Revert "check the existing of bpf helper by kernel symbols"

This reverts commit dff0e09.

Author: menglongdong

shared/bpf/skb_macro.h

@@ -41,8 +41,9 @@
 #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
 
@@ -54,6 +55,9 @@
 
 #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

@@ -41,9 +41,6 @@ struct {
 	__uint(max_entries, 1);
 } m_config SEC(".maps");
 
-const volatile bool bpf_syms_exist[BPF_SYM_MAX];
-#define bpf_core_helper_exist(name) bpf_syms_exist[BPF_SYM_bpf_##name##_proto]
-
 #define CONFIG() ({						\
 	int _key = 0;						\
 	void * _v = bpf_map_lookup_elem(&m_config, &_key);	\

shared/bpf/skb_shared.h

@@ -176,15 +176,4 @@ typedef struct {
 #endif
 typedef __u64 stack_trace_t[PERF_MAX_STACK_DEPTH];
 
-#define BPF_SYM_MAPPER(FN)				\
-	FN(bpf_jiffies64_proto)				\
-	FN(bpf_get_func_ret_proto)
-
-#define FN(name) BPF_SYM_##name,
-enum {
-	BPF_SYM_MAPPER(FN)
-	BPF_SYM_MAX,
-};
-#undef FN
-
 #endif

shared/bpf_utils.c

@@ -12,7 +12,6 @@
 
 #include <sys_utils.h>
 #include <bpf/btf.h>
-#include <parse_sym.h>
 
 #include "bpf_utils.h"
 
@@ -140,30 +139,9 @@ int btf_get_arg_count(char *name)
 	if (!t)
 		return -ENOENT;
 
-	/* find kfunction proto of this function */
 	t = btf__type_by_id(local_btf, t->type);
 	if (!t)
 		return -ENOENT;
 
 	return btf_vlen(t);
 }
-
-/* This is the way we check the exist of kernel function/symbol, before
- * the araise of "bpf_core_function_exist()"
- */
-#define DEF_BPF_SYM(name) #name,
-static const char *bpf_ksyms[] = {
-	BPF_SYM_MAPPER(DEF_BPF_SYM)
-};
-#undef DEF_BPF_SYM
-
-void bpf_syms_init(bool *data)
-{
-	const char *sym;
-	int i;
-
-	for (i = 0; i < BPF_SYM_MAX; i++) {
-		sym = bpf_ksyms[i];
-		data[i] = sym_get_type(sym) != SYM_NOT_EXIST;
-	}
-}

shared/bpf_utils.h

@@ -65,6 +65,5 @@ static inline int perf_output(int fd, perf_buffer_sample_fn fn)
 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);
-void bpf_syms_init(bool *data);
 
 #endif

src/trace.c

@@ -646,9 +646,6 @@ int trace_prepare()
 	return err;
 }
 
-/* This function is called after BPF is open and not loaded to the kernel
- * yet.
- */
 int trace_pre_load()
 {
 	char kret_name[128], regex[128], *func;

src/trace_probe.c

@@ -88,7 +88,6 @@ 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_syms_init(skel->rodata->bpf_syms_exist);
 
 	trace_ctx.obj = skel->obj;
 	if (trace_pre_load() || kprobe__load(skel)) {

src/trace_tracing.c

@@ -152,7 +152,6 @@ 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_syms_init(skel->rodata->bpf_syms_exist);
 
 	trace_ctx.obj = skel->obj;
 	tracing_load_rules();