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, 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 029A2C43381 for ; Mon, 15 Mar 2021 14:51:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCAB464E33 for ; Mon, 15 Mar 2021 14:51:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238423AbhCOOvo (ORCPT ); Mon, 15 Mar 2021 10:51:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237123AbhCOOgP (ORCPT ); Mon, 15 Mar 2021 10:36:15 -0400 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F8A7C0613D8 for ; Mon, 15 Mar 2021 07:35:56 -0700 (PDT) Received: by mail-wr1-x449.google.com with SMTP id p15so15045091wre.13 for ; Mon, 15 Mar 2021 07:35:56 -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=YZ/TJ8544r/cIimuF4tq7iBp2nvTUzw9xctrN4cslBs=; b=AY/u1mH3eVDmBX/B+MsmEGCoOU7pNrDV50CkR9fKMMsr+Oif7cI1ajXFxedjQgKt/y sKiDwfguHqTx0q/Po/HlIfnqyNAQTdKKW2E5vsN8bhGESmg93UAuYpr4HjO4SvTsyc5G tHC0QwzKY1MH3pP5UkPhiYZgiBC9cRJA9aW6QlewRpYeaC+X7iF7v2REapg7+u997Jpw Q22qFiPBqAkQeT2QBerbaxaG8Hb/3DA+TiUqF8ZhgqDi8fW7zTdp3FAVfpbmbGzBlw7X IRroZXfO5gNcib48xFvyRz+2ehEymI9c2D3If9a3IsT6iIiTA0NFfUy81HHOuCkLAhh8 aaug== 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=YZ/TJ8544r/cIimuF4tq7iBp2nvTUzw9xctrN4cslBs=; b=Xoi8wpZC1681SRzSC2b0/gUGrcwK94/kNx5WAvVi3RKLGeBuRldHzjoWnM1as+WvWV ehwwmLX+5A7DG+GtMjFs1kuwnV9eSfhHFBduQVWG1o0xB1mpPzL1bU6/4nkG5fqyrtmW wwGsorDQHzII9ypDs6uxgZFndZeHYTMhd1Io5Iz7aeRmvMJtKEit79Hv7ZcV8ihfqdAq wyEYBaCYccvras10x3WENNnZf1S10msEsE0IbYBt7xoRQJ0hXAd2oJeZBLxoVHBTxTqL jK004zUJt+txZ5YH6c571PT0SA+kZKFZszfnymLP+3pDMlZHVgom4jQMV6/2uB2u1Xao T6fw== X-Gm-Message-State: AOAM531/a7Tanybt3uiqrpf2gxyGDALNS721kEK+U/vSzUV9925nbHPM 2hKrhr1c7GYkfitQ30GtXIEB5OO1x4sD X-Google-Smtp-Source: ABdhPJzAP8GDMniHB+e8vB07G0Y5zSCnWugrj1o8MSaeFFNRNtxQgBGxeuDVNS2WyBRWX3zDHwOC4aE58S0l X-Received: from r2d2-qp.c.googlers.com ([fda3:e722:ac3:10:28:9cb1:c0a8:1652]) (user=qperret job=sendgmr) by 2002:a1c:df46:: with SMTP id w67mr12007wmg.176.1615818955131; Mon, 15 Mar 2021 07:35:55 -0700 (PDT) Date: Mon, 15 Mar 2021 14:35:07 +0000 In-Reply-To: <20210315143536.214621-1-qperret@google.com> Message-Id: <20210315143536.214621-8-qperret@google.com> Mime-Version: 1.0 References: <20210315143536.214621-1-qperret@google.com> X-Mailer: git-send-email 2.31.0.rc2.261.g7f71774620-goog Subject: [PATCH v5 07/36] 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, seanjc@google.com, mate.toth-pal@arm.com, linux-kernel@vger.kernel.org, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, tabba@google.com, ardb@kernel.org, mark.rutland@arm.com, dbrazdil@google.com, qperret@google.com 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) } -- 2.31.0.rc2.261.g7f71774620-goog