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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B80BC05027 for ; Fri, 20 Jan 2023 15:19:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7F6706B0072; Fri, 20 Jan 2023 10:19:09 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 77FBB6B0075; Fri, 20 Jan 2023 10:19:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 620426B0078; Fri, 20 Jan 2023 10:19:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 4F9D76B0072 for ; Fri, 20 Jan 2023 10:19:09 -0500 (EST) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 213EB1A0EEC for ; Fri, 20 Jan 2023 15:19:09 +0000 (UTC) X-FDA: 80375535618.16.49BE293 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf19.hostedemail.com (Postfix) with ESMTP id 69A801A0011 for ; Fri, 20 Jan 2023 15:19:06 +0000 (UTC) Authentication-Results: imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1674227947; a=rsa-sha256; cv=none; b=BAwRJ9mUQw3qTD42To1Zpj2XFSb7+Gc+D2KNO6605La/hYDlDJdX0YTjB4FSj5j8ebNLq1 DiQtddeCOd30WpTQB620OAoz/khVRQlW/yjnPbxYe64fuaziIGswAeVkmvwk1hasP+eGSH XdDAWgNxVjN64vN2sOPPrVwMXucFeX4= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=none; spf=pass (imf19.hostedemail.com: domain of mark.rutland@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=mark.rutland@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1674227947; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OfZNyv+wqpfXHUuRbGDIFT6MJ32MTvSFAMU2tWVxdbw=; b=7zlM5SUA9pdhsysrkoSAUB8h/8Tb0tF6QJLMdkiy+5R9jJZYDVC1/x1l0yib45EjKIpu88 QR5J99vRf3C9NKx82K67ziNDbG4u1x23bBQgdK/fTC6p1s/49IibNPMGGQqx4SnnEJEXmu CR4CG5n0ggGYr1MW+0+XGgGWLf/60jo= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B58B214BF; Fri, 20 Jan 2023 07:19:46 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.11.233]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 175CD3F67D; Fri, 20 Jan 2023 07:18:55 -0800 (PST) Date: Fri, 20 Jan 2023 15:18:48 +0000 From: Mark Rutland To: Yann Sionneau Cc: Arnd Bergmann , Jonathan Corbet , Thomas Gleixner , Marc Zyngier , Rob Herring , Krzysztof Kozlowski , Will Deacon , Peter Zijlstra , Boqun Feng , Eric Biederman , Kees Cook , Oleg Nesterov , Ingo Molnar , Waiman Long , "Aneesh Kumar K.V" , Andrew Morton , Nick Piggin , Paul Moore , Eric Paris , Christian Brauner , Paul Walmsley , Palmer Dabbelt , Albert Ou , Jules Maselbas , Guillaume Thouvenin , Clement Leger , Vincent Chardon , Marc =?utf-8?B?UG91bGhpw6hz?= , Julian Vetter , Samuel Jones , Ashley Lesdalons , Thomas Costis , Marius Gligor , Jonathan Borne , Julien Villette , Luc Michel , Louis Morhet , Julien Hascoet , Jean-Christophe Pince , Guillaume Missonnier , Alex Michon , Huacai Chen , WANG Xuerui , Shaokun Zhang , John Garry , Guangbin Huang , Bharat Bhushan , Bibo Mao , Atish Patra , "Jason A. Donenfeld" , Qi Liu , Jiaxun Yang , Catalin Marinas , Mark Brown , Janosch Frank , Alexey Dobriyan , Benjamin Mugnier , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-audit@redhat.com, linux-riscv@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [RFC PATCH v2 11/31] kvx: Add atomic/locking headers Message-ID: References: <20230120141002.2442-1-ysionneau@kalray.eu> <20230120141002.2442-12-ysionneau@kalray.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230120141002.2442-12-ysionneau@kalray.eu> X-Rspam-User: X-Rspamd-Queue-Id: 69A801A0011 X-Rspamd-Server: rspam01 X-Stat-Signature: dyy3kba3ahufcr51bs6xeg7mugqrhtha X-HE-Tag: 1674227946-943213 X-HE-Meta: