From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9618F3D8123; Sun, 6 Sep 2026 14:20:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788704442; cv=none; b=ZF6kcYSCPs9yFUYNDJ4bTAuy1v17qgVRgczz4g1xxDU00WdFII4Iad1VcfP+SoGPLFGoik6FMXq5h9bmE5L+tS9ZcULCbAHFi6SHgh3xcgijZ0DhgSugcO6/W3c7/KoDHCBv1FPZflx+s4wpVLCvu7/K4YdKRBelRYjkf3ZvZ6A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788704442; c=relaxed/simple; bh=mToAqu1R5KV2mlZG8ZGCAaj4KiJKJ1hAzowthm++9YE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=X0JcpGUpZUKoy4YaSNcAEYRL6h/q2ui3Z0r5kvEwxx2U8KlC2y3Iy8hTHEnQKs56sSUj3ZvHfzxeH2xDIiTy3F5/hic9I7PzGcM4D539cjP/8gdeUq9OCGwBGN7r+cVbHmCpjC+SprKv+BEMzhIw7Y/t0Rn4duVHMvArwGoC2BU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ELb99cvo; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ELb99cvo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B48D81F00A3A; Sun, 6 Sep 2026 14:20:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788704441; bh=0F1azxiMxjgKsUcEaIZbzvHWVTHkjTn5dRyqXspuLL0=; h=From:To:Cc:Subject:In-Reply-To:References:Date; b=ELb99cvo0evuCmxptKEsJk8cWtGxtnh626IQnH09g+HlTzMSC+eiqvhOZeoob0zrv EEL1tb7YbHjAocfoMPO0VntXZgkhKB74RRYfgPvnJX9wxTheLHQvfHW5YKA3b5THLP JJvGu6JuYhnSeWailjn9o6R4YY7gQMwVw/2Zm/qJ0SD+nKzvmjgaPBwM8zsciizzs7 3VS0I9oVevjratMqLqhCeJanBEHEmLVOr3HiajOaR84DZDZsPJ2n4J6SJNdWfRDNeS ef7fXtqnUzJHpZCo1mdU8fB4uka+eQCYc1Y3MDNlzdfARNZfr8YfGxgvk5j5pB4OdN KtTrLZKoSjs7Q== From: =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= To: Chen Pei , ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, memxor@gmail.com, puranjay@kernel.org Cc: ihor.solodrai@linux.dev, eddyz87@gmail.com, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org, emil@etsalapatis.com, pulehui@huawei.com, pjw@kernel.org, palmer@dabbelt.com, guoren@kernel.org, bpf@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH bpf v2] bpf, riscv: Make arena support depend on ZACAS In-Reply-To: <20260902061451.1416-1-cp0613@linux.alibaba.com> References: <20260902061451.1416-1-cp0613@linux.alibaba.com> Date: Sun, 06 Sep 2026 16:20:37 +0200 Message-ID: <874ig2pikq.fsf@all.your.base.are.belong.to.us> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Chen Pei writes: > The arena range tree allocates its nodes with kmalloc_nolock() since > commit f8c67d8550ee ("bpf: Use kmalloc_nolock() in range tree"). > kmalloc_nolock() requires slab caches with cmpxchg128 support > (__CMPXCHG_DOUBLE); on riscv cmpxchg128 is provided by the ZACAS > extension. On systems without ZACAS every arena map creation fails > with a misleading -ENOMEM. > > Report the missing support instead: make bpf_jit_supports_arena() > return system_has_cmpxchg128() where it is defined, so arena map > creation fails with -EOPNOTSUPP on systems without ZACAS. The macro > is only defined when both CONFIG_RISCV_ISA_ZACAS and > CONFIG_TOOLCHAIN_HAS_ZACAS are enabled, so guard it with #ifdef the > same way mm/slab.h consumes it, and reject arena otherwise. This > matches how arena BPF_CMPXCHG instructions are already gated on ZACAS > in bpf_jit_supports_insn(). > > Fixes: f8c67d8550ee ("bpf: Use kmalloc_nolock() in range tree") > Cc: stable@vger.kernel.org > Signed-off-by: Chen Pei > --- > Changes since v1: > - Guard system_has_cmpxchg128() with #ifdef instead of calling it > unconditionally: the macro is only defined when both > CONFIG_RISCV_ISA_ZACAS and CONFIG_TOOLCHAIN_HAS_ZACAS are enabled > (as reported by sashiko-bot), so v1 broke the build when either > was disabled. This mirrors how mm/slab.h consumes the macro. > > Why #ifdef rather than rv_ext_enabled(ZACAS)? The predicates differ > exactly in the configurations that matter: > > scenario (ISA_ZACAS/TOOLCHAIN/hw) v1 rv_ext_enabled #ifdef > ISA=3Dn or TOOLCHAIN=3Dn build fails rejects rej= ects > ISA=3Dy TOOLCHAIN=3Dn hw has ZACAS build fails accepts, then rej= ects > -ENOMEM again > ISA=3Dy TOOLCHAIN=3Dy hw has ZACAS exact exact exa= ct Thanks for clarifying this; Yeah, ZACAS requires runtime *and* toolchain support. Acked-by: Bj=C3=B6rn T=C3=B6pel 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1B559C79F85 for ; Sun, 6 Sep 2026 14:20:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:References :In-Reply-To:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Vt64UYo1aRN5gALvqRaSyswdKOwOnpda/O/HCHWsp94=; b=p2rCubJM1RxwZM 8VC6/10EfpnXSeHoOUt0KLyaMx3m+bdmfKWe5+3zm6gCWPyP/RxkAzrcdXcTtbKNOuO8+SF1sf87P aUWjHKnY36V+T+pEfqkMgEggnuzGb+ynxBJIsc2zU41nab34xcwgItznQXCHkl+Rq+iLonqfj5L/a 1KHQouKjPtybYH63hLIsfGclewhNrEIf23byDuOG3TY/nHvV2XuqgWZKwh02aTnTsBWGMNGiwpJHb FcCWOlwpqCrW16IZEqS8U2cX8jyl3MTSujnA6en/uL0waKAcgCCdbqTR1DlwOpu0TYkKxLxl+KWYd 0d3fbg3F8Ww1YxV8sIpg==; 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