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, 76 insertions, 0 deletions

diff --git a/include/net/selftests.h b/include/net/selftests.h
new file mode 100644
index 000000000..c36e07406
--- /dev/null
+++ b/include/net/selftests.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NET_SELFTESTS
+#define _NET_SELFTESTS
+
+#include <linux/ethtool.h>
+#include <linux/netdevice.h>
+
+struct net_packet_attrs {
+	const unsigned char *src;
+	const unsigned char *dst;
+	u32 ip_src;
+	u32 ip_dst;
+	bool tcp;
+	u16 sport;
+	u16 dport;
+	int timeout;
+	int size;
+	int max_size;
+	u8 id;
+	u16 queue_mapping;
+	bool bad_csum;
+};
+
+struct net_test_priv {
+	struct net_packet_attrs *packet;
+	struct packet_type pt;
+	struct completion comp;
+	int double_vlan;
+	int vlan_id;
+	int ok;
+};
+
+struct netsfhdr {
+	__be32 version;
+	__be64 magic;
+	u8 id;
+} __packed;
+
+#define NET_TEST_PKT_SIZE (sizeof(struct ethhdr) + sizeof(struct iphdr) + \
+			   sizeof(struct netsfhdr))
+#define NET_TEST_PKT_MAGIC	0xdeadcafecafedeadULL
+#define NET_LB_TIMEOUT		msecs_to_jiffies(200)
+
+#if IS_ENABLED(CONFIG_NET_SELFTESTS)
+
+struct sk_buff *net_test_get_skb(struct net_device *ndev, u8 id,
+				 struct net_packet_attrs *attr);
+void net_selftest(struct net_device *ndev, struct ethtool_test *etest,
+		  u64 *buf);
+int net_selftest_get_count(void);
+void net_selftest_get_strings(u8 *data);
+
+#else
+
+static inline struct sk_buff *net_test_get_skb(struct net_device *ndev, u8 id,
+					       struct net_packet_attrs *attr)
+{
+	return NULL;
+}
+
+static inline void net_selftest(struct net_device *ndev, struct ethtool_test *etest,
+				u64 *buf)
+{
+}
+
+static inline int net_selftest_get_count(void)
+{
+	return 0;
+}
+
+static inline void net_selftest_get_strings(u8 *data)
+{
+}
+
+#endif
+#endif /* _NET_SELFTESTS */