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* libnvdimm: use consistent naming for request_mem_region()Dan Williams2016-11-283-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here is an example /proc/iomem listing for a system with 2 namespaces, one in "sector" mode and one in "memory" mode: 1fc000000-2fbffffff : Persistent Memory (legacy) 1fc000000-2fbffffff : namespace1.0 340000000-34fffffff : Persistent Memory 340000000-34fffffff : btt0.1 Here is the corresponding ndctl listing: # ndctl list [ { "dev":"namespace1.0", "mode":"memory", "size":4294967296, "blockdev":"pmem1" }, { "dev":"namespace0.0", "mode":"sector", "size":267091968, "uuid":"f7594f86-badb-4592-875f-ded577da2eaf", "sector_size":4096, "blockdev":"pmem0s" } ] Notice that the ndctl listing is purely in terms of namespace devices, while the iomem listing leaks the internal "btt0.1" implementation detail. Given that ndctl requires the namespace device name to change the mode, for example: # ndctl create-namespace --reconfig=namespace0.0 --mode=raw --force ...use the namespace name in the iomem listing to keep the claiming device name consistent across different mode settings. Cc: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* nvdimm: use the right length of "pmem"Nicolas Iooss2016-11-111-1/+1
| | | | | | | | In order to test that the name of a resource begins with "pmem", call strncmp() with 4 as length instead of 3 to match the whole prefix. Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* libnvdimm: check and clear poison before writing to pmemDave Jiang2016-11-111-4/+26
| | | | | | | | | | | We need to clear any poison when we are writing to pmem. The granularity will be sector size. If it's less then we can't do anything about it barring corruption. Signed-off-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> [djbw: fixup 0-length write request to succeed] Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* tools/testing/nvdimm: dynamic label supportDan Williams2016-10-191-7/+23
| | | | | | | | | Update nfit_test infrastructure to enable labels for the dimm on the nfit_test.1 bus. This bus has a pmem region without aliased blk space, so it is a candidate for dynamically enabling label support by writing a namespace index block. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* libnvdimm: allow a platform to force enable label supportDan Williams2016-10-193-0/+10
| | | | | | | | | | | | | | | Platforms like QEMU-KVM implement an NFIT table and label DSMs. However, since that environment does not define an aliased configuration, the labels are currently ignored and the kernel registers a single full-sized pmem-namespace per region. Now that the kernel supports sub-divisions of pmem regions the labels have a purpose. Arrange for the labels to be honored when we find an existing / valid namespace index block. Cc: <qemu-devel@nongnu.org> Cc: Haozhong Zhang <haozhong.zhang@intel.com> Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* libnvdimm: use generic iostat interfacesToshi Kani2016-10-192-31/+9
| | | | | | | | | | | | | | | nd_iostat_start() and nd_iostat_end() implement the same functionality that generic_start_io_acct() and generic_end_io_acct() already provide. Change nd_iostat_start() and nd_iostat_end() to call the generic iostat interfaces. There is no change in the nd interfaces. Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Dave Chinner <david@fromorbit.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
* Linux 4.9-rc1v4.9-rc1Linus Torvalds2016-10-151-2/+2
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* Merge tag 'befs-v4.9-rc1' of git://github.com/luisbg/linux-befsLinus Torvalds2016-10-158-283/+244
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull befs fixes from Luis de Bethencourt: "I recently took maintainership of the befs file system [0]. This is the first time I send you a git pull request, so please let me know if all the below is OK. Salah Triki and myself have been cleaning the code and fixing a few small bugs. Sorry I couldn't send this sooner in the merge window, I was waiting to have my GPG key signed by kernel members at ELCE in Berlin a few days ago." [0] https://lkml.org/lkml/2016/7/27/502 * tag 'befs-v4.9-rc1' of git://github.com/luisbg/linux-befs: (39 commits) befs: befs: fix style issues in datastream.c befs: improve documentation in datastream.c befs: fix typos in datastream.c befs: fix typos in btree.c befs: fix style issues in super.c befs: fix comment style befs: add check for ag_shift in superblock befs: dump inode_size superblock information befs: remove unnecessary initialization befs: fix typo in befs_sb_info befs: add flags field to validate superblock state befs: fix typo in befs_find_key befs: remove unused BEFS_BT_PARMATCH fs: befs: remove ret variable fs: befs: remove in vain variable assignment fs: befs: remove unnecessary *befs_sb variable fs: befs: remove useless initialization to zero fs: befs: remove in vain variable assignment fs: befs: Insert NULL inode to dentry fs: befs: Remove useless calls to brelse in befs_find_brun_dblindirect ...
