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/fs/proc/softirqs.c b/fs/proc/softirqs.c
new file mode 100644
index 000000000..04bb29721
--- /dev/null
+++ b/fs/proc/softirqs.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+/*
+ * /proc/softirqs  ... display the number of softirqs
+ */
+static int show_softirqs(struct seq_file *p, void *v)
+{
+	int i, j;
+
+	seq_puts(p, "                    ");
+	for_each_possible_cpu(i)
+		seq_printf(p, "CPU%-8d", i);
+	seq_putc(p, '\n');
+
+	for (i = 0; i < NR_SOFTIRQS; i++) {
+		seq_printf(p, "%12s:", softirq_to_name[i]);
+		for_each_possible_cpu(j)
+			seq_put_decimal_ull_width(p, " ", kstat_softirqs_cpu(i, j), 10);
+		seq_putc(p, '\n');
+	}
+	return 0;
+}
+
+static int __init proc_softirqs_init(void)
+{
+	struct proc_dir_entry *pde;
+
+	pde = proc_create_single("softirqs", 0, NULL, show_softirqs);
+	pde_make_permanent(pde);
+	return 0;
+}
+fs_initcall(proc_softirqs_init);