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, 13 insertions, 0 deletions

diff --git a/fs/hostfs/Makefile b/fs/hostfs/Makefile
new file mode 100644
index 000000000..16be592e8
--- /dev/null
+++ b/fs/hostfs/Makefile
@@ -0,0 +1,13 @@
+#
+# Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
+# Licensed under the GPL
+#
+
+hostfs-objs := hostfs_kern.o
+
+hostfs-builtin-$(CONFIG_HOSTFS) += hostfs_user.o hostfs_user_exp.o
+
+obj-y := $(hostfs-builtin-y) $(hostfs-builtin-m)
+obj-$(CONFIG_HOSTFS) += hostfs.o
+
+include $(srctree)/arch/um/scripts/Makefile.rules