Commit graph

17 commits

Author SHA1 Message Date
Kees Cook
f6f8285132 pstore: pass allocated memory region back to caller
The buf_lock cannot be held while populating the inodes, so make the backend
pass forward an allocated and filled buffer instead. This solves the following
backtrace. The effect is that "buf" is only ever used to notify the backends
that something was written to it, and shouldn't be used in the read path.

To replace the buf_lock during the read path, isolate the open/read/close
loop with a separate mutex to maintain serialized access to the backend.

Note that is is up to the pstore backend to cope if the (*write)() path is
called in the middle of the read path.

[   59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847
[   59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount
[   59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1
[   59.691019] Call Trace:
[   59.691019]  [<810252d5>] __might_sleep+0xc3/0xca
[   59.691019]  [<810a26e6>] kmem_cache_alloc+0x32/0xf3
[   59.691019]  [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4
[   59.691019]  [<810b68b1>] alloc_inode+0x2a/0x64
[   59.691019]  [<810b6903>] new_inode+0x18/0x43
[   59.691019]  [<81142447>] pstore_get_inode.isra.1+0x11/0x98
[   59.691019]  [<81142623>] pstore_mkfile+0xae/0x26f
[   59.691019]  [<810a2a66>] ? kmem_cache_free+0x19/0xb1
[   59.691019]  [<8116c821>] ? ida_get_new_above+0x140/0x158
[   59.691019]  [<811708ea>] ? __init_rwsem+0x1e/0x2c
[   59.691019]  [<810b67e8>] ? inode_init_always+0x111/0x1b0
[   59.691019]  [<8102127e>] ? should_resched+0xd/0x27
[   59.691019]  [<8137977f>] ? _cond_resched+0xd/0x21
[   59.691019]  [<81142abf>] pstore_get_records+0x52/0xa7
[   59.691019]  [<8114254b>] pstore_fill_super+0x7d/0x91
[   59.691019]  [<810a7ff5>] mount_single+0x46/0x82
[   59.691019]  [<8114231a>] pstore_mount+0x15/0x17
[   59.691019]  [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98
[   59.691019]  [<810a8199>] mount_fs+0x5a/0x12d
[   59.691019]  [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a
[   59.691019]  [<810b9474>] vfs_kern_mount+0x4f/0x7d
[   59.691019]  [<810b9d7e>] do_kern_mount+0x34/0xb2
[   59.691019]  [<810bb15f>] do_mount+0x5fc/0x64a
[   59.691019]  [<810912fb>] ? strndup_user+0x2e/0x3f
[   59.691019]  [<810bb3cb>] sys_mount+0x66/0x99
[   59.691019]  [<8137b537>] sysenter_do_call+0x12/0x26

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-11-17 12:58:07 -08:00
Chen Gong
b238b8fa93 pstore: make pstore write function return normal success/fail value
Currently pstore write interface employs record id as return
value, but it is not enough because it can't tell caller if
the write operation is successful. Pass the record id back via
an argument pointer and return zero for success, non-zero for
failure.

Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-10-12 09:17:24 -07:00
Don Zickus
abd4d5587b pstore: change mutex locking to spin_locks
pstore was using mutex locking to protect read/write access to the
backend plug-ins.  This causes problems when pstore is executed in
an NMI context through panic() -> kmsg_dump().

This patch changes the mutex to a spin_lock_irqsave then also checks to
see if we are in an NMI context.  If we are in an NMI and can't get the
lock, just print a message stating that and blow by the locking.

All this is probably a hack around the bigger locking problem but it
solves my current situation of trying to sleep in an NMI context.

Tested by loading the lkdtm module and executing a HARDLOCKUP which
will cause the machine to panic inside the nmi handler.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-08-16 11:55:58 -07:00
Luck, Tony
6dda926691 pstore: defer inserting OOPS entries into pstore
Life is simple for all the kernel terminating types of kmsg_dump
call backs - pstore just saves the tail end of the console log. But
for "oops" the situation is more complex - the kernel may carry on
running (possibly for ever).  So we'd like to make the logged copy
of the oops appear in the pstore filesystem - so that the user has
a handle to clear the entry from the persistent backing store (if
we don't, the store may fill with "oops" entries (that are also
safely stashed in /var/log/messages) leaving no space for real
errors.

Current code calls pstore_mkfile() immediately. But this may
not be safe. The oops could have happened with arbitrary locks
held, or in interrupt or NMI context. So allocating memory and
calling into generic filesystem code seems unwise.

This patch defers making the entry appear. At the time
of the oops, we merely set a flag "pstore_new_entry" noting that
a new entry has been added. A periodic timer checks once a minute
to see if the flag is set - if so, it schedules a work queue to
rescan the backing store and make all new entries appear in the
pstore filesystem.

Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-08-16 11:53:01 -07:00
Matthew Garrett
dee28e72b6 pstore: Allow the user to explicitly choose a backend
pstore only allows one backend to be registered at present, but the
system may provide several. Add a parameter to allow the user to choose
which backend will be used rather than just relying on load order.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22 16:14:39 -07:00
Matthew Garrett
b94fdd077e pstore: Make "part" unsigned
We'll never have a negative part, so just make this an unsigned int.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22 16:14:29 -07:00
Matthew Garrett
56280682ce pstore: Add extra context for writes and erases
EFI only provides small amounts of individual storage, and conventionally
puts metadata in the storage variable name. Rather than add a metadata
header to the (already limited) variable storage, it's easier for us to
modify pstore to pass all the information we need to construct a unique
variable name to the appropriate functions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22 16:14:20 -07:00
Matthew Garrett
638c1fd303 pstore: Extend API for more flexibility in new backends
Some pstore implementations may not have a static context, so extend the
API to pass the pstore_info struct to all calls and allow for a context
pointer.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-07-22 16:14:06 -07:00
Chen Gong
06cf91b4b4 pstore: fix pstore filesystem mount/remount issue
Currently after mount/remount operation on pstore filesystem,
the content on pstore will be lost. It is because current ERST
implementation doesn't support multi-user usage, which moves
internal pointer to the end after accessing it. Adding
multi-user support for pstore usage.

Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-05-16 11:05:00 -07:00
Chen Gong
8d38d74b64 pstore: fix one type of return value in pstore
the return type of function _read_ in pstore is size_t,
but in the callback function of _read_, the logic doesn't
consider it too much, which means if negative value (assuming
error here) is returned, it will be converted to positive because
of type casting. ssize_t is enough for this function.

Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-05-16 11:04:51 -07:00
Lucas De Marchi
25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Tony Luck
9f6af27fb6 pstore: cleanups to pstore_dump()
pstore_dump() can be called with many different "reason" codes. Save
the name of the code in the persistent store record.

Also - only worthwhile calling pstore_mkfile for KMSG_DUMP_OOPS - that
is the only one where the kernel will continue running.

Reviewed-by: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-03-22 16:01:49 -07:00
Luck, Tony
366f7e7a79 pstore: use mount option instead sysfs to tweak kmsg_bytes
/sys/fs is a somewhat strange way to tweak what could more
obviously be tuned with a mount option.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-03-21 13:50:05 -07:00
Tony Luck
a872d51010 pstore: fix leaking ->i_private
Move kfree() of i_private out of ->unlink() and into ->evict_inode()

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-21 00:45:38 -04:00
Tony Luck
fbe0aa1f3d Some fixes for pstore
1) Change from ->get_sb() to ->mount()
2) Use mount_single() instead of mount_nodev()
3) Pulled in ramfs_get_inode() & trimmed to what I need for pstore
4) Drop the ugly pstore_writefile() Just save data using kmalloc() and
   provide a pstore_file_read() that uses simple_read_from_buffer().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-17 22:08:13 -04:00
Tony Luck
168f2e1431 pstore: fix build warning for unused return value from sysfs_create_file
fs/pstore/inode.c: In function 'init_pstore_fs':
fs/pstore/inode.c:266: warning: ignoring return value of 'sysfs_create_file', declared with attribute warn_unused_result

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2011-01-06 16:58:58 -08:00
Tony Luck
ca01d6dd2d pstore: new filesystem interface to platform persistent storage
Some platforms have a small amount of non-volatile storage that
can be used to store information useful to diagnose the cause of
a system crash.  This is the generic part of a file system interface
that presents information from the crash as a series of files in
/dev/pstore.  Once the information has been seen, the underlying
storage is freed by deleting the files.

Signed-off-by: Tony Luck <tony.luck@intel.com>
2010-12-28 14:25:21 -08:00