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 1F89CC433F5 for ; Thu, 6 Oct 2022 09:05:49 +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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=S9eis94DP+CinwgS02zQhbYwurNkiyHZ2R4NNF/9MY4=; b=FSY7xBOIlVMUVO Nch9+h1KnTtzdYzxKcatTMmAzoc17WfNeop4rNk2CsQFN7Gku8cG2wlBS2BG9hiUYlnZ4yX7Rsl6u AdjCbK6tcukOzeBTfXI57u8qIId7bmI/Y8kofKxMe9yVwKdH/MUAAHQjMvAWYcWHs08+EEMnucJlX 5yAbwwk8nt0PLwARtx7+bsCDu8jGBqbPBMA2tz6KXhUMbHXXi6l3wcrWKP330QtEHicNTIRAj2sle /BEIhQu1T/70TLwW8VsrnWFigXcyk7dJaJ8Gc7eR757dEn0ja0youQhR63WscZ2jFv8qTaR9T1jHk Be0G/0vckouSMuFKUy1g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ogMo4-000wHn-PE; Thu, 06 Oct 2022 09:04:40 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ogMnz-000wDD-1M for linux-arm-kernel@lists.infradead.org; Thu, 06 Oct 2022 09:04:36 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 81C94618C8; Thu, 6 Oct 2022 09:04:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BFA41C433C1; Thu, 6 Oct 2022 09:04:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665047073; bh=8/95+/6ABMJ/uxjvKl5XAk6L3AoFggCK8OTm2MLfJOY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jPS6CXjXu+VZbqVhmUXZ3W/fC74AHDAGMkY7HZugiuNzC97RxxchswmcpvZrOQsY7 mt3zOUTGd2j5jUmTyYkhi1U6+Vhv8yP20TEwxbsQ2E9bJsSEyzf7Gk8inaHJX2TrSq BxRkSLnNnG9ErRRqxzM2G7VsYv3WKfASJEFDB0vRJNGvKtE2gijFuhWXS22e+5PRv6 OhM19Zkjl/RGIzQOFHTEMvx8YPzRB8K6mCR58/3KNIaynjDEWxBL9TMF5iNSnxIIuD ZRYi37haZsHhbldTUmMKeN+xDxrLj8HkzSGlSHcUzOiB0TjkqkTz5vXQ/+C6WLrPzz XaCUb5HFopjEw== Date: Thu, 6 Oct 2022 16:55:00 +0800 From: Jisheng Zhang To: Ard Biesheuvel Cc: Catalin Marinas , Will Deacon , Peter Zijlstra , Josh Poimboeuf , Jason Baron , Steven Rostedt , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] arm64: jump_label: mark arguments as const to satisfy asm constraints Message-ID: References: <20221006075542.2658-1-jszhang@kernel.org> <20221006075542.2658-2-jszhang@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221006_020435_214065_2D23F5FF X-CRM114-Status: GOOD ( 26.52 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Oct 06, 2022 at 04:46:21PM +0800, Jisheng Zhang wrote: > On Thu, Oct 06, 2022 at 10:17:44AM +0200, Ard Biesheuvel wrote: > > On Thu, 6 Oct 2022 at 10:05, Jisheng Zhang wrote: > > > > > > Inspired by x86 commit 864b435514b2("x86/jump_label: Mark arguments as > > > const to satisfy asm constraints"), mark arch_static_branch()'s and > > > arch_static_branch_jump()'s arguments as const to satisfy asm > > > constraints. And Steven in [1] also pointed out that "The "i" > > > constraint needs to be a constant." > > > > > > Tested with building a simple external kernel module with "O0". > > > > > > [1]https://lore.kernel.org/all/20210212094059.5f8d05e8@gandalf.local.home/ > > > > > > Signed-off-by: Jisheng Zhang > > > --- > > > arch/arm64/include/asm/jump_label.h | 8 ++++---- > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h > > > index cea441b6aa5d..48ddc0f45d22 100644 > > > --- a/arch/arm64/include/asm/jump_label.h > > > +++ b/arch/arm64/include/asm/jump_label.h > > > @@ -15,8 +15,8 @@ > > > > > > #define JUMP_LABEL_NOP_SIZE AARCH64_INSN_SIZE > > > > > > -static __always_inline bool arch_static_branch(struct static_key *key, > > > - bool branch) > > > +static __always_inline bool arch_static_branch(struct static_key * const key, > > > + const bool branch) > > > { > > > asm_volatile_goto( > > > "1: nop \n\t" > > > > Is this still necessary if we specify the constraints in a more > > reasonable manner: > > > > " .quad %c0 - . + %1 \n\t" > > : : "i"(key), "i"(branch) : : l_yes); > > Just tried this locally with the simple external kernel module, the > asm operand 0 probably does not match constraints can still be > reproduced with "O0". I mean the "asm operand 0 probably does not match constraints" warning and related error can still be reproduced with "-O0" w/o the series. While after applying the series, I can't reproduce the build warning any more w/ and w/o the above modifications. > > Thanks > > > > > instead of the horrid hack with the char* cast and using a bool as an > > array index? > > > > > > > > > > > @@ -32,8 +32,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, > > > return true; > > > } > > > > > > -static __always_inline bool arch_static_branch_jump(struct static_key *key, > > > - bool branch) > > > +static __always_inline bool arch_static_branch_jump(struct static_key * const key, > > > + const bool branch) > > > { > > > asm_volatile_goto( > > > "1: b %l[l_yes] \n\t" > > > -- > > > 2.37.2 > > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel