From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CC1ADC25B07 for ; Tue, 9 Aug 2022 16:55:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245111AbiHIQzF (ORCPT ); Tue, 9 Aug 2022 12:55:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243307AbiHIQzE (ORCPT ); Tue, 9 Aug 2022 12:55:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A083522B17; Tue, 9 Aug 2022 09:55:03 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 28D58B81658; Tue, 9 Aug 2022 16:55:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C91DC433C1; Tue, 9 Aug 2022 16:55:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660064100; bh=K8o8qgPrj5J9A6+GrMQpiR8pTGn1sY02He1mKx0vTq0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jTE0oYw3+67b/0pE6Q41QON9uh/4DdFmcAh9hJFZg3bMY9/1Kl1xs0LFPJQr+3N8b +gIQzRv3kpEAnXPAAdSLldfDCRa/+1QhAeNhUoQpcZLzIhfEGBmVL5BMxbmzXDPZQf M8ip9LZjsDdy6ctxu3aQJ6k/4528n7KDv1LEqijhySaVGHZ0rfIRwl1j8p/HUvXZPC /E4vdgoZmfCFaVP1DV1ud0izZgkUbzDvzzt12eYtn3N/N265upkq2E5hi3GJ4c/iq8 J23vH4L3LZEbnN0fPWVDvsMdx6Ae95pEZHxPirBzvzPLwUFeZy/D/KxWuklsuxmVuu ALjVGxmDAJWWA== Date: Tue, 9 Aug 2022 19:54:57 +0300 From: Jarkko Sakkinen To: Roberto Sassu Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, corbet@lwn.net, dhowells@redhat.com, rostedt@goodmis.org, mingo@redhat.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, shuah@kernel.org, bpf@vger.kernel.org, linux-doc@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Benjamin Tissoires , Yosry Ahmed Subject: Re: [PATCH v9 01/10] btf: Add a new kfunc flag which allows to mark a function to be sleepable Message-ID: References: <20220809134603.1769279-1-roberto.sassu@huawei.com> <20220809134603.1769279-2-roberto.sassu@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220809134603.1769279-2-roberto.sassu@huawei.com> Precedence: bulk List-ID: On Tue, Aug 09, 2022 at 03:45:54PM +0200, Roberto Sassu wrote: > From: Benjamin Tissoires > > From: Benjamin Tissoires > > This allows to declare a kfunc as sleepable and prevents its use in > a non sleepable program. Nit: "Declare a kfunc as sleepable and prevent its use in a non-sleepable program." It's missing the part *how* the patch accomplishes its goals. > > Signed-off-by: Benjamin Tissoires > Co-developed-by: Yosry Ahmed > Signed-off-by: Yosry Ahmed > Signed-off-by: Hao Luo > --- > Documentation/bpf/kfuncs.rst | 6 ++++++ > include/linux/btf.h | 1 + > kernel/bpf/btf.c | 9 +++++++++ > 3 files changed, 16 insertions(+) > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst > index c0b7dae6dbf5..c8b21de1c772 100644 > --- a/Documentation/bpf/kfuncs.rst > +++ b/Documentation/bpf/kfuncs.rst > @@ -146,6 +146,12 @@ that operate (change some property, perform some operation) on an object that > was obtained using an acquire kfunc. Such kfuncs need an unchanged pointer to > ensure the integrity of the operation being performed on the expected object. > > +2.4.6 KF_SLEEPABLE flag > +----------------------- > + > +The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can only > +be called by sleepable BPF programs (BPF_F_SLEEPABLE). > + > 2.5 Registering the kfuncs > -------------------------- > > diff --git a/include/linux/btf.h b/include/linux/btf.h > index cdb376d53238..976cbdd2981f 100644 > --- a/include/linux/btf.h > +++ b/include/linux/btf.h > @@ -49,6 +49,7 @@ > * for this case. > */ > #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */ > +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ > > struct btf; > struct btf_member; > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 7e64447659f3..d3e4c86b8fcd 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -6175,6 +6175,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, > { > enum bpf_prog_type prog_type = resolve_prog_type(env->prog); > bool rel = false, kptr_get = false, trusted_arg = false; > + bool sleepable = false; > struct bpf_verifier_log *log = &env->log; > u32 i, nargs, ref_id, ref_obj_id = 0; > bool is_kfunc = btf_is_kernel(btf); > @@ -6212,6 +6213,7 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, > rel = kfunc_flags & KF_RELEASE; > kptr_get = kfunc_flags & KF_KPTR_GET; > trusted_arg = kfunc_flags & KF_TRUSTED_ARGS; > + sleepable = kfunc_flags & KF_SLEEPABLE; > } > > /* check that BTF function arguments match actual types that the > @@ -6419,6 +6421,13 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, > func_name); > return -EINVAL; > } > + > + if (sleepable && !env->prog->aux->sleepable) { > + bpf_log(log, "kernel function %s is sleepable but the program is not\n", > + func_name); > + return -EINVAL; > + } > + > /* returns argument register number > 0 in case of reference release kfunc */ > return rel ? ref_regno : 0; > } > -- > 2.25.1 > BR, Jarkko