check the supporting of bpf helper by libbpf_probe

Signed-off-by: Menglong Dong <imagedong@tencent.com>

Author: menglongdong

common.mk

@@ -54,9 +54,8 @@ ifeq ($(wildcard $(HEADERS)),)
 $(error kernel headers not exist in COMPAT mdoe, please install it)
 endif
 	kheaders_cmd	:= ln -s vmlinux_header.h kheaders.h
-	CFLAGS		+= -DCOMPAT_MODE
-	BPF_CFLAGS	+= $(KERNEL_CFLAGS) -DBPF_NO_GLOBAL_DATA \
-			   -g
+	CFLAGS		+= -DCOMPAT_MODE -DBPF_NO_GLOBAL_DATA
+	BPF_CFLAGS	+= $(KERNEL_CFLAGS) -g
 else
 	kheaders_cmd	:= ln -s ../shared/bpf/vmlinux.h kheaders.h
 	BPF_CFLAGS	+= -target bpf -g

shared/bpf/skb_macro.h

@@ -41,9 +41,8 @@
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
 #endif
 
+/* redefine all the CO-RE usage in COMPAT mode */
 #ifdef COMPAT_MODE
-#define bpf_core_helper_exist(name) false
-
 #undef bpf_core_type_exists
 #define bpf_core_type_exists(type) false
 
@@ -55,9 +54,6 @@
 
 #undef bpf_core_field_offset
 #define bpf_core_field_offset(type, field) offsetof(type, field)
-#else
-#define bpf_core_helper_exist(name)				\
-	bpf_core_enum_value_exists(enum bpf_func_id, BPF_FUNC_##name)
 #endif
 
 #endif

shared/bpf/skb_parse.h

@@ -41,6 +41,13 @@ struct {
 	__uint(max_entries, 1);
 } m_config SEC(".maps");
 
+#ifndef BPF_NO_GLOBAL_DATA
+static const volatile bool bpf_func_exist[BPF_LOCAL_FUNC_MAX] = {0};
+#define bpf_core_helper_exist(name) bpf_func_exist[BPF_LOCAL_FUNC_##name]
+#else
+#define bpf_core_helper_exist(name) false
+#endif
+
 #define CONFIG() ({						\
 	int _key = 0;						\
 	void * _v = bpf_map_lookup_elem(&m_config, &_key);	\

shared/bpf/skb_shared.h

@@ -176,4 +176,15 @@ typedef struct {
 #endif
 typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH];
 
+#define BPF_LOCAL_FUNC_MAPPER(FN, args...)	\
+	FN(jiffies64, ##args)			\
+	FN(get_func_ret, ##args)
+
+#define FN(name) BPF_LOCAL_FUNC_##name,
+enum {
+	BPF_LOCAL_FUNC_MAPPER(FN)
+	BPF_LOCAL_FUNC_MAX,
+};
+#undef FN
+
 #endif

shared/bpf_utils.h

@@ -66,4 +66,16 @@ int compat_bpf_attach_kprobe(int fd, char *name, bool ret);
 const struct btf_type *btf_get_type(char *name);
 int btf_get_arg_count(char *name);
 
+#ifndef BPF_NO_GLOBAL_DATA
+#undef BPF_FUNC_CHECK
+#define BPF_FUNC_CHECK(name, data, type)			\
+data[BPF_LOCAL_FUNC_##name] = libbpf_probe_bpf_helper(type,	\
+	BPF_FUNC_##name, NULL);
+
+#define bpf_func_init(skel, type)				\
+	BPF_LOCAL_FUNC_MAPPER(BPF_FUNC_CHECK, skel->rodata->bpf_func_exist, type)
+#else
+#define bpf_func_init(data, type)
+#endif
+
 #endif

src/trace_probe.c

@@ -88,6 +88,7 @@ static int probe_trace_load()
 
 	/* set the max entries of perf event map to current cpu count */
 	bpf_map__set_max_entries(skel->maps.m_event, get_nprocs_conf());
+	bpf_func_init(skel, BPF_PROG_TYPE_KPROBE);
 
 	trace_ctx.obj = skel->obj;
 	if (trace_pre_load() || kprobe__load(skel)) {

src/trace_tracing.c

@@ -152,6 +152,7 @@ static int tracing_trace_load()
 
 	/* set the max entries of perf event map to current cpu count */
 	bpf_map__set_max_entries(skel->maps.m_event, get_nprocs_conf());
+	bpf_func_init(skel, BPF_PROG_TYPE_TRACING);
 
 	trace_ctx.obj = skel->obj;
 	tracing_load_rules();