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 0A48930ACF1; Fri, 24 Apr 2026 01:32:35 +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=1776994356; cv=none; b=sSfs9Hp0iIFGDWi9Vzhm2guecalC1MAkvwE7ow8Ej+uz1VIWF2UhUYaAGtoygewfqxdwYM+OBB/fwu8BI7ZOTnPOYxz7DbOU11M8sNtPaX8AAyBhnN2sTws5waV6MkhKcO9nfmsckYe0FNfvXCh8yBVWFUN9Hkqa6PBgmqMInW8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776994356; c=relaxed/simple; bh=wgAZWZnwPTuTa4J/xCCTY035YQWlZi8On7A+A3CvQic=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=MZRTaU3hipTy4dD0wbfNKtKD1JzIXLGLSju6Pnrz3EcBumrbMDLzzGUmp3UBkVBEz6hipdYEqFt71oln7vZ8EjaJDPQ2ZP2yFJ0dYhDGeVr6b9nofL+jQgf5gvx3/0BEncdq1XiercgVxHk7726WbAzCcySqtL9FvJh60oLq6Q8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E4nuv2CD; 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="E4nuv2CD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97D77C2BCB3; Fri, 24 Apr 2026 01:32:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776994355; bh=wgAZWZnwPTuTa4J/xCCTY035YQWlZi8On7A+A3CvQic=; h=From:To:Cc:Subject:Date:From; b=E4nuv2CDk5axRHYJwoaT9yHN7fOJQ3m1pChJrqjM+uDNVFKRaTQFM7cMl5Pe5xBNK aKHyZLeSbHNMMWeuqK5BJRB1zlem2anDl4cLQOk1Uhyp5/aLpl1PpzkMXnYnkpKahh cZAeCqT1RudxlxeaSNurLqn/4+pSXp+Nzalo2ySE3qQDzSQMCA57UVt1elWLGTZFgp FND1Ec+6a0ir/ZHX0F0tA7ND0iY3Bcey7p8U3c1PT4ajtlgaxdGeW//6PCVR4zWUEL 44IZlzqfBnlXPLv/VepzLmSH1V/Grh0+IkFxhGHl6oG2w26ZSq8QuPLinuL+6c4C7V NNDNHpGFtao1Q== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, emil@etsalapatis.com, linux-kernel@vger.kernel.org, Cheng-Yang Chou , Zhao Mengmeng , Tejun Heo Subject: [PATCH 13/17] sched_ext: Forbid cpu-form kfuncs from cid-form schedulers Date: Thu, 23 Apr 2026 15:32:16 -1000 Message-ID: <20260424013220.2923402-14-tj@kernel.org> X-Mailer: git-send-email 2.53.0 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 Cc: Zhao Mengmeng --- kernel/sched/ext.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index abc0c798150d..37f37f31b025 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -9979,6 +9979,47 @@ 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 @@ -10042,6 +10083,7 @@ 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. */ @@ -10079,6 +10121,15 @@ 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; -- 2.53.0