U2FsdGVkX195mOuEc80FhkkcM/UAxo+2xS6egpwDy3WtFBVqZy6O8IyWnmVrW8A0aGYVgiiooJcSnsOpdo8/5WwF3RxPbZL/veb0dJBAyt+VCOc50UDChbn0EgweULmnEqk0sSC8MrmKtuUFCEZdqYfM93iUhok4NGCQqeAO0++qtMq2lejLazN/91E7ZA46K2VL213hpxoA+SF9prd/PAq7okLoMW82kfUNhPMQ4U6oOLGpsWBnukUiGBIPcsUsH/3LFGE2OmhH5LgZKlyZ5F/jkISEk+ohPDQdRShSdwU6Obvdem0OIviOSZ9/MkE/mTBdnlo7UoKIjZvLLtU+xyW/NTFHJYgZgDypasCzEy2Do4L9Z4wUJ0+kNjokG6L/pPYX5mopxIvsk15jnho05Qft/CIWWTOIYfTeJYlvTCbQdbWhbrrSl3jslSNS3GG2xhEJAcPFU209HmjAopcTiIzMWZvrftbuJbHa/Ay9raKVa2eO8/E++N50DrdMqwXQFUoPZJdvtLBlOVYijaDORr4qGrIvXHnykiQY1Iqw4k/TEXz4ohs35bdP+6uDOfxmAdNUObDH/zXx1MtpkB31JZ64Sh7O4ISVY+6ziU0p3fYgjD7XCD4PS4luhygpjA0S7yFTA3FvxR/HsJsM24phVbX7KjeIxiMz9Mr9ZXy3H9XJM5kV8850NW5xoQPjcyS+MpFTz8fsSI6p4ZWjCE/vP715QV/NRvjQSTFf65aP3jlGHD3gk7FkqRIGgMVP3M0LbnYarfICn1OyT0glxGHLIcu1jnvu2RJg8nnMs1OejI9RnnNPKmV0G9PuvJo1l2EQZDfG+tmcqmb18eQgRYo0SZGpHMw7fxJzo/dqZ9najkJjA1Fc0MbW2vISNCXAtu/Dq/I9BdBCpzX6QWANRzX+rHLVzFQdd7t9zCJ37emOByTP5as4xIN6yt339kcNo5ANvidxVaaSof4f96MKNpl k9y96VNK dW//SE3CA7T9OwNi2gVutnUY1b7u+NBHoHQQxvg6gW+NDvqC6F4Kb/aCxhb5kzJKOpMzNaySdUUqWdKCd+a6O/2u2fS5f2I0gP0Tps4UnnvThG2hBwaFZ+owtA0/lXt14omb9eRb3fG+Rb4omopE62m/oBazxI1dldFgSjQvFoaNueAsZ9L0OUWJ5knVL17Y0Vk8CQy+Al/pFrlK1pe9SRn3+tJvc8oVrNXB+rSDbTG3S2ea9UWUVXfnA/rnkFoUmsPVeiboP1MOJwraXc2ZlXy5E7RGc2HdiKNL43ncZxE0Kg+D09epBJ5Aq/w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jan 20, 2023 at 03:09:42PM +0100, Yann Sionneau wrote: > Add common headers (atomic, bitops, barrier and locking) for basic > kvx support. > > Co-developed-by: Clement Leger > Signed-off-by: Clement Leger > Co-developed-by: Jules Maselbas > Signed-off-by: Jules Maselbas > Co-developed-by: Julian Vetter > Signed-off-by: Julian Vetter > Co-developed-by: Julien Villette > Signed-off-by: Julien Villette > Co-developed-by: Yann Sionneau > Signed-off-by: Yann Sionneau > --- > > Notes: > V1 -> V2: > - use {READ,WRITE}_ONCE for arch_atomic64_{read,set} > - use asm-generic/bitops/atomic.h instead of __test_and_*_bit > - removed duplicated includes > - rewrite xchg and cmpxchg in C using builtins for acswap insn Thanks for those changes. I see one issue below (instantiated a few times), but other than that this looks good to me. [...] > +#define ATOMIC64_RETURN_OP(op, c_op) \ > +static inline long arch_atomic64_##op##_return(long i, atomic64_t *v) \ > +{ \ > + long new, old, ret; \ > + \ > + do { \ > + old = v->counter; \ This should be arch_atomic64_read(v), in order to avoid the potential for the compiler to replay the access and introduce ABA races and other such problems. For details, see: https://lore.kernel.org/lkml/Y70SWXHDmOc3RhMd@osiris/ https://lore.kernel.org/lkml/Y71LoCIl+IFdy9D8@FVFF77S0Q05N/ I see that the generic 32-bit atomic code suffers from that issue, and we should fix it. > + new = old c_op i; \ > + ret = arch_cmpxchg(&v->counter, old, new); \ > + } while (ret != old); \ > + \ > + return new; \ > +} > + > +#define ATOMIC64_OP(op, c_op) \ > +static inline void arch_atomic64_##op(long i, atomic64_t *v) \ > +{ \ > + long new, old, ret; \ > + \ > + do { \ > + old = v->counter; \ Likewise, arch_atomic64_read(v) here. > + new = old c_op i; \ > + ret = arch_cmpxchg(&v->counter, old, new); \ > + } while (ret != old); \ > +} > + > +#define ATOMIC64_FETCH_OP(op, c_op) \ > +static inline long arch_atomic64_fetch_##op(long i, atomic64_t *v) \ > +{ \ > + long new, old, ret; \ > + \ > + do { \ > + old = v->counter; \ Likewise, arch_atomic64_read(v) here. > + new = old c_op i; \ > + ret = arch_cmpxchg(&v->counter, old, new); \ > + } while (ret != old); \ > + \ > + return old; \ > +} > + > +#define ATOMIC64_OPS(op, c_op) \ > + ATOMIC64_OP(op, c_op) \ > + ATOMIC64_RETURN_OP(op, c_op) \ > + ATOMIC64_FETCH_OP(op, c_op) > + > +ATOMIC64_OPS(and, &) > +ATOMIC64_OPS(or, |) > +ATOMIC64_OPS(xor, ^) > +ATOMIC64_OPS(add, +) > +ATOMIC64_OPS(sub, -) > + > +#undef ATOMIC64_OPS > +#undef ATOMIC64_FETCH_OP > +#undef ATOMIC64_OP > + > +static inline int arch_atomic_add_return(int i, atomic_t *v) > +{ > + int new, old, ret; > + > + do { > + old = v->counter; Likewise, arch_atomic64_read(v) here. > + new = old + i; > + ret = arch_cmpxchg(&v->counter, old, new); > + } while (ret != old); > + > + return new; > +} > + > +static inline int arch_atomic_sub_return(int i, atomic_t *v) > +{ > + return arch_atomic_add_return(-i, v); > +} > + > +#include > + > +#endif /* _ASM_KVX_ATOMIC_H */ Otherwise, the atomics look good to me. Thanks, Mark.