linux-toradex.git/arch/powerpc, branch v3.16-rc5

powerpc/perf: Never program book3s PMCs with values >= 0x80000000

2014-07-11T03:50:47+00:00

We are seeing a lot of PMU warnings on POWER8:

    Can't find PMC that caused IRQ

Looking closer, the active PMC is 0 at this point and we took a PMU
exception on the transition from negative to 0. Some versions of POWER8
have an issue where they edge detect and not level detect PMC overflows.

A number of places program the PMC with (0x80000000 - period_left),
where period_left can be negative. We can either fix all of these or
just ensure that period_left is always >= 1.

This patch takes the second option.

Cc: 
Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Disable RELOCATABLE for COMPILE_TEST with PPC64

2014-07-11T02:55:09+00:00

powerpc:allmodconfig has been failing for some time with the following
error.

arch/powerpc/kernel/exceptions-64s.S: Assembler messages:
arch/powerpc/kernel/exceptions-64s.S:1312: Error: attempt to move .org backwards
make[1]: *** [arch/powerpc/kernel/head_64.o] Error 1

A number of attempts to fix the problem by moving around code have been
unsuccessful and resulted in failed builds for some configurations and
the discovery of toolchain bugs.

Fix the problem by disabling RELOCATABLE for COMPILE_TEST builds instead.
While this is less than perfect, it avoids substantial code changes
which would otherwise be necessary just to make COMPILE_TEST builds
happy and might have undesired side effects.

Signed-off-by: Guenter Roeck 
Signed-off-by: Benjamin Herrenschmidt

powerpc/perf: Clear MMCR2 when enabling PMU

2014-07-11T02:55:08+00:00

On POWER8 when switching to a KVM guest we set bits in MMCR2 to freeze
the PMU counters. Aside from on boot they are then never reset,
resulting in stuck perf counters for any user in the guest or host.

We now set MMCR2 to 0 whenever enabling the PMU, which provides a sane
state for perf to use the PMU counters under either the guest or the
host.

This was manifesting as a bug with ppc64_cpu --frequency:

    $ sudo ppc64_cpu --frequency
    WARNING: couldn't run on cpu 0
    WARNING: couldn't run on cpu 8
      ...
    WARNING: couldn't run on cpu 144
    WARNING: couldn't run on cpu 152
    min:    18446744073.710 GHz (cpu -1)
    max:    0.000 GHz (cpu -1)
    avg:    0.000 GHz

The command uses a perf counter to measure CPU cycles over a fixed
amount of time, in order to approximate the frequency of the machine.
The counters were returning zero once a guest was started, regardless of
weather it was still running or had been shut down.

By dumping the value of MMCR2, it was observed that once a guest is
running MMCR2 is set to 1s - which stops counters from running:

    $ sudo sh -c 'echo p > /proc/sysrq-trigger'
    CPU: 0 PMU registers, ppmu = POWER8 n_counters = 6
    PMC1:  5b635e38 PMC2: 00000000 PMC3: 00000000 PMC4: 00000000
    PMC5:  1bf5a646 PMC6: 5793d378 PMC7: deadbeef PMC8: deadbeef
    MMCR0: 0000000080000000 MMCR1: 000000001e000000 MMCRA: 0000040000000000
    MMCR2: fffffffffffffc00 EBBHR: 0000000000000000
    EBBRR: 0000000000000000 BESCR: 0000000000000000
    SIAR:  00000000000a51cc SDAR:  c00000000fc40000 SIER:  0000000001000000

This is done unconditionally in book3s_hv_interrupts.S upon entering the
guest, and the original value is only save/restored if the host has
indicated it was using the PMU. This is okay, however the user of the
PMU needs to ensure that it is in a defined state when it starts using
it.

Fixes: e05b9b9e5c10 ("powerpc/perf: Power8 PMU support")
Cc: stable@vger.kernel.org
Signed-off-by: Joel Stanley 
Acked-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc/perf: Add PPMU_ARCH_207S define

2014-07-11T02:55:07+00:00

Instead of separate bits for every POWER8 PMU feature, have a single one
for v2.07 of the architecture.

This saves us adding a MMCR2 define for a future patch.

Cc: stable@vger.kernel.org
Signed-off-by: Joel Stanley 
Acked-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc/kvm: Remove redundant save of SIER AND MMCR2

2014-07-11T02:55:07+00:00

These two registers are already saved in the block above. Aside from
being unnecessary, by the time we get down to the second save location
r8 no longer contains MMCR2, so we are clobbering the saved value with
PMC5.

MMCR2 primarily consists of counter freeze bits. So restoring the value
of PMC5 into MMCR2 will most likely have the effect of freezing
counters.

Fixes: 72cde5a88d37 ("KVM: PPC: Book3S HV: Save/restore host PMU registers that are new in POWER8")
Cc: stable@vger.kernel.org
Signed-off-by: Joel Stanley 
Acked-by: Michael Ellerman 
Acked-by: Paul Mackerras 
Reviewed-by: Alexander Graf 
Signed-off-by: Benjamin Herrenschmidt

powerpc/powernv: Check for IRQHAPPENED before sleeping

2014-07-11T02:55:06+00:00

Commit 8d6f7c5a: "powerpc/powernv: Make it possible to skip the IRQHAPPENED
check in power7_nap()" added code that prevents cpus from checking for
pending interrupts just before entering sleep state, which is wrong. These
interrupts are delivered during the soft irq disabled state of the cpu.

A cpu cannot enter any idle state with pending interrupts because they will
never be serviced until the next time the cpu is woken up by some other
interrupt. Its only then that the pending interrupts are replayed. This can result
in device timeouts or warnings about this cpu being stuck.

This patch fixes ths issue by ensuring that cpus check for pending interrupts
just before entering any idle state as long as they are not in the path of split
core operations.

Signed-off-by: Preeti U Murthy 
Acked-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Clean up MMU_FTRS_A2 and MMU_FTR_TYPE_3E

2014-07-11T02:55:05+00:00

In fb5a515704d7 "powerpc: Remove platforms/wsp and associated pieces",
we removed the last user of MMU_FTRS_A2. So remove it.

MMU_FTRS_A2 was the last user of MMU_FTR_TYPE_3E, so remove it also.
This leaves some unreachable code in mmu_context_nohash.c, so remove
that also.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc/cell: Fix compilation with CONFIG_COREDUMP=n

2014-07-11T02:55:05+00:00

Commit 046d662f4818 "coredump: make core dump functionality optional"
made the coredump optional, but didn't update the spufs code that
depends on it. That leads to build errors such as:

  arch/powerpc/platforms/built-in.o: In function `.spufs_arch_write_note':
  coredump.c:(.text+0x22cd4): undefined reference to `.dump_emit'
  coredump.c:(.text+0x22cf4): undefined reference to `.dump_emit'
  coredump.c:(.text+0x22d0c): undefined reference to `.dump_align'
  coredump.c:(.text+0x22d48): undefined reference to `.dump_emit'
  coredump.c:(.text+0x22e7c): undefined reference to `.dump_skip'

Fix it by adding some ifdefs in the cell code.

Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Don't skip ePAPR spin-table CPUs

2014-06-25T03:10:49+00:00

Commit 59a53afe70fd530040bdc69581f03d880157f15a "powerpc: Don't setup
CPUs with bad status" broke ePAPR SMP booting.  ePAPR says that CPUs
that aren't presently running shall have status of disabled, with
enable-method being used to determine whether the CPU can be enabled.

Fix by checking for spin-table, which is currently the only supported
enable-method.

Signed-off-by: Scott Wood 
Cc: Michael Neuling 
Cc: Emil Medve 
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt

powerpc/module: Fix TOC symbol CRC

2014-06-25T03:10:48+00:00

The commit 71ec7c55ed91 introduced the magic symbol ".TOC." for ELFv2 ABI.
This symbol is built manually and has no CRC value computed. A zero value
is put in the CRC section to avoid modpost complaining about a missing CRC.
Unfortunately, this breaks the kernel module loading when the kernel is
relocated (kdump case for instance) because of the relocation applied to
the kcrctab values.

This patch compute a CRC value for the TOC symbol which will match the one
compute by the kernel when it is relocated - aka '0 - relocate_start' done in
maybe_relocated called by check_version (module.c).

Signed-off-by: Laurent Dufour 
Cc: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt