linux-stable.git/arch/powerpc/kernel, branch v3.9.7

powerpc: Fix missing/delayed calls to irq_work

2013-06-20T19:01:38+00:00

commit 230b3034793247f61e6a0b08c44cf415f6d92981 upstream.

When replaying interrupts (as a result of the interrupt occurring
while soft-disabled), in the case of the decrementer, we are exclusively
testing for a pending timer target. However we also use decrementer
interrupts to trigger the new "irq_work", which in this case would
be missed.

This change the logic to force a replay in both cases of a timer
boundary reached and a decrementer interrupt having actually occurred
while disabled. The former test is still useful to catch cases where
a CPU having been hard-disabled for a long time completely misses the
interrupt due to a decrementer rollover.

Signed-off-by: Benjamin Herrenschmidt 
Tested-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Fix emulation of illegal instructions on PowerNV platform

2013-06-20T19:01:33+00:00

commit bf593907f7236e95698a76b7c7a2bbf8b1165327 upstream.

Normally, the kernel emulates a few instructions that are unimplemented
on some processors (e.g. the old dcba instruction), or privileged (e.g.
mfpvr).  The emulation of unimplemented instructions is currently not
working on the PowerNV platform.  The reason is that on these machines,
unimplemented and illegal instructions cause a hypervisor emulation
assist interrupt, rather than a program interrupt as on older CPUs.
Our vector for the emulation assist interrupt just calls
program_check_exception() directly, without setting the bit in SRR1
that indicates an illegal instruction interrupt.  This fixes it by
making the emulation assist interrupt set that bit before calling
program_check_interrupt().  With this, old programs that use no-longer
implemented instructions such as dcba now work again.

Signed-off-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Fix stack overflow crash in resume_kernel when ftracing

2013-06-20T19:01:32+00:00

commit 0e37739b1c96d65e6433998454985de994383019 upstream.

It's possible for us to crash when running with ftrace enabled, eg:

  Bad kernel stack pointer bffffd12 at c00000000000a454
  cpu 0x3: Vector: 300 (Data Access) at [c00000000ffe3d40]
      pc: c00000000000a454: resume_kernel+0x34/0x60
      lr: c00000000000335c: performance_monitor_common+0x15c/0x180
      sp: bffffd12
     msr: 8000000000001032
     dar: bffffd12
   dsisr: 42000000

If we look at current's stack (paca->__current->stack) we see it is
equal to c0000002ecab0000. Our stack is 16K, and comparing to
paca->kstack (c0000002ecab3e30) we can see that we have overflowed our
kernel stack. This leads to us writing over our struct thread_info, and
in this case we have corrupted thread_info->flags and set
_TIF_EMULATE_STACK_STORE.

Dumping the stack we see:

  3:mon> t c0000002ecab0000
  [c0000002ecab0000] c00000000002131c .performance_monitor_exception+0x5c/0x70
  [c0000002ecab0080] c00000000000335c performance_monitor_common+0x15c/0x180
  --- Exception: f01 (Performance Monitor) at c0000000000fb2ec .trace_hardirqs_off+0x1c/0x30
  [c0000002ecab0370] c00000000016fdb0 .trace_graph_entry+0xb0/0x280 (unreliable)
  [c0000002ecab0410] c00000000003d038 .prepare_ftrace_return+0x98/0x130
  [c0000002ecab04b0] c00000000000a920 .ftrace_graph_caller+0x14/0x28
  [c0000002ecab0520] c0000000000d6b58 .idle_cpu+0x18/0x90
  [c0000002ecab05a0] c00000000000a934 .return_to_handler+0x0/0x34
  [c0000002ecab0620] c00000000001e660 .timer_interrupt+0x160/0x300
  [c0000002ecab06d0] c0000000000025dc decrementer_common+0x15c/0x180
  --- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0
  [c0000002ecab09c0] c0000000000fe044 .trace_hardirqs_on+0x14/0x30 (unreliable)
  [c0000002ecab0fb0] c00000000016fe3c .trace_graph_entry+0x13c/0x280
  [c0000002ecab1050] c00000000003d038 .prepare_ftrace_return+0x98/0x130
  [c0000002ecab10f0] c00000000000a920 .ftrace_graph_caller+0x14/0x28
  [c0000002ecab1160] c0000000000161f0 .__ppc64_runlatch_on+0x10/0x40
  [c0000002ecab11d0] c00000000000a934 .return_to_handler+0x0/0x34
  --- Exception: 901 (Decrementer) at c0000000000104d4 .arch_local_irq_restore+0x74/0xa0

  ... and so on

__ppc64_runlatch_on() is called from RUNLATCH_ON in the exception entry
path. At that point the irq state is not consistent, ie. interrupts are
hard disabled (by the exception entry), but the paca soft-enabled flag
may be out of sync.

This leads to the local_irq_restore() in trace_graph_entry() actually
enabling interrupts, which we do not want. Because we have not yet
reprogrammed the decrementer we immediately take another decrementer
exception, and recurse.

The fix is twofold. Firstly make sure we call DISABLE_INTS before
calling RUNLATCH_ON. The badly named DISABLE_INTS actually reconciles
the irq state in the paca with the hardware, making it safe again to
call local_irq_save/restore().

Although that should be sufficient to fix the bug, we also mark the
runlatch routines as notrace. They are called very early in the
exception entry and we are asking for trouble tracing them. They are
also fairly uninteresting and tracing them just adds unnecessary
overhead.

[ This regression was introduced by fe1952fc0afb9a2e4c79f103c08aef5d13db1873
  "powerpc: Rework runlatch code" by myself --BenH
]

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: Perform proper max_bus_speed detection

2013-06-13T17:49:42+00:00

commit d82fb31abc46620b7c22758c75707069f2763646 upstream.

