1 files changed, 150 insertions, 0 deletions
diff --git a/kernel/bpf/dmabuf_iter.c b/kernel/bpf/dmabuf_iter.c
new file mode 100644
index 000000000000..4dd7ef7c145c
--- /dev/null
+++ b/kernel/bpf/dmabuf_iter.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2025 Google LLC */
+#include <linux/bpf.h>
+#include <linux/btf_ids.h>
+#include <linux/dma-buf.h>
+#include <linux/kernel.h>
+#include <linux/seq_file.h>
+
+static void *dmabuf_iter_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	if (*pos)
+		return NULL;
+
+	return dma_buf_iter_begin();
+}
+
+static void *dmabuf_iter_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct dma_buf *dmabuf = v;
+
+	++*pos;
+
+	return dma_buf_iter_next(dmabuf);
+}
+
+struct bpf_iter__dmabuf {
+	__bpf_md_ptr(struct bpf_iter_meta *, meta);
+	__bpf_md_ptr(struct dma_buf *, dmabuf);
+};
+
+static int __dmabuf_seq_show(struct seq_file *seq, void *v, bool in_stop)
+{
+	struct bpf_iter_meta meta = {
+		.seq = seq,
+	};
+	struct bpf_iter__dmabuf ctx = {
+		.meta = &meta,
+		.dmabuf = v,
+	};
+	struct bpf_prog *prog = bpf_iter_get_info(&meta, in_stop);
+
+	if (prog)
+		return bpf_iter_run_prog(prog, &ctx);
+
+	return 0;
+}
+
+static int dmabuf_iter_seq_show(struct seq_file *seq, void *v)
+{
+	return __dmabuf_seq_show(seq, v, false);
+}
+
+static void dmabuf_iter_seq_stop(struct seq_file *seq, void *v)
+{
+	struct dma_buf *dmabuf = v;
+
+	if (dmabuf)
+		dma_buf_put(dmabuf);
+}
+
+static const struct seq_operations dmabuf_iter_seq_ops = {
+	.start	= dmabuf_iter_seq_start,
+	.next	= dmabuf_iter_seq_next,
+	.stop	= dmabuf_iter_seq_stop,
+	.show	= dmabuf_iter_seq_show,
+};
+
+static void bpf_iter_dmabuf_show_fdinfo(const struct bpf_iter_aux_info *aux,
+					struct seq_file *seq)
+{
+	seq_puts(seq, "dmabuf iter\n");
+}
+
+static const struct bpf_iter_seq_info dmabuf_iter_seq_info = {
+	.seq_ops		= &dmabuf_iter_seq_ops,
+	.init_seq_private	= NULL,
+	.fini_seq_private	= NULL,
+	.seq_priv_size		= 0,
+};
+
+static struct bpf_iter_reg bpf_dmabuf_reg_info = {
+	.target			= "dmabuf",
+	.feature                = BPF_ITER_RESCHED,
+	.show_fdinfo		= bpf_iter_dmabuf_show_fdinfo,
+	.ctx_arg_info_size	= 1,
+	.ctx_arg_info		= {
+		{ offsetof(struct bpf_iter__dmabuf, dmabuf),
+		  PTR_TO_BTF_ID_OR_NULL },
+	},
+	.seq_info		= &dmabuf_iter_seq_info,
+};
+
+DEFINE_BPF_ITER_FUNC(dmabuf, struct bpf_iter_meta *meta, struct dma_buf *dmabuf)
+BTF_ID_LIST_SINGLE(bpf_dmabuf_btf_id, struct, dma_buf)
+
+static int __init dmabuf_iter_init(void)
+{
+	bpf_dmabuf_reg_info.ctx_arg_info[0].btf_id = bpf_dmabuf_btf_id[0];
+	return bpf_iter_reg_target(&bpf_dmabuf_reg_info);
+}
+
+late_initcall(dmabuf_iter_init);
+
+struct bpf_iter_dmabuf {
+	/*
+	 * opaque iterator state; having __u64 here allows to preserve correct
+	 * alignment requirements in vmlinux.h, generated from BTF
+	 */
+	__u64 __opaque[1];
+} __aligned(8);
+
+/* Non-opaque version of bpf_iter_dmabuf */
+struct bpf_iter_dmabuf_kern {
+	struct dma_buf *dmabuf;
+} __aligned(8);
+
+__bpf_kfunc_start_defs();
+
+__bpf_kfunc int bpf_iter_dmabuf_new(struct bpf_iter_dmabuf *it)
+{
+	struct bpf_iter_dmabuf_kern *kit = (void *)it;
+
+	BUILD_BUG_ON(sizeof(*kit) > sizeof(*it));
+	BUILD_BUG_ON(__alignof__(*kit) != __alignof__(*it));
+
+	kit->dmabuf = NULL;
+	return 0;
+}
+
+__bpf_kfunc struct dma_buf *bpf_iter_dmabuf_next(struct bpf_iter_dmabuf *it)
+{
+	struct bpf_iter_dmabuf_kern *kit = (void *)it;
+
+	if (kit->dmabuf)
+		kit->dmabuf = dma_buf_iter_next(kit->dmabuf);
+	else
+		kit->dmabuf = dma_buf_iter_begin();
+
+	return kit->dmabuf;
+}
+
+__bpf_kfunc void bpf_iter_dmabuf_destroy(struct bpf_iter_dmabuf *it)
+{
+	struct bpf_iter_dmabuf_kern *kit = (void *)it;
+
+	if (kit->dmabuf)
+		dma_buf_put(kit->dmabuf);
+}
+
+__bpf_kfunc_end_defs();