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 X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7BB0EC433F5 for ; Mon, 13 Sep 2021 10:43:59 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 4393761004 for ; Mon, 13 Sep 2021 10:43:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4393761004 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org 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:References:In-Reply-To: Message-Id:Date: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=2E5KcUqe0QgZriS+qc/wQRQQn20RAADeNQQVqn/JzcE=; b=axK2HUAK3uNNsO rI7NWxQuCWjAPAC/+a6e31iKiqOzLZQgG/lowc48gf1IpxhY0NuYj/0AYMNl97sVyVfpPokDwPkMt UCjpwSNl7XJETYyauya8/ZxjSVEW7+/NIkvBSkmcIlQ0pXBC1fqN6H5msGZodasR3cOlWByFF+xdU Nj87RRmTD+/nmshb02R3B4yaNBa3VTbzZ0fssq1tWHzsyhrm5jWF9GzNKKz10mHlwStIkaB34uwY9 AHz1s3NB+I12ow0jgZbwh09YnkzLJWcSOctuur7lGrPWUddGALGIRDiB/JR/MqFNTTObaSQy6GCvx GAERKpXQ2tAhZ2sBh20Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mPjPA-001LFc-3d; Mon, 13 Sep 2021 10:41:40 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mPjOE-001L22-Ng for linux-arm-kernel@lists.infradead.org; Mon, 13 Sep 2021 10:40:44 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id B30D861051; Mon, 13 Sep 2021 10:40:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631529642; bh=fFWrxLHpr8xNHrBOw7ng9TZOKBHc2hW0opgi0nPflyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r60IUThHFFUIcEUKwHP2CSYggI6EPfIvWhAIo7T+1Rwrw/OTqL5UEIahc3qz8buoP cbmOpLCkhZQ1joZXoo/QapznEcw700kuMdJBQRR2eXw2TB2ibgkJiCO7mYfUqmIcOB RA/A/lvUuR10OV9KMX2Rr2SHJYN2Q/hIuUsCS9ZFLYaoaZjuaHKFdrbrOBl4AqbWjP aGZf57NFfk8P0P2dZrugCdU1iJbABwhPgAxziPjIntlMWQNKUkhrCpDwBgN8GJYOet zqAlEewy32GrCPjyYKJ4Af4Vwwfzq4dSHZtpOgNoZHt301ELvIjpgYtnmQ+nECmfAr KWPCRvYGWbg4g== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Keith Packard , Russell King , Kees Cook , Arnd Bergmann , Linus Walleij Subject: [PATCH v4 3/5] ARM: smp: Free up the TLS register while running in the kernel Date: Mon, 13 Sep 2021 12:39:59 +0200 Message-Id: <20210913104001.3043132-4-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210913104001.3043132-1-ardb@kernel.org> References: <20210913104001.3043132-1-ardb@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210913_034042_850180_2BF7E8D8 X-CRM114-Status: GOOD ( 16.02 ) 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 To prepare for a subsequent patch that stores the current task pointer in the user space TLS register while running in the kernel, modify the set_tls and switch_tls routines not to touch the register directly, and update the return to user space code to load the correct value. Signed-off-by: Ard Biesheuvel --- arch/arm/include/asm/tls.h | 10 +++++++--- arch/arm/kernel/entry-header.S | 8 ++++++++ 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h index 5a66c3b13c92..c3296499176c 100644 --- a/arch/arm/include/asm/tls.h +++ b/arch/arm/include/asm/tls.h @@ -12,8 +12,8 @@ .macro switch_tls_v6k, base, tp, tpuser, tmp1, tmp2 mrc p15, 0, \tmp2, c13, c0, 2 @ get the user r/w register - mcr p15, 0, \tp, c13, c0, 3 @ set TLS register - mcr p15, 0, \tpuser, c13, c0, 2 @ and the user r/w register + @ TLS register update is deferred until return to user space + mcr p15, 0, \tpuser, c13, c0, 2 @ set the user r/w register str \tmp2, [\base, #TI_TP_VALUE + 4] @ save it .endm @@ -38,18 +38,22 @@ #ifdef CONFIG_TLS_REG_EMUL #define tls_emu 1 #define has_tls_reg 1 +#define defer_tls_reg_update 0 #define switch_tls switch_tls_none #elif defined(CONFIG_CPU_V6) #define tls_emu 0 #define has_tls_reg (elf_hwcap & HWCAP_TLS) +#define defer_tls_reg_update 0 #define switch_tls switch_tls_v6 #elif defined(CONFIG_CPU_32v6K) #define tls_emu 0 #define has_tls_reg 1 +#define defer_tls_reg_update 1 #define switch_tls switch_tls_v6k #else #define tls_emu 0 #define has_tls_reg 0 +#define defer_tls_reg_update 0 #define switch_tls switch_tls_software #endif @@ -77,7 +81,7 @@ static inline void set_tls(unsigned long val) */ barrier(); - if (!tls_emu) { + if (!tls_emu && !defer_tls_reg_update) { if (has_tls_reg) { asm("mcr p15, 0, %0, c13, c0, 3" : : "r" (val)); diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 40db0f9188b6..d5845cb820f3 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -292,6 +292,14 @@ .macro restore_user_regs, fast = 0, offset = 0 +#ifdef CONFIG_CPU_32v6K + @ The TLS register update is deferred until return to user space so we + @ can use it for other things while running in the kernel + get_thread_info r1 + ldr r1, [r1, #TI_TP_VALUE] + mcr p15, 0, r1, c13, c0, 3 @ set TLS register +#endif + uaccess_enable r1, isb=0 #ifndef CONFIG_THUMB2_KERNEL @ ARM mode restore -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel