When we do a treclaim or trecheckpoint we end up running with userspace
PPR and DSCR values.  Currently we don't do anything special to avoid
running with user values which could cause a severe performance
degradation.

This patch moves the PPR and DSCR save and restore around treclaim and
trecheckpoint so that we run with user values for a much shorter period.
More care is taken with the PPR as it's impact is greater than the DSCR.

This is similar to user exceptions, where we run HTM_MEDIUM early to
ensure that we don't run with a userspace PPR values in the kernel.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> # 3.9+
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We can't take IRQs in tm_reclaim as we might have a bogus r13 and r1.

This turns IRQs hard off in this function.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> # 3.9+
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 4df48999 "Add power8 EBB support" included a bug in the handling
of the FAB_CRESP_MATCH and FAB_TYPE_MATCH fields.

These values are pulled out of the event code using EVENT_THR_CTL_SHIFT,
however we were then or'ing that value directly into MMCR1.

This meant we were failing to set the FAB fields correctly, and also
potentially corrupting the value for PMC4SEL. Leading to no counts for
the FAB events and incorrect counts for PMC4.

The fix is simply to shift left the FAB value correctly before or'ing it
with MMCR1.
Reported-by: NSooraj Ravindran Nair <soonair3@in.ibm.com>
Signed-off-by: NMichael Ellerman <michael@ellerman.id.au>
Cc: <stable@vger.kernel.org> # 3.10+
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

modalias_show() should return an empty string on error, not -ENODEV.

This causes the following false and annoying error:

> find /sys/devices -name modalias -print0 | xargs -0 cat >/dev/null
cat: /sys/devices/vio/4000/modalias: No such device
cat: /sys/devices/vio/4001/modalias: No such device
cat: /sys/devices/vio/4002/modalias: No such device
cat: /sys/devices/vio/4004/modalias: No such device
cat: /sys/devices/vio/modalias: No such device
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org>

Under heavy (DLPAR?) stress, we tripped this panic() in
arch/powerpc/kernel/iommu.c::iommu_init_table():

	page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
	if (!page)
		panic("iommu_init_table: Can't allocate %ld bytes\n", sz);

Before the panic() we got a page allocation failure for an order-2
allocation. There appears to be memory free, but perhaps not in the
ATOMIC context. I looked through all the call-sites of
iommu_init_table() and didn't see any obvious reason to need an ATOMIC
allocation. Most call-sites in fact have an explicit GFP_KERNEL
allocation shortly before the call to iommu_init_table(), indicating we
are not in an atomic context. There is some indirection for some paths,
but I didn't see any locks indicating that GFP_KERNEL is inappropriate.

With this change under the same conditions, we have not been able to
reproduce the panic.
Signed-off-by: NNishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org>

arch/powerpc/kernel/sysfs.c exports PURR with write permission.
This may be valid for kernel in phyp mode. But writing to
the file in guest mode causes crash due to a priviledge violation
Signed-off-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org>

The csum_partial_copy_generic() function saves the PowerPC non-volatile
r14, r15, and r16 registers for the main checksum-and-copy loop.
Unfortunately, it fails to restore them upon error exit from this loop,
which results in silent corruption of these registers in the presumably
rare event of an access exception within that loop.

This commit therefore restores these register on error exit from the loop.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The csum_partial_copy_generic() uses register r7 to adjust the remaining
bytes to process.  Unfortunately, r7 also holds a parameter, namely the
address of the flag to set in case of access exceptions while reading
the source buffer.  Lacking a quantum implementation of PowerPC, this
commit instead uses register r9 to do the adjusting, leaving r7's
pointer uncorrupted.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Previous commit 46723bfa... introduced a new config option
HAVE_BOOTMEM_INFO_NODE that ended up breaking memory hot-remove for ppc
when sparse vmemmap is not defined.

