ARM: smp: Fix cpu_up() racing with sys_reboot

Nothing stops a process from hotplugging in a CPU concurrently
with a sys_reboot() call. In such a situation we could have
ipi_cpu_stop() mark a cpu as 'offline' and _cpu_up() ignore the
fact that the CPU is not really offline and call the
CPU_UP_PREPARE notifier. When this happens stop_machine code will
complain that the cpu thread already exists and BUG_ON().

CPU0                      CPU1

sys_reboot()
 kernel_restart()
  machine_restart()
   machine_shutdown()
    smp_send_stop()
    ...                   ipi_cpu_stop()
                           set_cpu_online(1, false)
                            local_irq_disable()
                             while(1)
    <PREEMPT>
cpu_up()
 _cpu_up()
   if (!cpu_online(1))
    __cpu_notify(CPU_UP_PREPARE...)

cpu_stop_cpu_callback()
  BUG_ON(stopper->thread)

This is easily reproducible by hotplugging in and out in a tight
loop while also rebooting.

Since the CPU is not really offline and hasn't gone through the
proper steps to be marked as such, let's mark the CPU as inactive.
This is just as easily testable as online and avoids any possibility
of _cpu_up() trying to bring the CPU back online when it never was
offline to begin with.

Change-Id: Ia1daea407220578d4212ef6c65c4be837ca370fd
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
ARM: 7587/1: implement optimized percpu variable access
Use the previously unused TPIDRPRW register to store percpu offsets.
TPIDRPRW is only accessible in PL1, so it can only be used in the kernel.

This replaces 2 loads with a mrc instruction for each percpu variable
access. With hackbench, the performance improvement is 1.4% on Cortex-A9
(highbank). Taking an average of 30 runs of "hackbench -l 1000" yields:

Before: 6.2191
After: 6.1348

Will Deacon reported similar delta on v6 with 11MPCore.

The asm "memory clobber" are needed here to ensure the percpu offset
gets reloaded. Testing by Will found that this would not happen in
__schedule() which is a bit of a special case as preemption is disabled
but the execution can move cores.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>

adapted by mrg666 for 3.0 kernel

Conflicts:
	arch/arm/kernel/smp.c

Conflicts:
	arch/arm/kernel/smp.c
ARM: 7133/1: SMP: fix per cpu timer setup before the cpu is marked online
The problem is related to the early enabling of interrupts and the
per cpu timer setup before the cpu is marked online. This doesn't
need to be done in order to call calibrate_delay().

calibrate_delay() monitors jiffies, which are updated from the CPU
which is waiting for the new CPU to set the online bit.

So simply calibrate_delay() can be called on the new CPU just from
the interrupt disabled region and move the local timer setup after
stored the cpu data and before enabling interrupts.

This solves both the cpu_online vs. cpu_active problem and the
affinity setting of the per cpu timers.

Signed-off-by: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 7124/1: smp: Add a localtimer handler callable from C code
In order to be able to handle localtimer directly from C code instead of
assembly code, introduce handle_local_timer(), which is modeled after
handle_IRQ().

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Conflicts:
	arch/arm/kernel/smp.c
fix previous commit for gcc implicit declaration warning
fix the previous commit properly

Conflicts:
	arch/arm/include/asm/localtimer.h
sched: Cleanup cpu_active madness
Stepan found:

CPU0		CPUn

_cpu_up()
  __cpu_up()

		boostrap()
		  notify_cpu_starting()
		  set_cpu_online()
		  while (!cpu_active())
		    cpu_relax()

<PREEMPT-out>

smp_call_function(.wait=1)
  /* we find cpu_online() is true */
  arch_send_call_function_ipi_mask()

  /* wait-forever-more */

<PREEMPT-in>
		  local_irq_enable()

  cpu_notify(CPU_ONLINE)
    sched_cpu_active()
      set_cpu_active()

Now the purpose of cpu_active is mostly with bringing down a cpu, where
we mark it !active to avoid the load-balancer from moving tasks to it
while we tear down the cpu. This is required because we only update the
sched_domain tree after we brought the cpu-down. And this is needed so
that some tasks can still run while we bring it down, we just don't want
new tasks to appear.

