Rather than storing each machine init hook separately, store a
pointer to the machine description record and dereference this
instead.  This pointer is only available while the init sections
are present, which is not a problem as we only use it from init
code.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Per subarch interrupt handler macros V3.

This patch breaks out code from the irq_handler macro
into arch_irq_handler and arch_irq_handler_default.

The macros are put in the header file "entry-macro-multi.S"

The arch_irq_handler_default macro is designed to be
used by irq_handler in entry-armv.S while arch_irq_handler
is suitable for per-subarch use.
Signed-off-by: NMagnus Damm <damm@opensource.se>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Normally different ARM platform has different way to decode the IRQ
hardware status and demultiplex to the corresponding IRQ handler.
This is highly optimized by macro irq_handler in entry-armv.S, and
each machine defines their own macro to decode the IRQ number.
However, this prevents multiple machine classes to be built into a
single kernel.

By allowing each machine to specify thier own handler, and making
function pointer 'handle_arch_irq' to point to it at run time, this
can be solved. And introduce CONFIG_MULTI_IRQ_HANDLER to allow both
solutions to work.

Comparing with the highly optimized macro of irq_handler, the new
function must be written with care not to lose too much performance.
And the IPI stuff on SMP is expected to move to the provided arch
IRQ handler as well.

The assembly code to invoke handle_arch_irq is optimized by Russell
King.
Signed-off-by: NEric Miao <eric.miao@canonical.com>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

As our SMP implementation uses MESI protocols.  Grouping together data
which is mostly only read together means that we avoid unnecessary
cache line bouncing when this code shares a cache line with other data.

In other words, cache lines associated with read-mostly data are
expected to spend most of their time in shared state.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

factorise some generic infrastructure to assist looking up struct clks
for the ARM & SH architecture.

as the code is identical at 99%

put the arch specific code for allocation as example in asm/clkdev.h
Signed-off-by: NJean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: NPaul Mundt <lethal@linux-sh.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch removes the domain switching functionality via the set_fs and
__switch_to functions on cores that have a TLS register.

Currently, the ioremap and vmalloc areas share the same level 1 page
tables and therefore have the same domain (DOMAIN_KERNEL). When the
kernel domain is modified from Client to Manager (via the __set_fs or in
the __switch_to function), the XN (eXecute Never) bit is overridden and
newer CPUs can speculatively prefetch the ioremap'ed memory.

Linux performs the kernel domain switching to allow user-specific
functions (copy_to/from_user, get/put_user etc.) to access kernel
memory. In order for these functions to work with the kernel domain set
to Client, the patch modifies the LDRT/STRT and related instructions to
the LDR/STR ones.

The user pages access rights are also modified for kernel read-only
access rather than read/write so that the copy-on-write mechanism still
works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register
(CPU_32v6K is defined) since writing the TLS value to the high vectors page
isn't possible.

The user addresses passed to the kernel are checked by the access_ok()
function so that they do not point to the kernel space.
Tested-by: NAnton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

DBG_MAX_REG_NUM incorrectly had the number of indices in the GDB regs
array rather than the number of registers, leading to an oops when the
"rd" command is used in KDB.

Cc: stable@kernel.org
Signed-off-by: NRabin Vincent <rabin@rab.in>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Will says:
| Commit e63075a3 removed the explicit MEMBLOCK_REAL_LIMIT #define
| and introduced the requirement that arch code calls
| memblock_set_current_limit to ensure that the __va macro can
| be used on physical addresses returned from memblock_alloc.

Unfortunately, ARM was missed out of this change.  Fix this.
Reported-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Since we no longer need to provide KM_type, the whole pte_*map_nested()
API is now redundant, remove it.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NChris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Keep the current interface but ignore the KM_type and use a stack based
approach.

The advantage is that we get rid of crappy code like:

	#define __KM_PTE			\
		(in_nmi() ? KM_NMI_PTE : 	\
		 in_irq() ? KM_IRQ_PTE :	\
		 KM_PTE0)

and in general can stop worrying about what context we're in and what kmap
slots might be appropriate for that.

The downside is that FRV kmap_atomic() gets more expensive.

For now we use a CPP trick suggested by Andrew:

  #define kmap_atomic(page, args...) __kmap_atomic(page)

to avoid having to touch all kmap_atomic() users in a single patch.

