From nobody Sun Feb 8 11:43:35 2026 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 317C8369220 for ; Wed, 28 Jan 2026 15:02:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769612532; cv=none; b=OhG6jlCL1hR/FKZIaq5kOA0JtQyKoVZTMibU6EUrDk5o5I2zYThF2PcG6vCMAD5xRRlll+2Lfrk2mWQ/zqzRz6CjUPoCD+2rVKMtovldP107bLGmvRjEQLSbPXEl3Kum3t90rSeE5sKl8gIxbFHJK89T/nQmqbHvXhvWZ/D2SC0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769612532; c=relaxed/simple; bh=lUZHuuWARG0DTUNrfcxR6s+uCFVTt5vXdXNOvLssSSQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mH00knVo5zMPIJ2o3/HwGLbFmjAr/fUYKe5Gql4LmwSDnuqtYDJVLlGr7p1TgB+YTiOZRlbr7TFughIP1y4JF+LLASiEKJaEijSeYGGNTuatlN1PIBZgFa81obzBZGBbpgaaHENEZNPgn9iwMd4KL7ms3I6OcNnh/uiPTYWITvQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=FKINyKn/; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="FKINyKn/" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1769612509; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2xms8qScC7+REkQSTKJnxMsp60camdO11DeRVL9RJUs=; b=FKINyKn/YA+c/RNTorxytEVB1s1o7BRoXRElT2rjhByDd9K2p9stmFbU5GWgKvGVCpkFou vDJPuyAJYo6ss40/UPbx4/IrtPeUTqzgrI4BtyV/89GLQqRQERY9Yw8qXsmNF1dNBjWA5b hgR0qhGlhoAVuajBTxhL3tLkjGL8akk= From: Leon Hwang To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Puranjay Mohan , Xu Kuohai , Catalin Marinas , Will Deacon , Shuah Khan , Menglong Dong , Leon Hwang , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-patches-bot@fb.com Subject: [PATCH bpf-next v2 1/3] bpf: Add bpf_arch_supports_fsession() Date: Wed, 28 Jan 2026 23:01:10 +0800 Message-ID: <20260128150112.8873-2-leon.hwang@linux.dev> In-Reply-To: <20260128150112.8873-1-leon.hwang@linux.dev> References: <20260128150112.8873-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" fsession programs can currently be loaded on architectures that do not implement fsession support, which leads to runtime errors instead of a clean verifier rejection. For example, running fsession selftests on arm64 before fsession support is added results in: test_fsession_basic:PASS:fsession_test__open_and_load 0 nsec test_fsession_basic:PASS:fsession_attach 0 nsec check_result:FAIL:test_run_opts err unexpected error: -14 (errno 14) Introduce bpf_arch_supports_fsession() to explicitly gate fsession usage based on architecture support. Architectures without fsession support will now fail program load with -EOPNOTSUPP, allowing selftests to skip cleanly instead of errors at runtime. x86 declares fsession support, while the default implementation returns false. Fixes: 2d419c44658f ("bpf: add fsession support") Signed-off-by: Leon Hwang --- arch/x86/net/bpf_jit_comp.c | 5 +++ include/linux/filter.h | 1 + kernel/bpf/core.c | 5 +++ kernel/bpf/verifier.c | 3 ++ .../selftests/bpf/prog_tests/fsession_test.c | 32 ++++++++++++++----- 5 files changed, 38 insertions(+), 8 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 5a075e06cf45..070ba80e39d7 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -4112,3 +4112,8 @@ bool bpf_jit_supports_timed_may_goto(void) { return true; } + +bool bpf_jit_supports_fsession(void) +{ + return true; +} diff --git a/include/linux/filter.h b/include/linux/filter.h index fd54fed8f95f..4e1cb4f91f49 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1167,6 +1167,7 @@ bool bpf_jit_supports_arena(void); bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena); bool bpf_jit_supports_private_stack(void); bool bpf_jit_supports_timed_may_goto(void); +bool bpf_jit_supports_fsession(void); u64 bpf_arch_uaddress_limit(void); void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, = u64 bp), void *cookie); u64 arch_bpf_timed_may_goto(void); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index e0b8a8a5aaa9..3b1eb632bf7c 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -3142,6 +3142,11 @@ bool __weak bpf_jit_supports_insn(struct bpf_insn *i= nsn, bool in_arena) return false; } =20 +bool __weak bpf_jit_supports_fsession(void) +{ + return false; +} + u64 __weak bpf_arch_uaddress_limit(void) { #if defined(CONFIG_64BIT) && defined(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRE= SS_SPACE) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c2f2650db9fd..6f867ebf78d1 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -24872,6 +24872,9 @@ int bpf_check_attach_target(struct bpf_verifier_log= *log, case BPF_TRACE_FENTRY: case BPF_TRACE_FEXIT: case BPF_TRACE_FSESSION: + if (prog->expected_attach_type =3D=3D BPF_TRACE_FSESSION && + !bpf_jit_supports_fsession()) + return -EOPNOTSUPP; if (!btf_type_is_func(t)) { bpf_log(log, "attach_btf_id %u is not a function\n", btf_id); diff --git a/tools/testing/selftests/bpf/prog_tests/fsession_test.c b/tools= /testing/selftests/bpf/prog_tests/fsession_test.c index 0c4b428e1cee..a299aeb8cc2e 100644 --- a/tools/testing/selftests/bpf/prog_tests/fsession_test.c +++ b/tools/testing/selftests/bpf/prog_tests/fsession_test.c @@ -29,8 +29,16 @@ static void test_fsession_basic(void) struct fsession_test *skel =3D NULL; int err; =20 - skel =3D fsession_test__open_and_load(); - if (!ASSERT_OK_PTR(skel, "fsession_test__open_and_load")) + skel =3D fsession_test__open(); + if (!ASSERT_OK_PTR(skel, "fsession_test__open")) + return; + + err =3D fsession_test__load(skel); + if (err =3D=3D -EOPNOTSUPP) { + test__skip(); + goto cleanup; + } + if (!ASSERT_OK(err, "fsession_test__load")) goto cleanup; =20 err =3D fsession_test__attach(skel); @@ -47,8 +55,16 @@ static void test_fsession_reattach(void) struct fsession_test *skel =3D NULL; int err; =20 - skel =3D fsession_test__open_and_load(); - if (!ASSERT_OK_PTR(skel, "fsession_test__open_and_load")) + skel =3D fsession_test__open(); + if (!ASSERT_OK_PTR(skel, "fsession_test__open")) + return; + + err =3D fsession_test__load(skel); + if (err =3D=3D -EOPNOTSUPP) { + test__skip(); + goto cleanup; + } + if (!ASSERT_OK(err, "fsession_test__load")) goto cleanup; =20 /* first attach */ @@ -94,6 +110,10 @@ static void test_fsession_cookie(void) bpf_program__set_autoload(skel->progs.test6, false); =20 err =3D fsession_test__load(skel); + if (err =3D=3D -EOPNOTSUPP) { + test__skip(); + goto cleanup; + } if (!ASSERT_OK(err, "fsession_test__load")) goto cleanup; =20 @@ -111,10 +131,6 @@ static void test_fsession_cookie(void) =20 void test_fsession_test(void) { -#if !defined(__x86_64__) - test__skip(); - return; -#endif if (test__start_subtest("fsession_test")) test_fsession_basic(); if (test__start_subtest("fsession_reattach")) --=20 2.52.0