On cpu-up however the sched_domain tree doesn't yet include the new cpu,
so its invisible to the load-balancer, regardless of the active state.
So instead of setting the active state after we boot the new cpu (and
consequently having to wait for it before enabling interrupts) set the
cpu active before we set it online and avoid the whole mess.

Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1323965362.18942.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>

adapted for 3.0 by mrg666 (only for arm)
ARM: 7499/1: mm: Fix vmalloc overlap check for !HIGHMEM

With !HIGHMEM, sanity_check_meminfo checks for banks that completely or
partially overlap the vmalloc region. The test for partial overlap checks
__va(bank->start + bank->size) > vmalloc_min. This is not appropriate if
there is a non-linear translation between virtual and physical addresses,
as bank->start + bank->size is actually in the bank following the one being
interrogated.

In most cases, even when using SPARSEMEM, this is not problematic as the
subsequent bank will start at a higher va than the one in question. However
if the physical to virtual address conversion is not monotonic increasing,
the incorrect test could result in a bank not being truncated when it
should be.

This patch ensures we perform the va-pa conversion on memory from the
bank we are interested in, not the following one.

Reported-by: ??? (Steve) <zhanzhenbo@gmail.com>
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 7500/1: io: avoid writeback addressing modes for __raw_ accessors

Data aborts taken to hyp mode do not provide a valid instruction
syndrome field in the HSR if the faulting instruction is a memory
access using a writeback addressing mode.

For hypervisors emulating MMIO accesses to virtual peripherals, taking
such an exception requires disassembling the faulting instruction in
order to determine the behaviour of the access. Since this requires
manually walking the two stages of translation, the world must be
stopped to prevent races against page aging in the guest, where the
first-stage translation is invalidated after the hypervisor has
translated to an IPA and the physical page is reused for something else.

This patch avoids taking this heavy performance penalty when running
Linux as a guest by ensuring that our I/O accessors do not make use of
writeback addressing modes.

Cc: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Conflicts:
	arch/arm/include/asm/io.h

Conflicts:
	arch/arm/include/asm/io.h
revert "ARM: 7500/1: io: avoid writeback addressing modes for __raw_ accessors"
revert:ARM: 7124/1: smp: Add a localtimer handler
ARM: 7006/1: Migrate to asm-generic wrapper support

With d8ecc5c (kbuild: asm-generic support, 2011-04-27) we can
remove a handful of asm-generic wrappers in ARM code. Since the
generic version of sizes.h doesn't contain SZ_48M, we replace
the 4 users of SZ_48M with the equivalent SZ_32M + SZ_16M.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Imre Kaloz <kaloz@openwrt.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Conflicts:
	arch/arm/include/asm/percpu.h
	arch/arm/include/asm/sizes.h
fix ARM: 7587/1: ...
ARM: 7006/1: Migrate to asm-generic wrapper support

With d8ecc5c (kbuild: asm-generic support, 2011-04-27) we can
remove a handful of asm-generic wrappers in ARM code. Since the
generic version of sizes.h doesn't contain SZ_48M, we replace
the 4 users of SZ_48M with the equivalent SZ_32M + SZ_16M.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Imre Kaloz <kaloz@openwrt.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Conflicts:
	arch/arm/include/asm/percpu.h
	arch/arm/include/asm/sizes.h

Conflicts:
	arch/arm/include/asm/Kbuild
fix ARM: 7587/1: ...
ARM: 7491/1: use generic version of identical asm headers
Inspired by the AArgh64 claim that it should be separate from ARM and one
reason was being able to use more asm-generic headers. Doing a diff of
arch/arm/include/asm and include/asm-generic there are numerous asm
headers which are functionally identical to their asm-generic counterparts.
Delete the ARM version and use the generic ones.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
adapt previous backport
ARM: 7493/1: use generic unaligned.h
This moves ARM over to the asm-generic/unaligned.h header. This has the
benefit of better code generated especially for ARMv7 on gcc 4.7+
compilers.

