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/scripts/dtc/fstree.c b/scripts/dtc/fstree.c
new file mode 100644
index 000000000..0f9a534ba
--- /dev/null
+++ b/scripts/dtc/fstree.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation.  2005.
+ */
+
+#include "dtc.h"
+
+#include <dirent.h>
+#include <sys/stat.h>
+
+static struct node *read_fstree(const char *dirname)
+{
+	DIR *d;
+	struct dirent *de;
+	struct stat st;
+	struct node *tree;
+
+	d = opendir(dirname);
+	if (!d)
+		die("Couldn't opendir() \"%s\": %s\n", dirname, strerror(errno));
+
+	tree = build_node(NULL, NULL, NULL);
+
+	while ((de = readdir(d)) != NULL) {
+		char *tmpname;
+
+		if (streq(de->d_name, ".")
+		    || streq(de->d_name, ".."))
+			continue;
+
+		tmpname = join_path(dirname, de->d_name);
+
+		if (stat(tmpname, &st) < 0)
+			die("stat(%s): %s\n", tmpname, strerror(errno));
+
+		if (S_ISREG(st.st_mode)) {
+			struct property *prop;
+			FILE *pfile;
+
+			pfile = fopen(tmpname, "rb");
+			if (! pfile) {
+				fprintf(stderr,
+					"WARNING: Cannot open %s: %s\n",
+					tmpname, strerror(errno));
+			} else {
+				prop = build_property(de->d_name,
+						      data_copy_file(pfile,
+								     st.st_size),
+						      NULL);
+				add_property(tree, prop);
+				fclose(pfile);
+			}
+		} else if (S_ISDIR(st.st_mode)) {
+			struct node *newchild;
+
+			newchild = read_fstree(tmpname);
+			newchild = name_node(newchild, xstrdup(de->d_name));
+			add_child(tree, newchild);
+		}
+
+		free(tmpname);
+	}
+
+	closedir(d);
+	return tree;
+}
+
+struct dt_info *dt_from_fs(const char *dirname)
+{
+	struct node *tree;
+
+	tree = read_fstree(dirname);
+	tree = name_node(tree, "");
+
+	return build_dt_info(DTSF_V1, NULL, tree, guess_boot_cpuid(tree));
+}