[ not compiled on:
  - mn10300: the arch doesn't actually build with highmem to begin with ]

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix up drivers/gpu/drm/i915/intel_overlay.c]
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NChris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The cache size is needed for to optimise range based
maintainance operations
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NLinus Walleij <linus.walleij@stericsson.com>

Replace tab with space after #define to be consisten with other
define in the file. Also move the bit mask below the register offsets.
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NLinus Walleij <linus.walleij@stericsson.com>

kexec does not disable the outer cache before disabling the inner
caches in cpu_proc_fin(). So L2 is enabled across the kexec jump. When
the new kernel enables chaches again, it randomly crashes.

Disabling L2 before calling cpu_proc_fin() cures the problem.

Disabling L2 requires the following new functions: flush_all(),
inv_all() and disable(). Add them to outer_cache_fns and call them
from the kexec code.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NLinus Walleij <linus.walleij@stericsson.com>

This patch adds L2X0 Prefetch and Power control register.
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>

This patch converts arm to use asm-generic/ioctls.h instead of its
own version.

The differences between the arch-specific version and the generic
version are as follows:

- ARM defines its own value for FIOQSIZE, asm-generic/ioctls.h keeps it
- The generic version adds support for termiox
Reviewed-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Since we're now using addruart to establish the debug mapping, we can
remove the io_pg_offst and phys_io members of struct machine_desc.

The various declarations were removed using the following script:

  grep -rl MACHINE_START arch/arm | xargs \
  sed -i '/MACHINE_START/,/MACHINE_END/ { /\.\(phys_io\|io_pg_offst\)/d }'

[ Initial patch was from Jeremy Kerr, example script from Russell King ]
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Eric Miao <eric.miao at canonical.com>

As mentioned in the comment right at the top, the first four fields
are directly accessed by assembly code in head.S.  Move nr_irqs so the
comment is true again.
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>

Provide a mechanism that allows running code in IRQ context. It is
most useful for NMI code that needs to interact with the rest of the
system -- like wakeup a task to drain buffers.

Perf currently has such a mechanism, so extract that and provide it as
a generic feature, independent of perf so that others may also
benefit.

The IRQ context callback is generated through self-IPIs where
possible, or on architectures like powerpc the decrementer (the
built-in timer facility) is set to generate an interrupt immediately.

Architectures that don't have anything like this get to do with a
callback from the timer tick. These architectures can call
irq_work_run() at the tail of any IRQ handlers that might enqueue such
work (like the perf IRQ handler) to avoid undue latencies in
processing the work.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NKyle McMartin <kyle@mcmartin.ca>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
[ various fixes ]
Signed-off-by: NHuang Ying <ying.huang@intel.com>
LKML-Reference: <1287036094.7768.291.camel@yhuang-dev>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The patch below updates broken web addresses in the arch directory.
Signed-off-by: NJustin P. Mattock <justinmattock@gmail.com>
Signed-off-by: NMaciej W. Rozycki <macro@linux-mips.org>
Cc: Finn Thain <fthain@telegraphics.com.au>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Reviewed-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

The core code now initializes the requested number of interrupts and
sets the flags in irq_desc.status which are requested by the
architecture via ARCH_IRQ_INIT_FLAGS.

Add ARCH_IRQ_INIT_FLAGS and remove the loop which sets those flags
after the irq descriptors are allocated.

[ This patch should have been in the original irq rework and got
  dropped accidentaly ]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Anand Gadiyar <gadiyar@ti.com>

In order for CPUidle to work on SMP systems, an implementation of
cpu_idle_wait() is needed.

This patch duplicates the x86 implementation of cpu_idle_wait() for
ARM.
Tested-by: NColin Cross <ccross@android.com>
Signed-off-by: NKevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Broadcast should not be needed when running SMP kernel on UP systems.

Also, this fixes an undefined instruction for SMP_ON_UP on earlier ARM
cores without the extended CPUID_EXT_MMFR3 register.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Fix the IRQ flag handling naming.  In linux/irqflags.h under one configuration,
it maps:

	local_irq_enable() -> raw_local_irq_enable()
	local_irq_disable() -> raw_local_irq_disable()
	local_irq_save() -> raw_local_irq_save()
	...

and under the other configuration, it maps:

	raw_local_irq_enable() -> local_irq_enable()
	raw_local_irq_disable() -> local_irq_disable()
	raw_local_irq_save() -> local_irq_save()
	...

This is quite confusing.  There should be one set of names expected of the
arch, and this should be wrapped to give another set of names that are expected
by users of this facility.

