From patchwork Fri Oct 6 02:45:27 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Pitre X-Patchwork-Id: 115017 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp1270214qgn; Thu, 5 Oct 2017 19:45:48 -0700 (PDT) X-Google-Smtp-Source: AOwi7QBZh0Zu+v7RNbHIV5RpZQ/KquXXKcQ3Uq0dfUMjMJs1TtbYLzHEP45RriisNis61PyDHWd9 X-Received: by 10.84.132.66 with SMTP id 60mr624535ple.158.1507257948669; Thu, 05 Oct 2017 19:45:48 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507257948; cv=none; d=google.com; s=arc-20160816; b=Ro/p8rrjtE+RgyE9bJJ0zlbasvY4ELGZOoeOBi7JjA8a/9pZGke+MWR6RvQ0mIq6rp rZEl2gc7X5G1YH/B4JRYByTqranqmqm0YxvhOvpbLtGiWPqVoVB7r0GIbmWzoGn7k0Ay 9LuT6ovWWpnEiO8JKINvMqGq38Lt6rw40yOEIYq+047r3Csv9HekkzbkKHhlx6w94fOL 8a8hyovzEusU3dP0aZa9+J40xLf+/vWe/1eNdj7oya9Yd1niEDOlWLJ2z6thseahMrQO 7dBVj1UnnQqtqHkcfSntq5YDrsXGJcqVr7b6ewVtJrw64Uf37WuU6ok/w930LrealAd9 3NqQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=wq9imYYv7HEa3iggrjrETTEpEdLRmrjQxd3WJYv5Kzs=; b=kfDuqJ7euPpNs0fi7VGHrBuw8VVAlWL5bRE8R1Ha+z7eZhy73cyypHXSacARDe6YWI 7HPPGaoQpEPs49d7Y7PxWnzq0z8P6/PHjoDGmVv8m4ZzJkGQ515HPFleMh8+Pv1ONkD7 dNlwwffXinKwQwaF6kAnU0RarfUq8y8CgeMcTKtaohsSo4MpS/TRAA5CfGL6wF36ubCX qHI/7rMzMS/ZoaqzCqlorwS6cEN23Fmma2thvVjxJCHxeI/pArWDkq3kRfTwA/L2fkDR +TuEX4+tBxinU2FCNOJJ/SS0quubs7j/n3V4Z5UVMINEuxOhUgdYRt85WZmoIkK4wm79 P1pg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=W0ZLKbcK; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id r17si321827pgu.619.2017.10.05.19.45.48; Thu, 05 Oct 2017 19:45:48 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=W0ZLKbcK; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751875AbdJFCpq (ORCPT + 26 others); Thu, 5 Oct 2017 22:45:46 -0400 Received: from pb-smtp1.pobox.com ([64.147.108.70]:64872 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751459AbdJFCpj (ORCPT ); Thu, 5 Oct 2017 22:45:39 -0400 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id A555499B0F; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; s=sasl; bh=7smc Tj/fOQHhcJ/AnguMvYxs3l0=; b=W0ZLKbcKkcyM3zJCFpeVWqAjlZ15WWJEzxi9 hYkjUTbYESmrV95CvA8+cdqzau86gNbRgJ56V2Elb13ZQUU1AV6eqx0ehWc6bnin d5SLEFH+hrcsJvMUj/DOZWj/yP2DYzHs5oxq8Cufes5LUJFwiL8W4L+CXErXXTp9 ceW0WNU= Received: from pb-smtp1.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id 9BB5299B0E; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) Received: from yoda.home (unknown [137.175.234.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp1.pobox.com (Postfix) with ESMTPSA id 19AAB99B09; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) Received: from xanadu.home (xanadu.home [192.168.2.2]) by yoda.home (Postfix) with ESMTP id 72D472DA05B4; Thu, 5 Oct 2017 22:45:37 -0400 (EDT) From: Nicolas Pitre To: Alexander Viro , Christoph Hellwig Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Brandt Subject: [PATCH v5 1/5] cramfs: direct memory access support Date: Thu, 5 Oct 2017 22:45:27 -0400 Message-Id: <20171006024531.8885-2-nicolas.pitre@linaro.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171006024531.8885-1-nicolas.pitre@linaro.org> References: <20171006024531.8885-1-nicolas.pitre@linaro.org> X-Pobox-Relay-ID: 6F5EB990-AA40-11E7-977A-8EF31968708C-78420484!pb-smtp1.pobox.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Small embedded systems typically execute the kernel code in place (XIP) directly from flash to save on precious RAM usage. This adds the ability to consume filesystem data directly from flash to the cramfs filesystem as well. Cramfs is particularly well suited to this feature as it is very simple and its RAM usage is already very low, and with this feature it is possible to use it with no block device support and even lower RAM usage. This patch was inspired by a similar patch from Shane Nay dated 17 years ago that used to be very popular in embedded circles but never made it into mainline. This is a cleaned-up implementation that uses far fewer memory address at run time when both methods are configured in. In the context of small IoT deployments, this functionality has become relevant and useful again. To distinguish between both access types, the cramfs_physmem filesystem type must be specified when using a memory accessible cramfs image, and the physaddr argument must provide the actual filesystem image's physical memory location. Signed-off-by: Nicolas Pitre Tested-by: Chris Brandt --- fs/cramfs/Kconfig | 29 +++++- fs/cramfs/inode.c | 270 +++++++++++++++++++++++++++++++++++++++++++----------- 2 files changed, 247 insertions(+), 52 deletions(-) -- 2.9.5 diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig index 11b29d491b..5b4e0b7e13 100644 --- a/fs/cramfs/Kconfig +++ b/fs/cramfs/Kconfig @@ -1,6 +1,5 @@ config CRAMFS tristate "Compressed ROM file system support (cramfs) (OBSOLETE)" - depends on BLOCK select ZLIB_INFLATE help Saying Y here includes support for CramFs (Compressed ROM File @@ -20,3 +19,31 @@ config CRAMFS in terms of performance and features. If unsure, say N. + +config CRAMFS_BLOCKDEV + bool "Support CramFs image over a regular block device" if EXPERT + depends on CRAMFS && BLOCK + default y + help + This option allows the CramFs driver to load data from a regular + block device such a disk partition or a ramdisk. + +config CRAMFS_PHYSMEM + bool "Support CramFs image directly mapped in physical memory" + depends on CRAMFS + default y if !CRAMFS_BLOCKDEV + help + This option allows the CramFs driver to load data directly from + a linear adressed memory range (usually non volatile memory + like flash) instead of going through the block device layer. + This saves some memory since no intermediate buffering is + necessary. + + The filesystem type for this feature is "cramfs_physmem". + The location of the CramFs image in memory is board + dependent. Therefore, if you say Y, you must know the proper + physical address where to store the CramFs image and specify + it using the physaddr=0x******** mount option (for example: + "mount -t cramfs_physmem -o physaddr=0x100000 none /mnt"). + + If unsure, say N. diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index 