linux-toradex.git/arch/arm/kernel/hw_breakpoint.c, branch v3.17

Merge tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2014-04-07T21:55:46+00:00

Pull CPU hotplug notifiers registration fixes from Rafael Wysocki:
 "The purpose of this single series of commits from Srivatsa S Bhat
  (with a small piece from Gautham R Shenoy) touching multiple
  subsystems that use CPU hotplug notifiers is to provide a way to
  register them that will not lead to deadlocks with CPU online/offline
  operations as described in the changelog of commit 93ae4f978ca7f ("CPU
  hotplug: Provide lockless versions of callback registration
  functions").

  The first three commits in the series introduce the API and document
  it and the rest simply goes through the users of CPU hotplug notifiers
  and converts them to using the new method"

* tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (52 commits)
  net/iucv/iucv.c: Fix CPU hotplug callback registration
  net/core/flow.c: Fix CPU hotplug callback registration
  mm, zswap: Fix CPU hotplug callback registration
  mm, vmstat: Fix CPU hotplug callback registration
  profile: Fix CPU hotplug callback registration
  trace, ring-buffer: Fix CPU hotplug callback registration
  xen, balloon: Fix CPU hotplug callback registration
  hwmon, via-cputemp: Fix CPU hotplug callback registration
  hwmon, coretemp: Fix CPU hotplug callback registration
  thermal, x86-pkg-temp: Fix CPU hotplug callback registration
  octeon, watchdog: Fix CPU hotplug callback registration
  oprofile, nmi-timer: Fix CPU hotplug callback registration
  intel-idle: Fix CPU hotplug callback registration
  clocksource, dummy-timer: Fix CPU hotplug callback registration
  drivers/base/topology.c: Fix CPU hotplug callback registration
  acpi-cpufreq: Fix CPU hotplug callback registration
  zsmalloc: Fix CPU hotplug callback registration
  scsi, fcoe: Fix CPU hotplug callback registration
  scsi, bnx2fc: Fix CPU hotplug callback registration
  scsi, bnx2i: Fix CPU hotplug callback registration
  ...

arm, hw-breakpoint: Fix CPU hotplug callback registration

2014-03-20T12:43:41+00:00

Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:

	get_online_cpus();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	register_cpu_notifier(&foobar_cpu_notifier);

	put_online_cpus();

This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).

Instead, the correct and race-free way of performing the callback
registration is:

	cpu_notifier_register_begin();

	for_each_online_cpu(cpu)
		init_cpu(cpu);

	/* Note the use of the double underscored version of the API */
	__register_cpu_notifier(&foobar_cpu_notifier);

	cpu_notifier_register_done();

Fix the hw-breakpoint code in arm by using this latter form of callback
registration.

Cc: Russell King 
Cc: Ingo Molnar 
Acked-by: Will Deacon 
Signed-off-by: Srivatsa S. Bhat 
Signed-off-by: Rafael J. Wysocki

ARM: 7948/1: hw_breakpoint: Add ARMv8 support

2014-02-10T11:48:05+00:00

Add the trivial support necessary to get hardware breakpoints
working for GDB on ARMv8 simulators running in AArch32 mode.

Acked-by: Will Deacon 
Signed-off-by: Christopher Covington 
Signed-off-by: Russell King

ARM: 7862/1: pcpu: replace __get_cpu_var_uses

2013-10-29T11:06:27+00:00

This is the ARM part of Christoph's patchset cleaning up the various
uses of __get_cpu_var across the tree.

The idea is to convert __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations
that use the offset. Thereby address calculations are avoided and fewer
registers are used when code is generated.

[will: fixed debug ref counting checks and pcpu array accesses]

Acked-by: Catalin Marinas 
Signed-off-by: Christoph Lameter 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

arm: delete cpuinit/CPUINIT usage from all ARM users

2013-07-14T23:36:52+00:00

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
and are flagged as __cpuinit  -- so if we remove the __cpuinit from
the arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
related content into no-ops as early as possible, since that will get
rid of these warnings.  In any case, they are temporary and harmless.

