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, 155 insertions, 0 deletions

diff --git a/io_uring/query.c b/io_uring/query.c
new file mode 100644
index 000000000..7bce2ec16
--- /dev/null
+++ b/io_uring/query.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "linux/io_uring/query.h"
+
+#include "query.h"
+#include "io_uring.h"
+#include "zcrx.h"
+
+union io_query_data {
+	struct io_uring_query_opcode opcodes;
+	struct io_uring_query_zcrx zcrx;
+	struct io_uring_query_zcrx_event zcrx_notif;
+	struct io_uring_query_scq scq;
+};
+
+#define IO_MAX_QUERY_SIZE		sizeof(union io_query_data)
+#define IO_MAX_QUERY_ENTRIES		1000
+
+static ssize_t io_query_ops(union io_query_data *data)
+{
+	struct io_uring_query_opcode *e = &data->opcodes;
+
+	e->nr_request_opcodes = IORING_OP_LAST;
+	e->nr_register_opcodes = IORING_REGISTER_LAST;
+	e->feature_flags = IORING_FEAT_FLAGS;
+	e->ring_setup_flags = IORING_SETUP_FLAGS;
+	e->enter_flags = IORING_ENTER_FLAGS;
+	e->sqe_flags = SQE_VALID_FLAGS;
+	e->nr_query_opcodes = __IO_URING_QUERY_MAX;
+	e->__pad = 0;
+	return sizeof(*e);
+}
+
+static ssize_t io_query_zcrx(union io_query_data *data)
+{
+	struct io_uring_query_zcrx *e = &data->zcrx;
+
+	e->register_flags = ZCRX_SUPPORTED_REG_FLAGS;
+	e->area_flags = IORING_ZCRX_AREA_DMABUF;
+	e->nr_ctrl_opcodes = __ZCRX_CTRL_LAST;
+	e->rq_hdr_size = sizeof(struct zcrx_rq_hdr);
+	e->rq_hdr_alignment = L1_CACHE_BYTES;
+	e->features = ZCRX_FEATURES;
+	e->__resv2 = 0;
+	return sizeof(*e);
+}
+
+static ssize_t io_query_zcrx_notif(union io_query_data *data)
+{
+	struct io_uring_query_zcrx_event *e = &data->zcrx_notif;
+
+	e->event_flags = ZCRX_EVENT_TYPE_MASK;
+	e->stats_size = sizeof(struct zcrx_stats);
+	e->stats_off_alignment = __alignof__(struct zcrx_stats);
+	e->__resv1 = 0;
+	memset(&e->__resv2, 0, sizeof(e->__resv2));
+	return sizeof(*e);
+}
+
+static ssize_t io_query_scq(union io_query_data *data)
+{
+	struct io_uring_query_scq *e = &data->scq;
+
+	e->hdr_size = sizeof(struct io_rings);
+	e->hdr_alignment = SMP_CACHE_BYTES;
+	return sizeof(*e);
+}
+
+static int io_handle_query_entry(union io_query_data *data, void __user *uhdr,
+				 u64 *next_entry)
+{
+	struct io_uring_query_hdr hdr;
+	size_t usize, res_size = 0;
+	ssize_t ret = -EINVAL;
+	void __user *udata;
+
+	if (copy_from_user(&hdr, uhdr, sizeof(hdr)))
+		return -EFAULT;
+	/* copy_struct_to_user() zeros up to usize bytes */
+	if (hdr.size > PAGE_SIZE)
+		return -E2BIG;
+	usize = hdr.size;
+	hdr.size = min(hdr.size, IO_MAX_QUERY_SIZE);
+	udata = u64_to_user_ptr(hdr.query_data);
+
+	if (hdr.query_op >= __IO_URING_QUERY_MAX) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+	if (!mem_is_zero(hdr.__resv, sizeof(hdr.__resv)) || hdr.result || !hdr.size)
+		goto out;
+	if (copy_from_user(data, udata, hdr.size))
+		return -EFAULT;
+
+	switch (hdr.query_op) {
+	case IO_URING_QUERY_OPCODES:
+		ret = io_query_ops(data);
+		break;
+	case IO_URING_QUERY_ZCRX:
+		ret = io_query_zcrx(data);
+		break;
+	case IO_URING_QUERY_ZCRX_EVENT:
+		ret = io_query_zcrx_notif(data);
+		break;
+	case IO_URING_QUERY_SCQ:
+		ret = io_query_scq(data);
+		break;
+	}
+
+	if (ret >= 0) {
+		if (WARN_ON_ONCE(ret > IO_MAX_QUERY_SIZE))
+			return -EFAULT;
+		res_size = ret;
+		ret = 0;
+	}
+out:
+	hdr.result = ret;
+	hdr.size = min_t(size_t, usize, res_size);
+
+	if (copy_struct_to_user(udata, usize, data, hdr.size, NULL))
+		return -EFAULT;
+	if (copy_to_user(uhdr, &hdr, sizeof(hdr)))
+		return -EFAULT;
+	*next_entry = hdr.next_entry;
+	return 0;
+}
+
+int io_query(void __user *arg, unsigned nr_args)
+{
+	union io_query_data entry_buffer;
+	void __user *uhdr = arg;
+	int ret, nr = 0;
+
+	memset(&entry_buffer, 0, sizeof(entry_buffer));
+
+	if (nr_args)
+		return -EINVAL;
+
+	while (uhdr) {
+		u64 next_hdr;
+
+		ret = io_handle_query_entry(&entry_buffer, uhdr, &next_hdr);
+		if (ret)
+			return ret;
+		uhdr = u64_to_user_ptr(next_hdr);
+
+		/* Have some limit to avoid a potential cycle */
+		if (++nr >= IO_MAX_QUERY_ENTRIES)
+			return -ERANGE;
+		if (fatal_signal_pending(current))
+			return -EINTR;
+		cond_resched();
+	}
+	return 0;
+}