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, 34 insertions, 0 deletions

diff --git a/scripts/stackusage b/scripts/stackusage
new file mode 100755
index 000000000..56ef1ab67
--- /dev/null
+++ b/scripts/stackusage
@@ -0,0 +1,34 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+outfile=""
+now=`date +%s`
+
+while [ $# -gt 0 ]
+do
+    case "$1" in
+        -o)
+	    outfile="$2"
+	    shift 2;;
+	-h)
+	    echo "usage: $0 [-o outfile] <make options/args>"
+	    exit 0;;
+	*)  break;;
+    esac
+done
+
+if [ -z "$outfile" ]
+then
+    outfile=`mktemp --tmpdir stackusage.$$.XXXX`
+fi
+
+KCFLAGS="${KCFLAGS} -fstack-usage" make "$@"
+
+# Prepend directory name to file names, remove column information,
+# make file:line/function/size/type properly tab-separated.
+find . -name '*.su' -newermt "@${now}" -print |                     \
+    xargs perl -MFile::Basename -pe                                 \
+        '$d = dirname($ARGV); s#([^:]+:[0-9]+):[0-9]+:#$d/$1\t#;' | \
+    sort -k3,3nr > "${outfile}"
+
+echo "$0: output written to ${outfile}"