This removes all the ARM uses of the __cpuinit macros from C code,
and all __CPUINIT from assembly code.  It also had two ".previous"
section statements that were paired off against __CPUINIT
(aka .section ".cpuinit.text") that also get removed here.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Russell King 
Cc: Will Deacon 
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Paul Gortmaker

ARM: 7697/1: hw_breakpoint: do not use __cpuinitdata for dbg_cpu_pm_nb

2013-04-17T15:54:06+00:00

We must not declare dbg_cpu_pm_nb as __cpuinitdata as we need it after
system initialization for Suspend and CPUIdle.

This was done in commit 9a6eb310eaa5 ("ARM: hw_breakpoint: Debug powerdown
support for self-hosted debug").

Cc: stable@vger.kernel.org
Cc: Dietmar Eggemann 
Signed-off-by: Bastian Hecht 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 7681/1: hw_breakpoint: use warn_once to avoid spam from reset_ctrl_regs()

2013-03-22T17:16:56+00:00

CPU debug features like hardware break, watchpoints can be used only
when the debug mode is enabled and available. Unfortunately on OMAP4
based devices, after a CPU power cycle, the debug feature gets disabled
which leads to a flood of messages coming from reset_ctrl_regs() which
gets called on every CPU_PM_EXIT with CPUidle enabled.

So make use of warn_once() so that system is usable.

Thanks to Will for pointers and Lokesh for the analysis of the issue.

Tested-by: Lokesh Vutla 
Signed-off-by: Santosh Shilimkar 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 7662/1: hw_breakpoint: reset debug logic on secondary CPUs in s2ram resume

2013-03-03T22:54:16+00:00

We must mask out the CPU_TASKS_FROZEN bit so that reset_ctrl_regs is
also called on a secondary CPU during s2ram resume, where only the boot
CPU will receive the PM_EXIT notification.

Signed-off-by: Dietmar Eggemann 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: hw_breakpoint: Debug powerdown support for self-hosted debug

2013-01-10T21:13:07+00:00

This patch introduces debug powerdown support for self-hosted debug for v7
and v7.1 debug architecture for a SinglePower system, i.e. a system without a
separate core and debug power domain. On a SinglePower system the OS Lock is
lost over a powerdown.

If CONFIG_CPU_PM is set the new function pm_init() registers hw_breakpoint
with CPU PM for a system supporting OS Save and Restore.

Receiving a CPU PM EXIT notifier indicates that a single CPU has exited a low
power state. A call to reset_ctrl_regs() is hooked into the CPU PM EXIT
notifier chain. This function makes sure that the sticky power-down is clear
(only v7 debug), the OS Double Lock is clear (only v7.1 debug) and it clears
the OS Lock for v7 debug (for a system supporting OS Save and Restore) and
v7.1 debug. Furthermore, it clears any vector-catch events and all
breakpoint/watchpoint control/value registers for v7 and v7.1 debug.

Signed-off-by: Dietmar Eggemann 
[will: removed redundant has_ossr check]
Signed-off-by: Will Deacon

ARM: hw_breakpoint: Check function for OS Save and Restore mechanism

2013-01-10T21:13:06+00:00

v7 debug introduced OS Save and Restore mechanism. On a v7 debug SinglePower
system, i.e a system without a separate core and debug power domain, which does
not support external debug over powerdown, it is implementation defined whether
OS Save and Restore is implemented.
v7.1 debug requires OS Save and Restore mechanism. v6 debug and v6.1 debug do
not implement it.

A new global variable bool has_ossr is introduced and is determined in
arch_hw_breakpoint_init() like debug_arch or the number of BRPs/WRPs.

The logic how to check if OS Save and Restore is supported has changed with
this patch. In reset_ctrl_regs() a mask consisting of OSLM[1] (OSLSR.3) and
OSLM[0] (OSLSR.0) was used to check if the system supports OS Save and
Restore. In the new function core_has_os_save_restore() only OSLM[0] is used.
It is not necessary to check OSLM[1] too since it is v7.1 debug specific and
v7.1 debug requires OS Save and Restore and thus OS Lock.

Signed-off-by: Dietmar Eggemann 
Signed-off-by: Will Deacon