This patch defines HAVE_BOOTMEM_INFO_NODE for ppc and adds the call to
register_page_bootmem_info_node. Without this we get a BUG_ON for memory
hot remove in put_page_bootmem().

This also adds a stub for register_page_bootmem_memmap to allow ppc to build
with sparse vmemmap defined. Leaving this as a stub is fine since the same
vmemmap addresses are also handled in vmemmap_populate and as such are
properly mapped.
Signed-off-by: NNathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org> [v3.9+]

Starting secondary CPUs early on from Open Firmware and placing them
in a holding spin loop slows down the boot process significantly under
some hypervisors such as KVM.

This is also unnecessary when RTAS supports querying the CPU state

So let's not do it.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

This makes the "OF" zImage wrapper (zImage.pseries, zImage.pmac,
zImage.maple) work if booted via a flat device-tree (ePAPR boot
mode), and thus potentially usable with kexec.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

We've been keeping that field in thread_struct for a while, it contains
the "limit" of the current stack pointer and is meant to be used for
detecting stack overflows.

It has a few problems however:

 - First, it was never actually *used* on 64-bit. Set and updated but
not actually exploited

 - When switching stack to/from irq and softirq stacks, it's update
is racy unless we hard disable interrupts, which is costly. This
is fine on 32-bit as we don't soft-disable there but not on 64-bit.

Thus rather than fixing 2 in order to implement 1 in some hypothetical
future, let's remove the code completely from 64-bit. In order to avoid
a clutter of ifdef's, we remove the updates from C code completely
during interrupt stack switching, and instead maintain it from the
asm helper that is used to do the stack switching in the first place.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Nowadays, irq_exit() calls __do_softirq() pretty much directly
instead of calling do_softirq() which switches to the decicated
softirq stack.

This has lead to observed stack overflows on powerpc since we call
irq_enter() and irq_exit() outside of the scope that switches to
the irq stack.

This fixes it by moving the stack switching up a level, making
irq_enter() and irq_exit() run off the irq stack.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

After the last architecture switched to generic hard irqs the config
options HAVE_GENERIC_HARDIRQS & GENERIC_HARDIRQS and the related code
for !CONFIG_GENERIC_HARDIRQS can be removed.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: NMichal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently hugepage migration works well only for pmd-based hugepages
(mainly due to lack of testing,) so we had better not enable migration of
other levels of hugepages until we are ready for it.

Some users of hugepage migration (mbind, move_pages, and migrate_pages) do
page table walk and check pud/pmd_huge() there, so they are safe.  But the
other users (softoffline and memory hotremove) don't do this, so without
this patch they can try to migrate unexpected types of hugepages.

To prevent this, we introduce hugepage_migration_support() as an
architecture dependent check of whether hugepage are implemented on a pmd
basis or not.  And on some architecture multiple sizes of hugepages are
available, so hugepage_migration_support() also checks hugepage size.
Signed-off-by: NNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When adding cpuidle support to pSeries, we introduced two
regressions:

  - The new cpuidle backend driver only works under hypervisors
    supporting the "SLPLAR" option, which isn't the case of the
    old POWER4 hypervisor and the HV "light" used on js2x blades

  - The cpuidle driver registers fairly late, meaning that for
    a significant portion of the boot process, we end up having
    all threads spinning. This slows down the boot process and
    increases the overall resource usage if the hypervisor has
    shared processors.

This fixes both by implementing a "default" idle that will cede
to the hypervisor when possible, in a very simple way without
all the bells and whisles of cpuidle.
Reported-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NVaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: NDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
CC: <stable@vger.kernel.org>

While cross-building for PPC64 I've got

WARNING: vmlinux.o(.text.unlikely+0x1ba): Section mismatch in
reference from the function .prom_rtas_call() to the variable
.init.data:dt_string_start The function .prom_rtas_call() references
the variable __initdata dt_string_start.  This is often because
.prom_rtas_call lacks a __initdata annotation or the annotation of
dt_string_start is wrong.

