From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 29EAD42316F; Wed, 29 Apr 2026 18:21:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777486907; cv=none; b=Nn05myqFzwcJVp5w1kxZcJMfaV0fVWhw3BVoAoz/nV6VV5tIm6sP3rc2pV7xTIDR+zl6jd/GjsefXAoju8uKKilDuDSHhhIatL3AjeNOVEkNgbNIjUcn7q0kc+c8oTc1mHGpez8njJTD9AxJrMXVLpfCXbRKr0kXO7jBTQPMeKE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777486907; c=relaxed/simple; bh=hbqttJF5jyJFSz0TLOeCS06MonNovnebKp2SS1A1zfA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s52j8gwLTb4P5DQRvjcc2pYKddYSruQpscaXEhNwImhSA7e4BXrk36dz/xL2eWMoZRchRW1/4r3m9RUis65XzF5hLt0vy4akJuyuuDA9ktEwnUKrgTVgDcnlrOpi+d2uYlrswJQTsENlJwpovWxZ9vagoJHMEgfTYlcS7ofWdFo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ceu1aSYK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ceu1aSYK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E3238C2BCB8; Wed, 29 Apr 2026 18:21:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777486907; bh=hbqttJF5jyJFSz0TLOeCS06MonNovnebKp2SS1A1zfA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ceu1aSYKFObafIokelHE3eXysfsy7YrcetAW3aH3ggq38TpBAjyH5SDOvfPk3YxQq fVPt9UnN7Ns26m+ZOtEiglv8NdXMm2yTrJYTib4KMAgMRJam5OfJEQ+lAx84Zckdy0 XldQtXJoLjE/FVPbdXaG+D+4LqxlOCsJg0qey6gh6e/2SSCKMPGnWIfexc/p19ostd q8BAXA+xc9g7j0sD9612ZEoPdqzcptOm7Yzv4Na+5Nf1knW9W6r6kEhaEYo1pONWYO n1oRvH4BsG6f5Rf+4cZfQCLVb9HjfN1MpAbQ+Ad4DWliV2Xk3juFNS3R4Mz7WZ33t+ JevKiNsiL4WoQ== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: Emil Tsalapatis , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org, Tejun Heo , Cheng-Yang Chou , Zhao Mengmeng Subject: [PATCH 13/17] sched_ext: Forbid cpu-form kfuncs from cid-form schedulers Date: Wed, 29 Apr 2026 08:21:27 -1000 Message-ID: <20260429182131.1780125-14-tj@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260429182131.1780125-1-tj@kernel.org> References: <20260429182131.1780125-1-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit cid and cpu are both small s32s, trivially confused when a cid-form scheduler calls a cpu-keyed kfunc. Reject cid-form programs that reference any kfunc in the new scx_kfunc_ids_cpu_only at verifier load time. The reverse direction is intentionally permissive: cpu-form schedulers can freely call cid-form kfuncs to ease a gradual cpumask -> cid migration. The check sits in scx_kfunc_context_filter() right after the SCX struct_ops gate and before the any/idle allow and per-op allow-list checks, so it catches cpu-only kfuncs regardless of which set they belong to (any, idle, or select_cpu). v2: Sync per-entry kfunc flags with their primary declarations (Zhao). pahole intersects flags across BTF_ID_FLAGS() occurrences, so omitting them drops the flags globally. Signed-off-by: Tejun Heo Reviewed-by: Cheng-Yang Chou Reviewed-by: Zhao Mengmeng Reviewed-by: Changwoo Min Reviewed-by: Andrea Righi --- kernel/sched/ext.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 79565fabd9b4..65a00c979691 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -10121,6 +10121,47 @@ static const struct btf_kfunc_id_set scx_kfunc_set_any = { .filter = scx_kfunc_context_filter, }; +/* + * cpu-form kfuncs that are forbidden from cid-form schedulers + * (bpf_sched_ext_ops_cid). Programs targeting the cid struct_ops type must + * use the cid-form alternative (cid/cmask kfuncs). + * + * Membership overlaps with scx_kfunc_ids_{any,idle,select_cpu}; the filter + * tests this set independently and rejects matches before the per-op + * allow-list check runs. + * + * pahole/resolve_btfids scans every BTF_ID_FLAGS() at build time and + * intersects flags across duplicate entries, so each entry must carry the + * same flags as the kfunc's primary declaration; otherwise the flags get + * dropped globally. + */ +BTF_KFUNCS_START(scx_kfunc_ids_cpu_only) +BTF_ID_FLAGS(func, scx_bpf_kick_cpu, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_task_cpu, KF_RCU) +BTF_ID_FLAGS(func, scx_bpf_cpu_rq, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_cpu_curr, KF_IMPLICIT_ARGS | KF_RET_NULL | KF_RCU_PROTECTED) +BTF_ID_FLAGS(func, scx_bpf_cpu_node, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_cpuperf_cap, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_cpuperf_cur, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_cpuperf_set, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_get_possible_cpumask, KF_ACQUIRE) +BTF_ID_FLAGS(func, scx_bpf_get_online_cpumask, KF_ACQUIRE) +BTF_ID_FLAGS(func, scx_bpf_put_cpumask, KF_RELEASE) +BTF_ID_FLAGS(func, scx_bpf_select_cpu_dfl, KF_IMPLICIT_ARGS | KF_RCU) +BTF_ID_FLAGS(func, __scx_bpf_select_cpu_and, KF_IMPLICIT_ARGS | KF_RCU) +BTF_ID_FLAGS(func, scx_bpf_select_cpu_and, KF_RCU) +BTF_ID_FLAGS(func, scx_bpf_get_idle_cpumask, KF_IMPLICIT_ARGS | KF_ACQUIRE) +BTF_ID_FLAGS(func, scx_bpf_get_idle_cpumask_node, KF_IMPLICIT_ARGS | KF_ACQUIRE) +BTF_ID_FLAGS(func, scx_bpf_get_idle_smtmask, KF_IMPLICIT_ARGS | KF_ACQUIRE) +BTF_ID_FLAGS(func, scx_bpf_get_idle_smtmask_node, KF_IMPLICIT_ARGS | KF_ACQUIRE) +BTF_ID_FLAGS(func, scx_bpf_put_idle_cpumask, KF_RELEASE) +BTF_ID_FLAGS(func, scx_bpf_test_and_clear_cpu_idle, KF_IMPLICIT_ARGS) +BTF_ID_FLAGS(func, scx_bpf_pick_idle_cpu, KF_IMPLICIT_ARGS | KF_RCU) +BTF_ID_FLAGS(func, scx_bpf_pick_idle_cpu_node, KF_IMPLICIT_ARGS | KF_RCU) +BTF_ID_FLAGS(func, scx_bpf_pick_any_cpu, KF_IMPLICIT_ARGS | KF_RCU) +BTF_ID_FLAGS(func, scx_bpf_pick_any_cpu_node, KF_IMPLICIT_ARGS | KF_RCU) +BTF_KFUNCS_END(scx_kfunc_ids_cpu_only) + /* * Per-op kfunc allow flags. Each bit corresponds to a context-sensitive kfunc * group; an op may permit zero or more groups, with the union expressed in @@ -10184,6 +10225,7 @@ int scx_kfunc_context_filter(const struct bpf_prog *prog, u32 kfunc_id) bool in_cpu_release = btf_id_set8_contains(&scx_kfunc_ids_cpu_release, kfunc_id); bool in_idle = btf_id_set8_contains(&scx_kfunc_ids_idle, kfunc_id); bool in_any = btf_id_set8_contains(&scx_kfunc_ids_any, kfunc_id); + bool in_cpu_only = btf_id_set8_contains(&scx_kfunc_ids_cpu_only, kfunc_id); u32 moff, flags; /* Not an SCX kfunc - allow. */ @@ -10221,6 +10263,15 @@ int scx_kfunc_context_filter(const struct bpf_prog *prog, u32 kfunc_id) prog->aux->st_ops != &bpf_sched_ext_ops_cid) return -EACCES; + /* + * cid-form schedulers must use cid/cmask kfuncs. cid and cpu are both + * small s32s and trivially confused, so cpu-only kfuncs are rejected at + * load time. The reverse (cpu-form calling cid-form kfuncs) is + * intentionally permissive to ease gradual cpumask -> cid migration. + */ + if (prog->aux->st_ops == &bpf_sched_ext_ops_cid && in_cpu_only) + return -EACCES; + /* SCX struct_ops: check the per-op allow list. */ if (in_any || in_idle) return 0; -- 2.54.0