From patchwork Thu Mar 10 14:09:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 550493 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 11245C433F5 for ; Thu, 10 Mar 2022 14:11:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242752AbiCJOMz (ORCPT ); Thu, 10 Mar 2022 09:12:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51062 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242748AbiCJOMg (ORCPT ); Thu, 10 Mar 2022 09:12:36 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 508D5151697; Thu, 10 Mar 2022 06:10:51 -0800 (PST) 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 E282961B7D; Thu, 10 Mar 2022 14:10:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CE3D4C340F3; Thu, 10 Mar 2022 14:10:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646921450; bh=25Hk37nJ7k4GM1ojM6Tgufom7M/GqJr5xVZym4GE6GU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2wiSzsLS2ePmzuNGy1x7y5Q9HO736ZvpM0ul6bctLgJf8RUOLj8opU3ewhdRNttsz 9m3VDA527JE/UeTOxBsWMBqSHVQN/U6PNKyQHYji9G/nwUMts0nhCsi7DuSDwC82FL lR5KOonlMWADdBNmBVYB9jInwBHuMEq+eml9e/DY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Russell King (Oracle)" , Catalin Marinas , James Morse Subject: [PATCH 5.16 21/53] arm64: entry: Free up another register on kptis tramp_exit path Date: Thu, 10 Mar 2022 15:09:26 +0100 Message-Id: <20220310140812.443539538@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220310140811.832630727@linuxfoundation.org> References: <20220310140811.832630727@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: James Morse commit 03aff3a77a58b5b52a77e00537a42090ad57b80b upstream. Kpti stashes x30 in far_el1 while it uses x30 for all its work. Making the vectors a per-cpu data structure will require a second register. Allow tramp_exit two registers before it unmaps the kernel, by leaving x30 on the stack, and stashing x29 in far_el1. Reviewed-by: Russell King (Oracle) Reviewed-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/entry.S | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -419,14 +419,16 @@ alternative_else_nop_endif ldp x24, x25, [sp, #16 * 12] ldp x26, x27, [sp, #16 * 13] ldp x28, x29, [sp, #16 * 14] - ldr lr, [sp, #S_LR] - add sp, sp, #PT_REGS_SIZE // restore sp .if \el == 0 -alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 +alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 + ldr lr, [sp, #S_LR] + add sp, sp, #PT_REGS_SIZE // restore sp + eret +alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 bne 4f - msr far_el1, x30 + msr far_el1, x29 tramp_alias x30, tramp_exit_native br x30 4: @@ -434,6 +436,9 @@ alternative_insn eret, nop, ARM64_UNMAP_ br x30 #endif .else + ldr lr, [sp, #S_LR] + add sp, sp, #PT_REGS_SIZE // restore sp + /* Ensure any device/NC reads complete */ alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412 @@ -674,10 +679,12 @@ alternative_else_nop_endif .macro tramp_exit, regsize = 64 adr x30, tramp_vectors msr vbar_el1, x30 - tramp_unmap_kernel x30 + ldr lr, [sp, #S_LR] + tramp_unmap_kernel x29 .if \regsize == 64 - mrs x30, far_el1 + mrs x29, far_el1 .endif + add sp, sp, #PT_REGS_SIZE // restore sp eret sb .endm