WARNING: vmlinux.o(.meminit.text+0xeb0): Section mismatch in reference
from the function .free_area_init_core.isra.47() to the function
.init.text:.set_pageblock_order() The function __meminit
.free_area_init_core.isra.47() references a function __init
.set_pageblock_order().  If .set_pageblock_order is only used by
.free_area_init_core.isra.47 then annotate .set_pageblock_order with a
matching annotation.

Fix it by proper annotation of prom_rtas_call.
Signed-off-by: NVladimir Murzin <murzin.v@gmail.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

 stack_grow_into/14082 is trying to acquire lock:
  (&mm->mmap_sem){++++++}, at: [<c000000000206d28>] .might_fault+0x78/0xe0

 but task is already holding lock:
  (&mm->mmap_sem){++++++}, at: [<c0000000007ffd8c>] .do_page_fault+0x24c/0x910

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&mm->mmap_sem);
   lock(&mm->mmap_sem);

  *** DEADLOCK ***

  May be due to missing lock nesting notation

 1 lock held by stack_grow_into/14082:
  #0:  (&mm->mmap_sem){++++++}, at: [<c0000000007ffd8c>] .do_page_fault+0x24c/0x910

 stack backtrace:
 CPU: 21 PID: 14082 Comm: stack_grow_into Not tainted 3.10.0-10.el7.ppc64.debug #1
 Call Trace:
 [c0000003d396b850] [c000000000016e7c] .show_stack+0x7c/0x1f0 (unreliable)
 [c0000003d396b920] [c000000000813fc8] .dump_stack+0x28/0x3c
 [c0000003d396b990] [c000000000124b90] .__lock_acquire+0x1640/0x1800
 [c0000003d396bab0] [c00000000012570c] .lock_acquire+0xac/0x250
 [c0000003d396bb80] [c000000000206d54] .might_fault+0xa4/0xe0
 [c0000003d396bbf0] [c0000000007ffe2c] .do_page_fault+0x2ec/0x910
 [c0000003d396be30] [c0000000000092e8] handle_page_fault+0x10/0x30
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc allmodconfig build fails with:

ERROR: ".cpu_to_chip_id" [drivers/block/mtip32xx/mtip32xx.ko] undefined!

The problem was introduced with commit 15863ff3 (powerpc: Make chip-id
information available to userspace).

Export the missing symbol.

Cc: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Cc: Shivaprasad G Bhat <sbhat@linux.vnet.ibm.com>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 74e400ce ("powerpc: Rework setting up H/FSCR bit definitions")
ended up with incorrect bit numbers for FSCR_PM_LG and FSCR_BHRB_LG.
This fixes them.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Acked-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Commit 24ec2125f3 ("powerpc/xmon: Use cpumask iterator to avoid warning")
replaced a loop from 0 to NR_CPUS-1 with a for_each_possible_cpu() loop,
which means that if the last possible cpu is in xmon, we print the
wrong value for the end of the range.  For example, if 4 cpus are
possible, NR_CPUS is 128, and all cpus are in xmon, we print "0-7f"
rather than "0-3".  The code also assumes that the set of possible
cpus is contiguous, which may not necessarily be true.

This fixes the code to check explicitly for contiguity, and to print
the ending value correctly.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

same story as with oprofilefs_mkdir()
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

it's always equal to ->d_sb of the second argument (parent dentry),
due to either being literally that, or ->d_sb of parent's parent.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This reworks kvmppc_mmu_book3s_64_xlate() to make it check the large
page bit in the hashed page table entries (HPTEs) it looks at, and
to simplify and streamline the code.  The checking of the first dword
of each HPTE is now done with a single mask and compare operation,
and all the code dealing with the matching HPTE, if we find one,
is consolidated in one place in the main line of the function flow.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Most architectures use the same implementation. Collapse the common ones
into a single weak function that can be overridden.
Signed-off-by: NGrant Likely <grant.likely@linaro.org>

It turns out that if we exit the guest due to a hcall instruction (sc 1),
and the loading of the instruction in the guest exit path fails for any
reason, the call to kvmppc_ld() in kvmppc_get_last_inst() fetches the
instruction after the hcall instruction rather than the hcall itself.
This in turn means that the instruction doesn't get recognized as an
hcall in kvmppc_handle_exit_pr() but gets passed to the guest kernel
as a sc instruction.  That usually results in the guest kernel getting
a return code of 38 (ENOSYS) from an hcall, which often triggers a
BUG_ON() or other failure.

