[PATCH bpf-next] libbpf: handle invalid typedef emitted by old GCC

* [PATCH bpf-next] libbpf: handle invalid typedef emitted by old GCC
@ 2019-10-11  3:29 Andrii Nakryiko
  2019-10-11 16:06 ` Martin Lau
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Andrii Nakryiko @ 2019-10-11  3:29 UTC (permalink / raw)
  To: bpf, netdev, ast, daniel, john.fastabend
  Cc: andrii.nakryiko, kernel-team, Andrii Nakryiko

Old GCC versions are producing invalid typedef for __gnuc_va_list
pointing to void. Special-case this and emit valid:

typedef __builtin_va_list __gnuc_va_list;

Reported-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/lib/bpf/btf_dump.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 87f27e2664c5..139812b46c7b 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -975,6 +975,17 @@ static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
 {
 	const char *name = btf_dump_ident_name(d, id);
 
+	/*
+	 * Old GCC versions are emitting invalid typedef for __gnuc_va_list
+	 * pointing to VOID. This generates warnings from btf_dump() and
+	 * results in uncompilable header file, so we are fixing it up here
+	 * with valid typedef into __builtin_va_list.
+	 */
+	if (t->type == 0 && strcmp(name, "__gnuc_va_list") == 0) {
+		btf_dump_printf(d, "typedef __builtin_va_list __gnuc_va_list");
+		return;
+	}
+
 	btf_dump_printf(d, "typedef ");
 	btf_dump_emit_type_decl(d, t->type, name, lvl);
 }
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread