This adds a platform agnostic early SMP init hook which is called on
Master core before calling setup_processor()
setup_arch()
smp_init_cpus()
smp_ops.init_early_smp()
...
setup_processor()
How this helps:
- Used for one time init of certain SMP centric IP blocks, before
calling setup_processor() which probes various bits of core,
possibly including this block
- Currently platforms need to call this IP block init from their
init routines, which doesn't make sense as this is specific to ARC
core and not platform and otherwise requires copy/paste in all
(and hence a possible point of failure)
e.g. MCIP init is called from 2 platforms currently (axs10x and sim)
which will go away once we have this.
This change only adds the hooks but they are empty for now. Next commit
will populate them and remove the explicit init calls from platforms.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
These are not in use for ARC platforms. Moreover DT mechanims exist to
probe them w/o explicit platform calls.
- clocksource drivers can use CLOCKSOURCE_OF_DECLARE()
- intc IRQCHIP_DECLARE() calls + cascading inside DT allows external
intc to be probed automatically
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The reason this was not done so far was lack of genuine IPI_IRQ for
ARC700, as we don't have a SMP version of core yet (which might change
soon thx to EZChip). Nevertheles to increase the build coverage, we
need to allow CONFIG_SMP for ARC700 and still be able to run it on a
UP platform (nsim or AXS101) with a UP Device Tree (SMP-on-UP)
The build itself requires some define for IPI_IRQ and even a dummy
value is fine since that code won't run anyways.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
For Run-on-reset, non masters need to spin wait. For Halt-on-reset they
can jump to entry point directly.
Also while at it, made reset vector handler as "the" entry point for
kernel including host debugger based boot (which uses the ELF header
entry point)
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Enable building all dtb files when CONFIG_OF_ALL_DTBS is enabled. The dtbs
are not really dependent on a platform being enabled or any other kernel
config, so for testing coverage it is convenient to build all of the dtbs.
This builds all dts files in the tree, not just targets listed.
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Use dtb-y and always make variables to build dtbs instead of explicit
dtbs rule. This is in preparation to support building all dtbs.
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
DesignWare MMC Controller's transfer mode should be decided
at runtime instead of compile-time. So we remove this config
option and read dw_mmc's register to select DMA master.
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
For non halt-on-reset case, all cores start of simultaneously in @stext.
Master core0 proceeds with kernel boot, while other spin-wait on
@wake_flag being set by master once it is ready. So NO hardware assist
is needed for master to "kick" the others.
This patch moves this soft implementation out of mcip.c (as there is no
hardware assist) into common smp.c
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This frees up some bits to hold more high level info such as PAE being
present, w/o increasing the size of already bloated cpuinfo struct
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This is done by improving the laddering logic !
Before:
if Exception
goto excep_or_pure_k_ret
if !Interrupt(L2)
goto l1_chk
else
INTERRUPT_EPILOGUE 2
l1_chk:
if !Interrupt(L1) (i.e. pure kernel mode)
goto excep_or_pure_k_ret
else
INTERRUPT_EPILOGUE 1
excep_or_pure_k_ret:
EXCEPTION_EPILOGUE
Now:
if !Interrupt(L1 or L2) (i.e. exception or pure kernel mode)
goto excep_or_pure_k_ret
; guaranteed to be an interrupt
if !Interrupt(L2)
goto l1_ret
else
INTERRUPT_EPILOGUE 2
; by virtue of above, no need to chk for L1 active
l1_ret:
INTERRUPT_EPILOGUE 1
excep_or_pure_k_ret:
EXCEPTION_EPILOGUE
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The requirement is to
- Reenable Exceptions (AE cleared)
- Reenable Interrupts (E1/E2 set)
We need to do wiggle these bits into ERSTATUS and call RTIE.
Prev version used the pre-exception STATUS32 as starting point for what
goes into ERSTATUS. This required explicit fixups of U/DE/L bits.
Instead, use the current (in-exception) STATUS32 as starting point.
Being in exception handler U/DE/L can be safely assumed to be correct.
Only AE/E1/E2 need to be fixed.
So the new implementation is slightly better
-Avoids read form memory
-Is 4 bytes smaller for the typical 1 level of intr configuration
-Depicts the semantics more clearly
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Historically this was done by ARC IDE driver, which is long gone.
IRQ core is pretty robust now and already checks if IRQs are enabled
in hard ISRs. Thus no point in checking this in arch code, for every
call of irq enabled.
Further if some driver does do that - let it bring down the system so we
notice/fix this sooner than covering up for sucker
This makes local_irq_enable() - for L1 only case atleast simple enough
so we can inline it.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Implement the TLB flush routine to evict a sepcific Super TLB entry,
vs. moving to a new ASID on every such flush.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
MMUv4 in HS38x cores supports Super Pages which are basis for Linux THP
support.