Change this to have the arch provide:

	flags = arch_local_save_flags()
	flags = arch_local_irq_save()
	arch_local_irq_restore(flags)
	arch_local_irq_disable()
	arch_local_irq_enable()
	arch_irqs_disabled_flags(flags)
	arch_irqs_disabled()
	arch_safe_halt()

Then linux/irqflags.h wraps these to provide:

	raw_local_save_flags(flags)
	raw_local_irq_save(flags)
	raw_local_irq_restore(flags)
	raw_local_irq_disable()
	raw_local_irq_enable()
	raw_irqs_disabled_flags(flags)
	raw_irqs_disabled()
	raw_safe_halt()

with type checking on the flags 'arguments', and then wraps those to provide:

	local_save_flags(flags)
	local_irq_save(flags)
	local_irq_restore(flags)
	local_irq_disable()
	local_irq_enable()
	irqs_disabled_flags(flags)
	irqs_disabled()
	safe_halt()

with tracing included if enabled.

The arch functions can now all be inline functions rather than some of them
having to be macros.

Signed-off-by: David Howells <dhowells@redhat.com> [X86, FRV, MN10300]
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> [Tile]
Signed-off-by: Michal Simek <monstr@monstr.eu> [Microblaze]
Tested-by: Catalin Marinas <catalin.marinas@arm.com> [ARM]
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> [AVR]
Acked-by: Tony Luck <tony.luck@intel.com> [IA-64]
Acked-by: Hirokazu Takata <takata@linux-m32r.org> [M32R]
Acked-by: Greg Ungerer <gerg@uclinux.org> [M68K/M68KNOMMU]
Acked-by: Ralf Baechle <ralf@linux-mips.org> [MIPS]
Acked-by: Kyle McMartin <kyle@mcmartin.ca> [PA-RISC]
Acked-by: Paul Mackerras <paulus@samba.org> [PowerPC]
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> [S390]
Acked-by: Chen Liqin <liqin.chen@sunplusct.com> [Score]
Acked-by: Matt Fleming <matt@console-pimps.org> [SH]
Acked-by: David S. Miller <davem@davemloft.net> [Sparc]
Acked-by: Chris Zankel <chris@zankel.net> [Xtensa]
Reviewed-by: Richard Henderson <rth@twiddle.net> [Alpha]
Reviewed-by: Yoshinori Sato <ysato@users.sourceforge.jp> [H8300]
Cc: starvik@axis.com [CRIS]
Cc: jesper.nilsson@axis.com [CRIS]
Cc: linux-cris-kernel@axis.com

Currently, the Kernel assumes that if a CPU has a non-aliasing D-cache
then the I-cache is also non-aliasing. This may not be true on ARM cores
from v6 onwards, which may have aliasing I-caches but non-aliasing
D-caches.

This patch adds a cpu_has_aliasing_icache function, which is called from
cacheid_init and adds CACHEID_VIPT_I_ALIASING to the cacheid when
appropriate. A utility macro, icache_is_vipt_aliasing(), is also
provided.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Do this by adding flush_icache_all to cache_fns for ARMv6 and 7.
As flush_icache_all may neeed to be called from flush_kern_cache_all,
add it as the first entry in the cache_fns.

Note that now we can remove the ARM_ERRATA_411920 dependency
to !SMP so it can be selected on UP ARMv6 processors, such
as omap2.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NAnand Gadiyar <gadiyar@ti.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

UP systems do not implement all the instructions that SMP systems have,
so in order to boot a SMP kernel on a UP system, we need to rewrite
parts of the kernel.

Do this using an 'alternatives' scheme, where the kernel code and data
is modified prior to initialization to replace the SMP instructions,
thereby rendering the problematical code ineffectual.  We use the linker
to generate a list of 32-bit word locations and their replacement values,
and run through these replacements when we detect a UP system.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Provide a common header to read the SMP CPU number from the MPIDR.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Use BIT() macro whenever it is sensible to do so.

Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NAlexander Shishkin <virtuoso@slind.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This is done so as to be able to make use of the coresight components'
registers in assembler code (like omap sleep code). Also, there shouldn't
be any users of this structure outside the etm driver.

Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NAlexander Shishkin <virtuoso@slind.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The kernel makes the high vector page visible to user space. This page
contains (amongst others) small code segments that can be executed in
user space.  Make this page visible through ptrace and /proc/<pid>/mem
in order to let gdb perform code parsing needed for proper unwinding.

For example, the ERESTART_RESTARTBLOCK handler actually has a stack
frame -- it returns to a PC value stored on the user's stack.   To
unwind after a "sleep" system call was interrupted twice, GDB would
have to recognize this situation and understand that stack frame
layout -- which it currently cannot do.

We could fix this by hard-coding addresses in the vector page range into
GDB, but that isn't really portable as not all of those addresses are
guaranteed to remain stable across kernel releases.  And having the gdb
process make an exception for this page and get  content from its own
address space for it looks strange, and it is not future proof either.

Being located above PAGE_OFFSET, this vma cannot be deleted by
user space code.
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>

Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>

There are very few legitimate use cases, if any, for directly accessing
system RAM through /dev/mem.  So let's mimic what they do on x86 and
forbid it when CONFIG_STRICT_DEVMEM is turned on.
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>

ARMv7 onwards requires that there are no aliases to the same physical
location using different memory types (i.e. Normal vs Strongly Ordered).
Access to SO mappings when the unaligned accesses are handled in
hardware is also Unpredictable (pgprot_noncached() mappings in user
space).

The /dev/mem driver requires uncached mappings with O_SYNC. The patch
implements the phys_mem_access_prot() function which generates Strongly
Ordered memory attributes if !pfn_valid() (independent of O_SYNC) and
Normal Noncacheable (writecombine) if O_SYNC.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Since page cache pages are now considered 'dirty' by default, the cache
flushing is handled via __flush_dcache_page() when a page gets mapped to
user space. Highmem pages on VIVT systems are flushed during kunmap()
and flush_kernel_dcache_page() was already a no-op in this case.

ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE is still defined since ARM needs
specific implementations for flush_kernel_vmap_range() and
invalidate_kernel_vmap_range().

Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

ARMv7 processors like Cortex-A9 broadcast the cache maintenance
operations in hardware. This patch allows the
flush_dcache_page/update_mmu_cache pair to work in lazy flushing mode
similar to the UP case.

Note that cache flushing on SMP systems now takes place via the
set_pte_at() call (__sync_icache_dcache) and there is no race with other
CPUs executing code from the new PTE before the cache flushing took
place.
Tested-by: NRabin Vincent <rabin.vincent@stericsson.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

On SMP systems, there is a small chance of a PTE becoming visible to a
different CPU before the current cache maintenance operations in
update_mmu_cache(). To avoid this, cache maintenance must be handled in
set_pte_at() (similar to IA-64 and PowerPC).

This patch provides a unified VIPT cache handling mechanism and
implements the __sync_icache_dcache() function for ARMv6 onwards
architectures. It is called from set_pte_at() and replaces the
update_mmu_cache(). The latter is still used on VIVT hardware where a
vm_area_struct is required.
Tested-by: NRabin Vincent <rabin.vincent@stericsson.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

There are places in Linux where writes to newly allocated page cache
pages happen without a subsequent call to flush_dcache_page() (several
PIO drivers including USB HCD). This patch changes the meaning of
PG_arch_1 to be PG_dcache_clean and always flush the D-cache for a newly
mapped page in update_mmu_cache().

The patch also sets the PG_arch_1 bit in the DMA cache maintenance
function to avoid additional cache flushing in update_mmu_cache().
Tested-by: NRabin Vincent <rabin.vincent@stericsson.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This reverts commit 4fa5518c, which causes a compilation regression for
IXP4xx platforms.
Reported-by: NRichard Cochran <richardcochran@gmail.com>
Acked-by: NEric Miao <eric.y.miao@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

For debuggers to take advantage of the hw-breakpoint framework in the kernel,
it is necessary to expose the API calls via a ptrace interface.

This patch exposes the hardware breakpoints framework as a collection of
virtual registers, accesible using PTRACE_SETHBPREGS and PTRACE_GETHBPREGS
requests. The breakpoints are stored in the debug_info struct of the running
thread.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: S. Karthikeyan <informkarthik@gmail.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

The hw-breakpoint framework in the kernel requires architecture-specific
support in order to install, remove, validate and manage hardware
breakpoints.

This patch adds initial support for this framework to the ARM architecture,
but restricts the number of watchpoints to a single resource to get around
the fact that the Data Fault Address Register is unknown when a watchpoint
debug exception is taken.

On cores with v7 debug, the Kernel can handle breakpoint and watchpoint
exceptions occuring from userspace. Older cores require clients to handle
the exception themselves by registering an appropriate overflow handler
or, in the case of ptrace, handling the raised SIGTRAP.

The memory-mapped extended debug interface is unsupported due to its
unreliability in real implementations.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: S. Karthikeyan <informkarthik@gmail.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>