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=-13.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 01F0BC433E2 for ; Mon, 20 Jul 2020 18:26:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D5122208E4 for ; Mon, 20 Jul 2020 18:26:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="SRV3gLWL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729334AbgGTS0M (ORCPT ); Mon, 20 Jul 2020 14:26:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726506AbgGTS0L (ORCPT ); Mon, 20 Jul 2020 14:26:11 -0400 Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7E5EC0619D2; Mon, 20 Jul 2020 11:26:11 -0700 (PDT) Received: by mail-wr1-x443.google.com with SMTP id f18so18853120wrs.0; Mon, 20 Jul 2020 11:26:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=lj9ZknVcrD3MA4t8QmNQ12rpsDUhjiYrWHP/I1wz74s=; b=SRV3gLWLaFDivOniTKfXDlRqb5BR+1ORl45h0alrybpcGwh7MwzAnhjDYScrdQqAqG lOq7WpXbxUWnuOLBbnG9RFx479KHXJndGnOfGK324YKDf6WK0tAWyhclNcP0Sz9BXvL0 h05LUSwfwEF9cS4s1p9XCgHvN9qskodgaabbClsTwme6/gsZsOE1/dwmzrIyFEgiXOJj hZSXFqFkwLAxF0jIQZhLz6lI5u9UTUUX7Fph6uS/tHMANVbjYFezP1ll6SOsKeidsNqB d6GwRwLDsJkqxky3JbTiVVK8aAXHZ9PwIk4SwUBjDuHaKT3aEY3xRIug92j1IxYnM4GG /3nw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=lj9ZknVcrD3MA4t8QmNQ12rpsDUhjiYrWHP/I1wz74s=; b=XvRz4G7RZ5eE3a0/fLJEVkMSPtZTooyxP+EdcD9/+GHG9DZpwbjwq3w8yiAvUqDKXD t3SlDENKG0l54USxooaSaSAAvaYhWlzAmGXYfqjinz+BEG7xwKlN/LKew6WwmdJS6r4n oBdAxiUTcBEm7m5nl/AzOrIk+s595lYEUTyVK1KfIpFTd7jIeq2oo5R8mWSdxPNZXuxX MseVFCKtZsW++lskLdqO7+mLWnLdb8TcpmkF+Cpjc0ZeCLMYlRTluSXeJJ72XusEtac7 Soh2Ih0DI7nOsB/tKqdcDxAmERkQUfGjnazRGDkuPPh2dgiC5oZz+KHYAyDYfoHMzWX9 GR7A== X-Gm-Message-State: AOAM531dzlXIr6mZr14Z0+MwHbOZWVILWXwpOIYdcRMeXsfeBwErCL4m eEo+JIuPUS0M0bAkUg5otfvflX7o X-Google-Smtp-Source: ABdhPJzTmHsYloYlnQp0ihbIybRCflF9ZffwP80u0Ay5lylmf7xqW8rfqcqRdHMBm/3lVw2qdPpZvQ== X-Received: by 2002:adf:d08d:: with SMTP id y13mr3145410wrh.313.1595269570059; Mon, 20 Jul 2020 11:26:10 -0700 (PDT) Received: from fainelli-desktop.igp.broadcom.net ([192.19.223.252]) by smtp.gmail.com with ESMTPSA id v11sm699363wmb.3.2020.07.20.11.26.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jul 2020 11:26:09 -0700 (PDT) From: Florian Fainelli To: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org, will@kernel.org, Will Deacon , Florian Fainelli , Catalin Marinas , Christoffer Dall , Marc Zyngier , Sasha Levin , Mark Rutland , Julien Thierry , Greg Kroah-Hartman , linux-arm-kernel@lists.infradead.org (moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)), kvmarm@lists.cs.columbia.edu (open list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)) Subject: [PATCH stable 4.19.y] arm64: entry: Place an SB sequence following an ERET instruction Date: Mon, 20 Jul 2020 11:25:37 -0700 Message-Id: <20200720182538.13304-1-f.fainelli@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Will Deacon commit 679db70801da9fda91d26caf13bf5b5ccc74e8e8 upstream Some CPUs can speculate past an ERET instruction and potentially perform speculative accesses to memory before processing the exception return. Since the register state is often controlled by a lower privilege level at the point of an ERET, this could potentially be used as part of a side-channel attack. This patch emits an SB sequence after each ERET so that speculation is held up on exception return. Signed-off-by: Will Deacon Signed-off-by: Florian Fainelli --- arch/arm64/kernel/entry.S | 2 ++ arch/arm64/kvm/hyp/entry.S | 1 + arch/arm64/kvm/hyp/hyp-entry.S | 4 ++++ 3 files changed, 7 insertions(+) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 5f800384cb9a..49f80b5627fa 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -363,6 +363,7 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 .else eret .endif + sb .endm .macro irq_stack_entry @@ -994,6 +995,7 @@ alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 mrs x30, far_el1 .endif eret + sb .endm .align 11 diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index fad1e164fe48..675fdc186e3b 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -83,6 +83,7 @@ ENTRY(__guest_enter) // Do not touch any register after this! eret + sb ENDPROC(__guest_enter) ENTRY(__guest_exit) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index 24b4fbafe3e4..e35abf84eb96 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -96,6 +96,7 @@ el1_sync: // Guest trapped into EL2 do_el2_call eret + sb el1_hvc_guest: /* @@ -146,6 +147,7 @@ wa_epilogue: mov x0, xzr add sp, sp, #16 eret + sb el1_trap: get_vcpu_ptr x1, x0 @@ -185,6 +187,7 @@ el2_error: b.ne __hyp_panic mov x0, #(1 << ARM_EXIT_WITH_SERROR_BIT) eret + sb ENTRY(__hyp_do_panic) mov lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\ @@ -193,6 +196,7 @@ ENTRY(__hyp_do_panic) ldr lr, =panic msr elr_el2, lr eret + sb ENDPROC(__hyp_do_panic) ENTRY(__hyp_panic) -- 2.17.1