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Add optimised library functions for metag.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add DMA mapping code.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add SMP support for metag. This allows Linux to take control of multiple
hardware threads on a single Meta core, treating them as separate Linux
CPUs.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add basic metag documentation. This includes an outline description of
the ABIs (including syscall ABI) and calling conventions, similar to the
one in Documentation/frv/.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Rob Landley <rob@landley.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: linux-doc@vger.kernel.org
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Add header files to implement Meta hardware thread locks (used by some
other atomic operations), atomics, spinlocks, and bitops.
There are 2 main types of atomic primitives for metag (in addition to
IRQs off on UP):
- LOCK instructions provide locking between hardware threads.
- LNKGET/LNKSET instructions provide load-linked/store-conditional
operations allowing for lighter weight atomics on Meta2
LOCK instructions allow for hardware threads to acquire voluntary or
exclusive hardware thread locks:
- LOCK0 releases exclusive and voluntary lock from the running hardware
thread.
- LOCK1 acquires the voluntary hardware lock, blocking until it becomes
available.
- LOCK2 implies LOCK1, and additionally acquires the exclusive hardware
lock, blocking all other hardware threads from executing.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add metag system call and gateway page interfaces. The metag
architecture port uses the generic system call numbers from
asm-generic/unistd.h, as well as a user gateway page mapped at
0x6ffff000 which contains fast atomic primitives (depending on SMP) and
a fast method of accessing TLS data.
System calls use the SWITCH instruction with the immediate 0x440001 to
signal a system call.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Meta core internal interrupts (from HWSTATMETA and friends) are vectored
onto the TR1 core trigger for the current thread. This is demultiplexed
in irq-metag.c to individual Linux IRQs for each internal interrupt.
External SoC interrupts (from HWSTATEXT and friends) are vectored onto
the TR2 core trigger for the current thread. This is demultiplexed in
irq-metag-ext.c to individual Linux IRQs for each external SoC interrupt.
The external irqchip has devicetree bindings for configuring the number
of irq banks and the type of masking available.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Cc: Dom Cobley <popcornmix@gmail.com>
Cc: Simon Arlott <simon@fire.lp0.eu>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-doc@vger.kernel.org
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Add core IRQ handling for metag. The code in irq.c exposes the TBX
signal numbers as Linux IRQs.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add trap code for metag. At the lowest level Meta traps (and return from
interrupt instruction - RTI) simply swap the PC and PCX registers and
optionally toggle the interrupt status bit (ISTAT). Low level TBX code
in tbipcx.S handles the core context save, determine the TBX signal
number based on the core trigger that fired (using the TXSTATI status
register), and call TBX signal handlers (mostly in traps.c) via a vector
table.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
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Add time keeping code for metag. Meta hardware threads have 2 timers.
The background timer (TXTIMER) is used as a free-running time base, and
the interrupt timer (TXTIMERI) is used for the timer interrupt. Both
counters traditionally count at approximately 1MHz.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
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The ptrace interface for metag provides access to some core register
sets using the PTRACE_GETREGSET and PTRACE_SETREGSET operations. The
details of the internal context structures is abstracted into user API
structures to both ease use and allow flexibility to change the internal
context layouts. Copyin and copyout functions for these register sets
are exposed to allow signal handling code to use them to copy to and
from the signal context.
struct user_gp_regs (NT_PRSTATUS) provides access to the core general
purpose register context.
struct user_cb_regs (NT_METAG_CBUF) provides access to the TXCATCH*
registers which contains information abuot a memory fault, unaligned
access error or watchpoint. This can be modified to alter the way the
fault is replayed on resume ("catch replay"), or to prevent the replay
taking place.
struct user_rp_state (NT_METAG_RPIPE) provides access to the state of
the Meta read pipeline which can be used to hide memory latencies in
hand optimised data loops.
Extended DSP register state, DSP RAM, and hardware breakpoint registers
aren't yet exposed through ptrace.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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Add device tree files to arch/metag.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Vineet Gupta <vgupta@synopsys.com>
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Add signal handling code for metag.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
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Add some TCM support
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add huge TLB support to the metag architecture.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Meta has instructions for accessing:
- bytes - GETB (1 byte)
- words - GETW (2 bytes)
- doublewords - GETD (4 bytes)
- longwords - GETL (8 bytes)
All accesses must be aligned. Unaligned accesses can be detected and
made to fault on Meta2, however it isn't possible to fix up unaligned
writes so we don't bother fixing up reads either.
