From: Andrii Nakryiko <andrii@kernel.org>
Date: Wed, 6 Jul 2022 03:56:48 +0000 (-0700)
Subject: libbpf: add bpf_core_type_matches() helper macro
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b8a195dc299391bc171c47971974ec6d5ea6fb14;p=linux.git

libbpf: add bpf_core_type_matches() helper macro

This patch finalizes support for the proposed type match relation in libbpf by
adding bpf_core_type_matches() macro which emits TYPE_MATCH relocation.

Clang support for this relocation was added in [0].

  [0] https://reviews.llvm.org/D126838

Signed-off-by: Daniel Müller <deso@posteo.net>¬
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>¬
Link: https://lore.kernel.org/bpf/20220628160127.607834-7-deso@posteo.net¬
---

diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index 2308f4990e963..496e6a8ee0dc9 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -184,6 +184,16 @@ enum bpf_enum_value_kind {
 #define bpf_core_type_exists(type)					    \
 	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_EXISTS)
 
+/*
+ * Convenience macro to check that provided named type
+ * (struct/union/enum/typedef) "matches" that in a target kernel.
+ * Returns:
+ *    1, if the type matches in the target kernel's BTF;
+ *    0, if the type does not match any in the target kernel
+ */
+#define bpf_core_type_matches(type)					    \
+	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_MATCHES)
+
 /*
  * Convenience macro to get the byte size of a provided named type
  * (struct/union/enum/typedef) in a target kernel.