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=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 CAFD3CA9EA9 for ; Fri, 18 Oct 2019 16:10:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9FD9E222C6 for ; Fri, 18 Oct 2019 16:10:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZvzQdFSz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2442935AbfJRQK6 (ORCPT ); Fri, 18 Oct 2019 12:10:58 -0400 Received: from mail-yw1-f73.google.com ([209.85.161.73]:42610 "EHLO mail-yw1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2442650AbfJRQK4 (ORCPT ); Fri, 18 Oct 2019 12:10:56 -0400 Received: by mail-yw1-f73.google.com with SMTP id o14so4756872ywa.9 for ; Fri, 18 Oct 2019 09:10:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=72rGRuWFiviz942NA6zVkn9gcWlAdBMK2y71uV80e5M=; b=ZvzQdFSzTLbEjP4zxdusVf3ReL3ljnpZzJfPdrbpnE9rMeefuhQHID/ee1FAoqvYLH O+/PdDLy+eoWqhA9UIEIUFRCMC5xqhNowPZWx2ww/HoS+63BhQ5I1HOf+y5t9GV4AlzB 4wvvMPqaOkuUSsDFHTVS6xJHhNUp3s1c9Y1ghonvzQD2ZPiXv5LmNp53Biqgoh9GKiCJ afEukw6/WMLv2boh6kNWUds4TgOnVVcCplvVwI02NOYpPnoOVZxpUv2JWmCC5FcJjdP9 qyuCgJgGG2jATFBKXIAZK/fXaf2KYXXK+X2rgvP6lspQZZSv0gH/6LOEhAEKe42LtQC+ cKeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=72rGRuWFiviz942NA6zVkn9gcWlAdBMK2y71uV80e5M=; b=KM9cLDQVbkXw8R8pQK3de3EhZz+xtiCoX4JVxt8+DtmDiPqQqYjHn+dCOgOEV90ld4 +3q34txxsMtLjaweWEF4UkcmsRWxBpjGh5C1YFBt3qXyQRJd4As70+Ltbv3GQeMm1hAY d5BIZd/6YVCoKg0tLiQSvKoCKWyadw9fpjjVbRNvKWiG30AlNaZYHSz2tscqWviyxZCE VXInN0C1viGICmXxbj0xzrvIae7CsofC4AVJcX6QhqCpPuhDrPLV4j9FKWSvRMUIpKSZ B54KBby6v3SMApRmZVf8njFRSkfblBXIme0Wtx5xEjlc2hUYvcUwdGT5xIJu1XzB9j0I SS9A== X-Gm-Message-State: APjAAAXQQh1diR16xUFviAghnSLROnVPL5CCiyeCXdAM3tllnSP2ZFBx fxsCLfjf/MOfxRp56aMmwOdCE4GAgXEt1RED3d8= X-Google-Smtp-Source: APXvYqxINkQeafZ9JYtVaWg+qUXlNkxSB5ctm2wREg/j/aMT/J4ez6ebkhDJlYmKEc3YyNUDF8Zxh7j2jKVxFaFkVRU= X-Received: by 2002:a0d:d804:: with SMTP id a4mr7899178ywe.454.1571415054615; Fri, 18 Oct 2019 09:10:54 -0700 (PDT) Date: Fri, 18 Oct 2019 09:10:18 -0700 In-Reply-To: <20191018161033.261971-1-samitolvanen@google.com> Message-Id: <20191018161033.261971-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> X-Mailer: git-send-email 2.23.0.866.gb869b98d4c-goog Subject: [PATCH 03/18] arm64: kvm: stop treating register x18 as caller save From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Ard Biesheuvel Cc: Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel In preparation of using x18 as a task struct pointer register when running in the kernel, stop treating it as caller save in the KVM guest entry/exit code. Currently, the code assumes there is no need to preserve it for the host, given that it would have been assumed clobbered anyway by the function call to __guest_enter(). Instead, preserve its value and restore it upon return. Link: https://patchwork.kernel.org/patch/9836891/ Signed-off-by: Ard Biesheuvel Signed-off-by: Sami Tolvanen --- arch/arm64/kvm/hyp/entry.S | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index e5cc8d66bf53..20bd9a20ea27 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -23,6 +23,7 @@ .pushsection .hyp.text, "ax" .macro save_callee_saved_regs ctxt + str x18, [\ctxt, #CPU_XREG_OFFSET(18)] stp x19, x20, [\ctxt, #CPU_XREG_OFFSET(19)] stp x21, x22, [\ctxt, #CPU_XREG_OFFSET(21)] stp x23, x24, [\ctxt, #CPU_XREG_OFFSET(23)] @@ -38,6 +39,7 @@ ldp x25, x26, [\ctxt, #CPU_XREG_OFFSET(25)] ldp x27, x28, [\ctxt, #CPU_XREG_OFFSET(27)] ldp x29, lr, [\ctxt, #CPU_XREG_OFFSET(29)] + ldr x18, [\ctxt, #CPU_XREG_OFFSET(18)] .endm /* @@ -87,12 +89,9 @@ alternative_else_nop_endif ldp x14, x15, [x18, #CPU_XREG_OFFSET(14)] ldp x16, x17, [x18, #CPU_XREG_OFFSET(16)] - // Restore guest regs x19-x29, lr + // Restore guest regs x18-x29, lr restore_callee_saved_regs x18 - // Restore guest reg x18 - ldr x18, [x18, #CPU_XREG_OFFSET(18)] - // Do not touch any register after this! eret sb @@ -114,7 +113,7 @@ ENTRY(__guest_exit) // Retrieve the guest regs x0-x1 from the stack ldp x2, x3, [sp], #16 // x0, x1 - // Store the guest regs x0-x1 and x4-x18 + // Store the guest regs x0-x1 and x4-x17 stp x2, x3, [x1, #CPU_XREG_OFFSET(0)] stp x4, x5, [x1, #CPU_XREG_OFFSET(4)] stp x6, x7, [x1, #CPU_XREG_OFFSET(6)] @@ -123,9 +122,8 @@ ENTRY(__guest_exit) stp x12, x13, [x1, #CPU_XREG_OFFSET(12)] stp x14, x15, [x1, #CPU_XREG_OFFSET(14)] stp x16, x17, [x1, #CPU_XREG_OFFSET(16)] - str x18, [x1, #CPU_XREG_OFFSET(18)] - // Store the guest regs x19-x29, lr + // Store the guest regs x18-x29, lr save_callee_saved_regs x1 get_host_ctxt x2, x3 -- 2.23.0.866.gb869b98d4c-goog