nr = 1;
-		prog->instances.array[0].fd = -1;
+		set_instance(prog, 0, -1, NULL);
 	}
 
 	if (!prog->preprocessor) {
@@ -977,7 +1032,7 @@ bpf_program__load(struct bpf_program *prog,
 		err = load_program(prog->insns, prog->insns_cnt,
 				   license, kern_version, &fd);
 		if (!err)
-			prog->instances.array[0].fd = fd;
+			prog->instan_fd(0) = fd;
 		goto out;
 	}
 
@@ -997,7 +1052,7 @@ bpf_program__load(struct bpf_program *prog,
 		if (!result.new_insn_ptr || !result.new_insn_cnt) {
 			pr_debug("Skip loading the %dth instance of program '%s'\n",
 				 i, prog->section_name);
-			prog->instances.array[i].fd = -1;
+			prog->instan_fd(i) = -1;
 			if (result.pfd)
 				*result.pfd = -1;
 			continue;
@@ -1015,7 +1070,7 @@ bpf_program__load(struct bpf_program *prog,
 
 		if (result.pfd)
 			*result.pfd = fd;
-		prog->instances.array[i].fd = fd;
+		prog->instan_fd(i) = fd;
 	}
 out:
 	if (err)
@@ -1301,12 +1356,11 @@ int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
 		return -ENOMEM;
 	}
 
-	/* fill all fd with -1 */
-	memset(array, -1, sizeof(array[0]) * nr_instances);
-
 	prog->instances.nr = nr_instances;
 	prog->instances.array = array;
 	prog->preprocessor = prep;
+
+	init_instance_array(prog);
 	return 0;
 }
 
@@ -1314,6 +1368,12 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)
 {
 	int fd;
 
+	if (prog->engine != ENGINE_KBPF) {
+		pr_warning("Can't get fd from program %s: engine not KBPF or not loaded\n",
+			   prog->section_name);
+		return -EINVAL;
+	}
+
 	if (n >= prog->instances.nr || n < 0) {
 		pr_warning("Can't get the %dth fd from program %s: only %d instances\n",
 			   n, prog->section_name, prog->instances.nr);
-- 
1.8.3.4