This patch adds metag memory handling code including:
- I/O memory (io.h, ioremap.c): Actually any virtual memory can be
accessed with these helpers. A part of the non-MMUable address space
is used for memory mapped I/O. The ioremap() function is implemented
one to one for non-MMUable addresses.
- User memory (uaccess.h, usercopy.c): User memory is directly
accessible from privileged code.
- Kernel memory (maccess.c): probe_kernel_write() needs to be
overwridden to use the I/O functions when doing a simple aligned
write to non-writecombined memory, otherwise the write may be split
by the generic version.
Note that due to the fact that a portion of the virtual address space is
non-MMUable, and therefore always maps directly to the physical address
space, metag specific I/O functions are made available (metag_in32,
metag_out32 etc). These cast the address argument to a pointer so that
they can be used with raw physical addresses. These accessors are only
to be used for accessing fixed core Meta architecture registers in the
non-MMU region, and not for any SoC/peripheral registers.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add memory management files for metag.
Meta's 32bit virtual address space is split into two halves:
- local (0x08000000-0x7fffffff): traditionally local to a hardware
thread and incoherent between hardware threads. Each hardware thread
has it's own local MMU table. On Meta2 the local space can be
globally coherent (GCOn) if the cache partitions coincide.
- global (0x88000000-0xffff0000): coherent and traditionally global
between hardware threads. On Meta2, each hardware thread has it's own
global MMU table.
The low 128MiB of each half is non-MMUable and maps directly to the
physical address space:
- 0x00010000-0x07ffffff: contains Meta core registers and maps SoC bus
- 0x80000000-0x87ffffff: contains low latency global core memories
Linux usually further splits the local virtual address space like this:
- 0x08000000-0x3fffffff: user mappings
- 0x40000000-0x7fffffff: kernel mappings
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add cache and TLB handling code for metag, including the required
callbacks used by MM switches and DMA operations. Caches can be
partitioned between the hardware threads and the global space, however
this is usually configured by the bootloader so Linux doesn't make any
changes to this configuration. TLBs aren't configurable, so only need
consideration to flush them.
On Meta1 the L1 cache was VIVT which required a full flush on MM switch.
Meta2 has a VIPT L1 cache so it doesn't require the full flush on MM
switch. Meta2 can also have a writeback L2 with hardware prefetch which
requires some special handling. Support is optional, and the L2 can be
detected and initialised by Linux.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add source files from the Thread Binary Interface (TBI) library which
provides useful low level operations and traps/context management.
Among other things it handles interrupt/exception/syscall entry (in
tbipcx.S).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add the main header for the Thread Binary Interface (TBI) library which
provides useful low level operations and trap/context management.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add boot code for metag. Due to the multi-threaded nature of Meta it is
not uncommon for an RTOS or bare metal application to be started on
other hardware threads by the bootloader. Since there is a single MMU
switch which affects all threads, the MMU is traditionally configured by
the bootloader prior to starting Linux. The bootloader passes a
structure to Linux which among other things contains information about
memory regions which have been mapped. Linux then assumes control of the
local heap memory region.
A kernel arguments string pointer or a flattened device tree pointer can
be provided in the third argument.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add the header <asm/metag_mem.h> describing addresses, fields, and bits
of various core memory mapped registers in the low non-MMU region.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add a couple of header files containing core architecture constants.
The first (<asm/metag_isa.h>) contains some constants relating to the
instruction set, such as values to give to the CACHEW and CACHER
instructions.
The second (<asm/metag_regs.h>) contains constants for the core register
units directly accessible to various instructions, and for the
registers, fields, and bits in those units. The main units described are
the control unit (CT.*), the trigger unit (TR.*), and the run-time trace
unit (TT.*).
Signed-off-by: James Hogan <james.hogan@imgtec.com>
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Add MAINTAINERS entry for the metag architecture port.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Cesar Eduardo Barros <cesarb@cesarb.net>
Cc: Joe Perches <joe@perches.com>
Cc: "David S. Miller" <davem@davemloft.net>
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Some 32 bit architectures require 64 bit values to be aligned (for
example Meta which has 64 bit read/write instructions). These require 8
byte alignment of event data too, so use
!CONFIG_HAVE_64BIT_ALIGNED_ACCESS instead of !CONFIG_64BIT ||
CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS to decide alignment, and align
buffer_data_page::data accordingly.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org> (previous version subtly different)
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On 64 bit architectures with no efficient unaligned access, padding and
explicit alignment must be added in various places to prevent unaligned
64bit accesses (such as taskstats and trace ring buffer).
However this also needs to apply to 32 bit architectures with 64 bit
accesses requiring alignment such as metag.
