Commit Graph

81 Commits

Author SHA1 Message Date
Martin Schwidefsky 90c53e6580 s390: move cputime accounting fields from thread_info to thread_struct
The user_timer and system_timer fields are used for the per-thread
cputime accounting code. The access to these values is simpler if
they are moved to the thread_struct as the task_thread_info(tsk)
indirection is not needed anymore.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-11-11 16:37:43 +01:00
Heiko Carstens d5c352cdd0 s390: move thread_info into task_struct
This is the s390 variant of commit 15f4eae70d ("x86: Move
thread_info into task_struct").

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-11-11 16:37:41 +01:00
Martin Schwidefsky c360192bf4 s390/preempt: move preempt_count to the lowcore
Convert s390 to use a field in the struct lowcore for the CPU
preemption count. It is a bit cheaper to access a lowcore field
compared to a thread_info variable and it removes the depencency
on a task related structure.

bloat-o-meter on the vmlinux image for the default configuration
(CONFIG_PREEMPT_NONE=y) reports a small reduction in text size:

add/remove: 0/0 grow/shrink: 18/578 up/down: 228/-5448 (-5220)

A larger improvement is achieved with the default configuration
but with CONFIG_PREEMPT=y and CONFIG_DEBUG_PREEMPT=n:

add/remove: 2/6 grow/shrink: 59/4477 up/down: 1618/-228762 (-227144)

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-11-11 16:37:40 +01:00
Martin Schwidefsky 75c7b6f3f6 s390/time: steer clocksource on STP sync events
On STP sync events the TOD clock will jump in time, either forward or
backward. The TOD clocksource claims to be continuous but in case of
an STP sync with a negative offset it is not.

Subtract the offset injected by the STP sync check from the result of
the TOD clocksource to make it continuous again. Add code to drift the
offset towards zero with a fixed rate, steering 1 second in ~9 hours.

Suggested-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-10-28 10:09:02 +02:00
David Hildenbrand 8953fb08ab KVM: s390: write external damage code on machine checks
Let's also write the external damage code already provided by
struct kvm_s390_mchk_info.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2016-09-08 09:07:52 +02:00
Martin Schwidefsky 1e133ab296 s390/mm: split arch/s390/mm/pgtable.c
The pgtable.c file is quite big, before it grows any larger split it
into pgtable.c, pgalloc.c and gmap.c. In addition move the gmap related
header definitions into the new gmap.h header and all of the pgste
helpers from pgtable.h to pgtable.c.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-03-08 15:00:15 +01:00
Martin Schwidefsky 249c543b97 s390/vdso: optimize getcpu system call
Add the CPU number to the per-cpu vdso data page and add the
__kernel_getcpu function to the vdso object to retrieve the
CPU number in user space.

Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-01-11 13:01:24 +01:00
Heiko Carstens c667aeacc1 s390: rename struct _lowcore to struct lowcore
Finally get rid of the leading underscore. I tried this already two or
three years ago, however Michael Holzheu objected since this would
break the crash utility (again).

However Michael integrated support for the new name into the crash
utility back then, so it doesn't break if the name will be changed
now.  So finally get rid of the ever confusing leading underscore.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-01-11 12:27:15 +01:00
Heiko Carstens 76cdd44c2e s390/facilities: always use lowcore's stfle field for storing facility bits
head.s contains an stfle instruction which stores it result at the
storage location that is assigned to the stfl instruction.

This is currently no problem, since we only care about one double
word. However if the number of double words in the ALS bitfield grows
the current code is not very stable.

E.g. before issuing the stfle command the memory to which it stores
must be cleared, since the instruction may or may not clear memory
contents where no bits are set.

In order to simplify the code a bit always use the storage location
that we reserved for the stfle result.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-12-18 14:59:19 +01:00
Martin Schwidefsky f08b841463 s390/dump: remove SAVE_AREA_BASE
Replace the SAVE_AREA_BASE offset calculations in reipl.S with the
assembler constant for the location of each register status area.

