linux-stable.git/arch/s390/kernel/setup.c, branch v4.2

revert "s390/mm: make hugepages_supported a boot time decision"

2015-07-17T23:39:52+00:00

Heiko noticed that the current check for hugepage support on s390 is a
little bit too harsh as systems which do not support will crash.

The reason is that pageblock_order can now get negative when we set
HPAGE_SHIFT to 0.  To avoid all this and to avoid opening another can of
worms with enabling HUGETLB_PAGE_SIZE_VARIABLE I think it would be best
to simply allow architectures to define their own hugepages_supported().

Revert bea41197ead3 ("s390/mm: make hugepages_supported a boot time
decision") in preparation.

Signed-off-by: Dominik Dingel 
Acked-by: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Christian Borntraeger 
Cc: Michael Holzheu 
Cc: Gerald Schaefer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2015-07-01T04:44:14+00:00

Pull more s390 updates from Martin Schwidefsky:
 "There is one larger patch for the AP bus code to make it work with the
  longer reset periods of the latest crypto cards.

  A new default configuration, a naming cleanup for SMP and a few fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/kdump: fix compile for !SMP
  s390/kdump: fix nosmt kernel parameter
  s390: new default configuration
  s390/smp: cleanup core vs. cpu in the SCLP interface
  s390/smp: fix sigp cpu detection loop
  s390/zcrypt: Fixed reset and interrupt handling of AP queues
  s390/kdump: fix REGSET_VX_LOW vector register ELF notes
  s390/bpf: Fix backward jumps

s390/mm: make hugepages_supported a boot time decision

2015-06-26T00:00:35+00:00

There is a potential bug with KVM and hugetlbfs if the hardware does not
support hugepages (EDAT1).  We fix this by making EDAT1 a hard requirement
for hugepages and therefore removing and simplifying code.

As s390, with the sw-emulated hugepages, was the only user of
arch_prepare/release_hugepage I also removed theses calls from common and
other architecture code.

This patch (of 5):

By dropping support for hugepages on machines which do not have the
hardware feature EDAT1, we fix a potential s390 KVM bug.

The bug would happen if a guest is backed by hugetlbfs (not supported
currently), but does not get pagetables with PGSTE.  This would lead to
random memory overwrites.

Signed-off-by: Dominik Dingel 
Acked-by: Martin Schwidefsky 
Cc: Heiko Carstens 
Cc: Christian Borntraeger 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

s390/kdump: fix nosmt kernel parameter

2015-06-25T07:39:26+00:00

It turned out that SIGP set-multi-threading can only be done once.
Therefore switching to a different MT level after switching to
sclp.mtid_prev in the dump case fails.

As a symptom specifying the "nosmt" parameter currently fails for
the kdump kernel and the kernel starts with multi-threading enabled.

So fix this and issue diag 308 subcode 1 call after collecting the
CPU states for the dump. Also enhance the diag308_reset() function to
be usable also with enabled lowcore protection and prefix register != 0.
After the reset it is possible to switch the MT level again. We have
to do the reset very early in order not to kill the already initialized
console. Therefore instead of kmalloc() the corresponding memblock
functions have to be used. To avoid copying the sclp cpu code into
sclp_early, we now use the simple sigp loop method for CPU detection.

Signed-off-by: Michael Holzheu 
Signed-off-by: Martin Schwidefsky

s390/setup: fix DMA_API_DEBUG warnings

2015-06-18T13:45:46+00:00

Addresses from the usable space in [_ehead, _stext] lead to false
positives in DMA_API_DEBUG code (which will complain when an address
is in [_text, _etext]).

Avoid these warnings by not using that memory in case of
CONFIG_DMA_API_DEBUG=y.

Signed-off-by: Sebastian Ott 
Signed-off-by: Martin Schwidefsky

s390/sclp: unify basic sclp access by exposing "struct sclp"

2015-05-13T07:58:17+00:00

Let's unify basic access to sclp fields by storing the data in an external
struct in asm/sclp.h.

The values can now directly be accessed by other components, so there is
no need for most accessor functions and external variables anymore.

The mtid, mtid_max and facility part will be cleaned up separately.

Acked-by: Martin Schwidefsky 
Signed-off-by: David Hildenbrand 
Signed-off-by: Martin Schwidefsky

s390: remove 31 bit support

2015-03-25T10:49:33+00:00

Remove the 31 bit support in order to reduce maintenance cost and
effectively remove dead code. Since a couple of years there is no
distribution left that comes with a 31 bit kernel.

The 31 bit kernel also has been broken since more than a year before
anybody noticed. In addition I added a removal warning to the kernel
shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning
message") which let everybody know about the plan to remove 31 bit
code. We didn't get any response.

Given that the last 31 bit only machine was introduced in 1999 let's
remove the code.
Anybody with 31 bit user space code can still use the compat mode.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/topology: delay initialization of topology cpu masks

2015-02-12T08:37:22+00:00

There is no reason to initialize the topology cpu masks already while
setup_arch() is being called. It is sufficient to initialize the masks
before the scheduler becomes SMP aware.
Therefore a pre-SMP initcall aka early_initcall is suffucient.

This also allows to convert the cpu_topology array into a per cpu
variable with a later patch. Without this patch this wouldn't be
possible since the per cpu memory areas are not allocated while setup_arch
is executed.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: add z13 code generation support

2015-01-22T11:15:57+00:00

Allow to generate code that only runs on z13 machines.

Signed-off-by: Martin Schwidefsky

s390/ftrace,kprobes: allow to patch first instruction

2014-10-27T12:27:27+00:00

If the function tracer is enabled, allow to set kprobes on the first
instruction of a function (which is the function trace caller):

If no kprobe is set handling of enabling and disabling function tracing
of a function simply patches the first instruction. Either it is a nop
(right now it's an unconditional branch, which skips the mcount block),
or it's a branch to the ftrace_caller() function.

If a kprobe is being placed on a function tracer calling instruction
we encode if we actually have a nop or branch in the remaining bytes
after the breakpoint instruction (illegal opcode).
This is possible, since the size of the instruction used for the nop
and branch is six bytes, while the size of the breakpoint is only
two bytes.
Therefore the first two bytes contain the illegal opcode and the last
four bytes contain either "0" for nop or "1" for branch. The kprobes
code will then execute/simulate the correct instruction.

Instruction patching for kprobes and function tracer is always done
with stop_machine(). Therefore we don't have any races where an
instruction is patched concurrently on a different cpu.
Besides that also the program check handler which executes the function
trace caller instruction won't be executed concurrently to any
stop_machine() execution.

This allows to keep full fault based kprobes handling which generates
correct pt_regs contents automatically.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky