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authorToke Høiland-Jørgensen <toke@redhat.com>2022-03-09 13:53:42 +0300
committerAlexei Starovoitov <ast@kernel.org>2022-03-10 01:19:22 +0300
commitb530e9e1063ed2b817eae7eec6ed2daa8be11608 (patch)
tree6e698ebc15e53430227cf0223a6501a48538f7e3 /net/bpf
parent3399dd9f372bf0f4f3fb1fb11eb60ebd7b52d79c (diff)
downloadlinux-b530e9e1063ed2b817eae7eec6ed2daa8be11608.tar.xz
bpf: Add "live packet" mode for XDP in BPF_PROG_RUN
This adds support for running XDP programs through BPF_PROG_RUN in a mode that enables live packet processing of the resulting frames. Previous uses of BPF_PROG_RUN for XDP returned the XDP program return code and the modified packet data to userspace, which is useful for unit testing of XDP programs. The existing BPF_PROG_RUN for XDP allows userspace to set the ingress ifindex and RXQ number as part of the context object being passed to the kernel. This patch reuses that code, but adds a new mode with different semantics, which can be selected with the new BPF_F_TEST_XDP_LIVE_FRAMES flag. When running BPF_PROG_RUN in this mode, the XDP program return codes will be honoured: returning XDP_PASS will result in the frame being injected into the networking stack as if it came from the selected networking interface, while returning XDP_TX and XDP_REDIRECT will result in the frame being transmitted out that interface. XDP_TX is translated into an XDP_REDIRECT operation to the same interface, since the real XDP_TX action is only possible from within the network drivers themselves, not from the process context where BPF_PROG_RUN is executed. Internally, this new mode of operation creates a page pool instance while setting up the test run, and feeds pages from that into the XDP program. The setup cost of this is amortised over the number of repetitions specified by userspace. To support the performance testing use case, we further optimise the setup step so that all pages in the pool are pre-initialised with the packet data, and pre-computed context and xdp_frame objects stored at the start of each page. This makes it possible to entirely avoid touching the page content on each XDP program invocation, and enables sending up to 9 Mpps/core on my test box. Because the data pages are recycled by the page pool, and the test runner doesn't re-initialise them for each run, subsequent invocations of the XDP program will see the packet data in the state it was after the last time it ran on that particular page. This means that an XDP program that modifies the packet before redirecting it has to be careful about which assumptions it makes about the packet content, but that is only an issue for the most naively written programs. Enabling the new flag is only allowed when not setting ctx_out and data_out in the test specification, since using it means frames will be redirected somewhere else, so they can't be returned. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20220309105346.100053-2-toke@redhat.com
Diffstat (limited to 'net/bpf')
-rw-r--r--net/bpf/test_run.c334
1 files changed, 320 insertions, 14 deletions
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index ba410b069824..25169908be4a 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -15,6 +15,7 @@
#include <net/sock.h>
#include <net/tcp.h>
#include <net/net_namespace.h>
+#include <net/page_pool.h>
#include <linux/error-injection.h>
#include <linux/smp.h>
#include <linux/sock_diag.h>
@@ -53,10 +54,11 @@ static void bpf_test_timer_leave(struct bpf_test_timer *t)
rcu_read_unlock();
}
-static bool bpf_test_timer_continue(struct bpf_test_timer *t, u32 repeat, int *err, u32 *duration)
+static bool bpf_test_timer_continue(struct bpf_test_timer *t, int iterations,
+ u32 repeat, int *err, u32 *duration)
__must_hold(rcu)
{
- t->i++;
+ t->i += iterations;
if (t->i >= repeat) {
/* We're done. */
t->time_spent += ktime_get_ns() - t->time_start;
@@ -88,6 +90,286 @@ reset:
return false;
}
+/* We put this struct at the head of each page with a context and frame
+ * initialised when the page is allocated, so we don't have to do this on each
+ * repetition of the test run.