Use __LC_FPREGS_SAVE_AREA instead of SAVE_AREA_BASE in the three
remaining code locations and remove the definition of SAVE_AREA_BASE.

Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-11-27 09:24:14 +01:00
Martin Schwidefsky d9a3a09af5 s390/kvm: remove dependency on struct save_area definition
Replace the offsets based on the struct area_area with the offset
constants from asm-offsets.c based on the struct _lowcore.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-11-27 09:24:13 +01:00
Christian Borntraeger e22cf8ca6f s390/cpumf: rework program parameter setting to detect guest samples
The program parameter can be used to mark hardware samples with
some token.  Previously, it was used to mark guest samples only.

Improve the program parameter doubleword by combining two parts,
the leftmost LPP part and the rightmost PID part.  Set the PID
part for processes by using the task PID.
To distinguish host and guest samples for the kernel (PID part
is zero), the guest must always set the program paramater to a
non-zero value.  Use the leftmost bit in the LPP part of the
program parameter to be able to detect guest kernel samples.

[brueckner@linux.vnet.ibm.com]: Split __LC_CURRENT and introduced
__LC_LPP. Corrected __LC_CURRENT users and adjusted assembler parts.
And updated the commit message accordingly.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-10-14 14:32:12 +02:00
Martin Schwidefsky 6a62b485ea s390/asm: make use of the OFFSET macro to define assember constants
The use of OFFSET instead of DEFINE makes the definitions in asm-offsets.c
more readable. While we are at it sort the defines for struct _lowcore
according to the field order and remove some unneeded defines.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-10-14 14:32:10 +02:00
Hendrik Brueckner b5510d9b68 s390/fpu: always enable the vector facility if it is available
If the kernel detects that the s390 hardware supports the vector
facility, it is enabled by default at an early stage.  To force
it off, use the novx kernel parameter.  Note that there is a small
time window, where the vector facility is enabled before it is
forced to be off.

With enabling the vector facility by default, the FPU save and
restore functions can be improved.  They do not longer require
to manage expensive control register updates to enable or disable
the vector enablement control for particular processes.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-10-14 14:32:08 +02:00
Martin Schwidefsky 72d38b1978 s390/vtime: correct scaled cputime of partially idle CPUs
The calculation for the SMT scaling factor for a hardware thread
which has been partially idle needs to disregard the cycles spent
by the other threads of the core while the thread is idle.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-09-30 16:22:38 +02:00
Hendrik Brueckner d0164ee20d s390/kernel: remove save_fpu_regs() parameter and use __LC_CURRENT instead
All calls to save_fpu_regs() specify the fpu structure of the current task
pointer as parameter.  The task pointer of the current task can also be
retrieved from the CPU lowcore directly.  Remove the parameter definition,
load the __LC_CURRENT task pointer from the CPU lowcore, and rebase the FPU
structure onto the task structure.  Apply the same approach for the
load_fpu_regs() function.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-08-03 10:04:37 +02:00
Hendrik Brueckner 9977e886cb s390/kernel: lazy restore fpu registers
Improve the save and restore behavior of FPU register contents to use the
vector extension within the kernel.

The kernel does not use floating-point or vector registers and, therefore,
saving and restoring the FPU register contents are performed for handling
signals or switching processes only.  To prepare for using vector
instructions and vector registers within the kernel, enhance the save
behavior and implement a lazy restore at return to user space from a
system call or interrupt.

To implement the lazy restore, the save_fpu_regs() sets a CPU information
flag, CIF_FPU, to indicate that the FPU registers must be restored.
Saving and setting CIF_FPU is performed in an atomic fashion to be
interrupt-safe.  When the kernel wants to use the vector extension or
wants to change the FPU register state for a task during signal handling,
the save_fpu_regs() must be called first.  The CIF_FPU flag is also set at
process switch.  At return to user space, the FPU state is restored.  In
particular, the FPU state includes the floating-point or vector register
contents, as well as, vector-enablement and floating-point control.  The
FPU state restore and clearing CIF_FPU is also performed in an atomic
fashion.

