bpf: Move ksym_tnode to bpf_ksym

Moving ksym_tnode list node to 'struct bpf_ksym' object,
so the symbol itself can be chained and used in other
objects like bpf_trampoline and bpf_dispatcher.

We need bpf_ksym object to be linked both in bpf_kallsyms
via lnode for /proc/kallsyms and in bpf_tree via tnode for
bpf address lookup functions like __bpf_address_lookup or
bpf_prog_kallsyms_find.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200312195610.346362-7-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -477,6 +477,7 @@ struct bpf_ksym {
 	unsigned long		 end;
 	char			 name[KSYM_NAME_LEN];
 	struct list_head	 lnode;
+	struct latch_tree_node	 tnode;
 };
 
 enum bpf_tramp_prog_type {
@@ -659,7 +660,6 @@ struct bpf_prog_aux {
 	void *jit_data; /* JIT specific data. arch dependent */
 	struct bpf_jit_poke_descriptor *poke_tab;
 	u32 size_poke_tab;
-	struct latch_tree_node ksym_tnode;
 	struct bpf_ksym ksym;
 	const struct bpf_prog_ops *ops;
 	struct bpf_map **used_maps;

kernel/bpf/core.c

@@ -572,31 +572,27 @@ bpf_prog_ksym_set_name(struct bpf_prog *prog)
 		*sym = 0;
 }
 
-static __always_inline unsigned long
-bpf_get_prog_addr_start(struct latch_tree_node *n)
+static unsigned long bpf_get_ksym_start(struct latch_tree_node *n)
 {
-	const struct bpf_prog_aux *aux;
-
-	aux = container_of(n, struct bpf_prog_aux, ksym_tnode);
-	return aux->ksym.start;
+	return container_of(n, struct bpf_ksym, tnode)->start;
 }
 
 static __always_inline bool bpf_tree_less(struct latch_tree_node *a,
 					  struct latch_tree_node *b)
 {
-	return bpf_get_prog_addr_start(a) < bpf_get_prog_addr_start(b);
+	return bpf_get_ksym_start(a) < bpf_get_ksym_start(b);
 }
 
 static __always_inline int bpf_tree_comp(void *key, struct latch_tree_node *n)
 {
 	unsigned long val = (unsigned long)key;
-	const struct bpf_prog_aux *aux;
+	const struct bpf_ksym *ksym;
 
-	aux = container_of(n, struct bpf_prog_aux, ksym_tnode);
+	ksym = container_of(n, struct bpf_ksym, tnode);
 
-	if (val < aux->ksym.start)
+	if (val < ksym->start)
 		return -1;
-	if (val >= aux->ksym.end)
+	if (val >= ksym->end)
 		return  1;
 
 	return 0;
@@ -615,7 +611,7 @@ static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux)
 {
 	WARN_ON_ONCE(!list_empty(&aux->ksym.lnode));
 	list_add_tail_rcu(&aux->ksym.lnode, &bpf_kallsyms);
-	latch_tree_insert(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops);
+	latch_tree_insert(&aux->ksym.tnode, &bpf_tree, &bpf_tree_ops);
 }
 
 static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux)
@@ -623,7 +619,7 @@ static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux)
 	if (list_empty(&aux->ksym.lnode))
 		return;
 
-	latch_tree_erase(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops);
+	latch_tree_erase(&aux->ksym.tnode, &bpf_tree, &bpf_tree_ops);
 	list_del_rcu(&aux->ksym.lnode);
 }
 
@@ -668,7 +664,7 @@ static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr)
 
 	n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops);
 	return n ?
-	       container_of(n, struct bpf_prog_aux, ksym_tnode)->prog :
+	       container_of(n, struct bpf_prog_aux, ksym.tnode)->prog :
 	       NULL;
 }