On pseries machines the detection for max_bus_speed should be done
through an OpenFirmware property. This patch adds a function to perform
this detection and a hook to perform dynamic adding of the function only
for pseries. This is done by overwriting the weak
pcibios_root_bridge_prepare function which is called by
pci_create_root_bus().

From: Lucas Kannebley Tavares 
Signed-off-by: Kleber Sacilotto de Souza 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc: Set default VGA device

2013-06-13T17:49:41+00:00

commit c2e1d84523ad2a19e5be08c1f01999cc9e82652e upstream.

Add a PCI quirk for VGA devices on Power to set the default VGA device.
Ensures a default VGA is always set if a graphics adapter is present,
even if firmware did not initialize it. If more than one graphics
adapter is present, ensure the one initialized by firmware is set
as the default VGA device. This ensures that X autoconfiguration
will work.

Signed-off-by: Brian King 
Signed-off-by: Michael Ellerman 
Signed-off-by: Kleber Sacilotto de Souza 
Signed-off-by: Greg Kroah-Hartman

powerpc: Fix build error in stable/3.9

2013-06-13T17:49:38+00:00

Commit e71c42189 (powerpc/tm: Abort on emulation and alignment faults)
introduced a powerpc build error in 3.9.5.

Signed-off-by: Guenter Roeck 
Acked-by: Michael Neuling 
Signed-off-by: Greg Kroah-Hartman

powerpc/hw_breakpoints: Add DABRX cpu feature to fix 32-bit regression

2013-06-13T17:49:28+00:00

commit 82a9f16adc12f51c3f8ea59a7c3c120241aff836 upstream.

When introducing support for DABRX in 4474ef0, we broke older 32-bit CPUs
that don't have that register.

Some CPUs have a DABR but not DABRX.  Configuration are:
- No 32bit CPUs have DABRX but some have DABR.
- POWER4+ and below have the DABR but no DABRX.
- 970 and POWER5 and above have DABR and DABRX.
- POWER8 has DAWR, hence no DABRX.

This introduces CPU_FTR_DABRX and sets it on appropriate CPUs.  We use
the top 64 bits for CPU FTR bits since only 64 bit CPUs have this.

Processors that don't have the DABRX will still work as they will fall
back to software filtering these breakpoints via perf_exclude_event().

Signed-off-by: Michael Neuling 
Reported-by: "Gorelik, Jacob (335F)" 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/tm: Abort on emulation and alignment faults

2013-06-07T19:53:20+00:00

commit 6ce6c629fd8254b3177650de99699682ff7f6707 upstream.

If we are emulating an instruction inside an active user transaction that
touches memory, the kernel can't emulate it as it operates in transactional
suspend context.  We need to abort these transactions and send them back to
userspace for the hardware to rollback.

We can service these if the user transaction is in suspend mode, since the
kernel will operate in the same suspend context.

This adds a check to all alignment faults and to specific instruction
emulations (only string instructions for now).  If the user process is in an
active (non-suspended) transaction, we abort the transaction go back to
userspace allowing the HW to roll back the transaction and tell the user of the
failure.  This also adds new tm abort cause codes to report the reason of the
persistent error to the user.

Crappy test case here http://neuling.org/devel/junkcode/aligntm.c

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/tm: Fix userspace stack corruption on signal delivery for active transactions

2013-06-07T19:53:19+00:00

commit 2b3f8e87cf99a33fb6faf5026d7147748bbd77b6 upstream.

When in an active transaction that takes a signal, we need to be careful with
the stack.  It's possible that the stack has moved back up after the tbegin.
The obvious case here is when the tbegin is called inside a function that
returns before a tend.  In this case, the stack is part of the checkpointed
transactional memory state.  If we write over this non transactionally or in
suspend, we are in trouble because if we get a tm abort, the program counter
and stack pointer will be back at the tbegin but our in memory stack won't be
valid anymore.

To avoid this, when taking a signal in an active transaction, we need to use
the stack pointer from the checkpointed state, rather than the speculated
state.  This ensures that the signal context (written tm suspended) will be
written below the stack required for the rollback.  The transaction is aborted
becuase of the treclaim, so any memory written between the tbegin and the
signal will be rolled back anyway.

For signals taken in non-TM or suspended mode, we use the
normal/non-checkpointed stack pointer.

Tested with 64 and 32 bit signals

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman

powerpc/32bit:Store temporary result in r0 instead of r8

2013-06-07T19:53:18+00:00

commit f7b3367774f92a688d39ed767f0ae9b93af7873a upstream.

Commit a9c4e541ea9b22944da356f2a9258b4eddcc953b
"powerpc/kprobe: Complete kprobe and migrate exception frame"
introduced a regression:

While returning from exception handling in case of PREEMPT enabled,
_TIF_NEED_RESCHED bit is checked in TI_FLAGS (thread_info flag) of current
task. Only if this bit is set, it should continue with the process of
calling preempt_schedule_irq() to schedule highest priority task if
available.

Current code assumes that r8 contains TI_FLAGS and check this for
_TIF_NEED_RESCHED, but as r8 is modified in the code which executes before
this check, r8 no longer contains the expected TI_FLAGS information.

As a result check for comparison with _TIF_NEED_RESCHED was failing even if
NEED_RESCHED bit is set in the current thread_info flag. Due to this,
preempt_schedule_irq() and in turn scheduler was not getting called even if
highest priority task is ready for execution.

So, store temporary results in r0 instead of r8 to prevent r8 from getting
modified as subsequent code is dependent on its value.

Signed-off-by: Priyanka Jain 
Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Greg Kroah-Hartman