For KVM, the restore of the FPU register state is performed when restoring
the general-purpose guest registers before the SIE instructions is started.
Because the path towards the SIE instruction is interruptible, the CIF_FPU
flag must be checked again right before going into SIE.  If set, the guest
registers must be reloaded again by re-entering the outer SIE loop.  This
is the same behavior as if the SIE critical section is interrupted.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-07-22 09:58:01 +02:00
Martin Schwidefsky 3827ec3d8f s390: adapt entry.S to the move of thread_struct
git commit 0c8c0f03e3
"x86/fpu, sched: Dynamically allocate 'struct fpu'"
moved the thread_struct to the end of the task_struct.

This causes some of the offsets used in entry.S to overflow their
instruction operand field. To fix this  use aghi to create a
dedicated pointer for the thread_struct.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-07-20 13:22:18 +02:00
Linus Torvalds fa2e5c073a Merge branch 'exec_domain_rip_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc
Pull exec domain removal from Richard Weinberger:
 "This series removes execution domain support from Linux.

  The idea behind exec domains was to support different ABIs.  The
  feature was never complete nor stable.  Let's rip it out and make the
  kernel signal handling code less complicated"

* 'exec_domain_rip_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc: (27 commits)
  arm64: Removed unused variable
  sparc: Fix execution domain removal
  Remove rest of exec domains.
  arch: Remove exec_domain from remaining archs
  arc: Remove signal translation and exec_domain
  xtensa: Remove signal translation and exec_domain
  xtensa: Autogenerate offsets in struct thread_info
  x86: Remove signal translation and exec_domain
  unicore32: Remove signal translation and exec_domain
  um: Remove signal translation and exec_domain
  tile: Remove signal translation and exec_domain
  sparc: Remove signal translation and exec_domain
  sh: Remove signal translation and exec_domain
  s390: Remove signal translation and exec_domain
  mn10300: Remove signal translation and exec_domain
  microblaze: Remove signal translation and exec_domain
  m68k: Remove signal translation and exec_domain
  m32r: Remove signal translation and exec_domain
  m32r: Autogenerate offsets in struct thread_info
  frv: Remove signal translation and exec_domain
  ...
2015-04-15 13:53:55 -07:00
Linus Torvalds bdfa54dfd9 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Martin Schwidefsky:
 "The major change in this merge is the removal of the support for
  31-bit kernels.  Naturally 31-bit user space will continue to work via
  the compat layer.

  And then some cleanup, some improvements and bug fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (23 commits)
  s390/smp: wait until secondaries are active & online
  s390/hibernate: fix save and restore of kernel text section
  s390/cacheinfo: add missing facility check
  s390/syscalls: simplify syscall_get_arch()
  s390/irq: enforce correct irqclass_sub_desc array size
  s390: remove "64" suffix from mem64.S and swsusp_asm64.S
  s390/ipl: cleanup macro usage
  s390/ipl: cleanup shutdown_action attributes
  s390/ipl: cleanup bin attr usage
  s390/uprobes: fix address space annotation
  s390: add missing arch_release_task_struct() declaration
  s390: make couple of functions and variables static
  s390/maccess: improve s390_kernel_write()
  s390/maccess: remove potentially broken probe_kernel_write()
  s390/watchdog: support for KVM hypervisors and delete pr_info messages
  s390/watchdog: enable KEEPALIVE for /dev/watchdog
  s390/dasd: remove setting of scheduler from driver
  s390/traps: panic() instead of die() on translation exception
  s390: remove test_facility(2) (== z/Architecture mode active) checks
  s390/cmpxchg: simplify cmpxchg_double
  ...
2015-04-14 20:51:44 -07:00
Richard Weinberger 6a32591a4a s390: Remove signal translation and exec_domain
As execution domain support is gone we can remove
signal translation from the signal code and remove
exec_domain from thread_info.

