bpf: Prepare btf_ctx_access for non raw_tp use case

This patch makes a few changes to btf_ctx_access() to prepare
it for non raw_tp use case where the attach_btf_id is not
necessary a BTF_KIND_TYPEDEF.

It moves the "btf_trace_" prefix check and typedef-follow logic to a new
function "check_attach_btf_id()" which is called only once during
bpf_check().  btf_ctx_access() only operates on a BTF_KIND_FUNC_PROTO
type now. That should also be more efficient since it is done only
one instead of every-time check_ctx_access() is called.

"check_attach_btf_id()" needs to find the func_proto type from
the attach_btf_id.  It needs to store the result into the
newly added prog->aux->attach_func_proto.  func_proto
btf type has no name, so a proper name should be stored into
"attach_func_name" also.

v2:
- Move the "btf_trace_" check to an earlier verifier phase (Alexei)

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191025001811.1718491-1-kafai@fb.com

2 files changed, 36 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2c2c29b49845..171be30fe0ae 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -392,6 +392,11 @@ struct bpf_prog_aux {
 	u32 attach_btf_id; /* in-kernel BTF type id to attach to */
 	bool verifier_zext; /* Zero extensions has been inserted by verifier. */
 	bool offload_requested;
+	bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */
+	/* BTF_KIND_FUNC_PROTO for valid attach_btf_id */
+	const struct btf_type *attach_func_proto;
+	/* function name for valid attach_btf_id */
+	const char *attach_func_name;
 	struct bpf_prog **func;
 	void *jit_data; /* JIT specific data. arch dependent */
 	struct latch_tree_node ksym_tnode;
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 55d43bc856be..9dee00859c5f 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -5,6 +5,7 @@
 #define _LINUX_BTF_H 1
 
 #include <linux/types.h>
+#include <uapi/linux/btf.h>
 
 struct btf;
 struct btf_member;
@@ -53,6 +54,36 @@ bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
 int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
 bool btf_type_is_void(const struct btf_type *t);
 
+static inline bool btf_type_is_ptr(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
+}
+
+static inline bool btf_type_is_int(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
+}
+
+static inline bool btf_type_is_enum(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
+}
+
+static inline bool btf_type_is_typedef(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
+}
+
+static inline bool btf_type_is_func(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
+}
+
+static inline bool btf_type_is_func_proto(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
+}
+
 #ifdef CONFIG_BPF_SYSCALL
 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
 const char *btf_name_by_offset(const struct btf *btf, u32 offset);