From c5866a6be47207b05c6eead6292c8551c8a91669 Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Thu, 2 Apr 2026 17:49:55 +0200 Subject: selftests: bpf: introduce a common routine for reading procfs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Parametrize current way of getting MAX_SKB_FRAGS value from {sys,proc}fs so that it can be re-used to get cache line size of system's CPU. All that just to mimic and compute size of kernel's struct skb_shared_info which for xsk and test suite interpret as tailroom. Introduce two variables to ifobject struct that will carry count of skb frags and tailroom size. Do the reading and computing once, at the beginning of test suite execution in xskxceiver, but for test_progs such way is not possible as in this environment each test setups and torns down ifobject structs. Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-6-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski --- tools/testing/selftests/bpf/prog_tests/test_xsk.c | 25 +---------------------- tools/testing/selftests/bpf/prog_tests/test_xsk.h | 23 +++++++++++++++++++++ tools/testing/selftests/bpf/prog_tests/xsk.c | 19 +++++++++++++++++ tools/testing/selftests/bpf/xskxceiver.c | 23 +++++++++++++++++++++ 4 files changed, 66 insertions(+), 24 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.c b/tools/testing/selftests/bpf/prog_tests/test_xsk.c index 7e38ec6e656b..62118ffba661 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_xsk.c +++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.c @@ -179,25 +179,6 @@ int xsk_configure_socket(struct xsk_socket_info *xsk, struct xsk_umem_info *umem return xsk_socket__create(&xsk->xsk, ifobject->ifindex, 0, umem->umem, rxr, txr, &cfg); } -#define MAX_SKB_FRAGS_PATH "/proc/sys/net/core/max_skb_frags" -static unsigned int get_max_skb_frags(void) -{ - unsigned int max_skb_frags = 0; - FILE *file; - - file = fopen(MAX_SKB_FRAGS_PATH, "r"); - if (!file) { - ksft_print_msg("Error opening %s\n", MAX_SKB_FRAGS_PATH); - return 0; - } - - if (fscanf(file, "%u", &max_skb_frags) != 1) - ksft_print_msg("Error reading %s\n", MAX_SKB_FRAGS_PATH); - - fclose(file); - return max_skb_frags; -} - static int set_ring_size(struct ifobject *ifobj) { int ret; @@ -2242,11 +2223,7 @@ int testapp_too_many_frags(struct test_spec *test) if (test->mode == TEST_MODE_ZC) { max_frags = test->ifobj_tx->xdp_zc_max_segs; } else { - max_frags = get_max_skb_frags(); - if (!max_frags) { - ksft_print_msg("Can't get MAX_SKB_FRAGS from system, using default (17)\n"); - max_frags = 17; - } + max_frags = test->ifobj_tx->max_skb_frags; max_frags += 1; } diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.h b/tools/testing/selftests/bpf/prog_tests/test_xsk.h index 8fc78a057de0..1ab8aee4ce56 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_xsk.h +++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.h @@ -31,6 +31,9 @@ #define SOCK_RECONF_CTR 10 #define USLEEP_MAX 10000 +#define MAX_SKB_FRAGS_PATH "/proc/sys/net/core/max_skb_frags" +#define SMP_CACHE_BYTES_PATH "/sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size" + extern bool opt_verbose; #define print_verbose(x...) do { if (opt_verbose) ksft_print_msg(x); } while (0) @@ -45,6 +48,24 @@ static inline u64 ceil_u64(u64 a, u64 b) return (a + b - 1) / b; } +static inline unsigned int read_procfs_val(const char *path) +{ + unsigned int read_val = 0; + FILE *file; + + file = fopen(path, "r"); + if (!file) { + ksft_print_msg("Error opening %s\n", path); + return 0; + } + + if (fscanf(file, "%u", &read_val) != 1) + ksft_print_msg("Error reading %s\n", path); + + fclose(file); + return read_val; +} + /* Simple test */ enum test_mode { TEST_MODE_SKB, @@ -115,6 +136,8 @@ struct ifobject { int mtu; u32 bind_flags; u32 xdp_zc_max_segs; + u32 umem_tailroom; + u32 max_skb_frags; bool tx_on; bool rx_on; bool use_poll; diff --git a/tools/testing/selftests/bpf/prog_tests/xsk.c b/tools/testing/selftests/bpf/prog_tests/xsk.c index dd4c35c0e428..6e2f63ee2a6c 100644 --- a/tools/testing/selftests/bpf/prog_tests/xsk.c +++ b/tools/testing/selftests/bpf/prog_tests/xsk.c @@ -62,6 +62,7 @@ int configure_ifobj(struct ifobject *tx, struct ifobject *rx) static void test_xsk(const struct test_spec *test_to_run, enum test_mode mode) { + u32 max_frags, umem_tailroom, cache_line_size; struct ifobject *ifobj_tx, *ifobj_rx; struct test_spec test; int ret; @@ -84,6 +85,24 @@ static void test_xsk(const struct test_spec *test_to_run, enum test_mode mode) ifobj_tx->set_ring.default_rx = ifobj_tx->ring.rx_pending; } + cache_line_size = read_procfs_val(SMP_CACHE_BYTES_PATH); + if (!cache_line_size) + cache_line_size = 64; + + max_frags = read_procfs_val(MAX_SKB_FRAGS_PATH); + if (!max_frags) + max_frags = 17; + + ifobj_tx->max_skb_frags = max_frags; + ifobj_rx->max_skb_frags = max_frags; + + /* 48 bytes is a part of skb_shared_info w/o frags array; + * 16 bytes is sizeof(skb_frag_t) + */ + umem_tailroom = ALIGN(48 + (max_frags * 16), cache_line_size); + ifobj_tx->umem_tailroom = umem_tailroom; + ifobj_rx->umem_tailroom = umem_tailroom; + if (!ASSERT_OK(init_iface(ifobj_rx, worker_testapp_validate_rx), "init RX")) goto delete_rx; if (!ASSERT_OK(init_iface(ifobj_tx, worker_testapp_validate_tx), "init TX")) diff --git a/tools/testing/selftests/bpf/xskxceiver.c b/tools/testing/selftests/bpf/xskxceiver.c index 05b3cebc5ca9..7dad8556a722 100644 --- a/tools/testing/selftests/bpf/xskxceiver.c +++ b/tools/testing/selftests/bpf/xskxceiver.c @@ -80,6 +80,7 @@ #include #include #include +#include #include #include #include @@ -333,6 +334,7 @@ static void print_tests(void) int main(int argc, char **argv) { const size_t total_tests = ARRAY_SIZE(tests) + ARRAY_SIZE(ci_skip_tests); + u32 cache_line_size, max_frags, umem_tailroom; struct pkt_stream *rx_pkt_stream_default; struct pkt_stream *tx_pkt_stream_default; struct ifobject *ifobj_tx, *ifobj_rx; @@ -354,6 +356,27 @@ int main(int argc, char **argv) setlocale(LC_ALL, ""); + cache_line_size = read_procfs_val(SMP_CACHE_BYTES_PATH); + if (!cache_line_size) { + ksft_print_msg("Can't get SMP_CACHE_BYTES from system, using default (64)\n"); + cache_line_size = 64; + } + + max_frags = read_procfs_val(MAX_SKB_FRAGS_PATH); + if (!max_frags) { + ksft_print_msg("Can't get MAX_SKB_FRAGS from system, using default (17)\n"); + max_frags = 17; + } + ifobj_tx->max_skb_frags = max_frags; + ifobj_rx->max_skb_frags = max_frags; + + /* 48 bytes is a part of skb_shared_info w/o frags array; + * 16 bytes is sizeof(skb_frag_t) + */ + umem_tailroom = ALIGN(48 + (max_frags * 16), cache_line_size); + ifobj_tx->umem_tailroom = umem_tailroom; + ifobj_rx->umem_tailroom = umem_tailroom; + parse_command_line(ifobj_tx, ifobj_rx, argc, argv); if (opt_print_tests) { -- cgit v1.2.3 From 3197c51ce2fa00410f86f4829e4f9223553632f6 Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Thu, 2 Apr 2026 17:49:56 +0200 Subject: selftests: bpf: fix pkt grow tests MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Skip tail adjust tests in xskxceiver for SKB mode as it is not very friendly for it. multi-buffer case does not work as xdp_rxq_info that is registered for generic XDP does not report ::frag_size. The non-mbuf path copies packet via skb_pp_cow_data() which only accounts for headroom, leaving us with no tailroom and causing underlying XDP prog to drop packets therefore. For multi-buffer test on other modes, change the amount of bytes we use for growth, assume worst-case scenario and take care of headroom and tailroom. Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-7-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski --- tools/testing/selftests/bpf/prog_tests/test_xsk.c | 24 ++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.c b/tools/testing/selftests/bpf/prog_tests/test_xsk.c index 62118ffba661..ee60bcc22ee4 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_xsk.c +++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.c @@ -2528,16 +2528,34 @@ int testapp_adjust_tail_shrink_mb(struct test_spec *test) int testapp_adjust_tail_grow(struct test_spec *test) { + if (test->mode == TEST_MODE_SKB) + return TEST_SKIP; + /* Grow by 4 bytes for testing purpose */ return testapp_adjust_tail(test, 4, MIN_PKT_SIZE * 2); } int testapp_adjust_tail_grow_mb(struct test_spec *test) { + u32 grow_size; + + if (test->mode == TEST_MODE_SKB) + return TEST_SKIP; + + /* worst case scenario is when underlying setup will work on 3k + * buffers, let us account for it; given that we will use 6k as + * pkt_len, expect that it will be broken down to 2 descs each + * with 3k payload; + * + * 4k is truesize, 3k payload, 256 HR, 320 TR; + */ + grow_size = XSK_UMEM__MAX_FRAME_SIZE - + XSK_UMEM__LARGE_FRAME_SIZE - + XDP_PACKET_HEADROOM - + test->ifobj_tx->umem_tailroom; test->mtu = MAX_ETH_JUMBO_SIZE; - /* Grow by (frag_size - last_frag_Size) - 1 to stay inside the last fragment */ - return testapp_adjust_tail(test, (XSK_UMEM__MAX_FRAME_SIZE / 2) - 1, - XSK_UMEM__LARGE_FRAME_SIZE * 2); + + return testapp_adjust_tail(test, grow_size, XSK_UMEM__LARGE_FRAME_SIZE * 2); } int testapp_tx_queue_consumer(struct test_spec *test) -- cgit v1.2.3 From 16546954e117e65661109e788682891b15d4e3ce Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Thu, 2 Apr 2026 17:49:57 +0200 Subject: selftests: bpf: have a separate variable for drop test MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently two different XDP programs share a static variable for different purposes (picking where to redirect on shared umem test & whether to drop a packet). This can be a problem when running full test suite - idx can be written by shared umem test and this value can cause a false behavior within XDP drop half test. Introduce a dedicated variable for drop half test so that these two don't step on each other toes. There is no real need for using __sync_fetch_and_add here as XSK tests are executed on single CPU. Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-8-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski --- tools/testing/selftests/bpf/progs/xsk_xdp_progs.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c index 683306db8594..023d8befd4ca 100644 --- a/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c +++ b/tools/testing/selftests/bpf/progs/xsk_xdp_progs.c @@ -26,8 +26,10 @@ SEC("xdp.frags") int xsk_def_prog(struct xdp_md *xdp) SEC("xdp.frags") int xsk_xdp_drop(struct xdp_md *xdp) { + static unsigned int drop_idx; + /* Drop every other packet */ - if (idx++ % 2) + if (drop_idx++ % 2) return XDP_DROP; return bpf_redirect_map(&xsk, 0, XDP_DROP); -- cgit v1.2.3 From 62838e363e4f0753d43b2b78e9d3f6ad3c9102ec Mon Sep 17 00:00:00 2001 From: Maciej Fijalkowski Date: Thu, 2 Apr 2026 17:49:58 +0200 Subject: selftests: bpf: adjust rx_dropped xskxceiver's test to respect tailroom MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since we have changed how big user defined headroom in umem can be, change the logic in testapp_stats_rx_dropped() so we pass updated headroom validation in xdp_umem_reg() and still drop half of frames. Test works on non-mbuf setup so __xsk_pool_get_rx_frame_size() that is called on xsk_rcv_check() will not account skb_shared_info size. Taking the tailroom size into account in test being fixed is needed as xdp_umem_reg() defaults to respect it. Reviewed-by: Björn Töpel Signed-off-by: Maciej Fijalkowski Link: https://patch.msgid.link/20260402154958.562179-9-maciej.fijalkowski@intel.com Signed-off-by: Jakub Kicinski --- tools/testing/selftests/bpf/prog_tests/test_xsk.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.c b/tools/testing/selftests/bpf/prog_tests/test_xsk.c index ee60bcc22ee4..7950c504ed28 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_xsk.c +++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.c @@ -1959,15 +1959,17 @@ int testapp_headroom(struct test_spec *test) int testapp_stats_rx_dropped(struct test_spec *test) { + u32 umem_tr = test->ifobj_tx->umem_tailroom; + if (test->mode == TEST_MODE_ZC) { ksft_print_msg("Can not run RX_DROPPED test for ZC mode\n"); return TEST_SKIP; } - if (pkt_stream_replace_half(test, MIN_PKT_SIZE * 4, 0)) + if (pkt_stream_replace_half(test, (MIN_PKT_SIZE * 3) + umem_tr, 0)) return TEST_FAILURE; test->ifobj_rx->umem->frame_headroom = test->ifobj_rx->umem->frame_size - - XDP_PACKET_HEADROOM - MIN_PKT_SIZE * 3; + XDP_PACKET_HEADROOM - (MIN_PKT_SIZE * 2) - umem_tr; if (pkt_stream_receive_half(test)) return TEST_FAILURE; test->ifobj_rx->validation_func = validate_rx_dropped; -- cgit v1.2.3