ARM: smp: flush L1 cache in cpu_die()

Flush the L1 cache for the CPU which is going down in cpu_die() so
that we don't end up with all platforms doing this.  This ensures
that any cache lines we own are pushed out before the cache becomes
inaccessible.

We may end up subsequently creating some dirty cache lines - for
example, with the complete() call, but this update must become
visible to other CPUs before __cpu_die() can proceed.  Subsequent
accesses from the platforms cpu_die() function should _not_ matter.

Also place a mb() after the complete() call to ensure that this is
visible to other CPUs.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
arch: mm: do not invoke OOM killer on kernel fault OOM

Kernel faults are expected to handle OOM conditions gracefully (gup,
uaccess etc.), so they should never invoke the OOM killer.  Reserve this
for faults triggered in user context when it is the only option.

Most architectures already do this, fix up the remaining few.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: mm: rename jump labels in v7_flush_dcache_all function

This patch renames jump labels in v7_flush_dcache_all in order to define
a specific flush cache levels entry point.

Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7606/1: cache: flush to LoUU instead of LoUIS on uniprocessor CPUs

flush_cache_louis flushes the D-side caches to the point of unification
inner-shareable. On uniprocessor CPUs, this is defined as zero and
therefore no flushing will take place. Rather than invent a new interface
for UP systems, instead use our SMP_ON_UP patching code to read the
LoUU from the CLIDR instead.

Cc: <stable@vger.kernel.org>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Tested-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7752/1: errata: LoUIS bit field in CLIDR register is incorrect

On Cortex-A9 before version r1p0, the LoUIS bit field of the CLIDR
register returns zero when it should return one. This leads to cache
maintenance operations which rely on this value to not function as
intended, causing data corruption.

The workaround for this errata is to detect affected CPUs and correct
the LoUIS value read.

Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7573/1: idmap: use flush_cache_louis() and flush TLBs only when necessary

Flushing the cache is needed for the hardware to see the idmap table
and therefore can be done at init time.  On ARMv7 it is not necessary to
flush L2 so flush_cache_louis() is used here instead.

There is no point flushing the cache in setup_mm_for_reboot() as the
caller should, and already is, taking care of this.  If switching the
memory map requires a cache flush, then cpu_switch_mm() already includes
that operation.

What is not done by cpu_switch_mm() on ASID capable CPUs is TLB flushing
as the whole point of the ASID is to tag the TLBs and avoid flushing them
on a context switch.  Since we don't have a clean ASID for the identity
mapping, we need to flush the TLB explicitly in that case.  Otherwise
this is already performed by cpu_switch_mm().

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: Section based HYP idmap

Add a method (hyp_idmap_setup) to populate a hyp pgd with an
identity mapping of the code contained in the .hyp.idmap.text
section.

Offer a method to drop this identity mapping through
hyp_idmap_teardown.

Make all the above depend on CONFIG_ARM_VIRT_EXT and CONFIG_ARM_LPAE.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: virt: allow the kernel to be entered in HYP mode

This patch does two things:

  * Ensure that asynchronous aborts are masked at kernel entry.
    The bootloader should be masking these anyway, but this reduces
    the damage window just in case it doesn't.

  * Enter svc mode via exception return to ensure that CPU state is
    properly serialised.  This does not matter when switching from
    an ordinary privileged mode ("PL1" modes in ARMv7-AR rev C
    parlance), but it potentially does matter when switching from a
    another privileged mode such as hyp mode.

This should allow the kernel to boot safely either from svc mode or
hyp mode, even if no support for use of the ARM Virtualization
Extensions is built into the kernel.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: virt: Add boot-time diagnostics

In order to easily detect pathological cases, print some diagnostics
when the kernel boots.

This also provides helpers to detect that HYP mode is actually available,
which can be used by other subsystems to enable HYP specific features.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

Conflicts:
	arch/arm/kernel/smp.c
ARM: virt: use PSR_N_BIT for detecting boot CPU mode mismatch

During boot, we detect whether or not all CPUs are brought up in the
same mode and signal this to the kernel using the N bit in the SPSR.

This patch tidies up the checking code to use the PSR_N_BIT macro,
rather than hardcoding the bit field and commenting it as such.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7787/1: virt: ensure visibility of __boot_cpu_mode

Secondary CPUs write to __boot_cpu_mode with caches disabled, and thus a
cached value of __boot_cpu_mode may be incoherent with that in memory.
This could lead to a failure to detect mismatched boot modes.

This patch adds flushing to ensure that writes by secondaries to
__boot_cpu_mode are made visible before we test against it.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: zImage/virt: hyp mode entry support for the zImage loader

The zImage loader needs to turn on the MMU in order to take
advantage of caching while decompressing the zImage.  Running this
in hyp mode would require the LPAE pagetable format to be
supported; to avoid this complexity, this patch switches out of hyp
mode, and returns back to hyp mode just before booting the kernel.

