linux.git/drivers/mtd/mtdchar.c, branch v3.10

Merge tag 'for-linus-20130509' of git://git.infradead.org/linux-mtd

2013-05-09T17:15:46+00:00

Pull MTD update from David Woodhouse:

 - Lots of cleanups from Artem, including deletion of some obsolete
   drivers

 - Support partitions larger than 4GiB in device tree

 - Support for new SPI chips

* tag 'for-linus-20130509' of git://git.infradead.org/linux-mtd: (83 commits)
  mtd: omap2: Use module_platform_driver()
  mtd: bf5xx_nand: Use module_platform_driver()
  mtd: denali_dt: Remove redundant use of of_match_ptr
  mtd: denali_dt: Change return value to fix smatch warning
  mtd: denali_dt: Use module_platform_driver()
  mtd: denali_dt: Fix incorrect error check
  mtd: nand: subpage write support for hardware based ECC schemes
  mtd: omap2: use msecs_to_jiffies()
  mtd: nand_ids: use size macros
  mtd: nand_ids: improve LEGACY_ID_NAND macro a bit
  mtd: add 4 Toshiba nand chips for the full-id case
  mtd: add the support to parse out the full-id nand type
  mtd: add new fields to nand_flash_dev{}
  mtd: sh_flctl: Use of_match_ptr() macro
  mtd: gpio: Use of_match_ptr() macro
  mtd: gpio: Use devm_kzalloc()
  mtd: davinci_nand: Use of_match_ptr()
  mtd: dataflash: Use of_match_ptr() macro
  mtd: remove h720x flash support
  mtd: onenand: remove OneNAND simulator
  ...

mtdchar: remove no-longer-used vma helpers

2013-04-19T17:05:39+00:00

With the conversion to vm_iomap_memory(), these vma helpers are no
longer used.

Signed-off-by: Linus Torvalds

vm: convert mtdchar mmap to vm_iomap_memory() helper

2013-04-19T16:53:07+00:00

This is my example conversion of a few existing mmap users.  The mtdchar
case is actually disabled right now (and stays disabled), but I did it
because it showed up on my "git grep", and I was familiar with the code
due to fixing an overflow problem in the code in commit 9c603e53d380
("mtdchar: fix offset overflow detection").

Signed-off-by: Linus Torvalds

mtd: merge mtdchar module with mtdcore

2013-04-05T12:16:54+00:00

The MTD subsystem has historically tried to be as configurable as possible. The
side-effect of this is that its configuration menu is rather large, and we are
gradually shrinking it. For example, we recently merged partitions support with
the mtdcore.

This patch does the next step - it merges the mtdchar module to mtdcore. And in
this case this is not only about eliminating too fine-grained separation and
simplifying the configuration menu. This is also about eliminating seemingly
useless kernel module.

Indeed, mtdchar is a module that allows user-space making use of MTD devices
via /dev/mtd* character devices. If users do not enable it, they simply cannot
use MTD devices at all. They cannot read or write the flash contents. Is it a
sane and useful setup? I believe not. And everyone just enables mtdchar.

Having mtdchar separate is also a little bit harmful. People sometimes miss the
fact that they need to enable an additional configuration option to have
user-space MTD interfaces, and then they wonder why on earth the kernel does
not allow using the flash? They spend time asking around.

Thus, let's just get rid of this module and make it part of mtd core.

Note, mtdchar had additional configuration option to enable OTP interfaces,
which are present on some flashes. I removed that option as well - it saves a
really tiny amount space.

[dwmw2: Strictly speaking, you can mount file systems on MTD devices just
        fine without the mtdchar (or mtdblock) devices; you just can't do
        other manipulations directly on the underlying device. But still I
        agree that it makes sense to make this unconditional. And Yay! we
        get to kill off an instance of checking CONFIG_foo_MODULE, which is
        an abomination that should never happen.]

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: mtdchar: use proper kernel print level

2013-04-05T12:15:38+00:00

We normally use 'pr_err()' for error messages, not 'pr_notice()'.

Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

mtd: mtdchar: handle chips that have user otp but no factory otp

2013-04-05T10:58:34+00:00

Before this patch mtd_read_fact_prot_reg was used to check availability
for both MTD_OTP_FACTORY and MTD_OTP_USER access. This made accessing
user otp for chips that don't have a factory otp area impossible. So use
the right wrapper depending on the intended area to be accessed.

Signed-off-by: Uwe Kleine-König 
Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse

fs: Limit sys_mount to only request filesystem modules.

2013-03-04T03:36:31+00:00

Modify the request_module to prefix the file system type with "fs-"
and add aliases to all of the filesystems that can be built as modules
to match.

