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  1. 20 May, 2014 19 commits
  3. 19 May, 2014 1 commit
    • Dave Airlie's avatar
      Merge tag 'drm-intel-fixes-2014-05-16' of git://anongit.freedesktop.org/drm-intel into drm-fixes · 4ba4801d
      Dave Airlie authored 
      Intel fixes for regressions, black screens and hangs, for 3.15.

* tag 'drm-intel-fixes-2014-05-16' of git://anongit.freedesktop.org/drm-intel:
  drm/i915: Increase WM memory latency values on SNB
  drm/i915: restore backlight precision when converting from ACPI
  drm/i915: Use the first mode if there is no preferred mode in the EDID
  drm/i915/dp: force eDP lane count to max available lanes on BDW
  drm/i915/vlv: reset VLV media force wake request register
  drm/i915/SDVO: For sysfs link put directory and target in correct order
  drm/i915: use lane count and link rate from VBT as minimums for eDP
  drm/i915: clean up VBT eDP link param decoding
  drm/i915: consider the source max DP lane count too
      4ba4801d
  5. 16 May, 2014 1 commit
    • Mark Salter's avatar
      arm64: fix pud_huge() for 2-level pagetables · 4797ec2d
      Mark Salter authored 
      The following happens when trying to run a kvm guest on a kernel
configured for 64k pages. This doesn't happen with 4k pages:

  BUG: failure at include/linux/mm.h:297/put_page_testzero()!
  Kernel panic - not syncing: BUG!
  CPU: 2 PID: 4228 Comm: qemu-system-aar Tainted: GF            3.13.0-0.rc7.31.sa2.k32v1.aarch64.debug #1
  Call trace:
  [<fffffe0000096034>] dump_backtrace+0x0/0x16c
  [<fffffe00000961b4>] show_stack+0x14/0x1c
  [<fffffe000066e648>] dump_stack+0x84/0xb0
  [<fffffe0000668678>] panic+0xf4/0x220
  [<fffffe000018ec78>] free_reserved_area+0x0/0x110
  [<fffffe000018edd8>] free_pages+0x50/0x88
  [<fffffe00000a759c>] kvm_free_stage2_pgd+0x30/0x40
  [<fffffe00000a5354>] kvm_arch_destroy_vm+0x18/0x44
  [<fffffe00000a1854>] kvm_put_kvm+0xf0/0x184
  [<fffffe00000a1938>] kvm_vm_release+0x10/0x1c
  [<fffffe00001edc1c>] __fput+0xb0/0x288
  [<fffffe00001ede4c>] ____fput+0xc/0x14
  [<fffffe00000d5a2c>] task_work_run+0xa8/0x11c
  [<fffffe0000095c14>] do_notify_resume+0x54/0x58

In arch/arm/kvm/mmu.c:unmap_range(), we end up doing an extra put_page()
on the stage2 pgd which leads to the BUG in put_page_testzero(). This
happens because a pud_huge() test in unmap_range() returns true when it
should always be false with 2-level pages tables used by 64k pages.
This patch removes support for huge puds if 2-level pagetables are
being used.
Signed-off-by: default avatarMark Salter <msalter@redhat.com>
[catalin.marinas@arm.com: removed #ifndef around PUD_SIZE check]
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org> # v3.11+
      4797ec2d
  7. 15 May, 2014 6 commits
  9. 14 May, 2014 6 commits
    • Linus Torvalds's avatar
      x86-64, modify_ldt: Make support for 16-bit segments a runtime option · fa81511b
      Linus Torvalds authored 
      Checkin:

b3b42ac2 x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

disabled 16-bit segments on 64-bit kernels due to an information
leak.  However, it does seem that people are genuinely using Wine to
run old 16-bit Windows programs on Linux.

A proper fix for this ("espfix64") is coming in the upcoming merge
window, but as a temporary fix, create a sysctl to allow the
administrator to re-enable support for 16-bit segments.

It adds a "/proc/sys/abi/ldt16" sysctl that defaults to zero (off). If
you hit this issue and care about your old Windows program more than
you care about a kernel stack address information leak, you can do

   echo 1 > /proc/sys/abi/ldt16

as root (add it to your startup scripts), and you should be ok.

