From nobody Sat May 10 02:18:15 2025 Delivered-To: importer2@patchew.org Received-SPF: pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; envelope-from=linux-kernel-owner@vger.kernel.org; helo=vger.kernel.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail(p=none dis=none) header.from=gmail.com ARC-Seal: i=1; a=rsa-sha256; t=1621328877; cv=none; d=zohomail.com; s=zohoarc; b=Dj0ClfCs08zctASvt3++dh5hM1PESgSz9wcvAvXu+02+7EsY+GixhICqRdgMd5v470MbuGJHamLTPOXD2wROVMh9T4+Eg1xicg+tvyZbiHZqej8uzEAqf1RGhkOJyYqScLWjnQmvwgMwuvTYcb4dqljM6gujAAV2F1KzTc836SQ= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1621328877; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Id:MIME-Version:Message-ID:References:Subject:To; bh=9rGi608qIyo5wwTAfm/9KSh42lmNIqRVhptkNqcqKak=; b=lRnfCcjpX+QHEA5IZOufZor8CQeV2wyiM7Fxb/VkoAC+Q1QhxDTg7pgQ0Z7s0moa1zQXT+QPluv903KghC9+rSZSkfYcxXwapRqp4cbwN4gBKgszIbv7x+nR4/bv5IZhhlZLGgBOH4PgHUZZjsbxyNkDy+rbKzAMq5hKzW8qEzc= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mx.zohomail.com with SMTP id 1621328877727310.2784170890103; Tue, 18 May 2021 02:07:57 -0700 (PDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347791AbhERJJN (ORCPT ); Tue, 18 May 2021 05:09:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347725AbhERJI2 (ORCPT ); Tue, 18 May 2021 05:08:28 -0400 Received: from mail-wr1-x431.google.com (mail-wr1-x431.google.com [IPv6:2a00:1450:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5D6EC061345 for ; Tue, 18 May 2021 02:07:10 -0700 (PDT) Received: by mail-wr1-x431.google.com with SMTP id v12so9329551wrq.6 for ; Tue, 18 May 2021 02:07:10 -0700 (PDT) Received: from amanieu-laptop.home ([2a00:23c6:f081:f801:91cf:b949:c46c:f5a9]) by smtp.gmail.com with ESMTPSA id z17sm7520306wrt.81.2021.05.18.02.07.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 May 2021 02:07:08 -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:in-reply-to:references :mime-version:content-transfer-encoding; bh=9rGi608qIyo5wwTAfm/9KSh42lmNIqRVhptkNqcqKak=; b=boNwMh1++w7TDzmUAg3tAWQaAtUpXq0nkaVL4P8ywlxWnnj3GizxF9D5FCopHzYH0l M392UtjwRQdiPZV4Nn5JI2GOdJ+18ZnwwY/Yc6DCynMepnDHLpTnHR3bvKPB7oR+QqB3 NBfxlbpLCIbfsyf5AfcoHUKdJmvEg7e3mj7gSeG+XZjVzDwRkLWQrIb6xdqcAXzDQK9C 2W6K257G0wB0LkXgThuBcB8JyHIKqqpKgI0qn8GOQ1KhMSM5Vqr5kOxyNL290VammKg/ t4LRWs1m68gYzNU0jl8giZsH9bb5PWDXWl4afmWTENaBJ7sJmnugegUMu/LWG9Hs/JXo 7tow== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=9rGi608qIyo5wwTAfm/9KSh42lmNIqRVhptkNqcqKak=; b=cMtsA/rFIyPHpHuI0AOpCGwMhwwJHMeIV7/BW7viVefqJndyF+Nyj/BLsrE048eG7w 85Lj3/onpx+BeCd+yVRzXrb/sKIaE1Koo2fI36x9UAv/74ZQ/QSeKucKl+gAb9hu+ZmI TheEE6KwcOpv3jTEIHX43RypyqamH/KoZWYETRyYiWstF89u7hNArZsUcO5fWlf22ZZ2 /6/kcctSvBNo9jEnCncTR/0zmjq7aqurFSxlgsXVcmMyr63dvgk3Jc2zxVIue4CPBwtt 3Tu/cUrkU4ZSHcYAdsbkmwd85gvMQHHINb3tZzkLEWg4Ac8Z+q6z/JHZBJ1MAgFIBncx kzMA== X-Gm-Message-State: AOAM5317JXsi8ZNXi0E0pM+BkOhjGI0KRqQPUOttBoCXPADfXwN3Blxl UfCxKuFfbh9W1CwtzA8Gp4gOyHNvv2rnS7g+ X-Google-Smtp-Source: ABdhPJwS9MdO+Qwxpqf9XZbH6OCB7DYTmx7uZPYqKcZVbpPMaJnWz94YV9xSRF/j8QdMOHfyvwkbnw== X-Received: by 2002:a5d:658e:: with SMTP id q14mr5355475wru.81.1621328829488; Tue, 18 May 2021 02:07:09 -0700 (PDT) From: Amanieu d'Antras Cc: Amanieu d'Antras , Ryan Houdek , Catalin Marinas , Will Deacon , Mark Rutland , Steven Price , Arnd Bergmann , David Laight , Mark Brown , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [RESEND PATCH v4 3/8] mm: Support mmap_compat_base with the generic layout Date: Tue, 18 May 2021 10:06:53 +0100 Message-Id: <20210518090658.9519-4-amanieu@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210518090658.9519-1-amanieu@gmail.com> References: <20210518090658.9519-1-amanieu@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" This enables architectures using the generic mmap layout to support 32-bit mmap calls from 64-bit processes and vice-versa. Architectures using this must define separate 32-bit and 64-bit versions of STACK_TOP, TASK_UNMAPPED_BASE and STACK_RND_MASK. Signed-off-by: Amanieu d'Antras Co-developed-by: Ryan Houdek Signed-off-by: Ryan Houdek --- mm/util.c | 46 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 8 deletions(-) diff --git a/mm/util.c b/mm/util.c index 54870226cea6..37bd764174b5 100644 --- a/mm/util.c +++ b/mm/util.c @@ -353,12 +353,12 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) return randomize_page(mm->brk, SZ_1G); } =20 -unsigned long arch_mmap_rnd(void) +static unsigned long mmap_rnd(bool compat) { unsigned long rnd; =20 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS - if (is_compat_task()) + if (compat) rnd =3D get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); else #endif /* CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS */ @@ -367,6 +367,11 @@ unsigned long arch_mmap_rnd(void) return rnd << PAGE_SHIFT; } =20 +unsigned long arch_mmap_rnd(void) +{ + return mmap_rnd(is_compat_task()); +} + static int mmap_is_legacy(struct rlimit *rlim_stack) { if (current->personality & ADDR_COMPAT_LAYOUT) @@ -383,16 +388,17 @@ static int mmap_is_legacy(struct rlimit *rlim_stack) * the face of randomisation. */ #define MIN_GAP (SZ_128M) -#define MAX_GAP (STACK_TOP / 6 * 5) +#define MAX_GAP (stack_top / 6 * 5) =20 -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stac= k) +static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stac= k, + unsigned long stack_top, unsigned long stack_rnd_mask) { unsigned long gap =3D rlim_stack->rlim_cur; unsigned long pad =3D stack_guard_gap; =20 /* Account for stack randomization if necessary */ if (current->flags & PF_RANDOMIZE) - pad +=3D (STACK_RND_MASK << PAGE_SHIFT); + pad +=3D (stack_rnd_mask << PAGE_SHIFT); =20 /* Values close to RLIM_INFINITY can overflow. */ if (gap + pad > gap) @@ -403,21 +409,45 @@ static unsigned long mmap_base(unsigned long rnd, str= uct rlimit *rlim_stack) else if (gap > MAX_GAP) gap =3D MAX_GAP; =20 - return PAGE_ALIGN(STACK_TOP - gap - rnd); + return PAGE_ALIGN(stack_top - gap - rnd); } =20 void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) { unsigned long random_factor =3D 0UL; +#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES + unsigned long compat_random_factor =3D 0UL; +#endif =20 - if (current->flags & PF_RANDOMIZE) + if (current->flags & PF_RANDOMIZE) { +#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES + random_factor =3D mmap_rnd(false); + compat_random_factor =3D mmap_rnd(true); +#else random_factor =3D arch_mmap_rnd(); +#endif + } =20 if (mmap_is_legacy(rlim_stack)) { +#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES + mm->mmap_base =3D TASK_UNMAPPED_BASE_64 + random_factor; + mm->mmap_compat_base =3D + TASK_UNMAPPED_BASE_32 + compat_random_factor; +#else mm->mmap_base =3D TASK_UNMAPPED_BASE + random_factor; +#endif mm->get_unmapped_area =3D arch_get_unmapped_area; } else { - mm->mmap_base =3D mmap_base(random_factor, rlim_stack); +#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES + mm->mmap_base =3D mmap_base(random_factor, rlim_stack, + STACK_TOP_64, STACK_RND_MASK_64); + mm->mmap_compat_base =3D mmap_base(compat_random_factor, + rlim_stack, STACK_TOP_32, + STACK_RND_MASK_32); +#else + mm->mmap_base =3D mmap_base(random_factor, rlim_stack, STACK_TOP, + STACK_RND_MASK); +#endif mm->get_unmapped_area =3D arch_get_unmapped_area_topdown; } } --=20 2.31.1