7919967488..89bce89c05 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -24,6 +24,7 @@ #include #include #include +#include #include "internal.h" @@ -36,6 +37,8 @@ struct cramfs_sb_info { unsigned long blocks; unsigned long files; unsigned long flags; + void *linear_virt_addr; + phys_addr_t linear_phys_addr; }; static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb) @@ -140,6 +143,9 @@ static struct inode *get_cramfs_inode(struct super_block *sb, * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to * worry about end-of-buffer issues even when decompressing a full * page cache. + * + * Note: This is all optimized away at compile time when + * CONFIG_CRAMFS_BLOCKDEV=n. */ #define READ_BUFFERS (2) /* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */ @@ -160,10 +166,10 @@ static struct super_block *buffer_dev[READ_BUFFERS]; static int next_buffer; /* - * Returns a pointer to a buffer containing at least LEN bytes of - * filesystem starting at byte offset OFFSET into the filesystem. + * Populate our block cache and return a pointer from it. */ -static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len) +static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset, + unsigned int len) { struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping; struct page *pages[BLKS_PER_BUF]; @@ -239,7 +245,39 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i return read_buffers[buffer] + offset; } -static void cramfs_kill_sb(struct super_block *sb) +/* + * Return a pointer to the linearly addressed cramfs image in memory. + */ +static void *cramfs_direct_read(struct super_block *sb, unsigned int offset, + unsigned int len) +{ + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + + if (!len) + return NULL; + if (len > sbi->size || offset > sbi->size - len) + return page_address(ZERO_PAGE(0)); + return sbi->linear_virt_addr + offset; +} + +/* + * Returns a pointer to a buffer containing at least LEN bytes of + * filesystem starting at byte offset OFFSET into the filesystem. + */ +static void *cramfs_read(struct super_block *sb, unsigned int offset, + unsigned int len) +{ + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + + if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM) && sbi->linear_virt_addr) + return cramfs_direct_read(sb, offset, len); + else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) + return cramfs_blkdev_read(sb, offset, len); + else + return NULL; +} + +static void cramfs_blkdev_kill_sb(struct super_block *sb) { struct cramfs_sb_info *sbi = CRAMFS_SB(sb); @@ -247,6 +285,16 @@ static void cramfs_kill_sb(struct super_block *sb) kfree(sbi); } +static void cramfs_physmem_kill_sb(struct super_block *sb) +{ + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + + if (sbi->linear_virt_addr) + memunmap(sbi->linear_virt_addr); + kill_anon_super(sb); + kfree(sbi); +} + static int cramfs_remount(struct super_block *sb, int *flags, char *data) { sync_filesystem(sb); @@ -254,34 +302,24 @@ static int cramfs_remount(struct super_block *sb, int *flags, char *data) return 0; } -static int cramfs_fill_super(struct super_block *sb, void *data, int silent) +static int cramfs_read_super(struct super_block *sb, + struct cramfs_super *super, int silent) { - int i; - struct cramfs_super super; + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); unsigned long root_offset; - struct cramfs_sb_info *sbi; - struct inode *root; - - sb->s_flags |= MS_RDONLY; - - sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); - if (!sbi) - return -ENOMEM; - sb->s_fs_info = sbi; - /* Invalidate the read buffers on mount: think disk change.. */ - mutex_lock(&read_mutex); - for (i = 0; i < READ_BUFFERS; i++) - buffer_blocknr[i] = -1; + /* We don't know the real size yet */ + sbi->size = PAGE_SIZE; /* Read the first block and get the superblock from it */ - memcpy(&super, cramfs_read(sb, 0, sizeof(super)), sizeof(super)); + mutex_lock(&read_mutex); + memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super)); mutex_unlock(&read_mutex); /* Do sanity checks on the superblock */ - if (super.magic != CRAMFS_MAGIC) { + if (super->magic != CRAMFS_MAGIC) { /* check for wrong endianness */ - if (super.magic == CRAMFS_MAGIC_WEND) { + if (super->magic == CRAMFS_MAGIC_WEND) { if (!silent) pr_err("wrong endianness\n"); return -EINVAL; @@ -289,10 +327,12 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent) /* check at 512 byte offset */ mutex_lock(&read_mutex); - memcpy(&super, cramfs_read(sb, 512, sizeof(super)), sizeof(super)); + memcpy(super, + cramfs_read(sb, 512, sizeof(*super)), + sizeof(*super)); mutex_unlock(&read_mutex); - if (super.magic != CRAMFS_MAGIC) { - if (super.magic == CRAMFS_MAGIC_WEND && !silent) + if (super->magic != CRAMFS_MAGIC) { + if (super->magic == CRAMFS_MAGIC_WEND && !silent) pr_err("wrong endianness\n"); else if (!silent) pr_err("wrong magic\n"); @@ -301,34 +341,34 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent) } /* get feature flags first */ - if (super.flags & ~CRAMFS_SUPPORTED_FLAGS) { + if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) { pr_err("unsupported filesystem features\n"); return -EINVAL; } /* Check that the root inode is in a sane state */ - if (!S_ISDIR(super.root.mode)) { + if (!S_ISDIR(super->root.mode)) { pr_err("root is not a directory\n"); return -EINVAL; } /* correct strange, hard-coded permissions of mkcramfs */ - super.root.mode |= (S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH); + super->root.mode |= 0555; - root_offset = super.root.offset << 2; - if (super.flags & CRAMFS_FLAG_FSID_VERSION_2) { - sbi->size = super.size; - sbi->blocks = super.fsid.blocks; - sbi->files = super.fsid.files; + root_offset = super->root.offset << 2; + if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) { + sbi->size = super->size; + sbi->blocks = super->fsid.blocks; + sbi->files = super->fsid.files; } else { sbi->size = 1<<28; sbi->blocks = 0; sbi->files = 0; } - sbi->magic = super.magic; - sbi->flags = super.flags; + sbi->magic = super->magic; + sbi->flags = super->flags; if (root_offset == 0) pr_info("empty filesystem"); - else if (!