objtool: Validate disassembler headers in libopcodes probegrafted

commit 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
tested for libopcodes availability by linking a test snippet with a forward
declaration of disassemble_init_for_target().

However, testing symbol linkage with an extern declaration only verifies
the presence of the library (.so/.a) and bypasses checking for development
headers (binutils-dev). On systems where libopcodes is present without
development headers installed, the probe succeeds, enabling BUILD_DISAS.
Subsequent compilation of objtool then fails:

  fatal error: 'bfd.h' file not found
    113 | #include <bfd.h>

Additionally, the probe invokes $(HOSTCC) without $(HOSTCFLAGS), ignoring
any sysroot or include flags specified for the host compiler.

Fix this by including <bfd.h> and <dis-asm.h> directly in the test snippet,
passing $(HOSTCFLAGS) so host compiler options are respected, and defining
PACKAGE="objtool" to satisfy the configuration check in <bfd.h>.

Fixes: 3f2de814c059 ("objtool: Fix libopcodes linking with static libraries")
Fixes: 436326bc525d ("objtool: fix build failure due to missing libopcodes check")
Reported-by: Alice Ryhl <aliceryhl@google.com>
Assisted-by: Antigravity:Gemini-Next
Signed-off-by: Ulises Mendez Martinez <umendez@google.com>
Link: https://patch.msgid.link/20260904150710.2997558-1-umendez@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

1 files changed, 52 insertions, 0 deletions

diff --git a/include/net/ife.h b/include/net/ife.h
new file mode 100644
index 000000000..7e2538d85
--- /dev/null
+++ b/include/net/ife.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_IFE_H
+#define __NET_IFE_H
+
+#include <linux/etherdevice.h>
+#include <linux/rtnetlink.h>
+#include <uapi/linux/ife.h>
+
+#if IS_ENABLED(CONFIG_NET_IFE)
+
+void *ife_encode(struct sk_buff *skb, u16 metalen);
+void *ife_decode(struct sk_buff *skb, u16 *metalen);
+
+void *ife_tlv_meta_decode(void *skbdata, const void *ifehdr_end, u16 *attrtype,
+			  u16 *dlen, u16 *totlen);
+int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen,
+			const void *dval);
+
+void *ife_tlv_meta_next(void *skbdata);
+
+#else
+
+static inline void *ife_encode(struct sk_buff *skb, u16 metalen)
+{
+	return NULL;
+}
+
+static inline void *ife_decode(struct sk_buff *skb, u16 *metalen)
+{
+	return NULL;
+}
+
+static inline void *ife_tlv_meta_decode(void *skbdata, u16 *attrtype, u16 *dlen,
+					u16 *totlen)
+{
+	return NULL;
+}
+
+static inline int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen,
+			const void *dval)
+{
+	return 0;
+}
+
+static inline void *ife_tlv_meta_next(void *skbdata)
+{
+	return NULL;
+}
+
+#endif
+
+#endif /* __NET_IFE_H */