Signed-off-by: Richard Weinberger <richard@nod.at>
2015-04-12 20:58:25 +02:00
Heiko Carstens 5a79859ae0 s390: remove 31 bit support
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: a960062e58 ("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 <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2015-03-25 11:49:33 +01:00
Eric Farman bc17de7c96 KVM: s390: Machine Check
Store additional status in the machine check handler, in order to
collect status (such as vector registers) that is not defined by
store status.

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2015-03-06 13:49:34 +01:00
Martin Schwidefsky f318a1229b s390/cmpxchg: use compiler builtins
The kernel build for s390 fails for gcc compilers with version 3.x,
set the minimum required version of gcc to version 4.3.

As the atomic builtins are available with all gcc 4.x compilers,
use the __sync_val_compare_and_swap and __sync_bool_compare_and_swap
functions to replace the complex macro and inline assembler magic
in include/asm/cmpxchg.h. The compiler can just-do-it and generates
better code with the builtins.

While we are at it use __sync_bool_compare_and_swap for the
_raw_compare_and_swap function in the spinlock code as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-11-03 13:29:47 +01:00
Heiko Carstens c933146a5e s390/ftrace,kprobes: allow to patch first instruction
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 <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-10-27 13:27:27 +01:00
Martin Schwidefsky b5f87f15e2 s390/idle: consolidate idle functions and definitions
Move the C functions and definitions related to the idle state handling
to arch/s390/include/asm/idle.h and arch/s390/kernel/idle.c. The function
s390_get_idle_time is renamed to arch_cpu_idle_time and vtime_stop_cpu to
enabled_wait.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-10-09 09:14:03 +02:00
Martin Schwidefsky b7eacb59cd s390/vdso: add vdso support for coarse clocks
Add CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE optimization to
the 64-bit and 31-bit vdso.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-09-09 08:53:27 +02:00
Linus Torvalds b05d59dfce At over 200 commits, covering almost all supported architectures, this
was a pretty active cycle for KVM.  Changes include:
 
 - a lot of s390 changes: optimizations, support for migration,
   GDB support and more
 
 - ARM changes are pretty small: support for the PSCI 0.2 hypercall
   interface on both the guest and the host (the latter acked by Catalin)
 
 - initial POWER8 and little-endian host support
 
 - support for running u-boot on embedded POWER targets
 
 - pretty large changes to MIPS too, completing the userspace interface
   and improving the handling of virtualized timer hardware
 
 - for x86, a larger set of changes is scheduled for 3.17.  Still,
   we have a few emulator bugfixes and support for running nested
   fully-virtualized Xen guests (para-virtualized Xen guests have
   always worked).  And some optimizations too.
 
 The only missing architecture here is ia64.  It's not a coincidence
 that support for KVM on ia64 is scheduled for removal in 3.17.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm into next

Pull KVM updates from Paolo Bonzini:
 "At over 200 commits, covering almost all supported architectures, this
  was a pretty active cycle for KVM.  Changes include:

   - a lot of s390 changes: optimizations, support for migration, GDB
     support and more

   - ARM changes are pretty small: support for the PSCI 0.2 hypercall
     interface on both the guest and the host (the latter acked by
     Catalin)

   - initial POWER8 and little-endian host support

   - support for running u-boot on embedded POWER targets

   - pretty large changes to MIPS too, completing the userspace
     interface and improving the handling of virtualized timer hardware

   - for x86, a larger set of changes is scheduled for 3.17.  Still, we
     have a few emulator bugfixes and support for running nested
     fully-virtualized Xen guests (para-virtualized Xen guests have
     always worked).  And some optimizations too.

  The only missing architecture here is ia64.  It's not a coincidence
  that support for KVM on ia64 is scheduled for removal in 3.17"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (203 commits)
  KVM: add missing cleanup_srcu_struct
  KVM: PPC: Book3S PR: Rework SLB switching code
  KVM: PPC: Book3S PR: Use SLB entry 0
  KVM: PPC: Book3S HV: Fix machine check delivery to guest
  KVM: PPC: Book3S HV: Work around POWER8 performance monitor bugs
  KVM: PPC: Book3S HV: Make sure we don't miss dirty pages
  KVM: PPC: Book3S HV: Fix dirty map for hugepages
  KVM: PPC: Book3S HV: Put huge-page HPTEs in rmap chain for base address
  KVM: PPC: Book3S HV: Fix check for running inside guest in global_invalidates()
  KVM: PPC: Book3S: Move KVM_REG_PPC_WORT to an unused register number
  KVM: PPC: Book3S: Add ONE_REG register names that were missed
  KVM: PPC: Add CAP to indicate hcall fixes
  KVM: PPC: MPIC: Reset IRQ source private members
  KVM: PPC: Graciously fail broken LE hypercalls
  PPC: ePAPR: Fix hypercall on LE guest
  KVM: PPC: BOOK3S: Remove open coded make_dsisr in alignment handler
  KVM: PPC: BOOK3S: Always use the saved DAR value
  PPC: KVM: Make NX bit available with magic page
  KVM: PPC: Disable NX for old magic page using guests
  KVM: PPC: BOOK3S: HV: Add mixed page-size support for guest
  ...
2014-06-04 08:47:12 -07:00
Martin Schwidefsky 63aef00b55 s390/lowcore: replace lowcore irb array with a per-cpu variable
Remove the 96-byte irb array from the lowcore and create a per-cpu
variable instead. That way we will pick up any change in the definition
of the struct irb automatically.

Acked-By: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-05-28 10:39:16 +02:00
Martin Schwidefsky d3a73acbc2 s390: split TIF bits into CIF, PIF and TIF bits
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-05-20 08:58:47 +02:00
Jens Freimann da7cf2570c s390: add fields to lowcore definition
This patch adds fields which are currently missing but needed for the correct
injection of interrupts.

This is based on a patch by David Hildenbrand

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2014-04-22 13:24:49 +02:00
Jens Freimann 21ee7ffd17 s390: rename and split lowcore field per_perc_atmid
per_perc_atmid is currently a two-byte field that combines two
fields, the PER code and the PER Addressing-and-Translation-Mode
Identification (ATMID)

Let's make them accessible indepently and also rename per_cause to
per_code.

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2014-04-22 13:24:48 +02:00
Jens Freimann 3d53b46ce8 s390: fix name of lowcore field at offset 0xa3
According to the Principles of Operation, at offset 0xA3
in the lowcore we have the "Architectural-Mode identification",
not an "access identification".

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
2014-04-22 13:24:48 +02:00
Heiko Carstens 457f218095 s390/uaccess: rework uaccess code - fix locking issues
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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-04-03 14:31:04 +02:00
Martin Schwidefsky b5e64b3de7 s390/vdso: ectg gettime support for CLOCK_THREAD_CPUTIME_ID
The code to use the ECTG instruction to calculate the cputime for the
current thread is currently used only for the per-thread CPU-clock
with the clockid -2 (PID=0, VIRT=1). Use the same code for the clockid
CLOCK_THREAD_CPUTIME_ID to speed up the more common clockid as well.

Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-12-02 15:31:10 +01:00
Martin Schwidefsky 79c74ecbeb s390/time,vdso: convert to the new update_vsyscall interface
Switch to the improved update_vsyscall interface that provides
sub-nanosecond precision for gettimeofday and clock_gettime.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-11-25 09:15:39 +01:00
Linus Torvalds fe489bf450 KVM fixes for 3.11
On the x86 side, there are some optimizations and documentation updates.
 The big ARM/KVM change for 3.11, support for AArch64, will come through
 Catalin Marinas's tree.  s390 and PPC have misc cleanups and bugfixes.
 
