bpf: Add prog flag to struct bpf_ksym object

Adding 'prog' bool flag to 'struct bpf_ksym' to mark that
this object belongs to bpf_prog object.

This change allows having bpf_prog objects together with
other types (trampolines and dispatchers) in the single
bpf_tree. It's used when searching for bpf_prog exception
tables by the bpf_prog_ksym_find function, where we need
to get the bpf_prog pointer.

>From now we can safely add bpf_ksym support for trampoline
or dispatcher objects, because we can differentiate them
from bpf_prog objects.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200312195610.346362-9-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf.h

@@ -478,6 +478,7 @@ struct bpf_ksym {
 	char			 name[KSYM_NAME_LEN];
 	struct list_head	 lnode;
 	struct latch_tree_node	 tnode;
+	bool			 prog;
 };
 
 enum bpf_tramp_prog_type {

kernel/bpf/core.c

@@ -642,6 +642,7 @@ void bpf_prog_kallsyms_add(struct bpf_prog *fp)
 
 	bpf_prog_ksym_set_addr(fp);
 	bpf_prog_ksym_set_name(fp);
+	fp->aux->ksym.prog = true;
 
 	spin_lock_bh(&bpf_lock);
 	bpf_prog_ksym_node_add(fp->aux);
@@ -658,16 +659,6 @@ void bpf_prog_kallsyms_del(struct bpf_prog *fp)
 	spin_unlock_bh(&bpf_lock);
 }
 
-static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr)
-{
-	struct latch_tree_node *n;
-
-	n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops);
-	return n ?
-	       container_of(n, struct bpf_prog_aux, ksym.tnode)->prog :
-	       NULL;
-}
-
 static struct bpf_ksym *bpf_ksym_find(unsigned long addr)
 {
 	struct latch_tree_node *n;
@@ -712,13 +703,22 @@ bool is_bpf_text_address(unsigned long addr)
 	return ret;
 }
 
+static struct bpf_prog *bpf_prog_ksym_find(unsigned long addr)
+{
+	struct bpf_ksym *ksym = bpf_ksym_find(addr);
+
+	return ksym && ksym->prog ?
+	       container_of(ksym, struct bpf_prog_aux, ksym)->prog :
+	       NULL;
+}
+
 const struct exception_table_entry *search_bpf_extables(unsigned long addr)
 {
 	const struct exception_table_entry *e = NULL;
 	struct bpf_prog *prog;
 
 	rcu_read_lock();
-	prog = bpf_prog_kallsyms_find(addr);
+	prog = bpf_prog_ksym_find(addr);
 	if (!prog)
 		goto out;
 	if (!prog->aux->num_exentries)