This is solved by adding a new Kconfig symbol HAVE_64BIT_ALIGNED_ACCESS
which defaults to 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS, and can be
explicitly selected by METAG and any other relevant architectures. This
can be used in various places to determine whether 64bit alignment is
required.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: Will Drewry <wad@chromium.org>
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The commit "binfmt_elf: cleanups"
(f670d0ecda73b7438eec9ed108680bc5f5362ad8) removed an ifndef elf_map but
this breaks compilation for metag which does define elf_map.
This adds the ifndef back in as it was before, but does not affect the
other cleanups made by that patch.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
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Some architectures have symbol prefixes and set CONFIG_SYMBOL_PREFIX,
but this wasn't taken into account by the generic cond_syscall. It's
easy enough to fix in a generic fashion, so add the symbol prefix to
symbol names in cond_syscall when CONFIG_SYMBOL_PREFIX is set.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
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Make asm-generic/io.h check CONFIG_VIRT_TO_BUS before defining
virt_to_bus() and bus_to_virt(), otherwise it's easy to accidentally
have a silently failing incorrect direct mapped definition rather then
no definition at all.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
Pull input subsystem fixes from Dmitry Torokhov:
"Two small driver fixups and a documentation update for managed input
devices"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: wacom - fix wacom_set_report retry logic
Input: document that unregistering managed devices is not necessary
Input: lm8323 - fix checking PWM interrupt status
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Commit c060f943d092 ("mm: use aligned zone start for pfn_to_bitidx
calculation") fixed out calculation of the index into the pageblock
bitmap when a !SPARSEMEM zome was not aligned to pageblock_nr_pages.
However, the _allocation_ of that bitmap had never taken this alignment
requirement into accout, so depending on the exact size and alignment of
the zone, the use of that index could then access past the allocation,
resulting in some very subtle memory corruption.
This was reported (and bisected) by Ingo Molnar: one of his random
config builds would hang with certain very specific kernel command line
options.
In the meantime, commit c060f943d092 has been marked for stable, so this
fix needs to be back-ported to the stable kernels that backported the
commit to use the right alignment.
Bisected-and-tested-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen
Pull xen fixes from Konrad Rzeszutek Wilk:
"Two fixes:
- A simple bug-fix for redundant NULL check.
- CVE-2013-0228/XSA-42: x86/xen: don't assume %ds is usable in
xen_iret for 32-bit PVOPS
and two reverts:
- Revert the PVonHVM kexec. The patch introduces a regression with
older hypervisor stacks, such as Xen 4.1."
* tag 'stable/for-linus-3.8-rc7-tag-two' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
Revert "xen PVonHVM: use E820_Reserved area for shared_info"
Revert "xen/PVonHVM: fix compile warning in init_hvm_pv_info"
xen: remove redundant NULL check before unregister_and_remove_pcpu().
x86/xen: don't assume %ds is usable in xen_iret for 32-bit PVOPS.
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As reported by Klaus Schmidinger:
"In VDR I use an ioctl() call with FE_READ_UNCORRECTED_BLOCKS on a
device (using stb0899). After this call I check 'errno' for
EOPNOTSUPP to determine whether this device supports this call. This
used to work just fine, until a few months ago I noticed that my
devices using stb0899 didn't display their signal quality in VDR's OSD
any more. After further investigation I found that
ioctl(FE_READ_UNCORRECTED_BLOCKS) no longer returns EOPNOTSUPP, but
rather ENOTTY. And since I stop getting the signal quality in case
any unknown errno value appears, this broke my signal quality query
function."
While the changes reflect what is there at:
http://comments.gmane.org/gmane.linux.kernel/1235728
it does cause regression on userspace. So, revert it to stop the
damage.
This reverts commit 177ffe506cf8 ("[media] dvb_frontend: return -ENOTTY
for unimplement IOCTL").
Reported-by: Klaus Schmidinger <Klaus.Schmidinger@tvdr.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull sparc fixes from David Miller:
"A couple small fixes for sparc including some THP brown-paper-bag
material:
1) During the merging of all the THP support for various
architectures, sparc missed adding a
HAVE_ARCH_TRANSPARENT_HUGEPAGE to it's Kconfig, oops.
2) Sparc needs to be mindful of hugepages in get_user_pages_fast().
3) Fix memory leak in SBUS probe, from Cong Ding.