| * befs: befs: fix style issues in datastream.cLuis de Bethencourt2016-10-081-15/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fixing the following checkpatch.pl errors: ERROR: "foo * bar" should be "foo *bar" + befs_blocknr_t blockno, befs_block_run * run); WARNING: Missing a blank line after declarations + struct buffer_head *bh; + befs_debug(sb, "---> %s length: %llu", __func__, len); WARNING: Block comments use * on subsequent lines + /* + Double indir block, plus all the indirect blocks it maps. (and other instances of these) Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: improve documentation in datastream.cLuis de Bethencourt2016-10-081-95/+98
| | | | | | | | | | | | | | Convert function descriptions to kernel-doc style. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: fix typos in datastream.cLuis de Bethencourt2016-10-081-4/+4
| | | | | | | | | | Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: fix typos in btree.cLuis de Bethencourt2016-10-081-4/+3
| | | | | | | | | | | | | | Fixing typos in kernel-doc function descriptions in fs/befs/btree.c. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: fix style issues in super.cLuis de Bethencourt2016-10-081-7/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fixing the following checkpatch.pl error: ERROR: "foo * bar" should be "foo *bar" +befs_load_sb(struct super_block *sb, befs_super_block * disk_sb) And the following warnings: WARNING: suspect code indent for conditional statements (8, 12) + if (disk_sb->fs_byte_order == BEFS_BYTEORDER_NATIVE_LE) + befs_sb->byte_order = BEFS_BYTESEX_LE; WARNING: suspect code indent for conditional statements (8, 12) + else if (disk_sb->fs_byte_order == BEFS_BYTEORDER_NATIVE_BE) + befs_sb->byte_order = BEFS_BYTESEX_BE; WARNING: break quoted strings at a space character + befs_error(sb, "blocksize(%u) cannot be larger" + "than system pagesize(%lu)", befs_sb->block_size, WARNING: line over 80 characters + if (befs_sb->log_start != befs_sb->log_end || befs_sb->flags == BEFS_DIRTY) { Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: fix comment styleLuis de Bethencourt2016-10-081-7/+3
| | | | | | | | | | | | | | | | | | | | | | The description of befs_load_sb was confusing the kernel-doc system since, because it starts with /**, it thinks it will document the function with kernel-doc formatting. Which it isn't. Fix other comment style issues in the file while we are at it. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: add check for ag_shift in superblockLuis de Bethencourt2016-10-081-0/+7
| | | | | | | | | | | | | | | | | | | | | | ag_shift and blocks_per_ag contain the same information in different ways, same as block_shift and block_size do. It is worth checking this two are consistent, but since blocks_per_ag isn't documented as mandatory to use some implementations of befs don't enforce this, so making it non-fatal if they don't match and just having it as a warning. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: dump inode_size superblock informationLuis de Bethencourt2016-10-081-0/+1
| | | | | | | | | | | | | | | | | | befs_dump_super_block() wasn't giving the inode_size information when dumping all elements of the superblock. Add this element to have complete information of the superblock. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: remove unnecessary initializationSalah Triki2016-10-081-1/+1
| | | | | | | | | | | | | | | | There is no need to init block, since it will be overwitten later by iaddr2blockno(). Signed-off-by: Salah Triki <salah.triki@gmail.com> Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: fix typo in befs_sb_infoSalah Triki2016-10-081-1/+1
| | | | | | | | | | | | | | Fixing jornal to Journal. Signed-off-by: Salah Triki <salah.triki@gmail.com> Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: add flags field to validate superblock stateSalah Triki2016-10-082-1/+6
| | | | | | | | | | | | | | | | For validating superblock state, add flags field to befs_sb_info, read the state from the disk and check if it is equal to BEFS_DIRTY. Signed-off-by: Salah Triki <salah.triki@gmail.com> Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: fix typo in befs_find_keyLuis de Bethencourt2016-10-081-1/+1