(super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) && + else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) && ((root_offset != sizeof(struct cramfs_super)) && (root_offset != 512 + sizeof(struct cramfs_super)))) { @@ -336,9 +376,18 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent) return -EINVAL; } + return 0; +} + +static int cramfs_finalize_super(struct super_block *sb, + struct cramfs_inode *cramfs_root) +{ + struct inode *root; + /* Set it all up.. */ + sb->s_flags |= MS_RDONLY; sb->s_op = &cramfs_ops; - root = get_cramfs_inode(sb, &super.root, 0); + root = get_cramfs_inode(sb, cramfs_root, 0); if (IS_ERR(root)) return PTR_ERR(root); sb->s_root = d_make_root(root); @@ -347,6 +396,95 @@ static int cramfs_fill_super(struct super_block *sb, void *data, int silent) return 0; } +static int cramfs_blkdev_fill_super(struct super_block *sb, void *data, + int silent) +{ + struct cramfs_sb_info *sbi; + struct cramfs_super super; + int i, err; + + sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); + if (!sbi) + return -ENOMEM; + sb->s_fs_info = sbi; + + /* Invalidate the read buffers on mount: think disk change.. */ + for (i = 0; i < READ_BUFFERS; i++) + buffer_blocknr[i] = -1; + + err = cramfs_read_super(sb, &super, silent); + if (err) + return err; + return cramfs_finalize_super(sb, &super.root); +} + +static int cramfs_physmem_fill_super(struct super_block *sb, void *data, + int silent) +{ + struct cramfs_sb_info *sbi; + struct cramfs_super super; + char *p; + int err; + + sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); + if (!sbi) + return -ENOMEM; + sb->s_fs_info = sbi; + + /* + * The physical location of the cramfs image is specified as + * a mount parameter. This parameter is mandatory for obvious + * reasons. Some validation is made on the phys address but this + * is not exhaustive and we count on the fact that someone using + * this feature is supposed to know what he/she's doing. + */ + if (!data || !(p = strstr((char *)data, "physaddr="))) { + pr_err("unknown physical address for linear cramfs image\n"); + return -EINVAL; + } + sbi->linear_phys_addr = memparse(p + 9, NULL); + if (!sbi->linear_phys_addr) { + pr_err("bad value for cramfs image physical address\n"); + return -EINVAL; + } + if (!PAGE_ALIGNED(sbi->linear_phys_addr)) { + pr_err("physical address %pap isn't page aligned\n", + &sbi->linear_phys_addr); + return -EINVAL; + } + + /* + * Map only one page for now. Will remap it when fs size is known. + * Although we'll only read from it, we want the CPU cache to + * kick in for the higher throughput it provides, hence MEMREMAP_WB. + */ + pr_info("checking physical address %pap for linear cramfs image\n", + &sbi->linear_phys_addr); + sbi->linear_virt_addr = memremap(sbi->linear_phys_addr, PAGE_SIZE, + MEMREMAP_WB); + if (!sbi->linear_virt_addr) { + pr_err("memremap of the linear cramfs image failed\n"); + return -ENOMEM; + } + + err = cramfs_read_super(sb, &super, silent); + if (err) + return err; + + /* Remap the whole filesystem now */ + pr_info("linear cramfs image appears to be %lu KB in size\n", + sbi->size/1024); + memunmap(sbi->linear_virt_addr); + sbi->linear_virt_addr = memremap(sbi->linear_phys_addr, sbi->size, + MEMREMAP_WB); + if (!sbi->linear_virt_addr) { + pr_err("ioremap of the linear cramfs image failed\n"); + return -ENOMEM; + } + + return cramfs_finalize_super(sb, &super.root); +} + static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf) { struct super_block *sb = dentry->d_sb; @@ -573,38 +711,68 @@ static const struct super_operations cramfs_ops = { .statfs = cramfs_statfs, }; -static struct dentry *cramfs_mount(struct file_system_type *fs_type, - int flags, const char *dev_name, void *data) +static struct dentry *cramfs_blkdev_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) +{ + return mount_bdev(fs_type, flags, dev_name, data, + cramfs_blkdev_fill_super); +} + +static struct dentry *cramfs_physmem_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data) { - return mount_bdev(fs_type, flags, dev_name, data, cramfs_fill_super); + return mount_nodev(fs_type, flags, data, cramfs_physmem_fill_super); } static struct file_system_type cramfs_fs_type = { .owner = THIS_MODULE, .name = "cramfs", - .mount = cramfs_mount, - .kill_sb = cramfs_kill_sb, + .mount = cramfs_blkdev_mount, + .kill_sb = cramfs_blkdev_kill_sb, .fs_flags = FS_REQUIRES_DEV, }; + +static struct file_system_type cramfs_physmem_fs_type = { + .owner = THIS_MODULE, + .name = "cramfs_physmem", + .mount = cramfs_physmem_mount, + .kill_sb = cramfs_physmem_kill_sb, +}; + +#ifdef CONFIG_CRAMFS_BLOCKDEV MODULE_ALIAS_FS("cramfs"); +#endif +#ifdef CONFIG_CRAMFS_PHYSMEM +MODULE_ALIAS_FS("cramfs_physmem"); +#endif static int __init init_cramfs_fs(void) { int rv; - rv = cramfs_uncompress_init(); - if (rv < 0) - return rv; - rv = register_filesystem(&cramfs_fs_type); - if (rv < 0) - cramfs_uncompress_exit(); - return rv; + if ((rv = cramfs_uncompress_init()) < 0) + goto err0; + if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && + (rv = register_filesystem(&cramfs_fs_type)) < 0) + goto err1; + if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM) && + (rv = register_filesystem(&cramfs_physmem_fs_type)) < 0) + goto err2; + return 0; + +err2: if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) + unregister_filesystem(&cramfs_fs_type); +err1: cramfs_uncompress_exit(); +err0: return rv; } static void __exit exit_cramfs_fs(void) { cramfs_uncompress_exit(); - unregister_filesystem(&cramfs_fs_type); + if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) + unregister_filesystem(&cramfs_fs_type); + if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM)) + unregister_filesystem(&cramfs_physmem_fs_type); } module_init(init_cramfs_fs) From patchwork Fri Oct 6 02:45:28 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Pitre X-Patchwork-Id: 115018 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp1270306qgn; Thu, 5 Oct 2017 19:46:00 -0700 (PDT) X-Google-Smtp-Source: AOwi7QDz8BgYHPKUtHbn8SMrye7USnLw7IZJEnOKtZ3jYDWxAqd/XB8rlUCOGYXOlccKurt9dn8d X-Received: by 10.159.206.134 with SMTP id bg6mr604338plb.273.1507257959998; Thu, 05 Oct 2017 19:45:59 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507257959; cv=none; d=google.com; s=arc-20160816; b=nDv7elXMt7QVtixmi61NC6kvkDvLppT3ImGSx2dqY43mG1dq++fdJGMEfO6ufTYqgO +JOVg99PNNAJr81NHoblpN8IPjhZlOZ1QwoQjlPJeGubNxdfr/aS8ElzEPYQm5stYziy PLeQHFKd/Q04mnaGfniKwQC2RlteBdE6MkVDPTPzvaZEsioVR//5Ae4Ih/HH+7Et4CTL lXwV4R0GBiOQt2MpVjkFvBJsMlZ/fHjB9kNi0HbdQNfdpD2mNDVJTaEQW5R+LQ1CLVxG wA6nxmfsh1hyuWbqfw7f3Jkl61oDvKnDa+IB7cPp2u0d5TcPgLBKJXKkzWd5hykwYOYX zUvg== ARC-Message-Signature: i=1; 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} + if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM) && root_fs_names && + !strcmp(root_fs_names, "cramfs_physmem")) { + int err = do_mount_root("cramfs", "cramfs_physmem", + root_mountflags, root_mount_data); + if (!err) + goto out; + } + /* * wait for the known devices to complete their probing * From patchwork Fri Oct 6 02:45:29 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Pitre X-Patchwork-Id: 115021 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp1270855qgn; Thu, 5 Oct 2017 19:46:53 -0700 (PDT) X-Google-Smtp-Source: AOwi7QBa+CXgb/3pem4gz3VbnSLveCXAIBjhNMrL6MS3xXVj75zxEftQUInTa5ISyYgTpmexVTFd X-Received: by 10.84.133.69 with SMTP id 63mr625435plf.98.1507258012951; Thu, 05 Oct 2017 19:46:52 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507258012; cv=none; d=google.com; s=arc-20160816; b=vldk1MrgJhDrN49gq/Ham+9A9OFJA/B6RATLEZ5XEhL0irGAkbt5V/ocXh4PS+ShrY erLLf/sdA/JH7WeRp93KgBczkKu1D9qt2sSH+vO4JXXoqP2CTH9pq7+sQwciottMXbMk uuMdA4++b0fgm73QLT1O/YHuKctFbdxeVmc2pnFlgzUUwF02BYaJ2YDhUno9vWy9m+gX rlBEY/eZbBCnQhe7XweE8uYK4Z+dC+jCu4Sa8blKe6g7cDFOXoiEk9KKqCcVa0mOkQVv cp6ItQNmFlIaebOyoq/foQKqEyZSqxgRRjYu65ufoNfEGw9DItumWcuVsjJ4ndWCWKpc cSsQ== ARC-Message-Signature: i=1; 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[209.132.180.67]) by mx.google.com with ESMTP id c2si354794pfj.240.2017.10.05.19.46.52; Thu, 05 Oct 2017 19:46:52 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=Ub4TJ+KW; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751996AbdJFCqv (ORCPT + 26 others); Thu, 5 Oct 2017 22:46:51 -0400 Received: from pb-smtp1.pobox.com ([64.147.108.70]:56564 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751526AbdJFCpj (ORCPT ); Thu, 5 Oct 2017 22:45:39 -0400 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id E8BC399B13; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; s=sasl; bh=qgyn cuEdbrUkOpbPpc8jA8ULJ1Q=; b=Ub4TJ+KWWQUa85oRKdMayTiJphPz7SiioA2S Jjgwk4zN1uQLXle53FUdBineEzOagIF+/rw9zcN/l0FFERE1626zvdYE7t7yJEkd Y1LROQLjDbSpRdPjZjtpK7KDD0Y5wIt0E9zapJ7ZmKYxM9Bo1ef9JjUx2QF5sHZE IZq0nGE= Received: from pb-smtp1.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id DE21E99B12; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) Received: from yoda.home (unknown [137.175.234.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp1.pobox.com (Postfix) with ESMTPSA id 670E899B0A; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) Received: from xanadu.home (xanadu.home [192.168.2.2]) by yoda.home (Postfix) with ESMTP id BE8502DA0677; Thu, 5 Oct 2017 22:45:37 -0400 (EDT) From: Nicolas Pitre To: Alexander Viro , Christoph Hellwig Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Brandt Subject: [PATCH v5 3/5] cramfs: implement uncompressed and arbitrary data block positioning Date: Thu, 5 Oct 2017 22:45:29 -0400 Message-Id: <20171006024531.8885-4-nicolas.pitre@linaro.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171006024531.8885-1-nicolas.pitre@linaro.org> References: <20171006024531.8885-1-nicolas.pitre@linaro.org> X-Pobox-Relay-ID: 6F8F9682-AA40-11E7-BB4B-8EF31968708C-78420484!pb-smtp1.pobox.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Two new capabilities are introduced here: - The ability to store some blocks uncompressed. - The ability to locate blocks anywhere. Those capabilities can be used independently, but the combination opens the possibility for execute-in-place (XIP) of program text segments that must remain uncompressed, and in the MMU case, must have a specific alignment. It is even possible to still have the writable data segments from the same file compressed as they have to be copied into RAM anyway. This is achieved by giving special meanings to some unused block pointer bits while remaining compatible with legacy cramfs images. Signed-off-by: Nicolas Pitre Tested-by: Chris Brandt --- fs/cramfs/README | 31 ++++++++++++++- fs/cramfs/inode.c | 90 +++++++++++++++++++++++++++++++++--------- include/uapi/linux/cramfs_fs.h | 26 +++++++++++- 3 files changed, 126 insertions(+), 21 deletions(-) -- 2.9.5 diff --git a/fs/cramfs/README b/fs/cramfs/README index 9d4e7ea311..d71b27e0ff 100644 --- a/fs/cramfs/README +++ b/fs/cramfs/README @@ -49,17 +49,46 @@ same as the start of the (i+1)'th if there is one). The first immediately follows the last for the file. s are each 32 bits long. +When the CRAMFS_FLAG_EXT_BLOCK_POINTERS capability bit is set, each +'s top bits may contain special flags as follows: + +CRAMFS_BLK_FLAG_UNCOMPRESSED (bit 31): + The block data is not compressed and should be copied verbatim. + +CRAMFS_BLK_FLAG_DIRECT_PTR (bit 30): + The stores the actual block start offset and not + its end, shifted right by 2 bits. The block must therefore be + aligned to a 4-byte boundary. The block size is either blksize + if CRAMFS_BLK_FLAG_UNCOMPRESSED is also specified, otherwise + the compressed data length is included in the first 2 bytes of + the block data. This is used to allow discontiguous data layout + and specific data block alignments e.g. for XIP applications. + + The order of 's is a depth-first descent of the directory tree, i.e. the same order as `find -size +0 \( -type f -o -type l \) -print'. : The i'th is the output of zlib's compress function -applied to the i'th blksize-sized chunk of the input data. +applied to the i'th blksize-sized chunk of the input data if the +corresponding