+ */
+struct xdp_page_head {
+ struct xdp_buff orig_ctx;
+ struct xdp_buff ctx;
+ struct xdp_frame frm;
+ u8 data[];
+};
+
+struct xdp_test_data {
+ struct xdp_buff *orig_ctx;
+ struct xdp_rxq_info rxq;
+ struct net_device *dev;
+ struct page_pool *pp;
+ struct xdp_frame **frames;
+ struct sk_buff **skbs;
+ u32 batch_size;
+ u32 frame_cnt;
+};
+
+#define TEST_XDP_FRAME_SIZE (PAGE_SIZE - sizeof(struct xdp_page_head) \
+ - sizeof(struct skb_shared_info))
+#define TEST_XDP_MAX_BATCH 256
+
+static void xdp_test_run_init_page(struct page *page, void *arg)
+{
+ struct xdp_page_head *head = phys_to_virt(page_to_phys(page));
+ struct xdp_buff *new_ctx, *orig_ctx;
+ u32 headroom = XDP_PACKET_HEADROOM;
+ struct xdp_test_data *xdp = arg;
+ size_t frm_len, meta_len;
+ struct xdp_frame *frm;
+ void *data;
+
+ orig_ctx = xdp->orig_ctx;
+ frm_len = orig_ctx->data_end - orig_ctx->data_meta;
+ meta_len = orig_ctx->data - orig_ctx->data_meta;
+ headroom -= meta_len;
+
+ new_ctx = &head->ctx;
+ frm = &head->frm;
+ data = &head->data;
+ memcpy(data + headroom, orig_ctx->data_meta, frm_len);
+
+ xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq);
+ xdp_prepare_buff(new_ctx, data, headroom, frm_len, true);
+ new_ctx->data = new_ctx->data_meta + meta_len;
+
+ xdp_update_frame_from_buff(new_ctx, frm);
+ frm->mem = new_ctx->rxq->mem;
+
+ memcpy(&head->orig_ctx, new_ctx, sizeof(head->orig_ctx));
+}
+
+static int xdp_test_run_setup(struct xdp_test_data *xdp, struct xdp_buff *orig_ctx)
+{
+ struct xdp_mem_info mem = {};
+ struct page_pool *pp;
+ int err = -ENOMEM;
+ struct page_pool_params pp_params = {
+ .order = 0,
+ .flags = 0,
+ .pool_size = xdp->batch_size,
+ .nid = NUMA_NO_NODE,
+ .max_len = TEST_XDP_FRAME_SIZE,
+ .init_callback = xdp_test_run_init_page,
+ .init_arg = xdp,
+ };
+
+ xdp->frames = kvmalloc_array(xdp->batch_size, sizeof(void *), GFP_KERNEL);
+ if (!xdp->frames)
+ return -ENOMEM;
+
+ xdp->skbs = kvmalloc_array(xdp->batch_size, sizeof(void *), GFP_KERNEL);
+ if (!xdp->skbs)
+ goto err_skbs;
+
+ pp = page_pool_create(&pp_params);
+ if (IS_ERR(pp)) {
+ err = PTR_ERR(pp);
+ goto err_pp;
+ }
+
+ /* will copy 'mem.id' into pp->xdp_mem_id */
+ err = xdp_reg_mem_model(&mem, MEM_TYPE_PAGE_POOL, pp);
+ if (err)
+ goto err_mmodel;
+
+ xdp->pp = pp;
+
+ /* We create a 'fake' RXQ referencing the original dev, but with an
+ * xdp_mem_info pointing to our page_pool
+ */
+ xdp_rxq_info_reg(&xdp->rxq, orig_ctx->rxq->dev, 0, 0);
+ xdp->rxq.mem.type = MEM_TYPE_PAGE_POOL;
+ xdp->rxq.mem.id = pp->xdp_mem_id;
+ xdp->dev = orig_ctx->rxq->dev;
+ xdp->orig_ctx = orig_ctx;
+
+ return 0;
+
+err_mmodel:
+ page_pool_destroy(pp);
+err_pp:
+ kfree(xdp->skbs);
+err_skbs:
+ kfree(xdp->frames);
+ return err;
+}
+
+static void xdp_test_run_teardown(struct xdp_test_data *xdp)
+{
+ page_pool_destroy(xdp->pp);
+ kfree(xdp->frames);
+ kfree(xdp->skbs);
+}
+
+static bool ctx_was_changed(struct xdp_page_head *head)
+{
+ return head->orig_ctx.data != head->ctx.data ||
+ head->orig_ctx.data_meta != head->ctx.data_meta ||
+ head->orig_ctx.data_end != head->ctx.data_end;
+}
+
+static void reset_ctx(struct xdp_page_head *head)
+{
+ if (likely(!ctx_was_changed(head)))
+ return;
+
+ head->ctx.data = head->orig_ctx.data;
+ head->ctx.data_meta = head->orig_ctx.data_meta;
+ head->ctx.data_end = head->orig_ctx.data_end;
+ xdp_update_frame_from_buff(&head->ctx, &head->frm);
+}
+
+static int xdp_recv_frames(struct xdp_frame **frames, int nframes,
+ struct sk_buff **skbs,
+ struct net_device *dev)
+{
+ gfp_t gfp = __GFP_ZERO | GFP_ATOMIC;
+ int i, n;
+ LIST_HEAD(list);
+
+ n = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, nframes, (void **)skbs);
+ if (unlikely(n == 0)) {
+ for (i = 0; i < nframes; i++)
+ xdp_return_frame(frames[i]);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < nframes; i++) {
+ struct xdp_frame *xdpf = frames[i];
+ struct sk_buff *skb = skbs[i];
+
+ skb = __xdp_build_skb_from_frame(xdpf, skb, dev);
