From patchwork Sun Oct 17 13:17:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 12564309 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E9636C433F5 for ; Sun, 17 Oct 2021 13:19:27 +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 B363D61260 for ; Sun, 17 Oct 2021 13:19:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B363D61260 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=m5karYvYsLlEZvpCPI4jJXZyg4bgOmt0l4ISN/CcNRo=; b=u/oDQvKw8c9nk4 6a23DNgPlLwVidNDAue9kjCjP+XEYG0N+k7UPpoyp8CxuAU0rL0bsgZdZxLPYguUEUljd/AMbFHAs MlhJSBSozrJO+jISwuz9LS0cqh0Q3aeuumCJUVIMFRBBNYZgm1dWxAm1STLo8OIpDiPV5PgbPj1u6 a6AT4+d1+QfH37t7kCSiGi23klTRfKditsiaMb7iUSqOx0L7Mn33W0nX1RyEPwP5cevkxMhxp79ix IDGgEe75bGP5D3fj/rIn5BvX8WOdbcWswQcihKMC8U+mkBQysCeqjFm5y3z0K4lceG7RwmEfdxfPO Q6Fl7/KsPH9+1gdVdv4w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mc63H-00CaiZ-2u; Sun, 17 Oct 2021 13:18:11 +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 1mc62l-00Cab5-PQ for linux-arm-kernel@lists.infradead.org; Sun, 17 Oct 2021 13:17:41 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 587F061248; Sun, 17 Oct 2021 13:17:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634476659; bh=G99G9KD+pR2ry5P+S6YGVbG/WqxJXWwyustgbvojX7E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hSOrnDWdg8HJfJeS4An+uXFmw3nqVJjGG3uWIzXAHTjCjKL8ziPucxHsErIMW8/1o 4O5acDHPXhBrQITQOyVbOoe0WW198sk4shRDXFVjwQIBs7JQ3wqzrujtUY90h5Cqel 4GtD7YO1iq0gbZQpVJbqrRUD9mYalg3GzpGMi8hLBftW7AtPRnmtHiAVvaN+gPAmKA CvbApI8BP3irSBIWsalbOtMoQfnGGdzzRi/czigLFRUQ6dIBUfFzAq+JEoxzkVd6v6 MtWm0Z0H7qYBceW+MWVwPAkBzndwR4UwEl190urn1PsJt1wuKAemZiDdUW/54vUno8 a2t99eQ3559tw== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Russell King , Arnd Bergmann , Kees Cook , Keith Packard , Linus Walleij , Nick Desaulniers , Nicolas Pitre Subject: [PATCH v3 03/10] ARM: optimize indirect call to handle_arch_irq for v7 cores Date: Sun, 17 Oct 2021 15:17:16 +0200 Message-Id: <20211017131723.4034662-4-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211017131723.4034662-1-ardb@kernel.org> References: <20211017131723.4034662-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1384; h=from:subject; bh=G99G9KD+pR2ry5P+S6YGVbG/WqxJXWwyustgbvojX7E=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBhbCJUiArqG4jnO54xjKLbnURKMLuDr6yiDr6r0wh2 1So/OOmJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYWwiVAAKCRDDTyI5ktmPJFVSC/ 9GtDgtSzwwAhSzG7EaF/aP3hGHvzE34MjEmfwU6UiUtDGi5olBPCtpE6mFwh3nY3aIvU/T71I3HdE/ DMx00yVmt9htvVxYhpn+vqAi+3Av1S5BWxw7GNVqqRGaZHgpiVVGZ5E1wNqXtw8pUgm8tYJX2mnlGt 7KqvwRLNAn4EU8Up+20RbN1hXXtga9mpdFrFLxRRkNfL3Q3LOxPa2tHOohDsd/GKDFzVQiVr5uGxl+ /XEjTcBJyZO4dqEVq6nAFdWFSUbCivoCW1NR0SrTsWaRexfQM0wk7DOlQM3xp4tr+eaCUw3DkVPoV+ 7AhkwSq4d0b3eUhg42JsoTfLhBZj2sRqj2ndoJYQBl6fhq0TT201DFamyt7pi2ffm+T/zlMW//Uhwr dHQimn0c5jTtVpXgw41I2Rd5KRMx4jcp5UcVXs5RclJGX9UtWdmaEv+7GJyVl7PSXT1wQrVSeMDC7T TtXqv+vwP2tHfVvOSVrjTgn8/LPHtBGIEwwI8qAkhoAY4= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211017_061739_868691_52D56821 X-CRM114-Status: GOOD ( 12.12 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The current irq_handler macro uses a literal load followed by an explicit assignment of lr before an indirect call, both of which are sub-optimal on recent ARM cores. Replace it by a mov_l call, which will evaluate to a movw/movt pair on v7 cores, avoiding one of the two loads, followed by a call to a newly introduced 'bl_m' macro, which will evaluate to a blx instruction on cores that support it. (Setting lr explicitly rather than via a bl or blx instruction confuses the return address prediction that modern out-of-order cores use to speculatively perform the function return.) Signed-off-by: Ard Biesheuvel Reviewed-by: Arnd Bergmann Acked-by: Linus Walleij Tested-by: Keith Packard --- arch/arm/kernel/entry-armv.S | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index a54b5044d406..21896f702447 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -38,14 +38,12 @@ */ .macro irq_handler #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER - ldr r1, =handle_arch_irq + mov_l r1, handle_arch_irq mov r0, sp - badr lr, 9997f - ldr pc, [r1] + bl_m [r1] #else arch_irq_handler_default #endif -9997: .endm .macro pabt_helper