CRAMFS_BLK_FLAG_UNCOMPRESSED bit is not set, +otherwise it is the input data directly. (For the last of the file, the input may of course be smaller.) Each may be a different size. (See above.) + s are merely byte-aligned, not generally u32-aligned. +When CRAMFS_BLK_FLAG_DIRECT_PTR is specified then the corresponding + may be located anywhere and not necessarily contiguous with +the previous/next blocks. In that case it is minimally u32-aligned. +If CRAMFS_BLK_FLAG_UNCOMPRESSED is also specified then the size is always +blksize except for the last block which is limited by the file length. +If CRAMFS_BLK_FLAG_DIRECT_PTR is set and CRAMFS_BLK_FLAG_UNCOMPRESSED +is not set then the first 2 bytes of the block contains the size of the +remaining block data as this cannot be determined from the placement of +logically adjacent blocks. + Holes ----- diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index 89bce89c05..6aa1d94ed8 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -640,34 +640,86 @@ static int cramfs_readpage(struct file *file, struct page *page) if (page->index < maxblock) { struct super_block *sb = inode->i_sb; - u32 blkptr_offset = OFFSET(inode) + page->index*4; - u32 start_offset, compr_len; + u32 blkptr_offset = OFFSET(inode) + page->index * 4; + u32 block_ptr, block_start, block_len; + bool uncompressed, direct; - start_offset = OFFSET(inode) + maxblock*4; mutex_lock(&read_mutex); - if (page->index) - start_offset = *(u32 *) cramfs_read(sb, blkptr_offset-4, - 4); - compr_len = (*(u32 *) cramfs_read(sb, blkptr_offset, 4) - - start_offset); - mutex_unlock(&read_mutex); + block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4); + uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED); + direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR); + block_ptr &= ~CRAMFS_BLK_FLAGS; + + if (direct) { + /* + * The block pointer is an absolute start pointer, + * shifted by 2 bits. The size is included in the + * first 2 bytes of the data block when compressed, + * or PAGE_SIZE otherwise. + */ + block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT; + if (uncompressed) { + block_len = PAGE_SIZE; + /* if last block: cap to file length */ + if (page->index == maxblock - 1) + block_len = + offset_in_page(inode->i_size); + } else { + block_len = *(u16 *) + cramfs_read(sb, block_start, 2); + block_start += 2; + } + } else { + /* + * The block pointer indicates one past the end of + * the current block (start of next block). If this + * is the first block then it starts where the block + * pointer table ends, otherwise its start comes + * from the previous block's pointer. + */ + block_start = OFFSET(inode) + maxblock * 4; + if (page->index) + block_start = *(u32 *) + cramfs_read(sb, blkptr_offset - 4, 4); + /* Beware... previous ptr might be a direct ptr */ + if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) { + /* See comments on earlier code. */ + u32 prev_start = block_start; + block_start = prev_start & ~CRAMFS_BLK_FLAGS; + block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT; + if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) { + block_start += PAGE_SIZE; + } else { + block_len = *(u16 *) + cramfs_read(sb, block_start, 2); + block_start += 2 + block_len; + } + } + block_start &= ~CRAMFS_BLK_FLAGS; + block_len = block_ptr - block_start; + } - if (compr_len == 0) + if (block_len == 0) ; /* hole */ - else if (unlikely(compr_len > (PAGE_SIZE << 1))) { - pr_err("bad compressed blocksize %u\n", - compr_len); + else if (unlikely(block_len > 2*PAGE_SIZE || + (uncompressed && block_len > PAGE_SIZE))) { + mutex_unlock(&read_mutex); + pr_err("bad data blocksize %u\n", block_len); goto err; + } else if (uncompressed) { + memcpy(pgdata, + cramfs_read(sb, block_start, block_len), + block_len); + bytes_filled = block_len; } else { - mutex_lock(&read_mutex); bytes_filled = cramfs_uncompress_block(pgdata, PAGE_SIZE, - cramfs_read(sb, start_offset, compr_len), - compr_len); - mutex_unlock(&read_mutex); - if (unlikely(bytes_filled < 0)) - goto err; + cramfs_read(sb, block_start, block_len), + block_len); } + mutex_unlock(&read_mutex); + if (unlikely(bytes_filled < 0)) + goto err; } memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled); diff --git a/include/uapi/linux/cramfs_fs.h b/include/uapi/linux/cramfs_fs.h index e4611a9b92..ce2c885133 100644 --- a/include/uapi/linux/cramfs_fs.h +++ b/include/uapi/linux/cramfs_fs.h @@ -73,6 +73,7 @@ struct cramfs_super { #define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */ #define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */ #define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */ +#define CRAMFS_FLAG_EXT_BLOCK_POINTERS 0x00000800 /* block pointer extensions */ /* * Valid values in super.flags. Currently we refuse to mount @@ -82,7 +83,30 @@ struct cramfs_super { #define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \ | CRAMFS_FLAG_HOLES \ | CRAMFS_FLAG_WRONG_SIGNATURE \ - | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET ) + | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET \ + | CRAMFS_FLAG_EXT_BLOCK_POINTERS ) +/* + * Block pointer flags + * + * The maximum block offset that needs to be represented is roughly: + * + * (1 << CRAMFS_OFFSET_WIDTH) * 4 + + * (1 << CRAMFS_SIZE_WIDTH) / PAGE_SIZE * (4 + PAGE_SIZE) + * = 0x11004000 + * + * That leaves room for 3 flag bits in the block pointer table. + */ +#define CRAMFS_BLK_FLAG_UNCOMPRESSED (1 << 31) +#define CRAMFS_BLK_FLAG_DIRECT_PTR (1 << 30) + +#define CRAMFS_BLK_FLAGS ( CRAMFS_BLK_FLAG_UNCOMPRESSED \ + | CRAMFS_BLK_FLAG_DIRECT_PTR ) + +/* + * Direct blocks are at least 4-byte aligned. + * Pointers to direct blocks are shifted down by 2 bits. + */ +#define CRAMFS_BLK_DIRECT_PTR_SHIFT 2 #endif /* _UAPI__CRAMFS_H */ From patchwork Fri Oct 6 02:45:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Pitre X-Patchwork-Id: 115022 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp1271020qgn; Thu, 5 Oct 2017 19:47:08 -0700 (PDT) X-Google-Smtp-Source: AOwi7QDdp1OXqJmf70YAP8ORu2hEPsmMtZTXvb23A77ZSzidmlrt+aQu4n3GVMhwGh3PEJ86hUl4 