4) The sunvdc virtual disk client driver has a test of the bitmask of
vdisk server supported operations which was off by one bit"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
sunvdc: Fix off-by-one in generic_request().
sparc64: Fix get_user_pages_fast() wrt. THP.
sparc64: Add missing HAVE_ARCH_TRANSPARENT_HUGEPAGE.
sparc: kernel/sbus.c: fix memory leakage
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull one more x86 fix from Peter Anvin:
"Sigh. One more patch in the "please don't brick my Samsung" series"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
efi: Clear EFI_RUNTIME_SERVICES rather than EFI_BOOT by "noefi" boot parameter
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git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci
Pull PCI fix from Bjorn Helgaas:
"This is another fix for v3.8. It fixes an oops that happens when a
Thunderbolt adapter is unplugged (remove device, poll for PME events
on no-longer-existing device, oops)."
* tag '3.8-pci-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
PCI/PM: Clean up PME state when removing a device
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Pull omapdss fixes from Tomi Valkeinen:
"It'd be great if these two late fixes would still make it into 3.8.
The other one fixes ARM kernel compilation when using 'allyesconfig',
and the other makes DPI displays function again on OMAP3630 boards:
- Fix ARM compilation with "allyesconfig" (omapdrm: fix the
dependency to omapdss)
- fix DPI displays on OMAP3630 (OMAPDSS: add FEAT_DPI_USES_VDDS_DSI
to omap3630_dss_feat_list)"
* tag 'omapdss-for-3.8-rc8' of git://gitorious.org/linux-omap-dss2/linux:
omapdrm: fix the dependency to omapdss
OMAPDSS: add FEAT_DPI_USES_VDDS_DSI to omap3630_dss_feat_list
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git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c maintainer info update from Wolfram Sang:
"Since my old email and repos are not working anymore, and this already
caused some confusion, I think a MAINTAINERS update for 3.8 is
helpful. So, people trying I2C with the new kernel can properly reach
me and find my repos."
* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
MAINTAINERS: change my email and repos
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This reverts commit 9d02b43dee0d7fb18dfb13a00915550b1a3daa9f.
We are doing this b/c on 32-bit PVonHVM with older hypervisors
(Xen 4.1) it ends up bothing up the start_info. This is bad b/c
we use it for the time keeping, and the timekeeping code loops
forever - as the version field never changes. Olaf says to
revert it, so lets do that.
Acked-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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This reverts commit a7be94ac8d69c037d08f0fd94b45a593f1d45176.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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The 'operations' bitmap corresponds one-for-one with the operation
codes, no adjustment is necessary.
Reported-by: Mark Kettenis <mark.kettenis@xs4all.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>
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omapdrm uses "select" in Kconfig to enable omapdss. This doesn't work
correctly, as "select" forces omapdss to be enabled in the config even
if it normally could not be enabled because of missing Kconfig
dependencies.
This causes a build break on ARM, when using allyesconfig:
drivers/video/omap2/dss/dss.c: In function 'dss_calc_clock_div':
drivers/video/omap2/dss/dss.c:572:20: error: 'CONFIG_OMAP2_DSS_MIN_FCK_PER_PCK' undeclared (first use in this function)
drivers/video/omap2/dss/dss.c:572:20: note: each undeclared identifier is reported only once for each function it appears in
Instead of using select, this patch changes omapdrm to use "depend
on".
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
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commit 195e672a76056478cc79f5c48343164c9237852e
OMAPDSS: DPI: Remove cpu_is_xxxx checks
made the mistake of assuming that cpu_is_omap34xx() is exclusive of
other cpu_is_* predicates whereas it includes cpu_is_omap3630().
So on an omap3630, code that was previously enabled by
if (cpu_is_omap34xx())
is now disabled as
dss_has_feature(FEAT_DPI_USES_VDDS_DSI)
fails.
So add FEAT_DPI_USES_VDDS_DSI to omap3630_dss_feat_list.
Cc: Chandrabhanu Mahapatra <cmahapatra@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
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There was a serious problem in samsung-laptop that its platform driver is
designed to run under BIOS and running under EFI can cause the machine to
become bricked or can cause Machine Check Exceptions.
Discussion about this problem:
https://bugs.launchpad.net/ubuntu-cdimage/+bug/1040557
https://bugzilla.kernel.org/show_bug.cgi?id=47121
The patches to fix this problem:
efi: Make 'efi_enabled' a function to query EFI facilities
83e68189745ad931c2afd45d8ee3303929233e7f
samsung-laptop: Disable on EFI hardware
e0094244e41c4d0c7ad69920681972fc45d8ce34
Unfortunately this problem comes back again if users specify "noefi" option.
