// SPDX-License-Identifier: GPL-2.0-only
/****************************************************************************
 * Driver for Solarflare network controllers and boards
 * Copyright 2005-2006 Fen Systems Ltd.
 * Copyright 2005-2013 Solarflare Communications Inc.
 */

#include <linux/socket.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/prefetch.h>
#include <linux/moduleparam.h>
#include <linux/iommu.h>
#include <net/ip.h>
#include <net/checksum.h>
#include <net/xdp.h>
#include <linux/bpf_trace.h>
#include "net_driver.h"
#include "efx.h"
#include "rx_common.h"
#include "filter.h"
#include "nic.h"
#include "selftest.h"
#include "workarounds.h"

/* Preferred number of descriptors to fill at once */
#define EFX_RX_PREFERRED_BATCH 8U

/* Maximum rx prefix used by any architecture. */
#define EFX_MAX_RX_PREFIX_SIZE 16

/* Size of buffer allocated for skb header area. */
#define EFX_SKB_HEADERS  128u

/* Each packet can consume up to ceil(max_frame_len / buffer_size) buffers */
#define EFX_RX_MAX_FRAGS DIV_ROUND_UP(EFX_MAX_FRAME_LEN(EFX_MAX_MTU), \
                                      EFX_RX_USR_BUF_SIZE)

static void efx_rx_packet__check_len(struct efx_rx_queue *rx_queue,
                                     struct efx_rx_buffer *rx_buf,
                                     int len)
{
        struct efx_nic *efx = rx_queue->efx;
        unsigned max_len = rx_buf->len - efx->type->rx_buffer_padding;

        if (likely(len <= max_len))
                return;

        /* The packet must be discarded, but this is only a fatal error
         * if the caller indicated it was
         */
        rx_buf->flags |= EFX_RX_PKT_DISCARD;

        if (net_ratelimit())
                netif_err(efx, rx_err, efx->net_dev,
                          "RX queue %d overlength RX event (%#x > %#x)\n",
                          efx_rx_queue_index(rx_queue), len, max_len);

        efx_rx_queue_channel(rx_queue)->n_rx_overlength++;
}

/* Allocate and construct an SKB around page fragments */
static struct sk_buff *efx_rx_mk_skb(struct efx_channel *channel,
                                     struct efx_rx_buffer *rx_buf,
                                     unsigned int n_frags,
                                     u8 *eh, int hdr_len)
{
        struct efx_nic *efx = channel->efx;
        struct sk_buff *skb;

        /* Allocate an SKB to store the headers */
        skb = netdev_alloc_skb(efx->net_dev,
                               efx->rx_ip_align + efx->rx_prefix_size +
                               hdr_len);
        if (unlikely(skb == NULL)) {
                atomic_inc(&efx->n_rx_noskb_drops);
                return NULL;
        }

        EFX_WARN_ON_ONCE_PARANOID(rx_buf->len < hdr_len);

        memcpy(skb->data + efx->rx_ip_align, eh - efx->rx_prefix_size,
               efx->rx_prefix_size + hdr_len);
        skb_reserve(skb, efx->rx_ip_align + efx->rx_prefix_size);
        __skb_put(skb, hdr_len);

        /* Append the remaining page(s) onto the frag list */
        if (rx_buf->len > hdr_len) {
                rx_buf->page_offset += hdr_len;
                rx_buf->len -= hdr_len;

                for (;;) {
                        skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags,
                                        rx_buf->page, rx_buf->page_offset,
                                        rx_buf->len, efx->rx_buffer_truesize);
                        rx_buf->page = NULL;

                        if (skb_shinfo(skb)->nr_frags == n_frags)
                                break;

                        rx_buf = efx_rx_buf_next(&channel->rx_queue, rx_buf);
                }
        } else {
                __free_pages(rx_buf->page, efx->rx_buffer_order);
                rx_buf->page = NULL;
                n_frags = 0;
        }

        /* Move past the ethernet header */
        skb->protocol = eth_type_trans(skb, efx->net_dev);

        skb_mark_napi_id(skb, &channel->napi_str);

        return skb;
}

void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
                   unsigned int n_frags, unsigned int len, u16 flags)
{
        struct efx_nic *efx = rx_queue->efx;
        struct efx_channel *channel = efx_rx_queue_channel(rx_queue);
        struct efx_rx_buffer *rx_buf;

        rx_queue->rx_packets++;

        rx_buf = efx_rx_buffer(rx_queue, index);
        rx_buf->flags |= flags;

