From patchwork Fri Oct 18 16:10:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11199057 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E4D841951 for ; Fri, 18 Oct 2019 16:14:01 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 43D2C21D7C for ; Fri, 18 Oct 2019 16:14:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZvzQdFSz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 43D2C21D7C Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17023-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 15681 invoked by uid 550); 18 Oct 2019 16:14:00 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 9780 invoked from network); 18 Oct 2019 16:11:06 -0000 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=COi6zfFZpazCCw9FnhK6DaDcjPTJGyOHvXrwmRgzieWzAAuQbMd8nC8pyQPa4HrcwW cPqG99ASSrBEDSa9rrkCwICmSuiv8S9yn2IMYPf6+h75N0NcbO7mYS8pVhE9ByrSbDoa vJJeN6IzSL6IsfRFcCpKE8e8Arzjl5toRpr0hysc9PSAZ4y6ca3+IRi/BxjAzkp54j3v EGvPOtJy5t/5QZeS5TmgEPJTZDcqkj4QBYpuhLf3d7fFIRbfUlTX6yILDGc7LdCMwTnV rnTf7b7nkRTfhiu7wkKUhcjqZzvk50dv0R/dLiRIlIgDEzx411irG1GYhYtEunye/wId rU3w== X-Gm-Message-State: APjAAAXEendp18GKXrj5vrK5yQqNPlKGWRnDPRmFdmF4ZepSKHo9OxYK rETSK09qTQj05QM7M4LGTWuaZyt7iSJLkeD7Wmk= 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 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