As Arnd Bergmann, points out: The asm-generic version uses the "struct"
version for native-endian unaligned access and the "byteshift" version
for the opposite endianess. The current ARM version however uses the
"byteshift" implementation for both.

Thanks to Nicolas Pitre for the excellent analysis:

Test case:

int foo (int *x) { return get_unaligned(x); }
long long bar (long long *x) { return get_unaligned(x); }

With the current ARM version:

foo:
	ldrb	r3, [r0, #2]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 2B], MEM[(const u8 *)x_1(D) + 2B]
	ldrb	r1, [r0, #1]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 1B], MEM[(const u8 *)x_1(D) + 1B]
	ldrb	r2, [r0, #0]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D)], MEM[(const u8 *)x_1(D)]
	mov	r3, r3, asl #16	@ tmp154, MEM[(const u8 *)x_1(D) + 2B],
	ldrb	r0, [r0, #3]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 3B], MEM[(const u8 *)x_1(D) + 3B]
	orr	r3, r3, r1, asl #8	@, tmp155, tmp154, MEM[(const u8 *)x_1(D) + 1B],
	orr	r3, r3, r2	@ tmp157, tmp155, MEM[(const u8 *)x_1(D)]
	orr	r0, r3, r0, asl #24	@,, tmp157, MEM[(const u8 *)x_1(D) + 3B],
	bx	lr	@

bar:
	stmfd	sp!, {r4, r5, r6, r7}	@,
	mov	r2, #0	@ tmp184,
	ldrb	r5, [r0, #6]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 6B], MEM[(const u8 *)x_1(D) + 6B]
	ldrb	r4, [r0, #5]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 5B], MEM[(const u8 *)x_1(D) + 5B]
	ldrb	ip, [r0, #2]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 2B], MEM[(const u8 *)x_1(D) + 2B]
	ldrb	r1, [r0, #4]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 4B], MEM[(const u8 *)x_1(D) + 4B]
	mov	r5, r5, asl #16	@ tmp175, MEM[(const u8 *)x_1(D) + 6B],
	ldrb	r7, [r0, #1]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 1B], MEM[(const u8 *)x_1(D) + 1B]
	orr	r5, r5, r4, asl #8	@, tmp176, tmp175, MEM[(const u8 *)x_1(D) + 5B],
	ldrb	r6, [r0, #7]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 7B], MEM[(const u8 *)x_1(D) + 7B]
	orr	r5, r5, r1	@ tmp178, tmp176, MEM[(const u8 *)x_1(D) + 4B]
	ldrb	r4, [r0, #0]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D)], MEM[(const u8 *)x_1(D)]
	mov	ip, ip, asl #16	@ tmp188, MEM[(const u8 *)x_1(D) + 2B],
	ldrb	r1, [r0, #3]	@ zero_extendqisi2	@ MEM[(const u8 *)x_1(D) + 3B], MEM[(const u8 *)x_1(D) + 3B]
	orr	ip, ip, r7, asl #8	@, tmp189, tmp188, MEM[(const u8 *)x_1(D) + 1B],
	orr	r3, r5, r6, asl #24	@,, tmp178, MEM[(const u8 *)x_1(D) + 7B],
	orr	ip, ip, r4	@ tmp191, tmp189, MEM[(const u8 *)x_1(D)]
	orr	ip, ip, r1, asl #24	@, tmp194, tmp191, MEM[(const u8 *)x_1(D) + 3B],
	mov	r1, r3	@,
	orr	r0, r2, ip	@ tmp171, tmp184, tmp194
	ldmfd	sp!, {r4, r5, r6, r7}
	bx	lr

In both cases the code is slightly suboptimal.  One may wonder why
wasting r2 with the constant 0 in the second case for example.  And all
the mov's could be folded in subsequent orr's, etc.