 There is a conflict due to "s390/pgtable: fix ipte notify bit" having
 entered 3.10 through Martin Schwidefsky's s390 tree.  This pull request
 has additional changes on top, so this tree's version is the correct one.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "On the x86 side, there are some optimizations and documentation
  updates.  The big ARM/KVM change for 3.11, support for AArch64, will
  come through Catalin Marinas's tree.  s390 and PPC have misc cleanups
  and bugfixes"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (87 commits)
  KVM: PPC: Ignore PIR writes
  KVM: PPC: Book3S PR: Invalidate SLB entries properly
  KVM: PPC: Book3S PR: Allow guest to use 1TB segments
  KVM: PPC: Book3S PR: Don't keep scanning HPTEG after we find a match
  KVM: PPC: Book3S PR: Fix invalidation of SLB entry 0 on guest entry
  KVM: PPC: Book3S PR: Fix proto-VSID calculations
  KVM: PPC: Guard doorbell exception with CONFIG_PPC_DOORBELL
  KVM: Fix RTC interrupt coalescing tracking
  kvm: Add a tracepoint write_tsc_offset
  KVM: MMU: Inform users of mmio generation wraparound
  KVM: MMU: document fast invalidate all mmio sptes
  KVM: MMU: document fast invalidate all pages
  KVM: MMU: document fast page fault
  KVM: MMU: document mmio page fault
  KVM: MMU: document write_flooding_count
  KVM: MMU: document clear_spte_count
  KVM: MMU: drop kvm_mmu_zap_mmio_sptes
  KVM: MMU: init kvm generation close to mmio wrap-around value
  KVM: MMU: add tracepoint for check_mmio_spte
  KVM: MMU: fast invalidate all mmio sptes
  ...
2013-07-03 13:21:40 -07:00
Martin Schwidefsky 48f6b00c6e s390/irq: store interrupt information in pt_regs
Copy the interrupt parameters from the lowcore to the pt_regs structure
in entry[64].S and reduce the arguments of the low level interrupt handler
to the pt_regs pointer only. In addition move the test-pending-interrupt
loop from do_IRQ to entry[64].S to make sure that interrupt information
is always delivered via pt_regs.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-06-26 21:10:23 +02:00
Christian Borntraeger 49b99e1e0d s390/kvm: Provide a way to prevent reentering SIE
Lets provide functions to prevent KVM from reentering SIE and
to kick cpus out of SIE. We cannot use the common kvm_vcpu_kick code,
since we need to kick out guests in places that hold architecture
specific locks (e.g. pgste lock) which might be necessary on the
other cpus - so no waiting possible.

So lets provide a bit in a private field of the sie control block
that acts as a gate keeper, after we claimed we are in SIE.
Please note that we do not reuse prog0c, since we want to access
that bit without atomic ops.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-05-21 11:55:23 +03:00
Christian Borntraeger 95d38fd0bc s390/kvm: Mark if a cpu is in SIE
Lets track in a private bit if the sie control block is active.
We want to track this as closely as possible, so we also have to
instrument the interrupt and program check handler. Lets use the
existing HANDLE_SIE_INTERCEPT macro.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
2013-05-21 11:55:21 +03:00
Martin Schwidefsky 616498813b s390: system call path micro optimization
Add a pointer to the system call table to the thread_info structure.
The TIF_31BIT bit is set or cleared by SET_PERSONALITY exactly once
for the lifetime of a process. With the pointer to the correct system
call table in thread_info the system call code in entry64.S path can
drop the check for TIF_31BIT which saves a couple of instructions.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2013-04-26 09:07:05 +02:00
Martin Schwidefsky d35339a42d s390: add support for transactional memory
Allow user-space processes to use transactional execution (TX).
If the TX facility is available user space programs can use
transactions for fine-grained serialization based on the data
objects that are referenced during a transaction. This is
useful for lockless data structures and speculative compiler
optimizations.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-09-26 15:45:02 +02:00
Martin Schwidefsky 27f6b41662 s390/vtimer: rework virtual timer interface
The current virtual timer interface is inherently per-cpu and hard to
use. The sole user of the interface is appldata which uses it to execute
a function after a specific amount of cputime has been used over all cpus.