        /* Validate the number of fragments and completed length */
        if (n_frags == 1) {
                if (!(flags & EFX_RX_PKT_PREFIX_LEN))
                        efx_rx_packet__check_len(rx_queue, rx_buf, len);
        } else if (unlikely(n_frags > EFX_RX_MAX_FRAGS) ||
                   unlikely(len <= (n_frags - 1) * efx->rx_dma_len) ||
                   unlikely(len > n_frags * efx->rx_dma_len) ||
                   unlikely(!efx->rx_scatter)) {
                /* If this isn't an explicit discard request, either
                 * the hardware or the driver is broken.
                 */
                WARN_ON(!(len == 0 && rx_buf->flags & EFX_RX_PKT_DISCARD));
                rx_buf->flags |= EFX_RX_PKT_DISCARD;
        }

        netif_vdbg(efx, rx_status, efx->net_dev,
                   "RX queue %d received ids %x-%x len %d %s%s\n",
                   efx_rx_queue_index(rx_queue), index,
                   (index + n_frags - 1) & rx_queue->ptr_mask, len,
                   (rx_buf->flags & EFX_RX_PKT_CSUMMED) ? " [SUMMED]" : "",
                   (rx_buf->flags & EFX_RX_PKT_DISCARD) ? " [DISCARD]" : "");

        /* Discard packet, if instructed to do so.  Process the
         * previous receive first.
         */
        if (unlikely(rx_buf->flags & EFX_RX_PKT_DISCARD)) {
                efx_rx_flush_packet(channel);
                efx_discard_rx_packet(channel, rx_buf, n_frags);
                return;
        }

        if (n_frags == 1 && !(flags & EFX_RX_PKT_PREFIX_LEN))
                rx_buf->len = len;

        /* Release and/or sync the DMA mapping - assumes all RX buffers
         * consumed in-order per RX queue.
         */
        efx_sync_rx_buffer(efx, rx_buf, rx_buf->len);

        /* Prefetch nice and early so data will (hopefully) be in cache by
         * the time we look at it.
         */
        prefetch(efx_rx_buf_va(rx_buf));

        rx_buf->page_offset += efx->rx_prefix_size;
        rx_buf->len -= efx->rx_prefix_size;

        if (n_frags > 1) {
                /* Release/sync DMA mapping for additional fragments.
                 * Fix length for last fragment.
                 */
                unsigned int tail_frags = n_frags - 1;

                for (;;) {
                        rx_buf = efx_rx_buf_next(rx_queue, rx_buf);
                        if (--tail_frags == 0)
                                break;
                        efx_sync_rx_buffer(efx, rx_buf, efx->rx_dma_len);
                }
                rx_buf->len = len - (n_frags - 1) * efx->rx_dma_len;
                efx_sync_rx_buffer(efx, rx_buf, rx_buf->len);
        }

        /* All fragments have been DMA-synced, so recycle pages. */
        rx_buf = efx_rx_buffer(rx_queue, index);
        efx_recycle_rx_pages(channel, rx_buf, n_frags);

        /* Pipeline receives so that we give time for packet headers to be
         * prefetched into cache.
         */
        efx_rx_flush_packet(channel);
        channel->rx_pkt_n_frags = n_frags;
        channel->rx_pkt_index = index;
}

static void efx_rx_deliver(struct efx_channel *channel, u8 *eh,
                           struct efx_rx_buffer *rx_buf,
                           unsigned int n_frags)
{
        struct sk_buff *skb;
        u16 hdr_len = min_t(u16, rx_buf->len, EFX_SKB_HEADERS);

        skb = efx_rx_mk_skb(channel, rx_buf, n_frags, eh, hdr_len);
        if (unlikely(skb == NULL)) {
                struct efx_rx_queue *rx_queue;

                rx_queue = efx_channel_get_rx_queue(channel);
                efx_free_rx_buffers(rx_queue, rx_buf, n_frags);
                return;
        }
        skb_record_rx_queue(skb, channel->rx_queue.core_index);

        /* Set the SKB flags */
        skb_checksum_none_assert(skb);
        if (likely(rx_buf->flags & EFX_RX_PKT_CSUMMED)) {
                skb->ip_summed = CHECKSUM_UNNECESSARY;
                skb->csum_level = !!(rx_buf->flags & EFX_RX_PKT_CSUM_LEVEL);
        }

        efx_rx_skb_attach_timestamp(channel, skb);

        if (channel->type->receive_skb)
                if (channel->type->receive_skb(channel, skb))
                        return;

        /* Pass the packet up */
        if (channel->rx_list != NULL)
                /* Add to list, will pass up later */
                list_add_tail(&skb->list, channel->rx_list);
        else
                /* No list, so pass it up now */
                netif_receive_skb(skb);
}

/** efx_do_xdp: perform XDP processing on a received packet
 *
 * Returns true if packet should still be delivered.
 */
static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel,
                       struct efx_rx_buffer *rx_buf, u8 **ehp)
{
        u8 rx_prefix[EFX_MAX_RX_PREFIX_SIZE];
        struct efx_rx_queue *rx_queue;
        struct bpf_prog *xdp_prog;
        struct xdp_frame *xdpf;
        struct xdp_buff xdp;
        u32 xdp_act;
        s16 offset;
        int err;

        rcu_read_lock();
        xdp_prog = rcu_dereference(efx->xdp_prog);
        if (!xdp_prog) {
                rcu_read_unlock();
                return true;
        }

        rx_queue = efx_channel_get_rx_queue(channel);

        if (unlikely(channel->rx_pkt_n_frags > 1)) {
                /* We can't do XDP on fragmented packets - drop. */
                rcu_read_unlock();
                efx_free_rx_buffers(rx_queue, rx_buf,
                                    channel->rx_pkt_n_frags);
                if (net_ratelimit())
                        netif_err(efx, rx_err, efx->net_dev,
                                  "XDP is not possible with multiple receive fragments (%d)\n",
                                  channel->rx_pkt_n_frags);
                channel->n_rx_xdp_bad_drops++;
                return false;
        }

        dma_sync_single_for_cpu(&efx->pci_dev->dev, rx_buf->dma_addr,
                                rx_buf->len, DMA_FROM_DEVICE);

