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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 8F13EC43332 for ; Wed, 10 Mar 2021 17:58:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E89364FB3 for ; Wed, 10 Mar 2021 17:58:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233646AbhCJR6Z (ORCPT ); Wed, 10 Mar 2021 12:58:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233416AbhCJR6K (ORCPT ); Wed, 10 Mar 2021 12:58:10 -0500 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 465E5C061760 for ; Wed, 10 Mar 2021 09:58:10 -0800 (PST) Received: by mail-qv1-xf49.google.com with SMTP id o14so13271938qvn.18 for ; Wed, 10 Mar 2021 09:58:10 -0800 (PST) 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=9K/nJk/Yl2gqbmnNeiM3LL/ayLtkmDAblR9vIKiL4JQ=; b=GO/2FBWOCecwwU9cbVkaCLcKOpNoYUEQxlXaOTju5rYBLJe6KVFOjZhrsr50oPi7cJ oixBWT8jN56XkSpGuyKtO7eFphPP+fGTZfyqjhPKFqd5yH5nSuUmj1pyzAf5pzxmu56q A+0qc/vZxgDTaFGM0qtohkzJjFQauPf5/o54cNNBWWToVoSBWWknU86U6JG86OhlV+G/ vZ5/5v1tIaKV0lowHVFm2NL0U6mxRVnpTeAe53hf5LDhQ4RuUfWYqTjD1ujQMQP6H/hw E5lUbIgyH/HaFOtUtqmH3lb3sXaCSAfTmPfh2bO716yMOy+JBoQaPhloemCr0YtCElvV juvw== 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=9K/nJk/Yl2gqbmnNeiM3LL/ayLtkmDAblR9vIKiL4JQ=; b=eLcpPuXALwFD/ZIA9DszpAJOEVME+sMAhbTCWV84rgRzTbxBkVSf8ciP3HCDH5cwxw fyZBj3eBEeHqFTpAtX6gogIp8/UC9yGgySush74ZZud/iuyQZNv92lRy3uJ2SuQE1Eww DZbsm5rdD2BKgOmU7tYN6xGvBbVqz/7fu7qePKQG+7RFiONdtcucngLQbklLEEuo3G/F AGfuMjl9OYtQvmegfrE4XgS93VhKNrxfsitBix+x8Aw/v/ejZduZZZ8FWtu/WA2XXnWQ mA2394sxQsRbz2HArUQ0iKv98Ae0S4x/kwZa3JVeboqmD7RSEaZCq4cEmqgrbdkrnq4B P13A== X-Gm-Message-State: AOAM530+Ep7d0RKI3q5NCrA8Cx8kIquzWzN2hEYrEKiqn8lYagTbI4bB WeW5zGIHe03GK2qclFY+MW+TG2OdPKry X-Google-Smtp-Source: ABdhPJzB9OC6KWOlWJUJdL2k6mNjWxJq7jz6ESdJuBvXdwVSCdMLhWW4203j676QenoaxLPF0EYv6dv6kppm X-Received: from r2d2-qp.c.googlers.com ([fda3:e722:ac3:10:28:9cb1:c0a8:1652]) (user=qperret job=sendgmr) by 2002:a05:6214:1870:: with SMTP id eh16mr4059145qvb.23.1615399089435; Wed, 10 Mar 2021 09:58:09 -0800 (PST) Date: Wed, 10 Mar 2021 17:57:24 +0000 In-Reply-To: <20210310175751.3320106-1-qperret@google.com> Message-Id: <20210310175751.3320106-8-qperret@google.com> Mime-Version: 1.0 References: <20210310175751.3320106-1-qperret@google.com> X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog Subject: [PATCH v4 07/34] KVM: arm64: Introduce a BSS section for use at Hyp From: Quentin Perret To: catalin.marinas@arm.com, will@kernel.org, maz@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com Cc: android-kvm@google.com, linux-kernel@vger.kernel.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, tabba@google.com, mark.rutland@arm.com, dbrazdil@google.com, mate.toth-pal@arm.com, seanjc@google.com, qperret@google.com, robh+dt@kernel.org, ardb@kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, the hyp code cannot make full use of a bss, as the kernel section is mapped read-only. While this mapping could simply be changed to read-write, it would intermingle even more the hyp and kernel state than they currently are. Instead, introduce a __hyp_bss section, that uses reserved pages, and create the appropriate RW hyp mappings during KVM init. Acked-by: Will Deacon Signed-off-by: Quentin Perret --- arch/arm64/include/asm/sections.h | 1 + arch/arm64/kernel/vmlinux.lds.S | 52 ++++++++++++++++++++----------- arch/arm64/kvm/arm.c | 14 ++++++++- arch/arm64/kvm/hyp/nvhe/hyp.lds.S | 1 + 4 files changed, 49 insertions(+), 19 deletions(-) diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h index 2f36b16a5b5d..e4ad9db53af1 100644 --- a/arch/arm64/include/asm/sections.h +++ b/arch/arm64/include/asm/sections.h @@ -13,6 +13,7 @@ extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[]; extern char __hyp_text_start[], __hyp_text_end[]; extern char __hyp_rodata_start[], __hyp_rodata_end[]; extern char __hyp_reloc_begin[], __hyp_reloc_end[]; +extern char __hyp_bss_start[], __hyp_bss_end[]; extern char __idmap_text_start[], __idmap_text_end[]; extern char __initdata_begin[], __initdata_end[]; extern char __inittext_begin[], __inittext_end[]; diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 7eea7888bb02..e96173ce211b 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -5,24 +5,7 @@ * Written by Martin Mares */ -#define RO_EXCEPTION_TABLE_ALIGN 8 -#define RUNTIME_DISCARD_EXIT - -#include -#include #include -#include -#include -#include - -#include "image.h" - -OUTPUT_ARCH(aarch64) -ENTRY(_text) - -jiffies = jiffies_64; - - #ifdef CONFIG_KVM #define HYPERVISOR_EXTABLE \ . = ALIGN(SZ_8); \ @@ -51,13 +34,43 @@ jiffies = jiffies_64; __hyp_reloc_end = .; \ } +#define BSS_FIRST_SECTIONS \ + __hyp_bss_start = .; \ + *(HYP_SECTION_NAME(.bss)) \ + . = ALIGN(PAGE_SIZE); \ + __hyp_bss_end = .; + +/* + * We require that __hyp_bss_start and __bss_start are aligned, and enforce it + * with an assertion. But the BSS_SECTION macro places an empty .sbss section + * between them, which can in some cases cause the linker to misalign them. To + * work around the issue, force a page alignment for __bss_start. + */ +#define SBSS_ALIGN PAGE_SIZE #else /* CONFIG_KVM */ #define HYPERVISOR_EXTABLE #define HYPERVISOR_DATA_SECTIONS #define HYPERVISOR_PERCPU_SECTION #define HYPERVISOR_RELOC_SECTION +#define SBSS_ALIGN 0 #endif +#define RO_EXCEPTION_TABLE_ALIGN 8 +#define RUNTIME_DISCARD_EXIT + +#include +#include +#include +#include +#include + +#include "image.h" + +OUTPUT_ARCH(aarch64) +ENTRY(_text) + +jiffies = jiffies_64; + #define HYPERVISOR_TEXT \ /* \ * Align to 4 KB so that \ @@ -276,7 +289,7 @@ SECTIONS __pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin); _edata = .; - BSS_SECTION(0, 0, 0) + BSS_SECTION(SBSS_ALIGN, 0, 0) . = ALIGN(PAGE_SIZE); init_pg_dir = .; @@ -324,6 +337,9 @@ ASSERT(__hibernate_exit_text_end - (__hibernate_exit_text_start & ~(SZ_4K - 1)) ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == PAGE_SIZE, "Entry trampoline text too big") #endif +#ifdef CONFIG_KVM +ASSERT(__hyp_bss_start == __bss_start, "HYP and Host BSS are misaligned") +#endif /* * If padding is applied before .head.text, virt<->phys conversions will fail. */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 2d1e7ef69c04..3f8bcf8db036 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -1770,7 +1770,19 @@ static int init_hyp_mode(void) goto out_err; } - err = create_hyp_mappings(kvm_ksym_ref(__bss_start), + /* + * .hyp.bss is guaranteed to be placed at the beginning of the .bss + * section thanks to an assertion in the linker script. Map it RW and + * the rest of .bss RO. + */ + err = create_hyp_mappings(kvm_ksym_ref(__hyp_bss_start), + kvm_ksym_ref(__hyp_bss_end), PAGE_HYP); + if (err) { + kvm_err("Cannot map hyp bss section: %d\n", err); + goto out_err; + } + + err = create_hyp_mappings(kvm_ksym_ref(__hyp_bss_end), kvm_ksym_ref(__bss_stop), PAGE_HYP_RO); if (err) { kvm_err("Cannot map bss section\n"); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S index cd119d82d8e3..f4562f417d3f 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S @@ -25,4 +25,5 @@ SECTIONS { BEGIN_HYP_SECTION(.data..percpu) PERCPU_INPUT(L1_CACHE_BYTES) END_HYP_SECTION + HYP_SECTION(.bss) } -- 2.30.1.766.gb4fecdf3b7-goog