Rework the virtual timer interface to hook into the cputime accounting.
This makes the interface independent from the CPU timer interrupts, and
makes the virtual timers global as opposed to per-cpu.
Overall the code is greatly simplified. The downside is that the accuracy
is not as good as the original implementation, but it is still good enough
for appldata.

Reviewed-by: Jan Glauber <jang@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-07-20 11:15:08 +02:00
Heiko Carstens fbe765680d s390/smp: make absolute lowcore / cpu restart parameter accesses more robust
Setting the cpu restart parameters is done in three different fashions:
- directly setting the four parameters individually
- copying the four parameters with memcpy (using 4 * sizeof(long))
- copying the four parameters using a private structure

In addition code in entry*.S relies on a certain order of the restart
members of struct _lowcore.

Make all of this more robust to future changes by adding a
mem_absolute_assign(dest, val) define, which assigns val to dest
using absolute addressing mode. Also the load multiple instructions
in entry*.S have been split into separate load instruction so the
order of the struct _lowcore members doesn't matter anymore.

In addition move the prototypes of memcpy_real/absolute from uaccess.h
to processor.h. These memcpy* variants are not related to uaccess at all.
string.h doesn't seem to match as well, so lets use processor.h.

Also replace the eight byte array in struct _lowcore which represents a
misaliged u64 with a u64. The compiler will always create code that
handles the misaligned u64 correctly.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-06-14 09:09:02 +02:00
David Howells a0616cdebc Disintegrate asm/system.h for S390
Disintegrate asm/system.h for S390.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-s390@vger.kernel.org
2012-03-28 18:30:02 +01:00
Martin Schwidefsky 4c1051e37a [S390] rework idle code
Whenever the cpu loads an enabled wait PSW it will appear as idle to the
underlying host system. The code in default_idle calls vtime_stop_cpu
which does the necessary voodoo to get the cpu time accounting right.
The udelay code just loads an enabled wait PSW. To correct this rework
the vtime_stop_cpu/vtime_start_cpu logic and move the difficult parts
to entry[64].S, vtime_stop_cpu can now be called from anywhere and
vtime_start_cpu is gone. The correction of the cpu time during wakeup
from an enabled wait PSW is done with a critical section in entry[64].S.
As vtime_start_cpu is gone, s390_idle_check can be removed as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:28 -04:00
Martin Schwidefsky 8b646bd759 [S390] rework smp code
Define struct pcpu and merge some of the NR_CPUS arrays into it, including
__cpu_logical_map, current_set and smp_cpu_state. Split smp related
functions to those operating on physical cpus and the functions operating
on a logical cpu number. Make the functions for physical cpus use a
pointer to a struct pcpu. This hides the knowledge about cpu addresses in
smp.c, entry[64].S and swsusp_asm64.S, thus remove the sigp.h header.

The PSW restart mechanism is used to start secondary cpus, calling a
function on an online cpu, calling a function on the ipl cpu, and for
the nmi signal. Replace the different assembler functions with a
single function restart_int_handler. The new entry point calls a function
whose pointer is stored in the lowcore of the target cpu and it can wait
for the source cpu to stop. This covers all existing use cases.

Overall the code is now simpler and there are ~380 lines less code.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:28 -04:00
Martin Schwidefsky 7e180bd802 [S390] rename lowcore field
The 16 bit value at the lowcore location with offset 0x84 is the
cpu address that is associated with an external interrupt. Rename
the field from cpu_addr to ext_cpu_addr to make that clear.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-03-11 11:59:27 -04:00
Martin Schwidefsky aa33c8cbba [S390] cleanup trap handling
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: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-12-27 11:27:12 +01:00
Martin Schwidefsky c5328901aa [S390] entry[64].S improvements
Another round of cleanup for entry[64].S, in particular the program check
handler looks more reasonable now. The code size for the 31 bit kernel
has been reduced by 616 byte and by 528 byte for the 64 bit version.
Even better the code is a bit faster as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-12-27 11:27:12 +01:00