The sysctl table is only added if you have COMPAT support enabled on
x86-64, but I assume anybody who runs old windows binaries very much
does that ;)
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/CA%2B55aFw9BPoD10U1LfHbOMpHWZkvJTkMcfCs9s3urPr1YyWBxw@mail.gmail.com
Cc: <stable@vger.kernel.org>
      fa81511b
    • James Hogan's avatar
      asm-generic: remove _STK_LIM_MAX · ffe6902b
      James Hogan authored 
      _STK_LIM_MAX could be used to override the RLIMIT_STACK hard limit from
an arch's include/uapi/asm-generic/resource.h file, but is no longer
used since both parisc and metag removed the override. Therefore remove
it entirely, setting the hard RLIMIT_STACK limit to RLIM_INFINITY
directly in include/asm-generic/resource.h.
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch@vger.kernel.org
Cc: Helge Deller <deller@gmx.de>
Cc: John David Anglin <dave.anglin@bell.net>
      ffe6902b
    • James Hogan's avatar
      metag: Remove _STK_LIM_MAX override · c70458f5
      James Hogan authored 
      Meta overrode _STK_LIM_MAX (the default RLIMIT_STACK hard limit) to
256MB, apparently in an attempt to prevent setup_arg_pages's
STACK_GROWSUP code from choosing the maximum stack size of 1GB, which is
far too large for Meta's limited virtual address space and hits a BUG_ON
(stack_top is usually 0x3ffff000).

However the commit "metag: Reduce maximum stack size to 256MB" reduces
the absolute stack size limit to a safe value for metag. This allows the
default _STK_LIM_MAX override to be removed, bringing the default
behaviour in line with all other architectures. Parisc in particular
recently removed their override of _STK_LIMT_MAX in commit e0d8898d
(parisc: remove _STK_LIM_MAX override) since it subtly affects stack
allocation semantics in userland. Meta's uapi/asm/resource.h can now be
removed and switch to using generic-y.
Suggested-by: default avatarHelge Deller <deller@gmx.de>
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.anglin@bell.net>
      c70458f5
    • Helge Deller's avatar
      parisc,metag: Do not hardcode maximum userspace stack size · 042d27ac
      Helge Deller authored 
      This patch affects only architectures where the stack grows upwards
(currently parisc and metag only). On those do not hardcode the maximum
initial stack size to 1GB for 32-bit processes, but make it configurable
via a config option.

The main problem with the hardcoded stack size is, that we have two
memory regions which grow upwards: stack and heap. To keep most of the
memory available for heap in a flexmap memory layout, it makes no sense
to hard allocate up to 1GB of the memory for stack which can't be used
as heap then.

This patch makes the stack size for 32-bit processes configurable and
uses 80MB as default value which has been in use during the last few
years on parisc and which hasn't showed any problems yet.
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: linux-parisc@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.anglin@bell.net>
      042d27ac
    • James Hogan's avatar
      metag: Reduce maximum stack size to 256MB · d71f290b
      James Hogan authored 
      Specify the maximum stack size for arches where the stack grows upward
(parisc and metag) in asm/processor.h rather than hard coding in
fs/exec.c so that metag can specify a smaller value of 256MB rather than
1GB.

This fixes a BUG on metag if the RLIMIT_STACK hard limit is increased
beyond a safe value by root. E.g. when starting a process after running
"ulimit -H -s unlimited" it will then attempt to use a stack size of the
maximum 1GB which is far too big for metag's limited user virtual
address space (stack_top is usually 0x3ffff000):

BUG: failure at fs/exec.c:589/shift_arg_pages()!
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: linux-parisc@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # only needed for >= v3.9 (arch/metag)
      d71f290b
    • Mikulas Patocka's avatar
      metag: fix memory barriers · 2425ce84
      Mikulas Patocka authored 
      Volatile access doesn't really imply the compiler barrier. Volatile access
is only ordered with respect to other volatile accesses, it isn't ordered
with respect to general memory accesses. Gcc may reorder memory accesses
around volatile access, as we can see in this simple example (if we
compile it with optimization, both increments of *b will be collapsed to
just one):

void fn(volatile int *a, long *b)
{
	(*b)++;
	*a = 10;
	(*b)++;
}

Consequently, we need the compiler barrier after a write to the volatile
variable, to make sure that the compiler doesn't reorder the volatile
write with something else.
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
      2425ce84
  11. 13 May, 2014 7 commits
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