| | | | | | | | | | | | | | Fixing skeep to skip. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * befs: remove unused BEFS_BT_PARMATCHLuis de Bethencourt2016-10-082-19/+16
| | | | | | | | | | | | | | | | | | | | befs_btree_find(), the only caller of befs_find_key(), only cares about if the return from that function is BEFS_BT_MATCH or not. It never uses the partial match given with BEFS_BT_PARMATCH. Make the overflow return clearer by having BEFS_BT_OVERFLOW instead of BEFS_BT_PARMATCH. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Salah Triki <salah.triki@gmail.com>
| * fs: befs: remove ret variableSalah Triki2016-10-081-2/+1
| | | | | | | | | | | | | | | | ret is initialized to -EIO and is never modified, so remove ret and use -EIO directly. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: remove in vain variable assignmentSalah Triki2016-10-081-1/+1
| | | | | | | | | | | | | | | | There is no need to init res, since it will be overwitten later by befs_fblock2brun(). Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: remove unnecessary *befs_sb variableSalah Triki2016-10-081-2/+1
| | | | | | | | | | | | | | | | Remove *befs_sb and just call BEFS_SB(sb) directly, since the returned value by this function is only used once. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: remove useless initialization to zeroSalah Triki2016-10-081-1/+1
| | | | | | | | | | | | | | | | node_off is unconditionally set to bt_super.root_node_ptr, so no need to init it to zero. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: remove in vain variable assignmentSalah Triki2016-10-081-2/+0
| | | | | | | | | | | | | | There is no need to set *value, it will be overwritten later. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: Insert NULL inode to dentrySalah Triki2016-10-081-0/+1
| | | | | | | | | | | | | | | | As VFS expects, lookup inserts NULL inode to dentry when the named inode does not exist. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: Remove useless calls to brelse in befs_find_brun_dblindirectSalah Triki2016-10-081-2/+0
| | | | | | | | | | | | | | | | The calls to brelse are useless since dbl_indir_block and indir_block are NULL. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: Coding style fixSalah Triki2016-10-081-3/+3
| | | | | | | | | | | | | | Constant has to be capitalized. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: Remove redundant validation from befs_find_brun_directSalah Triki2016-10-081-8/+0
| | | | | | | | | | | | | | | | | | The only caller of befs_find_brun_direct is befs_fblock2brun, which already validates that the block is within the range of direct blocks. So remove the duplicate validation. Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: fix typo in befs_bt_read_node documentationLuis de Bethencourt2016-10-081-2/+2
| | | | | | | | | | | | Fixing a grammatical error in the documentation. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: in memory free_node_ptr and max_size never readLuis de Bethencourt2016-10-081-2/+0
| | | | | | | | | | | | | | | | The only place the values of free_node_ptr and max_size are read is in befs_dump_index_entry(), which both times it is called, it is passed the on disk superblock. Removing assignment of unused values. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: make consistent use of befs_error()Luis de Bethencourt2016-10-083-4/+9
| | | | | | | | | | | | | | | | | | | | | | | | befs_error() is used in potential errors that could happen in befs to provide informational log messages. befs_debug() is silent when CONFIG_BEFS_DEBUG=no, and very verbose when switched on, which is why it is used for general debugging but not for errors. Fix a few cases where the befs debug utility usage isn't following the expected pattern. To make sure we have consistent information in the logs. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: use simpler while loopLuis de Bethencourt2016-10-081-36/+38
| | | | | | | | | | | | Replace goto with simpler while loop to make befs_readdir() more readable. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * befs: remove constant variableLuis de Bethencourt2016-10-081-5/+2
| | | | | | | | | | | | | | Use macro directly instead of via assigning it to an unchanging variable. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Acked-by: Salah Triki <salah.triki@gmail.com>
| * befs: avoid dereferencing dentry twiceLuis de Bethencourt2016-10-081-1/+1
| | | | | | | | | | | | | | No need to dereference dentry twice to get the name when we already have it stored in a local variable. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: remove comment that confuses kernel-docLuis de Bethencourt2016-10-081-4/+0
| | | | | | | | | | | | | | | | This comment with a mysterious unfinished line confuses the kernel-doc system since, because it starts with /**, it thinks it is documenting a function. Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
| * fs: befs: check silent flag before logging errorLuis de Bethencourt2016-10-081-1/+2
| | | | | | | | | | | | | | | | Log error only when silent flag is not set. Fixes: dbe6460388bc ("fs/befs/linuxvfs.c: check silent flag before logging errors") Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Acked-by: Salah Triki <salah.triki@gmail.com>
| * fs: befs: replace befs_bread by sb_breadSalah Triki2016-10-084-30/+4
| | | | | | | | | | | | | | | | | | Since befs_bread merely calls sb_bread, replace it by sb_bread. Link: http://lkml.kernel.org/r/1466800258-4542-1-git-send-email-salah.triki@gmail.com Signed-off-by: Salah Triki <salah.triki@gmail.com> Acked-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * befs: remove unused functionsLuis de Bethencourt2016-10-081-12/+0
| | | | | | | | | | | | | | | | befs_iaddr_is_empty() and befs_brun_size() are unused. Remove them. Link: http://lkml.kernel.org/r/1465700235-22881-3-git-send-email-luisbg@osg.samsung.com Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * befs: fix function name in documentationLuis de Bethencourt2016-10-081-1/+1
| | | | | | | | | | | | | | | | | | Documentation of function befs_load_cb() lists it as load_befs_sb(). Fix the misnomer. Link: http://lkml.kernel.org/r/1465700235-22881-2-git-send-email-luisbg@osg.samsung.com Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * befs: check return of sb_min_blocksizeLuis de Bethencourt2016-10-081-1/+6
| | | | | | | | | | | | | | | | Confirm sb_min_blocksize() succeeded before continuing. Link: http://lkml.kernel.org/r/1465700235-22881-1-git-send-email-luisbg@osg.samsung.com Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * fs: befs: remove useless pr_err in befs_init_inodecache()Salah Triki2016-10-081-4/+2
| | | | | | | | | | | | | | Remove pr_err since kmem_cache_create log error and dump stack. Link: http://lkml.kernel.org/r/e6d03cbc9542495dc6174b59e32fcd41c1393cfc.1464226521.git.salah.triki@acm.org Signed-off-by: Salah Triki <salah.triki@acm.org>
| * fs/befs/linuxvfs.c: remove useless befs_errorSalah Triki2016-10-081-2/+0
| | | | | | | | | | | | | | | | | | Remove befs_error since when kmalloc fails there is a generic out of memory and stack dump. Link: http://lkml.kernel.org/r/3de4d388d98bbb570462a5eb8e64623e17fb5d74.1464226521.git.salah.triki@acm.org Signed-off-by: Salah Triki <salah.triki@acm.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * fs/befs/linuxvfs.c: remove useless pr_err in befs_fill_super()Salah Triki2016-10-081-4/+2
| | | | | | | | | | | | | | | | | | Remove pr_err since when kzalloc fails there is a generic out of memory and stack dump. Link: http://lkml.kernel.org/r/c5a7f2d42ec0fc8465c118248e88cd221c483391.1464226521.git.salah.triki@acm.org Signed-off-by: Salah Triki <salah.triki@acm.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * fs/befs/linuxvfs.c: check silent flag before logging errorsSalah Triki2016-10-081-6/+9
| | | | | | | | | | | | | | | | Log errors only when silent flag is not set. Link: http://lkml.kernel.org/r/d400aaf5a7430de79bd956e40ec075fb1cb08474.1464226521.git.salah.triki@acm.org Signed-off-by: Salah Triki <salah.triki@acm.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| * fs/befs/linuxvfs.c: move useless assignmentSalah Triki2016-10-081-1/+1
