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 202A0C433E0 for ; Tue, 2 Mar 2021 17:33:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D326464F23 for ; Tue, 2 Mar 2021 17:33:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1580158AbhCBRaU (ORCPT ); Tue, 2 Mar 2021 12:30:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1444277AbhCBPG3 (ORCPT ); Tue, 2 Mar 2021 10:06:29 -0500 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 543C1C0698CE for ; Tue, 2 Mar 2021 07:01:06 -0800 (PST) Received: by mail-qk1-x749.google.com with SMTP id k185so17009880qkb.17 for ; Tue, 02 Mar 2021 07:01:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=fnu4kZLmantAPLgmfgZ7PZzVHqXbW8DjkSliDC/e8I8=; b=uUNW1RSwz/PPPl1Ua1IuQ64hOM0R+lTodrWU3UbAefyenAEai8RA0+im6R8w77uKKJ g4DVj/KqEe1TwMkcz/Ygt9jjIn5f38pgXuncyWnVA/+aa/N++uGeKO34r+o678oP9Mq8 67RAjq0NNwnf+jsn3QGIHhc250LRidVe1EfBP+5OIoO/7rtNLutaZrtEM1c24NPrdROO AFGrLf0EhJQzjScHxY2yPE6vMV/MjHb4X61lyzoWiVZ4RX2UG8RcNll2OE8OrY1N1eKg 6/SG5RQNSa0TOnAV1pRMMAOGJJqvxbtGjwYBUsH85FOGQKa/2mvXOYVgOo4Aa+FxfQOa yteA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=fnu4kZLmantAPLgmfgZ7PZzVHqXbW8DjkSliDC/e8I8=; b=fveHV5coVWupwIgZsMnMaxTE8IEQu6k/wniyXUyvG2vR2kqbavho4Y1i1oZnSDFyZU d/1McMB6VLVFXejsiga7dffPKLrm/mG1tTGPxbULD804clhlovgE4cRUhH18H86jxukf 1WxrkOTOoZrmOqH8g8a52jumx9Al/37rBHlBeWa7Cu3sLBM9KiZNoUheI0/F2B9SPpU+ Fcde9UdNp5pd9sXmyzJKRrCZLC+T7pvk8RylDhseIRyZfNqxKy3kLgH/7Mf+pvGN8ppL kzEea8xGtVvYriyOnIiUj75+AoBhMovi5VFqIpAhY6XReArHO80oA5j3ASofg2OL0mRa UrdA== X-Gm-Message-State: AOAM532X9p6MxTWKp2iBkPHds2mxD4ZcJVBdR+8TDIBwQO8HrmhJjGFu Dc7xo0YgChVUwnLtK3ng5+/AFPOmLP8N X-Google-Smtp-Source: ABdhPJw8Dq6/V08jN1owoo4yABfxU5wp1FwJVtfeIaUa56rS2EjFaWfxxNpGQxARvmsP7DWrgv0nk/HKhje6 Sender: "qperret via sendgmr" X-Received: from r2d2-qp.c.googlers.com ([fda3:e722:ac3:10:28:9cb1:c0a8:1652]) (user=qperret job=sendgmr) by 2002:a0c:c78c:: with SMTP id k12mr3964748qvj.47.1614697265404; Tue, 02 Mar 2021 07:01:05 -0800 (PST) Date: Tue, 2 Mar 2021 14:59:56 +0000 In-Reply-To: <20210302150002.3685113-1-qperret@google.com> Message-Id: <20210302150002.3685113-27-qperret@google.com> Mime-Version: 1.0 References: <20210302150002.3685113-1-qperret@google.com> X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog Subject: [PATCH v3 26/32] KVM: arm64: Introduce PROT_NONE mappings for stage 2 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 Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Once we start unmapping portions of memory from the host stage 2 (such as e.g. the hypervisor memory sections, or pages that belong to protected guests), we will need a way to track page ownership. And given that all mappings in the host stage 2 will be identity-mapped, we can use the host stage 2 page-table itself as a simplistic rmap. As a first step towards this, introduce a new protection attribute in the stage 2 page table code, called KVM_PGTABLE_PROT_NONE, which allows to annotate portions of the IPA space as inaccessible. For simplicity, PROT_NONE mappings are created as invalid mappings with a software bit set. Signed-off-by: Quentin Perret --- arch/arm64/include/asm/kvm_pgtable.h | 2 ++ arch/arm64/kvm/hyp/pgtable.c | 26 ++++++++++++++++++++++++-- 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 9935dbae2cc1..c9f6ed76e0ad 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -80,6 +80,7 @@ struct kvm_pgtable { * @KVM_PGTABLE_PROT_W: Write permission. * @KVM_PGTABLE_PROT_R: Read permission. * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + * @KVM_PGTABLE_PROT_NONE: No permission. */ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_X = BIT(0), @@ -87,6 +88,7 @@ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_R = BIT(2), KVM_PGTABLE_PROT_DEVICE = BIT(3), + KVM_PGTABLE_PROT_NONE = BIT(4), }; #define PAGE_HYP (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index bdd6e3d4eeb6..8e7059fcfd40 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -48,6 +48,8 @@ KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \ KVM_PTE_LEAF_ATTR_HI_S2_XN) +#define KVM_PTE_LEAF_SW_BIT_PROT_NONE BIT(55) + struct kvm_pgtable_walk_data { struct kvm_pgtable *pgt; struct kvm_pgtable_walker *walker; @@ -120,6 +122,16 @@ static bool kvm_pte_valid(kvm_pte_t pte) return pte & KVM_PTE_VALID; } +static bool kvm_pte_prot_none(kvm_pte_t pte) +{ + return pte & KVM_PTE_LEAF_SW_BIT_PROT_NONE; +} + +static inline bool stage2_is_permanent_mapping(kvm_pte_t pte) +{ + return kvm_pte_prot_none(pte); +} + static bool kvm_pte_table(kvm_pte_t pte, u32 level) { if (level == KVM_PGTABLE_MAX_LEVELS - 1) @@ -182,7 +194,8 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level) pte |= attr & (KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI); pte |= FIELD_PREP(KVM_PTE_TYPE, type); - pte |= KVM_PTE_VALID; + if (!kvm_pte_prot_none(pte)) + pte |= KVM_PTE_VALID; return pte; } @@ -317,7 +330,7 @@ static int hyp_map_set_prot_attr(enum kvm_pgtable_prot prot, u32 ap = (prot & KVM_PGTABLE_PROT_W) ? KVM_PTE_LEAF_ATTR_LO_S1_AP_RW : KVM_PTE_LEAF_ATTR_LO_S1_AP_RO; - if (!(prot & KVM_PGTABLE_PROT_R)) + if (!(prot & KVM_PGTABLE_PROT_R) || (prot & KVM_PGTABLE_PROT_NONE)) return -EINVAL; if (prot & KVM_PGTABLE_PROT_X) { @@ -489,6 +502,13 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, PAGE_S2_MEMATTR(NORMAL); u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS; + if (prot & KVM_PGTABLE_PROT_NONE) { + if (prot != KVM_PGTABLE_PROT_NONE) + return -EINVAL; + attr |= KVM_PTE_LEAF_SW_BIT_PROT_NONE; + goto out; + } + if (!(prot & KVM_PGTABLE_PROT_X)) attr |= KVM_PTE_LEAF_ATTR_HI_S2_XN; else if (device) @@ -502,6 +522,8 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh); attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF; + +out: data->attr = attr; return 0; } -- 2.30.1.766.gb4fecdf3b7-goog 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=-16.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 D5D88C433DB for ; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Once we start unmapping portions of memory from the host stage 2 (such as e.g. the hypervisor memory sections, or pages that belong to protected guests), we will need a way to track page ownership. And given that all mappings in the host stage 2 will be identity-mapped, we can use the host stage 2 page-table itself as a simplistic rmap. As a first step towards this, introduce a new protection attribute in the stage 2 page table code, called KVM_PGTABLE_PROT_NONE, which allows to annotate portions of the IPA space as inaccessible. For simplicity, PROT_NONE mappings are created as invalid mappings with a software bit set. Signed-off-by: Quentin Perret --- arch/arm64/include/asm/kvm_pgtable.h | 2 ++ arch/arm64/kvm/hyp/pgtable.c | 26 ++++++++++++++++++++++++-- 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 9935dbae2cc1..c9f6ed76e0ad 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -80,6 +80,7 @@ struct kvm_pgtable { * @KVM_PGTABLE_PROT_W: Write permission. * @KVM_PGTABLE_PROT_R: Read permission. * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + * @KVM_PGTABLE_PROT_NONE: No permission. */ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_X = BIT(0), @@ -87,6 +88,7 @@ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_R = BIT(2), KVM_PGTABLE_PROT_DEVICE = BIT(3), + KVM_PGTABLE_PROT_NONE = BIT(4), }; #define PAGE_HYP (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index bdd6e3d4eeb6..8e7059fcfd40 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -48,6 +48,8 @@ KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \ KVM_PTE_LEAF_ATTR_HI_S2_XN) +#define KVM_PTE_LEAF_SW_BIT_PROT_NONE BIT(55) + struct kvm_pgtable_walk_data { struct kvm_pgtable *pgt; struct kvm_pgtable_walker *walker; @@ -120,6 +122,16 @@ static bool kvm_pte_valid(kvm_pte_t pte) return pte & KVM_PTE_VALID; } +static bool kvm_pte_prot_none(kvm_pte_t pte) +{ + return pte & KVM_PTE_LEAF_SW_BIT_PROT_NONE; +} + +static inline bool stage2_is_permanent_mapping(kvm_pte_t pte) +{ + return kvm_pte_prot_none(pte); +} + static bool kvm_pte_table(kvm_pte_t pte, u32 level) { if (level == KVM_PGTABLE_MAX_LEVELS - 1) @@ -182,7 +194,8 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level) pte |= attr & (KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI); pte |= FIELD_PREP(KVM_PTE_TYPE, type); - pte |= KVM_PTE_VALID; + if (!kvm_pte_prot_none(pte)) + pte |= KVM_PTE_VALID; return pte; } @@ -317,7 +330,7 @@ static int hyp_map_set_prot_attr(enum kvm_pgtable_prot prot, u32 ap = (prot & KVM_PGTABLE_PROT_W) ? KVM_PTE_LEAF_ATTR_LO_S1_AP_RW : KVM_PTE_LEAF_ATTR_LO_S1_AP_RO; - if (!(prot & KVM_PGTABLE_PROT_R)) + if (!(prot & KVM_PGTABLE_PROT_R) || (prot & KVM_PGTABLE_PROT_NONE)) return -EINVAL; if (prot & KVM_PGTABLE_PROT_X) { @@ -489,6 +502,13 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, PAGE_S2_MEMATTR(NORMAL); u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS; + if (prot & KVM_PGTABLE_PROT_NONE) { + if (prot != KVM_PGTABLE_PROT_NONE) + return -EINVAL; + attr |= KVM_PTE_LEAF_SW_BIT_PROT_NONE; + goto out; + } + if (!(prot & KVM_PGTABLE_PROT_X)) attr |= KVM_PTE_LEAF_ATTR_HI_S2_XN; else if (device) @@ -502,6 +522,8 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh); attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF; + +out: data->attr = attr; return 0; } -- 2.30.1.766.gb4fecdf3b7-goog _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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=-16.