linux-stable.git/arch/s390/kernel, branch linux-3.7.y

s390/timer: avoid overflow when programming clock comparator

2013-02-17T18:53:12+00:00

commit d911e03d097bdc01363df5d81c43f69432eb785c upstream.

Since ed4f209 "s390/time: fix sched_clock() overflow" a new helper function
is used to avoid overflows when converting TOD format values to nanosecond
values.
The kvm interrupt code formerly however only worked by accident because of
an overflow. It tried to program a timer that would expire in more than ~29
years. Because of the old TOD-to-nanoseconds overflow bug the real expiry
value however was much smaller, but now it isn't anymore.
This however triggers yet another bug in the function that programs the clock
comparator s390_next_ktime(): if the absolute "expires" value is after 2042
this will result in an overflow and the programmed value is lower than the
current TOD value which immediatly triggers a clock comparator (= timer)
interrupt.
Since the timer isn't expired it will be programmed immediately again and so
on... the result is a dead system.
To fix this simply program the maximum possible value if an overflow is
detected.

Reported-by: Christian Borntraeger 
Tested-by: Christian Borntraeger 
Signed-off-by: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman

s390/time: fix sched_clock() overflow

2013-01-21T19:44:34+00:00

commit ed4f20943cd4c7b55105c04daedf8d63ab6d499c upstream.

Converting a 64 Bit TOD format value to nanoseconds means that the value
must be divided by 4.096. In order to achieve that we multiply with 125
and divide by 512.
When used within sched_clock() this triggers an overflow after appr.
417 days. Resulting in a sched_clock() return value that is much smaller
than previously and therefore may cause all sort of weird things in
subsystems that rely on a monotonic sched_clock() behaviour.

To fix this implement a tod_to_ns() helper function which converts TOD
values without overflow and call this function from both places that
open coded the conversion: sched_clock() and kvm_s390_handle_wait().

Reviewed-by: Martin Schwidefsky 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390/kvm: Fix address space mixup

2013-01-17T16:45:44+00:00

commit ce6a04ac1b759beafc88dbc443ae5da867579eeb upstream.

I was chasing down a bug of random validity intercepts on s390.
(guest prefix page not mapped in the host virtual aspace). Turns out
that the problem was a wrong address space control element. The
cause was quite complex:

During paging activity a DAT protection during SIE caused a program
interrupt. Normally, the sie retry loop tries to catch all
interrupts during and shortly before sie to rerun the setup. The
problem is now that protection causes a suppressing program interrupt,
causing the PSW to point to the instruction AFTER SIE in case of DAT
protection. This confused the logic of the retry loop to not trigger,
instead we jumped directly back to SIE after return from
the program  interrupt. (the protection fault handler itself did
a rewind of the psw). This usually works quite well, but:

If now the protection fault handler has to wait, another program
might be scheduled in. Later on the sie process will be schedules
in again. In that case the content of CR1 (primary address space)
will be wrong because switch_to will put the user space ASCE into CR1
and not the guest ASCE.

In addition the program parameter is also wrong for every protection
fault of a guest, since we dont issue the SPP instruction.

So lets also check for PSW == instruction after SIE in the program
check handler. Instead of expensively checking all program
interruption codes that might be suppressing we assume that a program
interrupt pointing after SIE was always a program interrupt in SIE.
(Otherwise we have a kernel bug anyway).

We also have to compensate the rewinding, since the C-level handlers
will do that. Therefore we need to add a nop with the same length
as SIE before the sie_loop.

Signed-off-by: Christian Borntraeger 
Signed-off-by: Martin Schwidefsky 
CC: Heiko Carstens 
Signed-off-by: Greg Kroah-Hartman

open*(2) compat fixes (s390, arm64)

2012-12-02T18:46:38+00:00

The usual rules for open()/openat()/open_by_handle_at() are
 1) native 32bit - don't force O_LARGEFILE in flags
 2) native 64bit - force O_LARGEFILE in flags
 3) compat on 64bit host - as for native 32bit
 4) native 32bit ABI for 64bit system (mips/n32, x86/x32) - as for
    native 64bit

There are only two exceptions - s390 compat has open() forcing
O_LARGEFILE and arm64 compat has open_by_handle_at() doing the same
thing.  The same binaries on native host (s390/31 and arm resp.) will
*not* force O_LARGEFILE, so IMO both are emulation bugs.

Objections? The fix is obvious...

Signed-off-by: Al Viro 
Signed-off-by: Linus Torvalds

s390/topology: fix core id vs physical package id mix-up

2012-11-12T15:24:38+00:00

The current topology code confuses core id vs physical package id.

In other words /sys/devices/system/cpu/cpuX/topology/core_id
displays the physical_package_id (aka socket id) instead of the
core id.
The physical_package_id sysfs attribute always displays "-1"
instead of the socket id.

Fix this mix-up with a small patch which defines and initializes
topology_physical_package_id correctly and fixes the broken
core id handling.

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

s390/signal: set correct address space control

2012-11-12T15:24:38+00:00

If user space is running in primary mode it can switch to secondary
or access register mode, this is used e.g. in the clock_gettime code
of the vdso. If a signal is delivered to the user space process while
it has been running in access register mode the signal handler is
executed in access register mode as well which will result in a crash
most of the time.

Set the address space control bits in the PSW to the default for the
execution of the signal handler and make sure that the previous
address space control is restored on signal return. Take care
that user space can not switch to the kernel address space by
modifying the registers in the signal frame.

Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky

s390/sclp: fix addressing mode clobber

2012-11-06T21:39:51+00:00

The early mini sclp driver may be called in zArch mode either in
31 or 64 bit addressing mode.
If called in 31 bit addressing mode the new external interrupt psw
however would switch to 64 bit addressing mode. This would cause an
addressing exception within the interrupt handler, since the code
didn't expect the zArch/31 bit addressing mode combination.

Fix this by setting the new psw addressing mode bits so they fit
the current addressing mode.

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

s390/cache: fix data/instruction cache output

2012-10-18T15:50:11+00:00

The sysfs and procfs output of the instruction and data caches were
wrong: the output of the data cache provided that instruction cache
values and vice versa.
Fix this by using the correct type indication when issueing the
ecag instruction.

Reported-by: Andreas Krebbel 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: fix linker script for 31 bit builds

2012-10-18T15:50:10+00:00

Because of a change in the s390 arch backend of binutils (commit 23ecd77
"Pick the default arch depending on the target size" in binutils repo)
31 bit builds will fail since the linker would now try to create 64 bit
binary output.
Fix this by setting OUTPUT_ARCH to s390:31-bit instead of s390.
Thanks to Andreas Krebbel for figuring out the issue.

Fixes this build error:

  LD      init/built-in.o
s390x-4.7.2-ld: s390:31-bit architecture of input file
 `arch/s390/kernel/head.o' is incompatible with s390:64-bit output

Cc: Andreas Krebbel 
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/kdump: Use 64 bit mode for 0x10000 entry point

2012-10-18T15:50:09+00:00

The 0x10000 entry point can be called in z/Arch architecture and 64 bit
addressing mode. Therefore this patch removes the unnecessary 31 bit
switch code from the kdump startup function.

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