        /* Save the rx prefix. */
        EFX_WARN_ON_PARANOID(efx->rx_prefix_size > EFX_MAX_RX_PREFIX_SIZE);
        memcpy(rx_prefix, *ehp - efx->rx_prefix_size,
               efx->rx_prefix_size);

        xdp_init_buff(&xdp, efx->rx_page_buf_step, &rx_queue->xdp_rxq_info);
        /* No support yet for XDP metadata */
        xdp_prepare_buff(&xdp, *ehp - EFX_XDP_HEADROOM, EFX_XDP_HEADROOM,
                         rx_buf->len, false);

        xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
        rcu_read_unlock();

        offset = (u8 *)xdp.data - *ehp;

        switch (xdp_act) {
        case XDP_PASS:
                /* Fix up rx prefix. */
                if (offset) {
                        *ehp += offset;
                        rx_buf->page_offset += offset;
                        rx_buf->len -= offset;
                        memcpy(*ehp - efx->rx_prefix_size, rx_prefix,
                               efx->rx_prefix_size);
                }
                break;

        case XDP_TX:
                /* Buffer ownership passes to tx on success. */
                xdpf = xdp_convert_buff_to_frame(&xdp);
                err = efx_xdp_tx_buffers(efx, 1, &xdpf, true);
                if (unlikely(err != 1)) {
                        efx_free_rx_buffers(rx_queue, rx_buf, 1);
                        if (net_ratelimit())
                                netif_err(efx, rx_err, efx->net_dev,
                                          "XDP TX failed (%d)\n", err);
                        channel->n_rx_xdp_bad_drops++;
                        trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
                } else {
                        channel->n_rx_xdp_tx++;
                }
                break;

        case XDP_REDIRECT:
                err = xdp_do_redirect(efx->net_dev, &xdp, xdp_prog);
                if (unlikely(err)) {
                        efx_free_rx_buffers(rx_queue, rx_buf, 1);
                        if (net_ratelimit())
                                netif_err(efx, rx_err, efx->net_dev,
                                          "XDP redirect failed (%d)\n", err);
                        channel->n_rx_xdp_bad_drops++;
                        trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
                } else {
                        channel->n_rx_xdp_redirect++;
                }
                break;

        default:
                bpf_warn_invalid_xdp_action(xdp_act);
                efx_free_rx_buffers(rx_queue, rx_buf, 1);
                channel->n_rx_xdp_bad_drops++;
                trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
                break;

        case XDP_ABORTED:
                trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act);
                fallthrough;
        case XDP_DROP:
                efx_free_rx_buffers(rx_queue, rx_buf, 1);
                channel->n_rx_xdp_drops++;
                break;
        }

        return xdp_act == XDP_PASS;
}

/* Handle a received packet.  Second half: Touches packet payload. */
void __efx_rx_packet(struct efx_channel *channel)
{
        struct efx_nic *efx = channel->efx;
        struct efx_rx_buffer *rx_buf =
                efx_rx_buffer(&channel->rx_queue, channel->rx_pkt_index);
        u8 *eh = efx_rx_buf_va(rx_buf);

        /* Read length from the prefix if necessary.  This already
         * excludes the length of the prefix itself.
         */
        if (rx_buf->flags & EFX_RX_PKT_PREFIX_LEN)
                rx_buf->len = le16_to_cpup((__le16 *)
                                           (eh + efx->rx_packet_len_offset));

        /* If we're in loopback test, then pass the packet directly to the
         * loopback layer, and free the rx_buf here
         */
        if (unlikely(efx->loopback_selftest)) {
                struct efx_rx_queue *rx_queue;

                efx_loopback_rx_packet(efx, eh, rx_buf->len);
                rx_queue = efx_channel_get_rx_queue(channel);
                efx_free_rx_buffers(rx_queue, rx_buf,
                                    channel->rx_pkt_n_frags);
                goto out;
        }

        if (!efx_do_xdp(efx, channel, rx_buf, &eh))
                goto out;

        if (unlikely(!(efx->net_dev->features & NETIF_F_RXCSUM)))
                rx_buf->flags &= ~EFX_RX_PKT_CSUMMED;

        if ((rx_buf->flags & EFX_RX_PKT_TCP) && !channel->type->receive_skb)
                efx_rx_packet_gro(channel, rx_buf, channel->rx_pkt_n_frags, eh, 0);
        else
                efx_rx_deliver(channel, eh, rx_buf, channel->rx_pkt_n_frags);
out:
        channel->rx_pkt_n_frags = 0;
}