This parameter clears EFI_BOOT and that driver continues to run even if running
under EFI. Refer to the document, this parameter should clear
EFI_RUNTIME_SERVICES instead.
Documentation/kernel-parameters.txt:
===============================================================================
...
noefi [X86] Disable EFI runtime services support.
...
===============================================================================
Documentation/x86/x86_64/uefi.txt:
===============================================================================
...
- If some or all EFI runtime services don't work, you can try following
kernel command line parameters to turn off some or all EFI runtime
services.
noefi turn off all EFI runtime services
...
===============================================================================
Signed-off-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Link: http://lkml.kernel.org/r/511C2C04.2070108@jp.fujitsu.com
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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unregister_and_remove_pcpu on a NULL pointer is a no-op, so the NULL check in
sync_pcpu can be removed.
Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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This fixes CVE-2013-0228 / XSA-42
Drew Jones while working on CVE-2013-0190 found that that unprivileged guest user
in 32bit PV guest can use to crash the > guest with the panic like this:
-------------
general protection fault: 0000 [#1] SMP
last sysfs file: /sys/devices/vbd-51712/block/xvda/dev
Modules linked in: sunrpc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4
iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6
xt_state nf_conntrack ip6table_filter ip6_tables ipv6 xen_netfront ext4
mbcache jbd2 xen_blkfront dm_mirror dm_region_hash dm_log dm_mod [last
unloaded: scsi_wait_scan]
Pid: 1250, comm: r Not tainted 2.6.32-356.el6.i686 #1
EIP: 0061:[<c0407462>] EFLAGS: 00010086 CPU: 0
EIP is at xen_iret+0x12/0x2b
EAX: eb8d0000 EBX: 00000001 ECX: 08049860 EDX: 00000010
ESI: 00000000 EDI: 003d0f00 EBP: b77f8388 ESP: eb8d1fe0
DS: 0000 ES: 007b FS: 0000 GS: 00e0 SS: 0069
Process r (pid: 1250, ti=eb8d0000 task=c2953550 task.ti=eb8d0000)
Stack:
00000000 0027f416 00000073 00000206 b77f8364 0000007b 00000000 00000000
Call Trace:
Code: c3 8b 44 24 18 81 4c 24 38 00 02 00 00 8d 64 24 30 e9 03 00 00 00
8d 76 00 f7 44 24 08 00 00 02 80 75 33 50 b8 00 e0 ff ff 21 e0 <8b> 40
10 8b 04 85 a0 f6 ab c0 8b 80 0c b0 b3 c0 f6 44 24 0d 02
EIP: [<c0407462>] xen_iret+0x12/0x2b SS:ESP 0069:eb8d1fe0
general protection fault: 0000 [#2]
---[ end trace ab0d29a492dcd330 ]---
Kernel panic - not syncing: Fatal exception
Pid: 1250, comm: r Tainted: G D ---------------
2.6.32-356.el6.i686 #1
Call Trace:
[<c08476df>] ? panic+0x6e/0x122
[<c084b63c>] ? oops_end+0xbc/0xd0
[<c084b260>] ? do_general_protection+0x0/0x210
[<c084a9b7>] ? error_code+0x73/
-------------
Petr says: "
I've analysed the bug and I think that xen_iret() cannot cope with
mangled DS, in this case zeroed out (null selector/descriptor) by either
xen_failsafe_callback() or RESTORE_REGS because the corresponding LDT
entry was invalidated by the reproducer. "
Jan took a look at the preliminary patch and came up a fix that solves
this problem:
"This code gets called after all registers other than those handled by
IRET got already restored, hence a null selector in %ds or a non-null
one that got loaded from a code or read-only data descriptor would
cause a kernel mode fault (with the potential of crashing the kernel
as a whole, if panic_on_oops is set)."
The way to fix this is to realize that the we can only relay on the
registers that IRET restores. The two that are guaranteed are the
%cs and %ss as they are always fixed GDT selectors. Also they are
inaccessible from user mode - so they cannot be altered. This is
the approach taken in this patch.
Another alternative option suggested by Jan would be to relay on
the subtle realization that using the %ebp or %esp relative references uses
the %ss segment. In which case we could switch from using %eax to %ebp and
would not need the %ss over-rides. That would also require one extra
instruction to compensate for the one place where the register is used
as scaled index. However Andrew pointed out that is too subtle and if
further work was to be done in this code-path it could escape folks attention
and lead to accidents.
Reviewed-by: Petr Matousek <pmatouse@redhat.com>
Reported-by: Petr Matousek <pmatouse@redhat.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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