Pull parisc updates from Helge Deller:
- add Kernel address space layout randomization support
- re-enable interrupts earlier now that we have a working IRQ stack
- optimize the timer interrupt function to better cope with missed
timer irqs
- fix error return code in parisc perf code (by Dan Carpenter)
- fix PAT debug code
* 'parisc-4.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
parisc: Optimize timer interrupt function
parisc: perf: return -EFAULT on error
parisc: Enhance CPU detection code on PAT machines
parisc: Re-enable interrupts early
parisc: Enable KASLR
Restructure the timer interrupt function to better cope with missed timer irqs.
Optimize the calculation when the next interrupt should happen and skip irqs if
they would happen too shortly after exit of the irq function.
The update_process_times() call is done anyway at every timer irq, so we can
safely drop the prof_counter and prof_multiplier variables from the per_cpu
structure.
Signed-off-by: Helge Deller <deller@gmx.de>
The definition of start_thread_som was planned to be used to execute
HP-UX SOM binaries. Since HP-UX compatibility was dropped with kernel 4.0
there is no need to carry it further.
Signed-off-by: Helge Deller <deller@gmx.de>
This patch affects only architectures where the stack grows upwards
(currently parisc and metag only). On those do not hardcode the maximum
initial stack size to 1GB for 32-bit processes, but make it configurable
via a config option.
The main problem with the hardcoded stack size is, that we have two
memory regions which grow upwards: stack and heap. To keep most of the
memory available for heap in a flexmap memory layout, it makes no sense
to hard allocate up to 1GB of the memory for stack which can't be used
as heap then.
This patch makes the stack size for 32-bit processes configurable and
uses 80MB as default value which has been in use during the last few
years on parisc and which hasn't showed any problems yet.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: linux-parisc@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.anglin@bell.net>
Specify the maximum stack size for arches where the stack grows upward
(parisc and metag) in asm/processor.h rather than hard coding in
fs/exec.c so that metag can specify a smaller value of 256MB rather than
1GB.
This fixes a BUG on metag if the RLIMIT_STACK hard limit is increased
beyond a safe value by root. E.g. when starting a process after running
"ulimit -H -s unlimited" it will then attempt to use a stack size of the
maximum 1GB which is far too big for metag's limited user virtual
address space (stack_top is usually 0x3ffff000):
BUG: failure at fs/exec.c:589/shift_arg_pages()!
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: linux-parisc@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # only needed for >= v3.9 (arch/metag)
Add support for the flexible mmap memory layout (as described in
http://lwn.net/Articles/91829). This is especially very interesting on
parisc since we currently only support 32bit userspace (even with a
64bit Linux kernel).
Signed-off-by: Helge Deller <deller@gmx.de>
The logic to detect if the irq stack was already in use with
raw_spin_trylock() is wrong, because it will generate a "trylock failure
on UP" error message with CONFIG_SMP=n and CONFIG_DEBUG_SPINLOCK=y.
arch_spin_trylock() can't be used either since in the CONFIG_SMP=n case
no atomic protection is given and we are reentrant here. A mutex didn't
worked either and brings more overhead by turning off interrupts.
So, let's use the fastest path for parisc which is the ldcw instruction.
Counting how often the irq stack was used is pretty useless, so just
drop this piece of code.
Signed-off-by: Helge Deller <deller@gmx.de>
This patch fixes few build issues which were introduced with the last
irq stack patch, e.g. the combination of stack overflow check and irq
stack.
Furthermore we now do proper locking and change the irq bh handler
to use the irq stack as well.
In /proc/interrupts one now can monitor how huge the irq stack has grown
and how often it was preferred over the kernel stack.
IRQ stacks are now enabled by default just to make sure that we not
overflow the kernel stack by accident.
Signed-off-by: Helge Deller <deller@gmx.de>
Default kernel stack size on parisc is 16k. During tests we found that the
kernel stack can easily grow beyond 13k, which leaves 3k left for irq
processing.
This patch adds the possibility to activate an additional stack of 16k per CPU
which is being used during irq processing. This implementation does not yet
uses this irq stack for the irq bh handler.
The assembler code for call_on_stack was heavily cleaned up by John
David Anglin.
CC: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
