linux-toradex.git/arch/powerpc, branch v3.11

powerpc: Work around gcc miscompilation of __pa() on 64-bit

2013-08-27T06:59:30+00:00

On 64-bit, __pa(&static_var) gets miscompiled by recent versions of
gcc as something like:

        addis 3,2,.LANCHOR1+4611686018427387904@toc@ha
        addi 3,3,.LANCHOR1+4611686018427387904@toc@l

This ends up effectively ignoring the offset, since its bottom 32 bits
are zero, and means that the result of __pa() still has 0xC in the top
nibble.  This happens with gcc 4.8.1, at least.

To work around this, for 64-bit we make __pa() use an AND operator,
and for symmetry, we make __va() use an OR operator.  Using an AND
operator rather than a subtraction ends up with slightly shorter code
since it can be done with a single clrldi instruction, whereas it
takes three instructions to form the constant (-PAGE_OFFSET) and add
it on.  (Note that MEMORY_START is always 0 on 64-bit.)

CC: 
Signed-off-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Don't Oops when accessing /proc/powerpc/lparcfg without hypervisor

2013-08-27T06:38:33+00:00

/proc/powerpc/lparcfg is an ancient facility (though still actively used)
which allows access to some informations relative to the partition when
running underneath a PAPR compliant hypervisor.

It makes no sense on non-pseries machines. However, currently, not only
can it be created on these if the kernel has pseries support, but accessing
it on such a machine will crash due to trying to do hypervisor calls.

In fact, it should also not do HV calls on older pseries that didn't have
an hypervisor either.

Finally, it has the plumbing to be a module but is a "bool" Kconfig option.

This fixes the whole lot by turning it into a machine_device_initcall
that is only created on pseries, and adding the necessary hypervisor
check before calling the H_GET_EM_PARMS hypercall

CC: 
Signed-off-by: Benjamin Herrenschmidt

powerpc/tm: Fix context switching TAR, PPR and DSCR SPRs

2013-08-09T08:07:12+00:00

If a transaction is rolled back, the Target Address Register (TAR), Processor
Priority Register (PPR) and Data Stream Control Register (DSCR) should be
restored to the checkpointed values before the transaction began.  Any changes
to these SPRs inside the transaction should not be visible in the abort
handler.

Currently Linux doesn't save or restore the checkpointed TAR, PPR or DSCR.  If
we preempt a processes inside a transaction which has modified any of these, on
process restore, that same transaction may be aborted we but we won't see the
checkpointed versions of these SPRs.

This adds checkpointed versions of these SPRs to the thread_struct and adds the
save/restore of these three SPRs to the treclaim/trechkpt code.

Without this if any of these SPRs are modified during a transaction, users may
incorrectly see a speculated SPR value even if the transaction is aborted.

Signed-off-by: Michael Neuling 
Cc:  [v3.10]
Signed-off-by: Benjamin Herrenschmidt

powerpc: Save the TAR register earlier

2013-08-09T08:07:08+00:00

This moves us to save the Target Address Register (TAR) a earlier in
__switch_to.  It introduces a new function save_tar() to do this.

We need to save the TAR earlier as we will overwrite it in the transactional
memory reclaim/recheckpoint path.  We are going to do this in a subsequent
patch which will fix saving the TAR register when it's modified inside a
transaction.

Signed-off-by: Michael Neuling 
Cc:  [v3.10]
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix context switch DSCR on POWER8

2013-08-09T08:07:05+00:00

POWER8 allows the DSCR to be accessed directly from userspace via a new SPR
number 0x3 (Rather than 0x11.  DSCR SPR number 0x11 is still used on POWER8 but
like POWER7, is only accessible in HV and OS modes).  Currently, we allow this
by setting H/FSCR DSCR bit on boot.

Unfortunately this doesn't work, as the kernel needs to see the DSCR change so
that it knows to no longer restore the system wide version of DSCR on context
switch (ie. to set thread.dscr_inherit).

This clears the H/FSCR DSCR bit initially.  If a process then accesses the DSCR
(via SPR 0x3), it'll trap into the kernel where we set thread.dscr_inherit in
facility_unavailable_exception().

We also change _switch() so that we set or clear the H/FSCR DSCR bit based on
the thread.dscr_inherit.

Signed-off-by: Michael Neuling 
Cc:  [v3.10]
Signed-off-by: Benjamin Herrenschmidt

powerpc: Rework setting up H/FSCR bit definitions

2013-08-09T08:07:01+00:00

This reworks the Facility Status and Control Regsiter (FSCR) config bit
definitions so that we can access the bit numbers.  This is needed for a
subsequent patch to fix the userspace DSCR handling.

HFSCR and FSCR bit definitions are the same, so reuse them.

Signed-off-by: Michael Neuling 
Cc:  [v3.10]
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix hypervisor facility unavaliable vector number

2013-08-09T08:06:58+00:00

Currently if we take hypervisor facility unavaliable (from 0xf80/0x4f80) we
mark it as an OS facility unavaliable (0xf60) as the two share the same code
path.

The becomes a problem in facility_unavailable_exception() as we aren't able to
see the hypervisor facility unavailable exceptions.

Below fixes this by duplication the required macros.

Signed-off-by: Michael Neuling 
Cc:  [v3.10]
Signed-off-by: Benjamin Herrenschmidt

powerpc/kvm/book3s_pr: Return appropriate error when allocation fails

2013-08-09T08:06:54+00:00

err was overwritten by a previous function call, and checked to be 0. If
the following page allocation fails, 0 is going to be returned instead
of -ENOMEM.

Signed-off-by: Thadeu Lima de Souza Cascardo 
Signed-off-by: Benjamin Herrenschmidt

powerpc/kvm: Add signed type cast for comparation

2013-08-09T08:06:51+00:00

'rmls' is 'unsigned long', lpcr_rmls() will return negative number when
failure occurs, so it need a type cast for comparing.

'lpid' is 'unsigned long', kvmppc_alloc_lpid() return negative number
when failure occurs, so it need a type cast for comparing.

Signed-off-by: Chen Gang 
Acked-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Add missing procfs entry for PowerNV

2013-08-09T08:06:47+00:00

The procfs entry for global statistics has been missed on PowerNV
platform and the patch is going to add that.

Signed-off-by: Mike Qiu 
Acked-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt