1 files changed, 262 insertions, 0 deletions
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
new file mode 100644
index 000000000..42b19feb2
--- /dev/null
+++ b/net/xdp/xdp_umem.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0
+/* XDP user-space packet buffer
+ * Copyright(c) 2018 Intel Corporation.
+ */
+
+#include <linux/init.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/bpf.h>
+#include <linux/mm.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/idr.h>
+#include <linux/vmalloc.h>
+
+#include "xdp_umem.h"
+#include "xsk_queue.h"
+
+#define XDP_UMEM_MIN_CHUNK_SIZE 2048
+
+static DEFINE_IDA(umem_ida);
+
+static void xdp_umem_unpin_pages(struct xdp_umem *umem)
+{
+	unpin_user_pages_dirty_lock(umem->pgs, umem->npgs, true);
+
+	kfree(umem->pgs);
+	umem->pgs = NULL;
+}
+
+static void xdp_umem_unaccount_pages(struct xdp_umem *umem)
+{
+	if (umem->user) {
+		atomic_long_sub(umem->npgs, &umem->user->locked_vm);
+		free_uid(umem->user);
+	}
+}
+
+static void xdp_umem_addr_unmap(struct xdp_umem *umem)
+{
+	vunmap(umem->addrs);
+	umem->addrs = NULL;
+}
+
+static int xdp_umem_addr_map(struct xdp_umem *umem, struct page **pages,
+			     u32 nr_pages)
+{
+	umem->addrs = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
+	if (!umem->addrs)
+		return -ENOMEM;
+	return 0;
+}
+
+static void xdp_umem_release(struct xdp_umem *umem)
+{
+	umem->zc = false;
+	ida_simple_remove(&umem_ida, umem->id);
+
+	xdp_umem_addr_unmap(umem);
+	xdp_umem_unpin_pages(umem);
+
+	xdp_umem_unaccount_pages(umem);
+	kfree(umem);
+}
+
+static void xdp_umem_release_deferred(struct work_struct *work)
+{
+	struct xdp_umem *umem = container_of(work, struct xdp_umem, work);
+
+	xdp_umem_release(umem);
+}
+
+void xdp_get_umem(struct xdp_umem *umem)
+{
+	refcount_inc(&umem->users);
+}
+
+void xdp_put_umem(struct xdp_umem *umem, bool defer_cleanup)
+{
+	if (!umem)
+		return;
+
+	if (refcount_dec_and_test(&umem->users)) {
+		if (defer_cleanup) {
+			INIT_WORK(&umem->work, xdp_umem_release_deferred);
+			schedule_work(&umem->work);
+		} else {
+			xdp_umem_release(umem);
+		}
+	}
+}
+
+static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
+{
+	unsigned int gup_flags = FOLL_WRITE;
+	long npgs;
+	int err;
+
+	umem->pgs = kcalloc(umem->npgs, sizeof(*umem->pgs),
+			    GFP_KERNEL | __GFP_NOWARN);
+	if (!umem->pgs)
+		return -ENOMEM;
+
+	mmap_read_lock(current->mm);
+	npgs = pin_user_pages(address, umem->npgs,
+			      gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
+	mmap_read_unlock(current->mm);
+
+	if (npgs != umem->npgs) {
+		if (npgs >= 0) {
+			umem->npgs = npgs;
+			err = -ENOMEM;
+			goto out_pin;
+		}
+		err = npgs;
+		goto out_pgs;
+	}
+	return 0;
+
+out_pin:
+	xdp_umem_unpin_pages(umem);
+out_pgs:
+	kfree(umem->pgs);
+	umem->pgs = NULL;
+	return err;
+}
+
+static int xdp_umem_account_pages(struct xdp_umem *umem)
+{
+	unsigned long lock_limit, new_npgs, old_npgs;
+
+	if (capable(CAP_IPC_LOCK))
+		return 0;
+
+	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+	umem->user = get_uid(current_user());
+
+	do {
+		old_npgs = atomic_long_read(&umem->user->locked_vm);
+		new_npgs = old_npgs + umem->npgs;
+		if (new_npgs > lock_limit) {
+			free_uid(umem->user);
+			umem->user = NULL;
+			return -ENOBUFS;
+		}
+	} while (atomic_long_cmpxchg(&umem->user->locked_vm, old_npgs,
+				     new_npgs) != old_npgs);
+	return 0;
+}
+
+static int xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg *mr)
+{
+	bool unaligned_chunks = mr->flags & XDP_UMEM_UNALIGNED_CHUNK_FLAG;
+	u32 chunk_size = mr->chunk_size, headroom = mr->headroom;
+	u64 addr = mr->addr, size = mr->len;
+	u32 chunks_rem, npgs_rem;
+	u64 chunks, npgs;
+	int err;
+
+	if (chunk_size < XDP_UMEM_MIN_CHUNK_SIZE || chunk_size > PAGE_SIZE) {
+		/* Strictly speaking we could support this, if:
+		 * - huge pages, or*
+		 * - using an IOMMU, or
+		 * - making sure the memory area is consecutive
+		 * but for now, we simply say "computer says no".
+		 */
+		return -EINVAL;
+	}
+
+	if (mr->flags & ~XDP_UMEM_UNALIGNED_CHUNK_FLAG)
+		return -EINVAL;
+
+	if (!unaligned_chunks && !is_power_of_2(chunk_size))
+		return -EINVAL;
+
+	if (!PAGE_ALIGNED(addr)) {
+		/* Memory area has to be page size aligned. For
+		 * simplicity, this might change.
+		 */
+		return -EINVAL;
+	}
+
+	if ((addr + size) < addr)
+		return -EINVAL;
+
+	npgs = div_u64_rem(size, PAGE_SIZE, &npgs_rem);
+	if (npgs_rem)
+		npgs++;
+	if (npgs > U32_MAX)
+		return -EINVAL;
+
+	chunks = div_u64_rem(size, chunk_size, &chunks_rem);
+	if (!chunks || chunks > U32_MAX)
+		return -EINVAL;
+
+	if (!unaligned_chunks && chunks_rem)
+		return -EINVAL;
+
+	if (headroom >= chunk_size - XDP_PACKET_HEADROOM)
+		return -EINVAL;
+
+	umem->size = size;
+	umem->headroom = headroom;
+	umem->chunk_size = chunk_size;
+	umem->chunks = chunks;
+	umem->npgs = npgs;
+	umem->pgs = NULL;
+	umem->user = NULL;
+	umem->flags = mr->flags;
+
+	INIT_LIST_HEAD(&umem->xsk_dma_list);
+	refcount_set(&umem->users, 1);
+
+	err = xdp_umem_account_pages(umem);
+	if (err)
+		return err;
+
+	err = xdp_umem_pin_pages(umem, (unsigned long)addr);
+	if (err)
+		goto out_account;
+
+	err = xdp_umem_addr_map(umem, umem->pgs, umem->npgs);
+	if (err)
+		goto out_unpin;
+
+	return 0;
+
+out_unpin:
+	xdp_umem_unpin_pages(umem);
+out_account:
+	xdp_umem_unaccount_pages(umem);
+	return err;
+}
+
+struct xdp_umem *xdp_umem_create(struct xdp_umem_reg *mr)
+{
+	struct xdp_umem *umem;
+	int err;
+
+	umem = kzalloc(sizeof(*umem), GFP_KERNEL);
+	if (!umem)
+		return ERR_PTR(-ENOMEM);
+
+	err = ida_simple_get(&umem_ida, 0, 0, GFP_KERNEL);
+	if (err < 0) {
+		kfree(umem);
+		return ERR_PTR(err);
+	}
+	umem->id = err;
+
+	err = xdp_umem_reg(umem, mr);
+	if (err) {
+		ida_simple_remove(&umem_ida, umem->id);
+		kfree(umem);
+		return ERR_PTR(err);
+	}
+
+	return umem;
+}