This implementation assumes that the Hyp mode view of memory and the
PL1 view of memory are coherent, providing that the MMU and caches
are off in both, as required by the boot protocol.  The zImage
decompression code must drain the write buffer on completion anyway, and
entry into Hyp mode should flush any prefetch buffer, avoiding hazards
associated with local write buffers and the pipeline.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

Conflicts:
	arch/arm/boot/compressed/Makefile
ARM: virt: arch_timers: enable access to physical timers

If booting in HYP mode, it makes sense to enable the use of the
physical timers, so the kernel can use them directly.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: virt: Avoid bx instruction for compatibility with <=ARMv4

Non-T variants of ARMv4 do not support the bx instruction.

However, __hyp_stub_install is always called from the same
instruction set used to build the bulk of the kernel, so bx should
not be necessary.

This patch uses the traditional "mov pc" instead of bx.

Cc: <stable@vger.kernel.org>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
[will: fixed up remaining bx instruction]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: virt: simplify __hyp_stub_install epilog

__hyp_stub_install duplicates quite a bit of safe_svcmode_maskall
by forcing the CPU back to SVC. This is unnecessary, as
safe_svcmode_maskall is called just after.

Furthermore, the way we build SPSR_hyp is buggy as we fail to mask
the interrupts, leading to interesting behaviours on TC2 + UEFI.

The fix is to simply remove this code and rely on safe_svcmode_maskall
to do the right thing.

Cc: <stable@vger.kernel.org>
Reviewed-by: Dave Martin <dave.martin@linaro.org>
Reported-by: Harry Liebel <harry.liebel@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: hyp: initialize CNTVOFF to zero

In order to be able to use the virtual counter in a safe way,
make sure it is initialized to zero before dropping to SVC.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: arch_timer: stop virtual timer when booted in HYP mode

When booting the kernel, a bootloader could have left the virtual
timer ticking away, potentially generating interrupts. This could
be troublesome if the user of the virtual timer is not careful
when enabling the interrupt.

In order to avoid any surprise, stop the virtual timer from
interrupting us when booted in HYP mode, as we'll use the physical
timer in this case.

Reported-by: Giridhar Maruthy <giridhar.m@samsung.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7786/1: hyp: fix macro parameterisation

Currently, compare_cpu_mode_with_primary uses a mixture of macro
arguments and hardcoded registers, and does so incorrectly, as it
stores (__boot_cpu_mode_offset | BOOT_CPU_MODE_MISMATCH) to
(__boot_cpu_mode + &__boot_cpu_mode_offset), which could corrupt an
arbitrary portion of memory.

This patch fixes up compare_cpu_mode_with_primary to use the macro
arguments, correctly updating __boot_cpu_mode.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <cdall@cs.columbia.edu>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7508/1: opcodes: Don't define the thumb32 byteswapping macros for BE32

The existing __mem_to_opcode_thumb32() is incorrect for BE32
platforms.  However, these don't support Thumb-2 kernels, so this
option is not so relevant for those platforms anyway.

This operation is complicated by the lack of unaligned memory
access support prior to ARMv6.

Rather than provide a "working" macro which will probably won't get
used (or worse, will get misused), this patch removes the macro for
BE32 kernels.  People manipulating Thumb opcodes prior to ARMv6
should almost certainly be splitting these operations into
halfwords anyway, using __opcode_thumb32_{first,second,compose}()
and the 16-bit opcode transformations.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7509/1: opcodes: Make opcode byteswapping macros assembly-compatible

Most of the existing macros don't work with assembler, due to the
use of type casts and C functions from <linux/swab.h>.

This patch abstracts out those operations and provides simple
explicit versions for use in assembly code.

__opcode_is_thumb32() and __opcode_is_thumb16() are also converted
to do bitmask-based testing to avoid confusion if these are used in
assembly code (the assembler typically treats all arithmetic values
as signed).

These changes avoid the need for the compiler to pre-evaluate
constant expressions used to generate opcodes.  By ensuring that
the forms of these expressions can be evaluated directly by the
assembler, we can just stringify the expressions directly into the
asm during the preprocessing pass.  The alternative approach
(passing the evaluated expression via an inline asm "i" constraint)
gets painful because the contents of the asm and the constraints
must be kept in sync.  This makes the resulting macros awkward to
use.

Retaining the C forms of the macros allows more efficient code to
be generated when opcodes are generated programmatically at run-
time, but there is no way to embed run-time-generated opcodes in
asm() blocks.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>