From nobody Fri Sep 12 07:27:16 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89991C001B0 for ; Thu, 10 Aug 2023 04:05:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231936AbjHJEFZ (ORCPT ); Thu, 10 Aug 2023 00:05:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232675AbjHJEFQ (ORCPT ); Thu, 10 Aug 2023 00:05:16 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34328E5B for ; Wed, 9 Aug 2023 21:04:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691640270; 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=VLwtkHrR4Hnv0SG2htyTx6O/VUdZ3YGDzB9YQqYciKw=; b=a7fZc30nn5A0fu6C+UEEAnHvDKtTYklJnVxbW8MFMub1FRC78+JKbkGFm9ZrM3oS5ZS/af 3ffBd5L+OGY+swKWFLcR8GCWjeXI2gIypR9UNHiMnwKYAcxXeiTeSGj6ptZZrUe25nEVnK YO8XjPNqGbWmLLvrQ4eEEcKzs7Iwp+E= Received: from mail-oi1-f199.google.com (mail-oi1-f199.google.com [209.85.167.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-436-Euk6dC1sOp2ePg5o-fUyVQ-1; Thu, 10 Aug 2023 00:04:29 -0400 X-MC-Unique: Euk6dC1sOp2ePg5o-fUyVQ-1 Received: by mail-oi1-f199.google.com with SMTP id 5614622812f47-3a7697e580fso597222b6e.1 for ; Wed, 09 Aug 2023 21:04:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691640268; x=1692245068; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=VLwtkHrR4Hnv0SG2htyTx6O/VUdZ3YGDzB9YQqYciKw=; b=FWEQ9nZdtJXGNUh6AM/klGNeSQpsDYcv510oRhXpOVtOn0m/4ULAZQi4uXkrYugk7O NfiQ17tR5YIYwNJV+gsR3p/Q9iYpoGMoujF60BMOle7uQgb4EalWhm+UYqo5x46//dIk oRrK8Ra/ZgiNbtqNLXjV5FnszjENBonXVNQ0N7vxVHplLCFfKMqIBgZVbN6dhOlGv1Gk pbMc+eong9++mLNF2Sj+0DS70Ti3PXzCbveqgLUkKUeb8wRxqq0maAPT88qmgggMZH/7 +OlaRV22eikSsdaCNnODt068dvkUngPeBkPDb5DTU1J53AzgOLCMeBDLYQumJTTCoep/ iRKQ== X-Gm-Message-State: AOJu0Yw1OGdDwXxohznE3nVi9BWvTCtxPDO4UclenRsX3rSNwEwCS0k7 8dvomI62iBq7vSfQfZmXtWvZTyqy1OTrsYRtCHZ7ZcyHyQYxFBs0BdXe1AsH3LW1+vEzdiQVaVo rxHCaW/VB2RMrA0E0ARHTCR9X X-Received: by 2002:a05:6808:10cc:b0:3a3:d7de:5cfa with SMTP id s12-20020a05680810cc00b003a3d7de5cfamr1819128ois.11.1691640268304; Wed, 09 Aug 2023 21:04:28 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEAdIAbs7Buum1URpEJTh5T57eb0r1XDUCa+aKbZcc1fbEPGJr7vKxHbONmynKMK+8Fsxl9cg== X-Received: by 2002:a05:6808:10cc:b0:3a3:d7de:5cfa with SMTP id s12-20020a05680810cc00b003a3d7de5cfamr1819092ois.11.1691640268064; Wed, 09 Aug 2023 21:04:28 -0700 (PDT) Received: from localhost.localdomain ([2804:431:c7ec:e667:6b7d:ed55:c363:a088]) by smtp.gmail.com with ESMTPSA id b12-20020aca674c000000b003a7b5193909sm310087oiy.19.2023.08.09.21.04.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Aug 2023 21:04:27 -0700 (PDT) From: Leonardo Bras To: Will Deacon , Peter Zijlstra , Boqun Feng , Mark Rutland , Paul Walmsley , Palmer Dabbelt , Albert Ou , Leonardo Bras , Andrea Parri , Andrzej Hajda , Arnd Bergmann , Palmer Dabbelt , Guo Ren Cc: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: [RFC PATCH v5 4/5] riscv/cmpxchg: Implement cmpxchg for variables of size 1 and 2 Date: Thu, 10 Aug 2023 01:03:46 -0300 Message-ID: <20230810040349.92279-6-leobras@redhat.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230810040349.92279-2-leobras@redhat.com> References: <20230810040349.92279-2-leobras@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" cmpxchg for variables of size 1-byte and 2-bytes is not yet available for riscv, even though its present in other architectures such as arm64 and x86. This could lead to not being able to implement some locking mechanisms or requiring some rework to make it work properly. Implement 1-byte and 2-bytes cmpxchg in order to achieve parity with other architectures. Signed-off-by: Leonardo Bras --- arch/riscv/include/asm/cmpxchg.h | 34 ++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpx= chg.h index e3e0ac7ba061..ac9d0eeb74e6 100644 --- a/arch/riscv/include/asm/cmpxchg.h +++ b/arch/riscv/include/asm/cmpxchg.h @@ -72,6 +72,35 @@ * indicated by comparing RETURN with OLD. */ =20 +#define __arch_cmpxchg_masked(sc_sfx, prepend, append, r, p, o, n) \ +({ \ + u32 *__ptr32b =3D (u32 *)((ulong)(p) & ~0x3); \ + ulong __s =3D ((ulong)(p) & (0x4 - sizeof(*p))) * BITS_PER_BYTE; \ + ulong __mask =3D GENMASK(((sizeof(*p)) * BITS_PER_BYTE) - 1, 0) \ + << __s; \ + ulong __newx =3D (ulong)(n) << __s; \ + ulong __oldx =3D (ulong)(o) << __s; \ + ulong __retx; \ + ulong __rc; \ + \ + __asm__ __volatile__ ( \ + prepend \ + "0: lr.w %0, %2\n" \ + " and %1, %0, %z5\n" \ + " bne %1, %z3, 1f\n" \ + " and %1, %0, %z6\n" \ + " or %1, %1, %z4\n" \ + " sc.w" sc_sfx " %1, %1, %2\n" \ + " bnez %1, 0b\n" \ + append \ + "1:\n" \ + : "=3D&r" (__retx), "=3D&r" (__rc), "+A" (*(__ptr32b)) \ + : "rJ" ((long)__oldx), "rJ" (__newx), \ + "rJ" (__mask), "rJ" (~__mask) \ + : "memory"); \ + \ + r =3D (__typeof__(*(p)))((__retx & __mask) >> __s); \ +}) =20 #define __arch_cmpxchg(lr_sfx, sc_sfx, prepend, append, r, p, co, o, n) \ ({ \ @@ -98,6 +127,11 @@ __typeof__(*(__ptr)) __ret; \ \ switch (sizeof(*__ptr)) { \ + case 1: \ + case 2: \ + __arch_cmpxchg_masked(sc_sfx, prepend, append, \ + __ret, __ptr, __old, __new); \ + break; \ case 4: \ __arch_cmpxchg(".w", ".w" sc_sfx, prepend, append, \ __ret, __ptr, (long), __old, __new); \ --=20 2.41.0