From patchwork Thu Oct 24 00:55:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejun Heo X-Patchwork-Id: 13848144 X-Patchwork-Delegate: bpf@iogearbox.net 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 4C7F91BC41; Thu, 24 Oct 2024 00:55:22 +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=1729731323; cv=none; b=jeputCvpMnVycokiXUAmF9yoMyECBmbByY2k+PEfD4BUe9gqVNDkmI/qoCmUUTKlXQRWV2tHsTDvB3MS4X5+lPSGZVy+sHWCZZPcnM/moi08yS/7s3aYGxvnXHJzrs/lRMxUx2YutCZZhsLmvatdoeWUibDLpw7RsVUaxEwLZrs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729731323; c=relaxed/simple; bh=dp4KhNIsrbR2yd624ggpLA6yLLFMoNRs2mmFq+4bfns=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=t29TlO2EITYv7ZI8e98fWYPGGyxD8KylK5csSn0Sq8Ql0xLinv3Qw16HtKYD3t8a4s3ZmWzwkAvwlXm+KWvMhORjzCfSunpK3Z4kU6nAByaTWczeUROLbFTt03fwd+qRFZzFii35KlBaDv98vDVb0ipFNd09FSuy/jyfhGcDSZ0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Wjpy0s5d; 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="Wjpy0s5d" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B173CC4CEC6; Thu, 24 Oct 2024 00:55:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729731322; bh=dp4KhNIsrbR2yd624ggpLA6yLLFMoNRs2mmFq+4bfns=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wjpy0s5dLhicS8UBMHhtDrzm12rSxZEVMWn//6Pk3/K397pBHLXdrhUeODcs/VGiv gb9ed/Z4IIzygmiMP05VI7xrtn2R9xUqIxWz/4UwVtYE1BTs3QuDDqdxnCGrpJ6s26 /PCie1Ow3tfSs6I8J2hGrJrjfdIsvtSsWEyB63LO70NRW9qqoVBGHLCwjGlSDetGPt 2JCgWHyQSOzRAi2RIIPDj7Yp18VZUEHh4FzLubNKdb9n1VvRTQxdyeQ5smpq4HazIO tPUEx+2eUtJSH8ShaNRmDOP5U/H/C7Djt0w4+KvqrFMcZf/xzRvMrHqNKUHBgJ7IiJ fGeMmXRUCa/nA== Date: Wed, 23 Oct 2024 14:55:21 -1000 From: Tejun Heo To: David Vernet Cc: bpf@vger.kernel.org, Martin KaFai Lau , Alexei Starovoitov , kernel-team@meta.com, sched-ext@meta.com, linux-kernel@vger.kernel.org Subject: [PATCH sched_ext/for-6.13 2/2] sched_ext: Replace set_arg_maybe_null() with __nullable CFI stub tags Message-ID: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: ops.dispatch() and ops.yield() may be fed a NULL task_struct pointer. set_arg_maybe_null() is used to tell the verifier that they should be NULL checked before being dereferenced. BPF now has an a lot prettier way to express this - tagging arguments in CFI stubs with __nullable. Replace set_arg_maybe_null() with __nullable CFI stub tags. Signed-off-by: Tejun Heo Cc: Martin KaFai Lau Cc: Alexei Starovoitov Acked-by: Alexei Starovoitov Acked-by: Martin KaFai Lau --- kernel/sched/ext.c | 66 +---------------------------------------------------- 1 file changed, 2 insertions(+), 64 deletions(-) --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -5407,67 +5407,8 @@ err_disable: #include #include -extern struct btf *btf_vmlinux; static const struct btf_type *task_struct_type; -static bool set_arg_maybe_null(const char *op, int arg_n, int off, int size, - enum bpf_access_type type, - const struct bpf_prog *prog, - struct bpf_insn_access_aux *info) -{ - struct btf *btf = bpf_get_btf_vmlinux(); - const struct bpf_struct_ops_desc *st_ops_desc; - const struct btf_member *member; - const struct btf_type *t; - u32 btf_id, member_idx; - const char *mname; - - /* struct_ops op args are all sequential, 64-bit numbers */ - if (off != arg_n * sizeof(__u64)) - return false; - - /* btf_id should be the type id of struct sched_ext_ops */ - btf_id = prog->aux->attach_btf_id; - st_ops_desc = bpf_struct_ops_find(btf, btf_id); - if (!st_ops_desc) - return false; - - /* BTF type of struct sched_ext_ops */ - t = st_ops_desc->type; - - member_idx = prog->expected_attach_type; - if (member_idx >= btf_type_vlen(t)) - return false; - - /* - * Get the member name of this struct_ops program, which corresponds to - * a field in struct sched_ext_ops. For example, the member name of the - * dispatch struct_ops program (callback) is "dispatch". - */ - member = &btf_type_member(t)[member_idx]; - mname = btf_name_by_offset(btf_vmlinux, member->name_off); - - if (!strcmp(mname, op)) { - /* - * The value is a pointer to a type (struct task_struct) given - * by a BTF ID (PTR_TO_BTF_ID). It is trusted (PTR_TRUSTED), - * however, can be a NULL (PTR_MAYBE_NULL). The BPF program - * should check the pointer to make sure it is not NULL before - * using it, or the verifier will reject the program. - * - * Longer term, this is something that should be addressed by - * BTF, and be fully contained within the verifier. - */ - info->reg_type = PTR_MAYBE_NULL | PTR_TO_BTF_ID | PTR_TRUSTED; - info->btf = btf_vmlinux; - info->btf_id = btf_tracing_ids[BTF_TRACING_TYPE_TASK]; - - return true; - } - - return false; -} - static bool bpf_scx_is_valid_access(int off, int size, enum bpf_access_type type, const struct bpf_prog *prog, @@ -5475,9 +5416,6 @@ static bool bpf_scx_is_valid_access(int { if (type != BPF_READ) return false; - if (set_arg_maybe_null("dispatch", 1, off, size, type, prog, info) || - set_arg_maybe_null("yield", 1, off, size, type, prog, info)) - return true; if (off < 0 || off >= sizeof(__u64) * MAX_BPF_FUNC_ARGS) return false; if (off % size != 0) @@ -5637,13 +5575,13 @@ static int bpf_scx_validate(void *kdata) static s32 sched_ext_ops__select_cpu(struct task_struct *p, s32 prev_cpu, u64 wake_flags) { return -EINVAL; } static void sched_ext_ops__enqueue(struct task_struct *p, u64 enq_flags) {} static void sched_ext_ops__dequeue(struct task_struct *p, u64 enq_flags) {} -static void sched_ext_ops__dispatch(s32 prev_cpu, struct task_struct *p) {} +static void sched_ext_ops__dispatch(s32 prev_cpu, struct task_struct *prev__nullable) {} static void sched_ext_ops__tick(struct task_struct *p) {} static void sched_ext_ops__runnable(struct task_struct *p, u64 enq_flags) {} static void sched_ext_ops__running(struct task_struct *p) {} static void sched_ext_ops__stopping(struct task_struct *p, bool runnable) {} static void sched_ext_ops__quiescent(struct task_struct *p, u64 deq_flags) {} -static bool sched_ext_ops__yield(struct task_struct *from, struct task_struct *to) { return false; } +static bool sched_ext_ops__yield(struct task_struct *from, struct task_struct *to__nullable) { return false; } static bool sched_ext_ops__core_sched_before(struct task_struct *a, struct task_struct *b) { return false; } static void sched_ext_ops__set_weight(struct task_struct *p, u32 weight) {} static void sched_ext_ops__set_cpumask(struct task_struct *p, const struct cpumask *mask) {}