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, 45 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-probe.c b/drivers/clocksource/timer-probe.c
new file mode 100644
index 000000000..b7860bc0d
--- /dev/null
+++ b/drivers/clocksource/timer-probe.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/clocksource.h>
+
+extern struct of_device_id __timer_of_table[];
+
+static const struct of_device_id __timer_of_table_sentinel
+	__used __section("__timer_of_table_end");
+
+void __init timer_probe(void)
+{
+	struct device_node *np;
+	const struct of_device_id *match;
+	of_init_fn_1_ret init_func_ret;
+	unsigned timers = 0;
+	int ret;
+
+	for_each_matching_node_and_match(np, __timer_of_table, &match) {
+		if (!of_device_is_available(np))
+			continue;
+
+		init_func_ret = match->data;
+
+		ret = init_func_ret(np);
+		if (ret) {
+			if (ret != -EPROBE_DEFER)
+				pr_err("Failed to initialize '%pOF': %d\n", np,
+				       ret);
+			continue;
+		}
+
+		timers++;
+	}
+
+	timers += acpi_probe_device_table(timer);
+
+	if (!timers)
+		pr_crit("%s: no matching timers found\n", __func__);
+}