From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 66-220-144-179.mail-mxout.facebook.com (66-220-144-179.mail-mxout.facebook.com [66.220.144.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9BBF01A3A80 for ; Thu, 12 Jun 2025 03:50:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=66.220.144.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749700250; cv=none; b=TPUQlACHpBDpc80Y1dwU5cVuB/1PjQnOwN+uWm1ObU647AvbGXT/qWlMtGgiL9ERCQjsOULqnw3aSwH1d1mX99Wznbcz5bs4KgYKA+EkFmXONwFlT/FM2qy7XRhnmzCMCBgfHVEJ4XLOfsf3ii+ROrRIugFFKDJ3W6ZHWn+vEgc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749700250; c=relaxed/simple; bh=jXaz8wbgZn548CE6oO4x/9hAeFnwzFzbktNPFUD6coU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pLdqf8Nt4d45evt3vgYx+seTm+osr6ZnTszLL+sXwFGsYkrPY+yQpROqDjQIWTb303FrgV9lOhzmKJoDxCN6xRxCM+tErmhtQYbMApQAyCwvNMAzjYB9XW4kiHs7B+GG18ytLOGAaMjpAok5ZqPuEX9vqaU1KeDSnxvyr2sHCUc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev; spf=fail smtp.mailfrom=linux.dev; arc=none smtp.client-ip=66.220.144.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=linux.dev Received: by devvm16039.vll0.facebook.com (Postfix, from userid 128203) id ADBAD96FFDB3; Wed, 11 Jun 2025 20:50:37 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau Subject: [PATCH bpf-next v3 2/3] selftests/bpf: Fix two net related test failures with 64K page size Date: Wed, 11 Jun 2025 20:50:37 -0700 Message-ID: <20250612035037.2207911-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250612035027.2207299-1-yonghong.song@linux.dev> References: <20250612035027.2207299-1-yonghong.song@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable When running BPF selftests on arm64 with a 64K page size, I encountered the following two test failures: sockmap_basic/sockmap skb_verdict change tail:FAIL tc_change_tail:FAIL With further debugging, I identified the root cause in the following kernel code within __bpf_skb_change_tail(): u32 max_len =3D BPF_SKB_MAX_LEN; u32 min_len =3D __bpf_skb_min_len(skb); int ret; if (unlikely(flags || new_len > max_len || new_len < min_len)) return -EINVAL; With a 4K page size, new_len =3D 65535 and max_len =3D 16064, the functio= n returns -EINVAL. However, With a 64K page size, max_len increases to 261824, allowing execution to proceed further in the function. This is because BPF_SKB_MAX_LEN scales with the page size and larger page sizes result in higher max_len values. Updating the new_len parameter in both tests based on actual kernel page size resolved both failures. Signed-off-by: Yonghong Song --- .../selftests/bpf/progs/test_sockmap_change_tail.c | 9 +++++++-- .../selftests/bpf/progs/test_tc_change_tail.c | 14 +++++++------- 2 files changed, 14 insertions(+), 9 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c= b/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c index 2796dd8545eb..1c7941a4ad00 100644 --- a/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c +++ b/tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c @@ -1,8 +1,13 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2024 ByteDance */ -#include +#include "vmlinux.h" #include =20 +#ifndef PAGE_SIZE +#define PAGE_SIZE __PAGE_SIZE +#endif +#define BPF_SKB_MAX_LEN (PAGE_SIZE << 2) + struct { __uint(type, BPF_MAP_TYPE_SOCKMAP); __uint(max_entries, 1); @@ -31,7 +36,7 @@ int prog_skb_verdict(struct __sk_buff *skb) change_tail_ret =3D bpf_skb_change_tail(skb, skb->len + 1, 0); return SK_PASS; } else if (data[0] =3D=3D 'E') { /* Error */ - change_tail_ret =3D bpf_skb_change_tail(skb, 65535, 0); + change_tail_ret =3D bpf_skb_change_tail(skb, BPF_SKB_MAX_LEN, 0); return SK_PASS; } return SK_PASS; diff --git a/tools/testing/selftests/bpf/progs/test_tc_change_tail.c b/to= ols/testing/selftests/bpf/progs/test_tc_change_tail.c index 28edafe803f0..fcba8299f0bc 100644 --- a/tools/testing/selftests/bpf/progs/test_tc_change_tail.c +++ b/tools/testing/selftests/bpf/progs/test_tc_change_tail.c @@ -1,11 +1,11 @@ // SPDX-License-Identifier: GPL-2.0 -#include +#include "vmlinux.h" #include -#include -#include -#include -#include -#include + +#ifndef PAGE_SIZE +#define PAGE_SIZE __PAGE_SIZE +#endif +#define BPF_SKB_MAX_LEN (PAGE_SIZE << 2) =20 long change_tail_ret =3D 1; =20 @@ -94,7 +94,7 @@ int change_tail(struct __sk_buff *skb) bpf_skb_change_tail(skb, len, 0); return TCX_PASS; } else if (payload[0] =3D=3D 'E') { /* Error */ - change_tail_ret =3D bpf_skb_change_tail(skb, 65535, 0); + change_tail_ret =3D bpf_skb_change_tail(skb, BPF_SKB_MAX_LEN, 0); return TCX_PASS; } else if (payload[0] =3D=3D 'Z') { /* Zero */ change_tail_ret =3D bpf_skb_change_tail(skb, 0, 0); --=20 2.47.1