X-Received: by 10.84.218.131 with SMTP id r3mr587397pli.271.1507258028165; Thu, 05 Oct 2017 19:47:08 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507258028; cv=none; d=google.com; s=arc-20160816; b=hRfMaiY918hx31Buaa+K830ogeCehsuJmeOEuDsC0NHb+Xnmgrw1TZkV7nki1UqoWX YJ6ePGJm7z8EAdgzEs6UanmN0Nr73+mbgb+Ep6YXzBmHnRtzovXUlcg+gqAKYuui2L5f 3KbxiiLcLAVoxcj8dhF1Qw8bxJ2Qf0CJYnjDA780OKPsUAsAFOjLLfeQpQ1GMxrMRNkR +LkbrCvsi+MD0WiQ47zbndXBvHLAWHYhLV6L6LVdd2xvRMKroky8z1rAraDaefZYtp6d Qe9gc2L0eojTcVE7Nt6SP1D6XB6Gf+2AeNe3k4UAeOiJkxvS7U3UpK0XkX+j1CI/dpBc T9UQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=DB8q9GINsf/PdupsvkADcQp34NMnlqHQhEf1L/Yb7Vw=; b=rnFa7IB03VwU/xsoqQ3RQJUt6ok7JwM3zKLqe8dc/ISAj1WoDQBSPLzTPKGZJLCVMG AsdIbdUB8r30WIJ1fALIHL85ns+SzvNY60Uin1XPtnDKlnyyy6RFnOl9794xjs1e6bLG fWYY8MLbYlBcdjR5wYvhiScutmmIFO3+yfDVSGNhvlPSREFhxiCGE7I9aP6qIrsRpwUb gykHmkGCXQKm0SfumHAWTxAwVDknphhHaZVvEr6Yfm6p9RAkNNZlDfwxGJFr5nffxoxQ jYZfiLMuU6e1XXgtC2KsD967yhIhKOUlPUekiFaWpPsamCkTK4qlNknGeTqRnXgjAWDN YX0Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=NjorPLqT; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id b27si315245pge.711.2017.10.05.19.47.07; Thu, 05 Oct 2017 19:47:08 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=NjorPLqT; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751969AbdJFCqt (ORCPT + 26 others); Thu, 5 Oct 2017 22:46:49 -0400 Received: from pb-smtp1.pobox.com ([64.147.108.70]:51832 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751528AbdJFCpj (ORCPT ); Thu, 5 Oct 2017 22:45:39 -0400 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id 22CE799B15; Thu, 5 Oct 2017 22:45:39 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; s=sasl; bh=zIWg gcpEm/2vurKJq5AFCrGm7l0=; b=NjorPLqTli6xTzVpwca/aizqy3JJ/uLpzyla I06ncaFOw9PDgry8dRSzxgam8O6Jdmm2xvsUClTuWhHdFbfz15hJEO4ffc2cLsLI MLt56ZDwltOWAaP55nRFKtxw6EnTbppaJnZAgrVGhz0Gx6aWxOQNPvkOXqVdsIqq G2ur+gc= Received: from pb-smtp1.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id 18C2599B14; Thu, 5 Oct 2017 22:45:39 -0400 (EDT) Received: from yoda.home (unknown [137.175.234.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp1.pobox.com (Postfix) with ESMTPSA id 8C22499B0D; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) Received: from xanadu.home (xanadu.home [192.168.2.2]) by yoda.home (Postfix) with ESMTP id D94F32DA06DA; Thu, 5 Oct 2017 22:45:37 -0400 (EDT) From: Nicolas Pitre To: Alexander Viro , Christoph Hellwig Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Brandt Subject: [PATCH v5 4/5] cramfs: add mmap support Date: Thu, 5 Oct 2017 22:45:30 -0400 Message-Id: <20171006024531.8885-5-nicolas.pitre@linaro.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171006024531.8885-1-nicolas.pitre@linaro.org> References: <20171006024531.8885-1-nicolas.pitre@linaro.org> X-Pobox-Relay-ID: 6FA70BBE-AA40-11E7-AA5F-8EF31968708C-78420484!pb-smtp1.pobox.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When cramfs_physmem is used then we have the opportunity to map files directly from ROM, directly into user space, saving on RAM usage. This gives us Execute-In-Place (XIP) support. For a file to be mmap()-able, the map area has to correspond to a range of uncompressed and contiguous blocks, and in the MMU case it also has to be page aligned. A version of mkcramfs with appropriate support is necessary to create such a filesystem image. In the MMU case it may happen for a vma structure to extend beyond the actual file size. This is notably the case in binfmt_elf.c:elf_map(). Or the file's last block is shared with other files and cannot be mapped as is. Rather than refusing to mmap it, we do a "mixed" map and let the regular fault handler populate the unmapped area with RAM-backed pages. In practice the unmapped area is seldom accessed so page faults might never occur before this area is discarded. In the non-MMU case it is the get_unmapped_area method that is responsible for providing the address where the actual data can be found. No mapping is necessary of course. Signed-off-by: Nicolas Pitre Tested-by: Chris Brandt --- fs/cramfs/inode.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 194 insertions(+) -- 2.9.5 diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index 6aa1d94ed8..071ce1eb58 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -15,7 +15,10 @@ #include #include +#include #include +#include +#include #include #include #include @@ -49,6 +52,7 @@ static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb) static const struct super_operations cramfs_ops; static const struct inode_operations cramfs_dir_inode_operations; static const struct file_operations cramfs_directory_operations; +static const struct file_operations cramfs_physmem_fops; static const struct address_space_operations cramfs_aops; static DEFINE_MUTEX(read_mutex); @@ -96,6 +100,10 @@ static struct inode *get_cramfs_inode(struct super_block *sb, case S_IFREG: inode->i_fop = &generic_ro_fops; inode->i_data.a_ops = &cramfs_aops; + if (IS_ENABLED(CONFIG_CRAMFS_PHYSMEM) && + CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS && + CRAMFS_SB(sb)->linear_phys_addr) + inode->i_fop = &cramfs_physmem_fops; break; case S_IFDIR: inode->i_op = &cramfs_dir_inode_operations; @@ -277,6 +285,192 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, return NULL; } +/* + * For a mapping to be possible, we need a range of uncompressed and + * contiguous blocks. Return the offset for the first block and number of + * valid blocks for which that is true, or zero otherwise. + */ +static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages) +{ + struct super_block *sb = inode->i_sb; + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + int i; + u32 *blockptrs, first_block_addr; + + /* + * We can dereference memory directly here as this code may be + * reached only when there is a direct filesystem image mapping + * available in memory. + */ + blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4); + first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS; + i = 0; + do { + u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT); + u32 expect = (first_block_addr + block_off) | + CRAMFS_BLK_FLAG_DIRECT_PTR | + CRAMFS_BLK_FLAG_UNCOMPRESSED; + if (blockptrs[i] != expect) { + pr_debug("range: block %d/%d got %#x expects %#x\n", + pgoff+i, pgoff + *pages - 1, + blockptrs[i], expect); + if (i == 0) + return 0; + break; + } + } while (++i < *pages); + + *pages = i; + return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT; +} + +#ifdef CONFIG_MMU + +static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + unsigned int pages, max_pages, offset; + unsigned long address, pgoff = vma->vm_pgoff; + char *bailout_reason; + int ret; + + if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE)) + return -EINVAL; + + /* Could COW work here? */ + bailout_reason = "vma is writable"; + if (vma->vm_flags & VM_WRITE) + goto bailout; + + max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; + bailout_reason = "beyond file limit"; + if (pgoff >= max_pages) + goto bailout; + pages = min(vma_pages(vma), max_pages - pgoff); + + offset = cramfs_get_block_range(inode, pgoff, &pages); + bailout_reason = "unsuitable block layout"; + if (!offset) + goto bailout; + address = sbi->linear_phys_addr + offset; + bailout_reason = "data is not page aligned"; + if (!PAGE_ALIGNED(address)) + goto bailout; + + /* Don't map the last page if it contains some other data */ + if (unlikely(pgoff + pages == max_pages)) { + unsigned int partial = offset_in_page(inode->i_size); + if (partial) { + char *data = sbi->linear_virt_addr + offset; + data += (max_pages - 1) * PAGE_SIZE + partial; + if (memchr_inv(data, 0, PAGE_SIZE - partial) != NULL) { + pr_debug("mmap: %s: last page is shared\n", + file_dentry(file)->d_name.name); + pages--; + } + } + } + + if (!pages) { + bailout_reason = "no suitable block remaining"; + goto bailout; + } + + if (pages != vma_pages(vma)) { + /* Let's create a mixed map if we can't map it all. */ + int i; + vma->vm_flags |= VM_MIXEDMAP; + for (i = 0; i < pages; i++) { + unsigned long off = i * PAGE_SIZE; + pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV); + ret = vm_insert_mixed(vma, vma->vm_start + off, pfn); + if (ret) + return ret; + } + /* + * The normal paging machinery will take care of the + * unpopulated ptes via cramfs_readpage(). + */ + vma->vm_ops = &generic_file_vm_ops; + } else { + /* + * The entire vma is mappable. remap_pfn_range() will + * make it distinguishable from a non-direct mapping + * in /proc//maps by substituting the file offset + * with the actual physical address. + */ + ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT, + pages * PAGE_SIZE, vma->vm_page_prot); + if (ret) + return ret; + } + + pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) to vma 0x%08lx, " + "page_prot 0x%llx\n", file_dentry(file)->d_name.name, pgoff, + address, pages, vma_pages(vma), vma->vm_start, + (unsigned long long)pgprot_val(vma->vm_page_prot)); + return 0; + +bailout: + pr_debug("%s[%lu]: direct mmap impossible: %s\n", + file_dentry(file)->d_name.name, pgoff, bailout_reason); + + /* We didn't manage a direct map, but normal paging is still possible */ + vma->vm_ops = &generic_file_vm_ops; + return 0; +} + +#else /* CONFIG_MMU */ + +static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma) +{ + return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; +} + +static unsigned long cramfs_physmem_get_unmapped_area(struct file *file, + unsigned long addr, unsigned long len, + unsigned long pgoff, unsigned long flags) +{ + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + struct cramfs_sb_info *sbi = CRAMFS_SB(sb); + unsigned int pages, block_pages, max_pages, offset; + + pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; + max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (pgoff >= max_pages || pages > max_pages - pgoff) + return -EINVAL; + block_pages = pages; + offset = cramfs_get_block_range(inode, pgoff, &block_pages); + if (!offset || block_pages != pages) + return -ENOSYS; + addr = sbi->linear_phys_addr + offset; + pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n", + file_dentry(file)->d_name.name, pgoff*PAGE_SIZE, len, addr); + return addr; +} + +static unsigned int cramfs_physmem_mmap_capabilities(struct file *file) +{ + return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | + NOMMU_MAP_READ | NOMMU_MAP_EXEC; +} + +#endif /* CONFIG_MMU */ + +static const struct file_operations cramfs_physmem_fops = { + .llseek = generic_file_llseek, + .read_iter = generic_file_read_iter, + .splice_read = generic_file_splice_read, + .mmap = cramfs_physmem_mmap, +#ifndef CONFIG_MMU + .get_unmapped_area = cramfs_physmem_get_unmapped_area, + .mmap_capabilities = cramfs_physmem_mmap_capabilities, +#endif +}; + static void cramfs_blkdev_kill_sb(struct super_block *sb) { struct cramfs_sb_info *sbi = CRAMFS_SB(sb); From patchwork Fri Oct 6 02:45:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Pitre X-Patchwork-Id: 115020 Delivered-To: patch@linaro.org Received: by 10.140.22.163 with SMTP id 32csp1270622qgn; Thu, 5 Oct 2017 19:46:29 -0700 (PDT) X-Google-Smtp-Source: AOwi7QAPlcXW8ra1ToGfd98c18cUaM1jqFEGHlaF9ualnn4cWssd3etG3h1DTvVN/2pQRi6iepAh X-Received: by 10.101.83.4 with SMTP id m4mr628114pgq.266.1507257989873; Thu, 05 Oct 2017 19:46:29 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1507257989; cv=none; d=google.com; s=arc-20160816; b=qh/8RstErQUTneJHBaqlXz4+vHATh94q/D9rQRC3xMS0PSS/jwxHNLlYLYZo8AI48j Zg3GfniJqDvzcMxVTN8wNeev2c/hfwUwzDrgcR/n7PeEbbDSoMx35hO8DEXD5j/i6AMp BeifCxsdOr4DnMpeSqSzK8/erjVN1qHrv/v0/2+1wKRxYHpbb0Gx0bZbmFMCgdFzwrGz wtxiTXjePJtUDDEkUYc7Ayc30wfivi8ShcGeetIThC4GxLXbVvFosMz4T7ZTfvaunZRh 1LN2POfTjMh6+xCvEINd6fqC/eFVdOyiod8uPvz12+XKf0mIERNdghJ4LwEU79/4eHD0 NY6w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=EA55KHDmQ7ayh5wcaphD1tiD0hZALg0qUBQwUe33q6E=; b=gN7cvmQ2jAsIcuWV4r2AWOow49NBVxVD71WKlt+Y38qUtESJOl40DTbEkx806Pz+u8 fA6Yu+mf1hRmK9viznJKTE67UfjjgjaVxb86V+8AslZ0f79RqqLid6J/h4gpdTlkqcal phap0HLpOlmzZA/rMm4upJc0q6x9h6M9mtiEhti4SPklBJrCd5loIbXjLEhFYD15b0pw pEiOvcZdXwc9fsvofEeJfFpFse0zvtil2gAv8DSzeA0KzdkYvK2agj80fJ4VybACw3Hp Q49pjdaer8HIOjh8cdeWfAqNpFFd5c4tqjK0xpEsJaN5qM58mVR0xfmZBhwe18jhVdfZ WX8w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=VTA0rIM0; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id c2si354794pfj.240.2017.10.05.19.46.29; Thu, 05 Oct 2017 19:46:29 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@pobox.com header.s=sasl header.b=VTA0rIM0; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751932AbdJFCq1 (ORCPT + 26 others); Thu, 5 Oct 2017 22:46:27 -0400 Received: from pb-smtp1.pobox.com ([64.147.108.70]:52534 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751536AbdJFCpk (ORCPT ); Thu, 5 Oct 2017 22:45:40 -0400 Received: from sasl.smtp.pobox.