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, 37 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/ipcbuf.h b/include/uapi/asm-generic/ipcbuf.h
new file mode 100644
index 000000000..41a01b494
--- /dev/null
+++ b/include/uapi/asm-generic/ipcbuf.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef __ASM_GENERIC_IPCBUF_H
+#define __ASM_GENERIC_IPCBUF_H
+
+#include <linux/posix_types.h>
+
+/*
+ * The generic ipc64_perm structure:
+ * Note extra padding because this structure is passed back and forth
+ * between kernel and user space.
+ *
+ * ipc64_perm was originally meant to be architecture specific, but
+ * everyone just ended up making identical copies without specific
+ * optimizations, so we may just as well all use the same one.
+ *
+ * Pad space is left for:
+ * - 32-bit mode_t on architectures that only had 16 bit
+ * - 32-bit seq
+ * - 2 miscellaneous 32-bit values
+ */
+
+struct ipc64_perm {
+	__kernel_key_t		key;
+	__kernel_uid32_t	uid;
+	__kernel_gid32_t	gid;
+	__kernel_uid32_t	cuid;
+	__kernel_gid32_t	cgid;
+	__kernel_mode_t		mode;
+				/* pad if mode_t is u16: */
+	unsigned char		__pad1[4 - sizeof(__kernel_mode_t)];
+	unsigned short		seq;
+	unsigned short		__pad2;
+	__kernel_ulong_t	__unused1;
+	__kernel_ulong_t	__unused2;
+};
+
+#endif /* __ASM_GENERIC_IPCBUF_H */