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 B4FBEC433DB for ; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Once we start unmapping portions of memory from the host stage 2 (such as e.g. the hypervisor memory sections, or pages that belong to protected guests), we will need a way to track page ownership. And given that all mappings in the host stage 2 will be identity-mapped, we can use the host stage 2 page-table itself as a simplistic rmap. As a first step towards this, introduce a new protection attribute in the stage 2 page table code, called KVM_PGTABLE_PROT_NONE, which allows to annotate portions of the IPA space as inaccessible. For simplicity, PROT_NONE mappings are created as invalid mappings with a software bit set. Signed-off-by: Quentin Perret --- arch/arm64/include/asm/kvm_pgtable.h | 2 ++ arch/arm64/kvm/hyp/pgtable.c | 26 ++++++++++++++++++++++++-- 2 files changed, 26 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h index 9935dbae2cc1..c9f6ed76e0ad 100644 --- a/arch/arm64/include/asm/kvm_pgtable.h +++ b/arch/arm64/include/asm/kvm_pgtable.h @@ -80,6 +80,7 @@ struct kvm_pgtable { * @KVM_PGTABLE_PROT_W: Write permission. * @KVM_PGTABLE_PROT_R: Read permission. * @KVM_PGTABLE_PROT_DEVICE: Device attributes. + * @KVM_PGTABLE_PROT_NONE: No permission. */ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_X = BIT(0), @@ -87,6 +88,7 @@ enum kvm_pgtable_prot { KVM_PGTABLE_PROT_R = BIT(2), KVM_PGTABLE_PROT_DEVICE = BIT(3), + KVM_PGTABLE_PROT_NONE = BIT(4), }; #define PAGE_HYP (KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W) diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index bdd6e3d4eeb6..8e7059fcfd40 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -48,6 +48,8 @@ KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \ KVM_PTE_LEAF_ATTR_HI_S2_XN) +#define KVM_PTE_LEAF_SW_BIT_PROT_NONE BIT(55) + struct kvm_pgtable_walk_data { struct kvm_pgtable *pgt; struct kvm_pgtable_walker *walker; @@ -120,6 +122,16 @@ static bool kvm_pte_valid(kvm_pte_t pte) return pte & KVM_PTE_VALID; } +static bool kvm_pte_prot_none(kvm_pte_t pte) +{ + return pte & KVM_PTE_LEAF_SW_BIT_PROT_NONE; +} + +static inline bool stage2_is_permanent_mapping(kvm_pte_t pte) +{ + return kvm_pte_prot_none(pte); +} + static bool kvm_pte_table(kvm_pte_t pte, u32 level) { if (level == KVM_PGTABLE_MAX_LEVELS - 1) @@ -182,7 +194,8 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level) pte |= attr & (KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI); pte |= FIELD_PREP(KVM_PTE_TYPE, type); - pte |= KVM_PTE_VALID; + if (!kvm_pte_prot_none(pte)) + pte |= KVM_PTE_VALID; return pte; } @@ -317,7 +330,7 @@ static int hyp_map_set_prot_attr(enum kvm_pgtable_prot prot, u32 ap = (prot & KVM_PGTABLE_PROT_W) ? KVM_PTE_LEAF_ATTR_LO_S1_AP_RW : KVM_PTE_LEAF_ATTR_LO_S1_AP_RO; - if (!(prot & KVM_PGTABLE_PROT_R)) + if (!(prot & KVM_PGTABLE_PROT_R) || (prot & KVM_PGTABLE_PROT_NONE)) return -EINVAL; if (prot & KVM_PGTABLE_PROT_X) { @@ -489,6 +502,13 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, PAGE_S2_MEMATTR(NORMAL); u32 sh = KVM_PTE_LEAF_ATTR_LO_S2_SH_IS; + if (prot & KVM_PGTABLE_PROT_NONE) { + if (prot != KVM_PGTABLE_PROT_NONE) + return -EINVAL; + attr |= KVM_PTE_LEAF_SW_BIT_PROT_NONE; + goto out; + } + if (!(prot & KVM_PGTABLE_PROT_X)) attr |= KVM_PTE_LEAF_ATTR_HI_S2_XN; else if (device) @@ -502,6 +522,8 @@ static int stage2_map_set_prot_attr(enum kvm_pgtable_prot prot, attr |= FIELD_PREP(KVM_PTE_LEAF_ATTR_LO_S2_SH, sh); attr |= KVM_PTE_LEAF_ATTR_LO_S2_AF; + +out: data->attr = attr; return 0; } -- 2.30.1.766.gb4fecdf3b7-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel