linux-kernel - [PATCH AUTOSEL 5.15 49/69] libbpf: Disable SEC pragma macro on GCC

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Date:   Thu, 11 Aug 2022 11:55:58 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     James Hilliard <james.hilliard1@...il.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Sasha Levin <sashal@...nel.org>, ast@...nel.org,
        daniel@...earbox.net, bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 49/69] libbpf: Disable SEC pragma macro on GCC

From: James Hilliard <james.hilliard1@...il.com>

[ Upstream commit 18410251f66aee7e82234073ce6656ca20a732a9 ]

It seems the gcc preprocessor breaks with pragmas when surrounding
__attribute__.

Disable these pragmas on GCC due to upstream bugs see:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400

Fixes errors like:
error: expected identifier or '(' before '#pragma'
  106 | SEC("cgroup/bind6")
      | ^~~

error: expected '=', ',', ';', 'asm' or '__attribute__' before '#pragma'
  114 | char _license[] SEC("license") = "GPL";
      | ^~~

Signed-off-by: James Hilliard <james.hilliard1@...il.com>
Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
Link: https://lore.kernel.org/bpf/20220706111839.1247911-1-james.hilliard1@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/lib/bpf/bpf_helpers.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index b9987c3efa3c..409b85d1cbd0 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -30,12 +30,25 @@
  * To allow use of SEC() with externs (e.g., for extern .maps declarations),
  * make sure __attribute__((unused)) doesn't trigger compilation warning.
  */
+#if __GNUC__ && !__clang__
+
+/*
+ * Pragma macros are broken on GCC
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400
+ */
+#define SEC(name) __attribute__((section(name), used))
+
+#else
+
 #define SEC(name) \
 	_Pragma("GCC diagnostic push")					    \
 	_Pragma("GCC diagnostic ignored \"-Wignored-attributes\"")	    \
 	__attribute__((section(name), used))				    \
 	_Pragma("GCC diagnostic pop")					    \
 
+#endif
+
 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */
 #undef __always_inline
 #define __always_inline inline __attribute__((always_inline))
-- 
2.35.1