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id 5B46B99B17; Thu, 5 Oct 2017 22:45:39 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:date:message-id:in-reply-to:references; s=sasl; bh=yq1d /lUsoFpCSBXkNr5MfSp2YVk=; b=VTA0rIM0CNCR+4qoNlHPABhZ+8+b/LlCvyMb Yfos3KqKlmhMDrw5IQD2q5f8ZwDfSZKfZepSspA7d5K3y7i4nbblwlWSwjy2uDL/ J3zEr9QaEAMnGUE5JKSweL9dnfO/m+2Jl4+F0xUSGSVtSxHK59lb9meVQ1Pxnr7q UIbAVW4= Received: from pb-smtp1.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp1.pobox.com (Postfix) with ESMTP id 5342699B16; Thu, 5 Oct 2017 22:45:39 -0400 (EDT) Received: from yoda.home (unknown [137.175.234.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp1.pobox.com (Postfix) with ESMTPSA id D5EAD99B11; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) Received: from xanadu.home (xanadu.home [192.168.2.2]) by yoda.home (Postfix) with ESMTP id 00F272DA06E6; Thu, 5 Oct 2017 22:45:38 -0400 (EDT) From: Nicolas Pitre To: Alexander Viro , Christoph Hellwig Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-embedded@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Brandt Subject: [PATCH v5 5/5] cramfs: rehabilitate it Date: Thu, 5 Oct 2017 22:45:31 -0400 Message-Id: <20171006024531.8885-6-nicolas.pitre@linaro.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171006024531.8885-1-nicolas.pitre@linaro.org> References: <20171006024531.8885-1-nicolas.pitre@linaro.org> X-Pobox-Relay-ID: 6FD482C4-AA40-11E7-AEDC-8EF31968708C-78420484!pb-smtp1.pobox.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Update documentation, pointer to latest tools, appoint myself as maintainer. Given it's been unloved for so long, I don't expect anyone will protest. Signed-off-by: Nicolas Pitre Tested-by: Chris Brandt --- Documentation/filesystems/cramfs.txt | 42 ++++++++++++++++++++++++++++++++++++ MAINTAINERS | 4 ++-- fs/cramfs/Kconfig | 9 +++++--- 3 files changed, 50 insertions(+), 5 deletions(-) -- 2.9.5 diff --git a/Documentation/filesystems/cramfs.txt b/Documentation/filesystems/cramfs.txt index 4006298f67..8875d306bc 100644 --- a/Documentation/filesystems/cramfs.txt +++ b/Documentation/filesystems/cramfs.txt @@ -45,6 +45,48 @@ you can just change the #define in mkcramfs.c, so long as you don't mind the filesystem becoming unreadable to future kernels. +Memory Mapped cramfs image +-------------------------- + +The CRAMFS_PHYSMEM Kconfig option adds support for loading data directly +from a physical linear memory range (usually non volatile memory like Flash) +to cramfs instead of going through the block device layer. This saves some +memory since no intermediate buffering is necessary to hold the data before +decompressing. + +And when data blocks are kept uncompressed and properly aligned, they will +automatically be mapped directly into user space whenever possible providing +eXecute-In-Place (XIP) from ROM of read-only segments. Data segments mapped +read-write (hence they have to be copied to RAM) may still be compressed in +the cramfs image in the same file along with non compressed read-only +segments. Both MMU and no-MMU systems are supported. This is particularly +handy for tiny embedded systems with very tight memory constraints. + +The filesystem type for this feature is "cramfs_physmem" to distinguish it +from the block device (or MTD) based access. The location of the cramfs +image in memory is system dependent. You must know the proper physical +address where the cramfs image is located and specify it using the +physaddr=0x******** mount option (for example, if the physical address +of the cramfs image is 0x80100000, the following command would mount it +on /mnt: + +$ mount -t cramfs_physmem -o physaddr=0x80100000 none /mnt + +To boot such an image as the root filesystem, the following kernel +commandline parameters must be provided: + + "rootfstype=cramfs_physmem rootflags=physaddr=0x80100000" + + +Tools +----- + +A version of mkcramfs that can take advantage of the latest capabilities +described above can be found here: + +https://github.com/npitre/cramfs-tools + + For /usr/share/magic -------------------- diff --git a/MAINTAINERS b/MAINTAINERS index 1c3feffb1c..f00aec6a66 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3612,8 +3612,8 @@ F: drivers/cpuidle/* F: include/linux/cpuidle.h CRAMFS FILESYSTEM -W: http://sourceforge.net/projects/cramfs/ -S: Orphan / Obsolete +M: Nicolas Pitre +S: Maintained F: Documentation/filesystems/cramfs.txt F: fs/cramfs/ diff --git a/fs/cramfs/Kconfig b/fs/cramfs/Kconfig index 5b4e0b7e13..ae1fe6c795 100644 --- a/fs/cramfs/Kconfig +++ b/fs/cramfs/Kconfig @@ -1,5 +1,5 @@ config CRAMFS - tristate "Compressed ROM file system support (cramfs) (OBSOLETE)" + tristate "Compressed ROM file system support (cramfs)" select ZLIB_INFLATE help Saying Y here includes support for CramFs (Compressed ROM File @@ -15,8 +15,11 @@ config CRAMFS cramfs. Note that the root file system (the one containing the directory /) cannot be compiled as a module. - This filesystem is obsoleted by SquashFS, which is much better - in terms of performance and features. + This filesystem is limited in capabilities and performance on + purpose to remain small and low on RAM usage. It is most suitable + for small embedded systems. For a more capable compressed filesystem + you should look at SquashFS which is much better in terms of + performance and features. If unsure, say N.