From patchwork Mon Oct 28 13:46:00 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Leon Hwang X-Patchwork-Id: 13853478 X-Patchwork-Delegate: bpf@iogearbox.net Received: from out-187.mta0.migadu.com (out-187.mta0.migadu.com [91.218.175.187]) (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 1B534194080 for ; Mon, 28 Oct 2024 13:46:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.187 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730123190; cv=none; b=qOzI+4GO/mUuK9OFKGuIEkpkrqRIcGGeMBxPhGtWCNdGBXqu9ZPXzTfHZOE9Y1lQUoQYsQQzk/mtOocIiyuITCgrOxUOAPIzXr2WdLu4RXxDsbylZOEJgMd//l3RmiS3T2St/a5jpA4qQfpYeFsJFYGp6emP6lizjIfMFa5f63c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730123190; c=relaxed/simple; bh=V6zHtq9mop+qm1qA0wIlrInjPq6pOZUIXph54OQEDT4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VCaT109ZoR+na76h38vm2dk/20qXxHfXUp06uGHtE5DNrVvaD7pWoGlUU34aN++8u5y7H0WUtbYHxuL1F6ScqxYfxqggVoBuTRxH+9dbojEJbzYtE2tllJ6eZt3uVEiXMHXKRIqU2B4oX2GYZT2Qcd7mNfsEYcH5qzNRM8BiYVM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=GLGz1qXO; arc=none smtp.client-ip=91.218.175.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="GLGz1qXO" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1730123183; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=JxZsp+juY5eKmUQaTTp4fwAs/SdSr/IsGBvHa5tNrkQ=; b=GLGz1qXOfdeFBr8VuPSXBHghlXdF36YWCncupQZf2PbHYUV5TfjI/0b3P7onPRnDJe5gVj hgXhSdIY1tsrB6i6dqANkUAXavUGdwjH8gqUjGoDZWAt5x/xs7gEz4YStiQ4hKT1PznY8h 3w9WSEDvgH4tI7u1YTsCc2rorTR+M3E= From: Leon Hwang To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, eddyz87@gmail.com, leon.hwang@linux.dev, kernel-patches-bot@fb.com Subject: [RESEND PATCH bpf-next v2 2/2] bpf, verifier: Check trampoline target is tail_call_reachable subprog Date: Mon, 28 Oct 2024 21:46:00 +0800 Message-ID: <20241028134601.95448-3-leon.hwang@linux.dev> In-Reply-To: <20241028134601.95448-1-leon.hwang@linux.dev> References: <20241028134601.95448-1-leon.hwang@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Patchwork-Delegate: bpf@iogearbox.net In the x86_64 JIT, tailcall info is propagated through the trampoline when the target program is tail_call_reachable. However, this propagation is unnecessary if the target is a main prog, or a subprog that is not tail_call_reachable. Since the verifier can determine if a subprog is tail_call_reachable, it should only propagate tailcall info when the target is subprog and the subprog is actually tail_call_reachable. Acked-by: Yonghong Song Signed-off-by: Leon Hwang --- include/linux/bpf.h | 1 + kernel/bpf/verifier.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c3ba4d4751747..0c3b147c84af9 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1253,6 +1253,7 @@ struct bpf_attach_target_info { struct module *tgt_mod; const char *tgt_name; const struct btf_type *tgt_type; + bool tgt_tail_call_reachable; }; #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 797cf3ed32e0f..2e2f027b86375 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -21946,6 +21946,8 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, bpf_log(log, "Subprog %s doesn't exist\n", tname); return -EINVAL; } + tgt_info->tgt_tail_call_reachable = subprog && + aux->func[subprog]->aux->tail_call_reachable; if (aux->func && aux->func[subprog]->aux->exception_cb) { bpf_log(log, "%s programs cannot attach to exception callback\n", @@ -22315,7 +22317,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) if (!tr) return -ENOMEM; - if (tgt_prog && tgt_prog->aux->tail_call_reachable) + if (tgt_prog && tgt_info.tgt_tail_call_reachable) tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX; prog->aux->dst_trampoline = tr;