+ if (!skb) {
+ xdp_return_frame(xdpf);
+ continue;
+ }
+
+ list_add_tail(&skb->list, &list);
+ }
+ netif_receive_skb_list(&list);
+
+ return 0;
+}
+
+static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog,
+ u32 repeat)
+{
+ struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
+ int err = 0, act, ret, i, nframes = 0, batch_sz;
+ struct xdp_frame **frames = xdp->frames;
+ struct xdp_page_head *head;
+ struct xdp_frame *frm;
+ bool redirect = false;
+ struct xdp_buff *ctx;
+ struct page *page;
+
+ batch_sz = min_t(u32, repeat, xdp->batch_size);
+
+ local_bh_disable();
+ xdp_set_return_frame_no_direct();
+
+ for (i = 0; i < batch_sz; i++) {
+ page = page_pool_dev_alloc_pages(xdp->pp);
+ if (!page) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ head = phys_to_virt(page_to_phys(page));
+ reset_ctx(head);
+ ctx = &head->ctx;
+ frm = &head->frm;
+ xdp->frame_cnt++;
+
+ act = bpf_prog_run_xdp(prog, ctx);
+
+ /* if program changed pkt bounds we need to update the xdp_frame */
+ if (unlikely(ctx_was_changed(head))) {
+ ret = xdp_update_frame_from_buff(ctx, frm);
+ if (ret) {
+ xdp_return_buff(ctx);
+ continue;
+ }
+ }
+
+ switch (act) {
+ case XDP_TX:
+ /* we can't do a real XDP_TX since we're not in the
+ * driver, so turn it into a REDIRECT back to the same
+ * index
+ */
+ ri->tgt_index = xdp->dev->ifindex;
+ ri->map_id = INT_MAX;
+ ri->map_type = BPF_MAP_TYPE_UNSPEC;
+ fallthrough;
+ case XDP_REDIRECT:
+ redirect = true;
+ ret = xdp_do_redirect_frame(xdp->dev, ctx, frm, prog);
+ if (ret)
+ xdp_return_buff(ctx);
+ break;
+ case XDP_PASS:
+ frames[nframes++] = frm;
+ break;
+ default:
+ bpf_warn_invalid_xdp_action(NULL, prog, act);
+ fallthrough;
+ case XDP_DROP:
+ xdp_return_buff(ctx);
+ break;
+ }
+ }
+
+out:
+ if (redirect)
+ xdp_do_flush();
+ if (nframes) {
+ ret = xdp_recv_frames(frames, nframes, xdp->skbs, xdp->dev);
+ if (ret)
+ err = ret;
+ }
+
+ xdp_clear_return_frame_no_direct();
+ local_bh_enable();
+ return err;
+}
+
+static int bpf_test_run_xdp_live(struct bpf_prog *prog, struct xdp_buff *ctx,
+ u32 repeat, u32 batch_size, u32 *time)
+
+{
+ struct xdp_test_data xdp = { .batch_size = batch_size };
+ struct bpf_test_timer t = { .mode = NO_MIGRATE };
+ int ret;
+
+ if (!repeat)
+ repeat = 1;
+
+ ret = xdp_test_run_setup(&xdp, ctx);
+ if (ret)
+ return ret;
+
+ bpf_test_timer_enter(&t);
+ do {
+ xdp.frame_cnt = 0;
+ ret = xdp_test_run_batch(&xdp, prog, repeat - t.i);
+ if (unlikely(ret < 0))
+ break;
+ } while (bpf_test_timer_continue(&t, xdp.frame_cnt, repeat, &ret, time));
+ bpf_test_timer_leave(&t);
+
+ xdp_test_run_teardown(&xdp);
+ return ret;
+}
+
static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
u32 *retval, u32 *time, bool xdp)
{
@@ -119,7 +401,7 @@ static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
*retval = bpf_prog_run_xdp(prog, ctx);
else
*retval = bpf_prog_run(prog, ctx);
- } while (bpf_test_timer_continue(&t, repeat, &ret, time));
+ } while (bpf_test_timer_continue(&t, 1, repeat, &ret, time));
bpf_reset_run_ctx(old_ctx);
bpf_test_timer_leave(&t);
@@ -446,7 +728,7 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
int b = 2, err = -EFAULT;
u32 retval = 0;
- if (kattr->test.flags || kattr->test.cpu)
+ if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
return -EINVAL;
switch (prog->expected_attach_type) {
@@ -510,7 +792,7 @@ int bpf_prog_test_run_raw_tp(struct bpf_prog *prog,
/* doesn't support data_in/out, ctx_out, duration, or repeat */
if (kattr->test.data_in || kattr->test.data_out ||
kattr->test.ctx_out || kattr->test.duration ||
- kattr->test.repeat)
+ kattr->test.repeat || kattr->test.batch_size)
return -EINVAL;
if (ctx_size_in < prog->aux->max_ctx_offset ||
@@ -741,7 +1023,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
void *data;
int ret;
- if (kattr->test.flags || kattr->test.cpu)
+ if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
return -EINVAL;
