Use NOKPROBE_SYMBOL() instead of __kprobes annotation.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Store the target address for the gmap segments in a radix tree
instead of using invalid segment table entries. gmap_translate
becomes a simple radix_tree_lookup, gmap_fault is split into the
address translation with gmap_translate and the part that does
the linking of the gmap shadow page table with the process page
table.
A second radix tree is used to keep the pointers to the segment
table entries for segments that are mapped in the guest address
space. On unmap of a segment the pointer is retrieved from the
radix tree and is used to carry out the segment invalidation in
the gmap shadow page table. As the radix tree can only store one
pointer, each host segment may only be mapped to exactly one
guest location.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Make the order of arguments for the gmap calls more consistent,
if the gmap pointer is passed it is always the first argument.
In addition distinguish between guest address and user address
by naming the variables gaddr for a guest address and vmaddr for
a user address.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The oi and ni instructions used in entry[64].S to set and clear bits
in the thread-flags are not guaranteed to be atomic in regard to other
CPUs. Split the TIF bits into CPU, pt_regs and thread-info specific
bits. Updates on the TIF bits are done with atomic instructions,
updates on CPU and pt_regs bits are done with non-atomic instructions.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Print extra debugging information to the console if the kernel or a user
space process crashed (with user space debugging enabled):

- contents of control register 7 and 13
- failing address and translation exception identification
- page table walk for the failing address
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The current uaccess code uses a page table walk in some circumstances,
e.g. in case of the in atomic futex operations or if running on old
hardware which doesn't support the mvcos instruction.

However it turned out that the page table walk code does not correctly
lock page tables when accessing page table entries.
In other words: a different cpu may invalidate a page table entry while
the current cpu inspects the pte. This may lead to random data corruption.

Adding correct locking however isn't trivial for all uaccess operations.
Especially copy_in_user() is problematic since that requires to hold at
least two locks, but must be protected against ABBA deadlock when a
different cpu also performs a copy_in_user() operation.

So the solution is a different approach where we change address spaces:

User space runs in primary address mode, or access register mode within
vdso code, like it currently already does.

The kernel usually also runs in home space mode, however when accessing
user space the kernel switches to primary or secondary address mode if
the mvcos instruction is not available or if a compare-and-swap (futex)
instruction on a user space address is performed.
KVM however is special, since that requires the kernel to run in home
address space while implicitly accessing user space with the sie
instruction.

So we end up with:

User space:
- runs in primary or access register mode
- cr1 contains the user asce
- cr7 contains the user asce
- cr13 contains the kernel asce

Kernel space:
- runs in home space mode
- cr1 contains the user or kernel asce
  -> the kernel asce is loaded when a uaccess requires primary or
     secondary address mode
- cr7 contains the user or kernel asce, (changed with set_fs())
- cr13 contains the kernel asce

In case of uaccess the kernel changes to:
- primary space mode in case of a uaccess (copy_to_user) and uses
  e.g. the mvcp instruction to access user space. However the kernel
  will stay in home space mode if the mvcos instruction is available
- secondary space mode in case of futex atomic operations, so that the
  instructions come from primary address space and data from secondary
  space

In case of kvm the kernel runs in home space mode, but cr1 gets switched
to contain the gmap asce before the sie instruction gets executed. When
the sie instruction is finished cr1 will be switched back to contain the
user asce.

A context switch between two processes will always load the kernel asce
for the next process in cr1. So the first exit to user space is a bit
more expensive (one extra load control register instruction) than before,
however keeps the code rather simple.

In sum this means there is no need to perform any error prone page table
walks anymore when accessing user space.

The patch seems to be rather large, however it mainly removes the
the page table walk code and restores the previously deleted "standard"
uaccess code, with a couple of changes.

The uaccess without mvcos mode can be enforced with the "uaccess_primary"
kernel parameter.
Reported-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Use the new defines for external interruption codes to get rid
of "magic" numbers in the s390 source code. And while we're at it,
also rename the (un-)register_external_interrupt function to
something shorter so that this patch does not exceed the 80
columns all over the place.
Signed-off-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

In the case of a fault, we will retry to exit sie64 but with gmap fault
indication for this thread set. This makes it possible to handle async
page faults.