This fixes the problem by adding a new variant of kvmppc_get_last_inst()
called kvmppc_get_last_sc(), which fetches the instruction if necessary
from pc - 4 rather than pc.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Currently the code assumes that once we load up guest FP/VSX or VMX
state into the CPU, it stays valid in the CPU registers until we
explicitly flush it to the thread_struct.  However, on POWER7,
copy_page() and memcpy() can use VMX.  These functions do flush the
VMX state to the thread_struct before using VMX instructions, but if
this happens while we have guest state in the VMX registers, and we
then re-enter the guest, we don't reload the VMX state from the
thread_struct, leading to guest corruption.  This has been observed
to cause guest processes to segfault.

To fix this, we check before re-entering the guest that all of the
bits corresponding to facilities owned by the guest, as expressed
in vcpu->arch.guest_owned_ext, are set in current->thread.regs->msr.
Any bits that have been cleared correspond to facilities that have
been used by kernel code and thus flushed to the thread_struct, so
for them we reload the state from the thread_struct.

We also need to check current->thread.regs->msr before calling
giveup_fpu() or giveup_altivec(), since if the relevant bit is
clear, the state has already been flushed to the thread_struct and
to flush it again would corrupt it.
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

Commit 8e44ddc3 ("powerpc/kvm/book3s: Add support for H_IPOLL and
H_XIRR_X in XICS emulation") added a call to get_tb() but didn't
include the header that defines it, and on some configs this means
book3s_xics.c fails to compile:

arch/powerpc/kvm/book3s_xics.c: In function ‘kvmppc_xics_hcall’:
arch/powerpc/kvm/book3s_xics.c:812:3: error: implicit declaration of function ‘get_tb’ [-Werror=implicit-function-declaration]

Cc: stable@vger.kernel.org [v3.10, v3.11]
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

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: NThadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

'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: NChen Gang <gang.chen@asianux.com>
Acked-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAlexander Graf <agraf@suse.de>

This file is entirely pseries specific nowadays, so move it out
of arch/powerpc/kernel where it doesn't belong anymore.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

With OPAL v3 we can return secondary CPUs to firmware on kexec. This
allows firmware to do various cleanups making things generally more
reliable, and will enable the "new" kernel to call OPAL to perform
some reconfiguration tasks early on that can only be done while
all the CPUs are in firmware.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

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: <stable@vger.kernel.org>
Signed-off-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

/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: <stable@vger.kernel.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

The "rmci" stuff only exists on 64-bit
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

As suggested by paulus we can simplify the Data Stream Control Register
(DSCR) Facility Status and Control Register (FSCR) handling.

Firstly, we simplify the asm by using a rldimi.

Secondly, we now use the FSCR only to control the DSCR facility, rather
than both the FSCR and HFSCR.  Users will see no functional change from
this but will get a minor speedup as they will trap into the kernel only
once (rather than twice) when they first touch the DSCR.  Also, this
changes removes a bunch of ugly FTR_SECTION code.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

Calls to dlpar_detach_node do not iterate over child nodes detaching them as
well. By iterating and detaching the child nodes we ensure that they have the
OF_DETACHED flag set and that their reference counts are decremented such that
the node will be freed from memory by of_node_release.
Signed-off-by: NTyrel Datwyler <tyreld@linux.vnet.ibm.com>
Acked-by: NNathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>