linux-stable.git/arch/s390/lib, branch linux-3.13.y

s390/uaccess: add missing page table walk range check

2013-11-25T08:15:38+00:00

When translating a user space address, the address must be checked against
the ASCE limit of the process. If the address is larger than the maximum
address that is reachable with the ASCE, an ASCE type exception must be
generated.

The current code simply ignored the higher order bits. This resulted in an
address wrap around in user space instead of an exception in user space.

Cc: stable@vger.kernel.org # v3.9+
Reviewed-by: Gerald Schaefer 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/uaccess: always run the kernel in home space

2013-10-24T15:16:57+00:00

Simplify the uaccess code by removing the user_mode=home option.
The kernel will now always run in the home space mode.

Signed-off-by: Martin Schwidefsky

s390/bitops: rename find_first_bit_left() to find_first_bit_inv()

2013-10-24T15:16:56+00:00

find_first_bit_left() and friends have nothing to do with the normal
LSB0 bit numbering for big endian machines used in Linux (least
significant bit has bit number 0).
Instead they use MSB0 bit numbering, where the most signficant bit has
bit number 0. So rename find_first_bit_left() and friends to
find_first_bit_inv(), to avoid any confusion.
Also provide inv versions of set_bit, clear_bit and test_bit.

This also removes the confusing use of e.g. set_bit() in airq.c which
uses a "be_to_le" bit number conversion, which could imply that instead
set_bit_le() could be used. But that is entirely wrong since the _le
bitops variant uses yet another bit numbering scheme.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/bitops: use generic find bit functions / reimplement _left variant

2013-10-24T15:16:55+00:00

Just like all other architectures we should use out-of-line find bit
operations, since the inline variant bloat the size of the kernel image.
And also like all other architecures we should only supply optimized
variants of the __ffs, ffs, etc. primitives.

Therefore this patch removes the inlined s390 find bit functions and uses
the generic out-of-line variants instead.

The optimization of the primitives follows with the next patch.

With this patch also the functions find_first_bit_left() and
find_next_bit_left() have been reimplemented, since logically, they are
nothing else but a find_first_bit()/find_next_bit() implementation that
use an inverted __fls() instead of __ffs().
Also the restriction that these functions only work on machines which
support the "flogr" instruction is gone now.

This reduces the size of the kernel image (defconfig, -march=z9-109)
by 144,482 bytes.
Alone the size of the function build_sched_domains() gets reduced from
7 KB to 3,5 KB.

We also git rid of unused functions like find_first_bit_le()...

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/time: correct use of store clock fast

2013-10-22T07:16:40+00:00

The result of the store-clock-fast (STCKF) instruction is a bit fuzzy.
It can happen that the value stored on one CPU is smaller than the value
stored on another CPU, although the order of the stores is the other
way around. This can cause deltas of get_tod_clock() values to become
negative when they should not be.

We need to be more careful with store-clock-fast, this patch partially
reverts git commit e4b7b4238e666682555461fa52eecd74652f36bb "time:
always use stckf instead of stck if available". The get_tod_clock()
function now uses the store-clock-extended (STCKE) instruction.
get_tod_clock_fast() can be used if the fuzziness of store-clock-fast
is acceptable e.g. for wait loops local to a CPU.

Signed-off-by: Martin Schwidefsky

s390/time: return with irqs disabled from psw_idle

2013-08-28T07:19:23+00:00

Modify the psw_idle waiting logic in entry[64].S to return with
interrupts disabled. This avoids potential issues with udelay
and interrupt loops as interrupts are not reenabled after
clock comparator interrupts.

Signed-off-by: Martin Schwidefsky

s390/mm: cleanup page table definitions

2013-08-22T10:20:06+00:00

Improve the encoding of the different pte types and the naming of the
page, segment table and region table bits. Due to the different pte
encoding the hugetlbfs primitives need to be adapted as well. To improve
compatability with common code make the huge ptes use the encoding of
normal ptes. The conversion between the pte and pmd encoding for a huge
pte is done with set_huge_pte_at and huge_ptep_get.
Overall the code is now easier to understand.

Reviewed-by: Gerald Schaefer 
Signed-off-by: Martin Schwidefsky

s390/uaccess: add "fallthrough" comments

2013-05-02T13:50:19+00:00

Add "fallthrough" comments so nobody wonders if a break statement is missing.

Reported-by: Joe Perches 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

Kconfig: consolidate CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

2013-05-01T00:04:09+00:00

The help text for this config is duplicated across the x86, parisc, and
s390 Kconfig.debug files.  Arnd Bergman noted that the help text was
slightly misleading and should be fixed to state that enabling this
option isn't a problem when using pre 4.4 gcc.

To simplify the rewording, consolidate the text into lib/Kconfig.debug
and modify it there to be more explicit about when you should say N to
this config.

Also, make the text a bit more generic by stating that this option
enables compile time checks so we can cover architectures which emit
warnings vs.  ones which emit errors.  The details of how an
architecture decided to implement the checks isn't as important as the
concept of compile time checking of copy_from_user() calls.

While we're doing this, remove all the copy_from_user_overflow() code
that's duplicated many times and place it into lib/ so that any
architecture supporting this option can get the function for free.

Signed-off-by: Stephen Boyd 
Acked-by: Arnd Bergmann 
Acked-by: Ingo Molnar 
Acked-by: H. Peter Anvin 
Cc: Arjan van de Ven 
Acked-by: Helge Deller 
Cc: Heiko Carstens 
Cc: Stephen Rothwell 
Cc: Chris Metcalf 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

s390/uaccess: fix page table walk

2013-04-02T06:53:08+00:00

When translating user space addresses to kernel addresses the follow_table()
function had two bugs:

- PROT_NONE mappings could be read accessed via the kernel mapping. That is
  e.g. putting a filename into a user page, then protecting the page with
  PROT_NONE and afterwards issuing the "open" syscall with a pointer to
  the filename would incorrectly succeed.

- when walking the page tables it used the pgd/pud/pmd/pte primitives which
  with dynamic page tables give no indication which real level of page tables
  is being walked (region2, region3, segment or page table). So in case of an
  exception the translation exception code passed to __handle_fault() is not
  necessarily correct.
  This is not really an issue since __handle_fault() doesn't evaluate the code.
  Only in case of e.g. a SIGBUS this code gets passed to user space. If user
  space can do something sane with the value is a different question though.

To fix these issues don't use any Linux primitives. Only walk the page tables
like the hardware would do it, however we leave quite some checks away since
we know that we only have full size page tables and each index is within bounds.

In theory this should fix all issues...

Signed-off-by: Heiko Carstens 
Reviewed-by: Gerald Schaefer 
Signed-off-by: Martin Schwidefsky