| | | | | | | | | | | | | | | | | | | | Control is transfered to unacquire_none when sb->s_fs_info is equal to NULL, so the assignment to NULL is useless and it is moved above unacquire_none. Link: http://lkml.kernel.org/r/ed41da113fc693c7daa4e8813ca04cc766ddfc05.1464226521.git.salah.triki@acm.org Signed-off-by: Salah Triki <salah.triki@acm.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
* | Merge tag 'gcc-plugins-v4.9-rc1' of ↵Linus Torvalds2016-10-1524-22/+725
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull gcc plugins update from Kees Cook: "This adds a new gcc plugin named "latent_entropy". It is designed to extract as much possible uncertainty from a running system at boot time as possible, hoping to capitalize on any possible variation in CPU operation (due to runtime data differences, hardware differences, SMP ordering, thermal timing variation, cache behavior, etc). At the very least, this plugin is a much more comprehensive example for how to manipulate kernel code using the gcc plugin internals" * tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: latent_entropy: Mark functions with __latent_entropy gcc-plugins: Add latent_entropy plugin
| * | latent_entropy: Mark functions with __latent_entropyEmese Revfy2016-10-1019-22/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The __latent_entropy gcc attribute can be used only on functions and variables. If it is on a function then the plugin will instrument it for gathering control-flow entropy. If the attribute is on a variable then the plugin will initialize it with random contents. The variable must be an integer, an integer array type or a structure with integer fields. These specific functions have been selected because they are init functions (to help gather boot-time entropy), are called at unpredictable times, or they have variable loops, each of which provide some level of latent entropy. Signed-off-by: Emese Revfy <re.emese@gmail.com> [kees: expanded commit message] Signed-off-by: Kees Cook <keescook@chromium.org>
| * | gcc-plugins: Add latent_entropy pluginEmese Revfy2016-10-108-1/+689
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds a new gcc plugin named "latent_entropy". It is designed to extract as much possible uncertainty from a running system at boot time as possible, hoping to capitalize on any possible variation in CPU operation (due to runtime data differences, hardware differences, SMP ordering, thermal timing variation, cache behavior, etc). At the very least, this plugin is a much more comprehensive example for how to manipulate kernel code using the gcc plugin internals. The need for very-early boot entropy tends to be very architecture or system design specific, so this plugin is more suited for those sorts of special cases. The existing kernel RNG already attempts to extract entropy from reliable runtime variation, but this plugin takes the idea to a logical extreme by permuting a global variable based on any variation in code execution (e.g. a different value (and permutation function) is used to permute the global based on loop count, case statement, if/then/else branching, etc). To do this, the plugin starts by inserting a local variable in every marked function. The plugin then adds logic so that the value of this variable is modified by randomly chosen operations (add, xor and rol) and random values (gcc generates separate static values for each location at compile time and also injects the stack pointer at runtime). The resulting value depends on the control flow path (e.g., loops and branches taken). Before the function returns, the plugin mixes this local variable into the latent_entropy global variable. The value of this global variable is added to the kernel entropy pool in do_one_initcall() and _do_fork(), though it does not credit any bytes of entropy to the pool; the contents of the global are just used to mix the pool. Additionally, the plugin can pre-initialize arrays with build-time random contents, so that two different kernel builds running on identical hardware will not have the same starting values. Signed-off-by: Emese Revfy <re.emese@gmail.com> [kees: expanded commit message and code comments] Signed-off-by: Kees Cook <keescook@chromium.org>
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