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, 53 insertions, 0 deletions

diff --git a/scripts/checkdeclares.pl b/scripts/checkdeclares.pl
new file mode 100755
index 000000000..f6d551c84
--- /dev/null
+++ b/scripts/checkdeclares.pl
@@ -0,0 +1,53 @@
+#!/usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# checkdeclares: find struct declared more than once
+#
+# Copyright 2021 Wan Jiabing<wanjiabing@vivo.com>
+# Inspired by checkincludes.pl
+#
+# This script checks for duplicate struct declares.
+# Note that this will not take into consideration macros so
+# you should run this only if you know you do have real dups
+# and do not have them under #ifdef's.
+# You could also just review the results.
+
+use strict;
+
+sub usage {
+	print "Usage: checkdeclares.pl file1.h ...\n";
+	print "Warns of struct declaration duplicates\n";
+	exit 1;
+}
+
+if ($#ARGV < 0) {
+	usage();
+}
+
+my $dup_counter = 0;
+
+foreach my $file (@ARGV) {
+	open(my $f, '<', $file)
+	    or die "Cannot open $file: $!.\n";
+
+	my %declaredstructs = ();
+
+	while (<$f>) {
+		if (m/^\s*struct\s*(\w*);$/o) {
+			++$declaredstructs{$1};
+		}
+	}
+
+	close($f);
+
+	foreach my $structname (keys %declaredstructs) {
+		if ($declaredstructs{$structname} > 1) {
+			print "$file: struct $structname is declared more than once.\n";
+			++$dup_counter;
+		}
+	}
+}
+
+if ($dup_counter == 0) {
+	print "No duplicate struct declares found.\n";
+}