Based on a patch from Martin Schwidefsky.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The IDTE instruction used to flush TLB entries for a specific address
space uses the address-space-control element (ASCE) to identify
affected TLB entries. The upgrade of a page table adds a new top
level page table which changes the ASCE. The TLB entries associated
with the old ASCE need to be flushed and the ASCE for the address space
needs to be replaced synchronously on all CPUs which currently use it.
The concept of a lazy ASCE update with an exception handler is broken.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Simplify the uaccess code by removing the user_mode=home option.
The kernel will now always run in the home space mode.
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>

Let's not add a function for every external interrupt subclass for
which we need reference counting. Just have two register/unregister
functions which have a subclass parameter:

void irq_subclass_register(enum irq_subclass subclass);
void irq_subclass_unregister(enum irq_subclass subclass);
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

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 5e427ec2 ("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)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
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 arch/s390 uses of the __cpuinit macros from
all C files.  Currently s390 does not have any __CPUINIT used in
assembly files.

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

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

Protection exception usually are suppressing and the fault handler
needs to rewind the PSW by the instruction length to get the correct
fault address. Except for protection exceptions while the CPU is in
the middle of a transaction. The CPU stores the transaction abort
PSW at the start of the transaction, if the transaction is aborted
the PSW is already correct and may not be modified by the fault
handler.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Now that irq sum accounting for /proc/stat's "intr" line works again we
have the oddity that the sum field (first field) contains only the sum
of the second (external irqs) and third field (I/O interrupts).
The reason for that is that these two fields are already sums of all other
fields. So if we would sum up everything we would count every interrupt
twice.
This is broken since the split interrupt accounting was merged two years
ago: 052ff461 "[S390] irq: have detailed
statistics for interrupt types".
To fix this remove the split interrupt fields from /proc/stat's "intr"
line again and only have them in /proc/interrupts.

This restores the old behaviour, seems to be the only sane fix and mimics
a behaviour from other architectures where /proc/interrupts also contains
more than /proc/stat's "intr" line does.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The current single step code is racy in regard to concurrent delivery
of signals. If a signal is delivered after a PER program check occurred
but before the TIF_PER_TRAP bit has been checked in entry[64].S the code
clears TIF_PER_TRAP and then calls do_signal. This is wrong, if the
instruction completed (or has been suppressed) a SIGTRAP should be
delivered to the debugger in any case. Only if the instruction has been
nullified the SIGTRAP may not be send.

The new logic always sets TIF_PER_TRAP if the program check indicates PER
tracing but removes it again for all program checks that are nullifying.
The effect is that for each change in the PSW address we now get a
single SIGTRAP.
Reported-by: NAndreas Arnez <arnez@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Just convert fault_init() to an early initcall. That's still early
enough since it only needs be called before user space processes get
executed. No reason to externalize it.
Also add the function to the init section and move the store_indication
variable to the read_mostly section.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

.fault now can retry.  The retry can break state machine of .fault.  In
filemap_fault, if page is miss, ra->mmap_miss is increased.  In the second
try, since the page is in page cache now, ra->mmap_miss is decreased.  And
these are done in one fault, so we can't detect random mmap file access.

Add a new flag to indicate .fault is tried once.  In the second try, skip
ra->mmap_miss decreasing.  The filemap_fault state machine is ok with it.

I only tested x86, didn't test other archs, but looks the change for other
archs is obvious, but who knows :)
Signed-off-by: NShaohua Li <shaohua.li@fusionio.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is the s390 port of 70627654 "x86, extable: Switch to relative
exception table entries".
Reduces the size of our exception tables by 50% on 64 bit builds.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Renaming the globally visible variable "user_mode" to "addressing_mode" in
order to fix a name clash was not a good idea. (Commit 37fe1d73 "s390/mm:
rename user_mode variable to addressing_mode")
Looking at the code after a couple of weeks one thinks: addressing mode of
what?
So rename the variable again. This time to s390_user_mode. Which hopefully
makes more sense.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Unify all our cpu hotplug notifiers to mask out the CPU_TASKS_FROZEN
bit, so we don't have to add all the *_FROZEN variant cases to the
notifiers.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

We use the user_mode() helper already at several places but also
have the open coded variant at other places.
Convert the code to always use the helper function.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Fix name clash with user_mode() define which is also used in common code.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Make sure the kernel does not incorrectly create a SIGBUS signal during
user space accesses:

For user space accesses in the switched addressing mode case the kernel
may walk page tables and access user address space via the kernel
mapping. If a page table entry is invalid the function __handle_fault()
gets called in order to emulate a page fault and trigger all the usual
actions like paging in a missing page etc. by calling handle_mm_fault().

If handle_mm_fault() returns with an error fixup handling is necessary.
For the switched addressing mode case all errors need to be mapped to
-EFAULT, so that the calling uaccess function can return -EFAULT to
user space.

Unfortunately the __handle_fault() incorrectly calls do_sigbus() if
VM_FAULT_SIGBUS is set. This however should only happen if a page fault
was triggered by a user space instruction. For kernel mode uaccesses
the correct action is to only return -EFAULT.
So user space may incorrectly see SIGBUS signals because of this bug.

For current machines this would only be possible for the switched
addressing mode case in conjunction with futex operations.

Cc: stable@vger.kernel.org
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

This is the s390 variant of 37b23e05 "x86,mm: make pagefault killable".
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

If the task that was found on an initial interrupt doesn't match the
current task execute a WARN_ON_ONCE() and don't put the task to sleep.

When this happened something went wrong between the interface of the
hypervisor and the kernel. In such a case keep the tasks alive to
avoid a hanging system.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Use __set_task_state() instead of set_task_state(). Saves a couple of
instructions, since the memory barrier is not needed here.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Make the code a bit more symmetric and always search for the task of the
reported pid. This simplifies the code a bit.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

When setting the current task state to TASK_UNINTERRUPTIBLE this can
race with a different cpu. The other cpu could set the task state after
it inspected it (while it was still TASK_RUNNING) to TASK_RUNNING which
would change the state from TASK_UNINTERRUPTIBLE to TASK_RUNNING again.

This race was always present in the pfault interrupt code but didn't
cause anything harmful before commit f2db2e6c "[S390] pfault: cpu hotplug
vs missing completion interrupts" which relied on the fact that after
setting the task state to TASK_UNINTERRUPTIBLE the task would really
sleep.
Since this is not necessarily the case the result may be a list corruption
of the pfault_list or, as observed, a use-after-free bug while trying to
access the task_struct of a task which terminated itself already.

To fix this, we need to get a reference of the affected task when receiving
the initial pfault interrupt and add special handling if we receive yet
another initial pfault interrupt when the task is already enqueued in the
pfault list.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <stable@vger.kernel.org> # needed for v3.0 and newer
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Replace the check for TIF_SIE in the fault handler by a check for PF_VCPU.
With the last user of TIF_SIE gone we can now remove the bit.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Disintegrate asm/system.h for S390.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
cc: linux-s390@vger.kernel.org

The external interrupt handlers have a parameter called ext_int_code.
Besides the name this paramter does not only contain the ext_int_code
but in addition also the "cpu address" (POP) which caused the external
interrupt.
To make the code a bit more obvious pass a struct instead so the called
function can easily distinguish between external interrupt code and
cpu address. The cpu address field however is named "subcode" since
some external interrupt sources do not pass a cpu address but a
different parameter (or none at all).
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The new is_compat_task() define for the !COMPAT case in
include/linux/compat.h conflicts with a similar define in
arch/s390/include/asm/compat.h.

This is the minimal patch which fixes the build issues.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move the program interruption code and the translation exception identifier
to the pt_regs structure as 'int_code' and 'int_parm_long' and make the
first level interrupt handler in entry[64].S store the two values. That
makes it possible to drop 'prot_addr' and 'trap_no' from the thread_struct
and to reduce the number of arguments to a lot of functions. Finally
un-inline do_trap. Overall this saves 5812 bytes in the .text section of
the 64 bit kernel.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

This patch disables the check for MACHINE_IS_VM when initializing the
pfault infrastructure. The code checks for successful completion of
diag 258 anyway, thus it's safe to try initialization on LPAR anyway.
This is needed to use pfault on kvm
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Ignore completion interrupts if the initial interrupt hasn't been
received and the addressed task is not running. This case can only
happen if leftover (pending) completion interrupt gets delivered
which wasn't removed with the PFAULT CANCEL operation during cpu
hotplug.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

gmap_fault needs to walk the guest page table. However, parts of
that may change if some other thread does munmap. In that case
gmap_unmap_notifier will also unmap the corresponding parts from
the guest page table. We need to take mmap_sem in order to serialize
these operations.
do_exception now calls __gmap_fault with mmap_sem held which does
not get exported to modules. The exported function, which is called
from KVM, now takes mmap_sem.
Reported-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Split out addressing mode bits from PSW_BASE_BITS, rename PSW_BASE_BITS
to PSW_MASK_BASE, get rid of psw_user32_bits, remove unused function
enabled_wait(), introduce PSW_MASK_USER, and drop PSW_MASK_MERGE macros.
Change psw_kernel_bits / psw_user_bits to contain only the bits that
are always set in the respective mode.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

An instruction with an address right below the adress limit for the
current addressing mode will wrap. The instruction restart logic in
the protection fault handler and the signal code need to follow the
wrapping rules to find the correct instruction address.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>