Now with the asm-generic version:

foo:
	ldr	r0, [r0, #0]	@ unaligned	@,* x
	bx	lr	@

bar:
	mov	r3, r0	@ x, x
	ldr	r0, [r0, #0]	@ unaligned	@,* x
	ldr	r1, [r3, #4]	@ unaligned	@,
	bx	lr	@

This is way better of course, but only because this was compiled for
ARMv7. In this case the compiler knows that the hardware can do
unaligned word access.  This isn't that obvious for foo(), but if we
remove the get_unaligned() from bar as follows:

long long bar (long long *x) {return *x; }

then the resulting code is:

bar:
	ldmia	r0, {r0, r1}	@ x,,
	bx	lr	@

So this proves that the presumed aligned vs unaligned cases does have
influence on the instructions the compiler may use and that the above
unaligned code results are not just an accident.

Still... this isn't fully conclusive without at least looking at the
resulting assembly fron a pre ARMv6 compilation.  Let's see with an
ARMv5 target:

foo:
	ldrb	r3, [r0, #0]	@ zero_extendqisi2	@ tmp139,* x
	ldrb	r1, [r0, #1]	@ zero_extendqisi2	@ tmp140,
	ldrb	r2, [r0, #2]	@ zero_extendqisi2	@ tmp143,
	ldrb	r0, [r0, #3]	@ zero_extendqisi2	@ tmp146,
	orr	r3, r3, r1, asl #8	@, tmp142, tmp139, tmp140,
	orr	r3, r3, r2, asl #16	@, tmp145, tmp142, tmp143,
	orr	r0, r3, r0, asl #24	@,, tmp145, tmp146,
	bx	lr	@

bar:
	stmfd	sp!, {r4, r5, r6, r7}	@,
	ldrb	r2, [r0, #0]	@ zero_extendqisi2	@ tmp139,* x
	ldrb	r7, [r0, #1]	@ zero_extendqisi2	@ tmp140,
	ldrb	r3, [r0, #4]	@ zero_extendqisi2	@ tmp149,
	ldrb	r6, [r0, #5]	@ zero_extendqisi2	@ tmp150,
	ldrb	r5, [r0, #2]	@ zero_extendqisi2	@ tmp143,
	ldrb	r4, [r0, #6]	@ zero_extendqisi2	@ tmp153,
	ldrb	r1, [r0, #7]	@ zero_extendqisi2	@ tmp156,
	ldrb	ip, [r0, #3]	@ zero_extendqisi2	@ tmp146,
	orr	r2, r2, r7, asl #8	@, tmp142, tmp139, tmp140,
	orr	r3, r3, r6, asl #8	@, tmp152, tmp149, tmp150,
	orr	r2, r2, r5, asl #16	@, tmp145, tmp142, tmp143,
	orr	r3, r3, r4, asl #16	@, tmp155, tmp152, tmp153,
	orr	r0, r2, ip, asl #24	@,, tmp145, tmp146,
	orr	r1, r3, r1, asl #24	@,, tmp155, tmp156,
	ldmfd	sp!, {r4, r5, r6, r7}
	bx	lr

Compared to the initial results, this is really nicely optimized and I
couldn't do much better if I were to hand code it myself.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 7494/1: use generic termios.h
As pointed out by Arnd Bergmann, this fixes a couple of issues but will
increase code size:

The original macro user_termio_to_kernel_termios was not endian safe. It
used an unsigned short ptr to access the low bits in a 32-bit word.

Both user_termio_to_kernel_termios and kernel_termios_to_user_termio are
missing error checking on put_user/get_user and copy_to/from_user.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: MSM: use SGI0 to wake secondary CPUs
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>