From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 69-171-232-180.mail-mxout.facebook.com (69-171-232-180.mail-mxout.facebook.com [69.171.232.180]) (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 AEFA22D780E for ; Fri, 24 Apr 2026 17:15:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=69.171.232.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777050911; cv=none; b=tLangJM8mfKEXUekHJMDG/BzvR268dLfkyTyYAY3lasuLmbu55dYPXiQNVwKfPIHBW1zybk9zYCZzazHse2iWXNYXbkhkufozYok5O6HrzvmZRh1V6qF/23TFiJlFN0FxmGj+XLaGlkfit5VcSBB/l4PafhXodhFtdjFyd+VSms= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777050911; c=relaxed/simple; bh=y7keRLSVa9GvrfTuWU+Nu4yz0eA0Ezdn9VBCCvdZvmQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CBZVAGCEvB0zQvMUdRJM5h65HWUxDSYZ7HBaSPoQkJdNbLsjeG8IEZg66MWhfHCk/qI3itHdikZh9JEJ6bR4KgC81uy5kV+i5b/8rI3GUqRfS4wiC7xkPGqnKFwlpq7neQks/kWKOChD+WJ32XkQHsgUdbZ62WAfdDpTHJc3HKY= 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=69.171.232.180 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 62DF4474A64C1; Fri, 24 Apr 2026 10:15:04 -0700 (PDT) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , "Jose E . Marchesi" , kernel-team@fb.com, Martin KaFai Lau , Puranjay Mohan Subject: [PATCH bpf-next 06/18] bpf: Prepare architecture JIT support for stack arguments Date: Fri, 24 Apr 2026 10:15:04 -0700 Message-ID: <20260424171504.2039094-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260424171433.2034470-1-yonghong.song@linux.dev> References: <20260424171433.2034470-1-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 Add bpf_jit_supports_stack_args() as a weak function defaulting to false. Architectures that implement JIT support for stack arguments override it to return true. Reject BPF functions and kfuncs with more than 5 parameters at verification time if the architecture does not support stack arguments. Acked-by: Puranjay Mohan Signed-off-by: Yonghong Song --- include/linux/filter.h | 1 + kernel/bpf/btf.c | 8 +++++++- kernel/bpf/core.c | 5 +++++ kernel/bpf/verifier.c | 5 +++++ 4 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index b77d0b06db6e..911205dd670e 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -1163,6 +1163,7 @@ bool bpf_jit_inlines_helper_call(s32 imm); bool bpf_jit_supports_subprog_tailcalls(void); bool bpf_jit_supports_percpu_insn(void); bool bpf_jit_supports_kfunc_call(void); +bool bpf_jit_supports_stack_args(void); bool bpf_jit_supports_far_kfunc_call(void); bool bpf_jit_supports_exceptions(void); bool bpf_jit_supports_ptr_xchg(void); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index cfb35a2decf6..fa4b971c5289 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7890,8 +7890,14 @@ int btf_prepare_func_args(struct bpf_verifier_env = *env, int subprog) tname, nargs, MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } - if (nargs > MAX_BPF_FUNC_REG_ARGS) + if (nargs > MAX_BPF_FUNC_REG_ARGS) { + if (!bpf_jit_supports_stack_args()) { + bpf_log(log, "JIT does not support function %s() with %d args\n", + tname, nargs); + return -ENOTSUPP; + } sub->incoming_stack_arg_depth =3D (nargs - MAX_BPF_FUNC_REG_ARGS) * BP= F_REG_SIZE; + } =20 /* check that function is void or returns int, exception cb also requir= es this */ t =3D btf_type_by_id(btf, t->type); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ec8523e6e4eb..7522b3d7b267 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -3217,6 +3217,11 @@ bool __weak bpf_jit_supports_kfunc_call(void) return false; } =20 +bool __weak bpf_jit_supports_stack_args(void) +{ + return false; +} + bool __weak bpf_jit_supports_far_kfunc_call(void) { return false; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e041c182c614..0ba140dabe93 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12254,6 +12254,11 @@ static int check_kfunc_args(struct bpf_verifier_= env *env, struct bpf_kfunc_call_ MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } + if (nargs > MAX_BPF_FUNC_REG_ARGS && !bpf_jit_supports_stack_args()) { + verbose(env, "JIT does not support kfunc %s() with %d args\n", + func_name, nargs); + return -ENOTSUPP; + } =20 /* Check that BTF function arguments match actual types that the * verifier sees. --=20 2.52.0