A common practice is to build all of the kernel code and leave code
that is not commonly needed as modules, with the result that many
users are exposed to any bug anywhere in the kernel.

Looking for filesystems with a fs- prefix limits the pool of possible
modules that can be loaded by mount to just filesystems trivially
making things safer with no real cost.

Using aliases means user space can control the policy of which
filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf
with blacklist and alias directives.  Allowing simple, safe,
well understood work-arounds to known problematic software.

This also addresses a rare but unfortunate problem where the filesystem
name is not the same as it's module name and module auto-loading
would not work.  While writing this patch I saw a handful of such
cases.  The most significant being autofs that lives in the module
autofs4.

This is relevant to user namespaces because we can reach the request
module in get_fs_type() without having any special permissions, and
people get uncomfortable when a user specified string (in this case
the filesystem type) goes all of the way to request_module.

After having looked at this issue I don't think there is any
particular reason to perform any filtering or permission checks beyond
making it clear in the module request that we want a filesystem
module.  The common pattern in the kernel is to call request_module()
without regards to the users permissions.  In general all a filesystem
module does once loaded is call register_filesystem() and go to sleep.
Which means there is not much attack surface exposed by loading a
filesytem module unless the filesystem is mounted.  In a user
namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT,
which most filesystems do not set today.

Acked-by: Serge Hallyn 
Acked-by: Kees Cook 
Reported-by: Kees Cook 
Signed-off-by: "Eric W. Biederman"

mtd: Disable mtdchar mmap on MMU systems

2012-10-09T14:08:42+00:00

This code was broken because it assumed that all MTD devices were map-based.
Disable it for now, until it can be fixed properly for the next merge window.

Signed-off-by: David Woodhouse

mm: kill vma flag VM_RESERVED and mm->reserved_vm counter

2012-10-09T07:22:19+00:00

A long time ago, in v2.4, VM_RESERVED kept swapout process off VMA,
currently it lost original meaning but still has some effects:

 | effect                 | alternative flags
-+------------------------+---------------------------------------------
1| account as reserved_vm | VM_IO
2| skip in core dump      | VM_IO, VM_DONTDUMP
3| do not merge or expand | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
4| do not mlock           | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP

This patch removes reserved_vm counter from mm_struct.  Seems like nobody
cares about it, it does not exported into userspace directly, it only
reduces total_vm showed in proc.

Thus VM_RESERVED can be replaced with VM_IO or pair VM_DONTEXPAND | VM_DONTDUMP.

remap_pfn_range() and io_remap_pfn_range() set VM_IO|VM_DONTEXPAND|VM_DONTDUMP.
remap_vmalloc_range() set VM_DONTEXPAND | VM_DONTDUMP.

[akpm@linux-foundation.org: drivers/vfio/pci/vfio_pci.c fixup]
Signed-off-by: Konstantin Khlebnikov 
Cc: Alexander Viro 
Cc: Carsten Otte 
Cc: Chris Metcalf 
Cc: Cyrill Gorcunov 
Cc: Eric Paris 
Cc: H. Peter Anvin 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: James Morris 
Cc: Jason Baron 
Cc: Kentaro Takeda 
Cc: Matt Helsley 
Cc: Nick Piggin 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Robert Richter 
Cc: Suresh Siddha 
Cc: Tetsuo Handa 
Cc: Venkatesh Pallipadi 
Acked-by: Linus Torvalds 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mtdchar: fix offset overflow detection

2012-09-28T19:13:46+00:00

Sasha Levin has been running trinity in a KVM tools guest, and was able
to trigger the BUG_ON() at arch/x86/mm/pat.c:279 (verifying the range of
the memory type).  The call trace showed that it was mtdchar_mmap() that
created an invalid remap_pfn_range().

The problem is that mtdchar_mmap() does various really odd and subtle
things with the vma page offset etc, and uses the wrong types (and the
wrong overflow) detection for it.

For example, the page offset may well be 32-bit on a 32-bit
architecture, but after shifting it up by PAGE_SHIFT, we need to use a
potentially 64-bit resource_size_t to correctly hold the full value.

Also, we need to check that the vma length plus offset doesn't overflow
before we check that it is smaller than the length of the mtdmap region.

This fixes things up and tries to make the code a bit easier to read.

Reported-and-tested-by: Sasha Levin 
Acked-by: Suresh Siddha 
Acked-by: Artem Bityutskiy 
Cc: David Woodhouse 
Cc: linux-mtd@lists.infradead.org
Signed-off-by: Linus Torvalds