data = bpf_test_init(kattr, kattr->test.data_size_in,
@@ -922,7 +1204,9 @@ static void xdp_convert_buff_to_md(struct xdp_buff *xdp, struct xdp_md *xdp_md)
int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
+ bool do_live = (kattr->test.flags & BPF_F_TEST_XDP_LIVE_FRAMES);
u32 tailroom = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
+ u32 batch_size = kattr->test.batch_size;
u32 size = kattr->test.data_size_in;
u32 headroom = XDP_PACKET_HEADROOM;
u32 retval, duration, max_data_sz;
@@ -938,6 +1222,18 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
prog->expected_attach_type == BPF_XDP_CPUMAP)
return -EINVAL;
+ if (kattr->test.flags & ~BPF_F_TEST_XDP_LIVE_FRAMES)
+ return -EINVAL;
+
+ if (do_live) {
+ if (!batch_size)
+ batch_size = NAPI_POLL_WEIGHT;
+ else if (batch_size > TEST_XDP_MAX_BATCH)
+ return -E2BIG;
+ } else if (batch_size) {
+ return -EINVAL;
+ }
+
ctx = bpf_ctx_init(kattr, sizeof(struct xdp_md));
if (IS_ERR(ctx))
return PTR_ERR(ctx);
@@ -946,14 +1242,20 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
/* There can't be user provided data before the meta data */
if (ctx->data_meta || ctx->data_end != size ||
ctx->data > ctx->data_end ||
- unlikely(xdp_metalen_invalid(ctx->data)))
+ unlikely(xdp_metalen_invalid(ctx->data)) ||
+ (do_live && (kattr->test.data_out || kattr->test.ctx_out)))
goto free_ctx;
/* Meta data is allocated from the headroom */
headroom -= ctx->data;
}
max_data_sz = 4096 - headroom - tailroom;
- size = min_t(u32, size, max_data_sz);
+ if (size > max_data_sz) {
+ /* disallow live data mode for jumbo frames */
+ if (do_live)
+ goto free_ctx;
+ size = max_data_sz;
+ }
data = bpf_test_init(kattr, size, max_data_sz, headroom, tailroom);
if (IS_ERR(data)) {
@@ -1011,7 +1313,10 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
if (repeat > 1)
bpf_prog_change_xdp(NULL, prog);
- ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
+ if (do_live)
+ ret = bpf_test_run_xdp_live(prog, &xdp, repeat, batch_size, &duration);
+ else
+ ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
/* We convert the xdp_buff back to an xdp_md before checking the return
* code so the reference count of any held netdevice will be decremented
* even if the test run failed.
@@ -1073,7 +1378,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
if (prog->type != BPF_PROG_TYPE_FLOW_DISSECTOR)
return -EINVAL;
- if (kattr->test.flags || kattr->test.cpu)
+ if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
return -EINVAL;
if (size < ETH_HLEN)
@@ -1108,7 +1413,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
do {
retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
size, flags);
- } while (bpf_test_timer_continue(&t, repeat, &ret, &duration));
+ } while (bpf_test_timer_continue(&t, 1, repeat, &ret, &duration));
bpf_test_timer_leave(&t);
if (ret < 0)
@@ -1140,7 +1445,7 @@ int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kat
if (prog->type != BPF_PROG_TYPE_SK_LOOKUP)
return -EINVAL;
- if (kattr->test.flags || kattr->test.cpu)
+ if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
return -EINVAL;
if (kattr->test.data_in || kattr->test.data_size_in || kattr->test.data_out ||
@@ -1203,7 +1508,7 @@ int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kat
do {
ctx.selected_sk = NULL;
retval = BPF_PROG_SK_LOOKUP_RUN_ARRAY(progs, ctx, bpf_prog_run);
- } while (bpf_test_timer_continue(&t, repeat, &ret, &duration));
+ } while (bpf_test_timer_continue(&t, 1, repeat, &ret, &duration));
bpf_test_timer_leave(&t);
if (ret < 0)
@@ -1242,7 +1547,8 @@ int bpf_prog_test_run_syscall(struct bpf_prog *prog,
/* doesn't support data_in/out, ctx_out, duration, or repeat or flags */
if (kattr->test.data_in || kattr->test.data_out ||
kattr->test.ctx_out || kattr->test.duration ||
- kattr->test.repeat || kattr->test.flags)
+ kattr->test.repeat || kattr->test.flags ||
+ kattr->test.batch_size)
return -EINVAL;
if (ctx_size_in < prog->aux->max_ctx_offset ||