[PATCH 05/10] bpf tools: Support load different type of programs

[Wang Nan <wangnan0@huawei.com>]

Before this patch libbpf can only load program with type
BPF_PROG_TYPE_KPROBE program. To make libbpf useful in other scenarios,
this patch introduced bpf_program__set_type() and
bpf_object__set_type() which allows setting program type.

This changes doesn't break old API. The default program type is
BPF_PROG_TYPE_KPROBE. If caller wants to load program with other type,
one of these API should be called before bpf_object__load() or
in callback function of loader.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/lib/bpf/libbpf.c | 43 ++++++++++++++++++++++++++++++++++++++-----
 tools/lib/bpf/libbpf.h | 16 ++++++++++++++++
 2 files changed, 54 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8334a5a..99be7f1 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -66,6 +66,7 @@ void libbpf_set_print(libbpf_print_fn_t warn,
 #define ERRNO_OFFSET(e)		((e) - __LIBBPF_ERRNO__START)
 #define ERRCODE_OFFSET(c)	ERRNO_OFFSET(LIBBPF_ERRNO__##c)
 #define NR_ERRNO	(__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
+#define BPF_PROG_TYPE_MAX	BPF_PROG_TYPE_SCHED_ACT
 
 static const char *libbpf_strerror_table[NR_ERRNO] = {
 	[ERRCODE_OFFSET(LIBELF)]	= "Something wrong in libelf",
@@ -161,6 +162,7 @@ struct bpf_program {
 	struct bpf_object *obj;
 	void *priv;
 	bpf_program_clear_priv_t clear_priv;
+	enum bpf_prog_type type;
 };
 
 struct bpf_map {
@@ -323,6 +325,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
 	obj->programs = progs;
 	obj->nr_programs = nr_progs + 1;
 	prog.obj = obj;
+	prog.type = BPF_PROG_TYPE_KPROBE;
 	progs[nr_progs] = prog;
 	return 0;
 }
@@ -871,7 +874,7 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
 }
 
 static int
-load_program(struct bpf_insn *insns, int insns_cnt,
+load_program(struct bpf_insn *insns, int insns_cnt, enum bpf_prog_type type,
 	     char *license, u32 kern_version, int *pfd)
 {
 	int ret;
@@ -884,9 +887,8 @@ load_program(struct bpf_insn *insns, int insns_cnt,
 	if (!log_buf)
 		pr_warning("Alloc log buffer for bpf loader error, continue without log\n");
 
-	ret = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns,
-			       insns_cnt, license, kern_version,
-			       log_buf, BPF_LOG_BUF_SIZE);
+	ret = bpf_load_program(type, insns, insns_cnt, license,
+			       kern_version, log_buf, BPF_LOG_BUF_SIZE);
 
 	if (ret >= 0) {
 		*pfd = ret;
@@ -945,7 +947,7 @@ bpf_program__load(struct bpf_program *prog,
 			pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n",
 				   prog->section_name, prog->instances.nr);
 		}
-		err = load_program(prog->insns, prog->insns_cnt,
+		err = load_program(prog->insns, prog->insns_cnt, prog->type,
 				   license, kern_version, &fd);
 		if (!err)
 			prog->instances.fds[0] = fd;
@@ -976,6 +978,7 @@ bpf_program__load(struct bpf_program *prog,
 
 		err = load_program(result.new_insn_ptr,
 				   result.new_insn_cnt,
+				   prog->type,
 				   license, kern_version, &fd);
 
 		if (err) {
@@ -1192,6 +1195,25 @@ bpf_object__get_kversion(struct bpf_object *obj)
 	return obj->kern_version;
 }
 
+int bpf_object__set_type(struct bpf_object *obj,
+			 enum bpf_prog_type type)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj || type <= BPF_PROG_TYPE_UNSPEC ||
+	    type > BPF_PROG_TYPE_MAX)
+		return -EINVAL;
+
+	bpf_object__for_each_program(prog, obj) {
+		err = bpf_program__set_type(prog, type);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 struct bpf_program *
 bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
 {
@@ -1281,6 +1303,17 @@ int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
 	return 0;
 }
 
+int bpf_program__set_type(struct bpf_program *prog,
+			  enum bpf_prog_type type)
+{
+	if (!prog || type <= BPF_PROG_TYPE_UNSPEC ||
+	    type > BPF_PROG_TYPE_MAX)
+		return -EINVAL;
+
+	prog->type = type;
+	return 0;
+}
+
 int bpf_program__nth_fd(struct bpf_program *prog, int n)
 {
 	int fd;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index a51594c..c9d4130 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include <linux/err.h>
+#include <linux/bpf.h>
 
 enum libbpf_errno {
 	__LIBBPF_ERRNO__START = 4000,
@@ -58,6 +59,13 @@ int bpf_object__unload(struct bpf_object *obj);
 const char *bpf_object__get_name(struct bpf_object *obj);
 unsigned int bpf_object__get_kversion(struct bpf_object *obj);
 
+/*
+ * Set type of all programs in an object.
+ * See bpf_program__set_type().
+ */
+int bpf_object__set_type(struct bpf_object *obj,
+			 enum bpf_prog_type type);
+
 struct bpf_object *bpf_object__next(struct bpf_object *prev);
 #define bpf_object__for_each_safe(pos, tmp)			\
 	for ((pos) = bpf_object__next(NULL),		\
@@ -150,6 +158,14 @@ typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n,
 int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,
 			  bpf_program_prep_t prep);
 
+/*
+ * Set type of a program. Default is BPF_PROG_TYPE_KPROBE.
+ * This function should be called before bpf_object__load()
+ * or in bpf_program_prep callback.
+ */
+int bpf_program__set_type(struct bpf_program *prog,
+			  enum bpf_prog_type type);
+
 int bpf_program__nth_fd(struct bpf_program *prog, int n);
 
 /*
-- 
1.8.3.4