Normal and Super pages can co-exist (ofcourse not overlap) in TLB with a
new bit "SZ" in TLB page desciptor to distinguish between them.
Super Page size is configurable in hardware (4K to 16M), but fixed once
RTL builds.
The exact THP size a Linx configuration will support is a function of:
- MMU page size (typical 8K, RTL fixed)
- software page walker address split between PGD:PTE:PFN (typical
11:8:13, but can be changed with 1 line)
So for above default, THP size supported is 8K * 256 = 2M
Default Page Walker is 2 levels, PGD:PTE:PFN, which in THP regime
reduces to 1 level (as PTE is folded into PGD and canonically referred
to as PMD).
Thus thp PMD accessors are implemented in terms of PTE (just like sparc)
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC is the only arch with unsigned long type (vs. struct page *).
Historically this was done to avoid the page_address() calls in various
arch hooks which need to get the virtual/logical address of the table.
Some arches alternately define it as pte_t *, and is as efficient as
unsigned long (generated code doesn't change)
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Pull strscpy string copy function implementation from Chris Metcalf.
Chris sent this during the merge window, but I waffled back and forth on
the pull request, which is why it's going in only now.
The new "strscpy()" function is definitely easier to use and more secure
than either strncpy() or strlcpy(), both of which are horrible nasty
interfaces that have serious and irredeemable problems.
strncpy() has a useless return value, and doesn't NUL-terminate an
overlong result. To make matters worse, it pads a short result with
zeroes, which is a performance disaster if you have big buffers.
strlcpy(), by contrast, is a mis-designed "fix" for strlcpy(), lacking
the insane NUL padding, but having a differently broken return value
which returns the original length of the source string. Which means
that it will read characters past the count from the source buffer, and
you have to trust the source to be properly terminated. It also makes
error handling fragile, since the test for overflow is unnecessarily
subtle.
strscpy() avoids both these problems, guaranteeing the NUL termination
(but not excessive padding) if the destination size wasn't zero, and
making the overflow condition very obvious by returning -E2BIG. It also
doesn't read past the size of the source, and can thus be used for
untrusted source data too.
So why did I waffle about this for so long?
Every time we introduce a new-and-improved interface, people start doing
these interminable series of trivial conversion patches.
And every time that happens, somebody does some silly mistake, and the
conversion patch to the improved interface actually makes things worse.
Because the patch is mindnumbing and trivial, nobody has the attention
span to look at it carefully, and it's usually done over large swatches
of source code which means that not every conversion gets tested.
So I'm pulling the strscpy() support because it *is* a better interface.
But I will refuse to pull mindless conversion patches. Use this in
places where it makes sense, but don't do trivial patches to fix things
that aren't actually known to be broken.
* 'strscpy' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
tile: use global strscpy() rather than private copy
string: provide strscpy()
Make asm/word-at-a-time.h available on all architectures
This patch makes sure that atomic_{read,set}() are at least
{READ,WRITE}_ONCE().
We already had the 'requirement' that atomic_read() should use
ACCESS_ONCE(), and most archs had this, but a few were lacking.
All are now converted to use READ_ONCE().
And, by a symmetry and general paranoia argument, upgrade atomic_set()
to use WRITE_ONCE().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: james.hogan@imgtec.com
Cc: linux-kernel@vger.kernel.org
Cc: oleg@redhat.com
Cc: will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Most interrupt flow handlers do not use the irq argument. Those few
which use it can retrieve the irq number from the irq descriptor.
Remove the argument.
Search and replace was done with coccinelle and some extra helper
scripts around it. Thanks to Julia for her help!
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Pull locking and atomic updates from Ingo Molnar:
"Main changes in this cycle are:
- Extend atomic primitives with coherent logic op primitives
(atomic_{or,and,xor}()) and deprecate the old partial APIs
(atomic_{set,clear}_mask())
The old ops were incoherent with incompatible signatures across
architectures and with incomplete support. Now every architecture
supports the primitives consistently (by Peter Zijlstra)
- Generic support for 'relaxed atomics':
- _acquire/release/relaxed() flavours of xchg(), cmpxchg() and {add,sub}_return()
- atomic_read_acquire()
- atomic_set_release()
This came out of porting qwrlock code to arm64 (by Will Deacon)
- Clean up the fragile static_key APIs that were causing repeat bugs,
by introducing a new one:
DEFINE_STATIC_KEY_TRUE(name);
DEFINE_STATIC_KEY_FALSE(name);
which define a key of different types with an initial true/false
value.
Then allow:
static_branch_likely()
static_branch_unlikely()
to take a key of either type and emit the right instruction for the
case. To be able to know the 'type' of the static key we encode it
in the jump entry (by Peter Zijlstra)
- Static key self-tests (by Jason Baron)
- qrwlock optimizations (by Waiman Long)
- small futex enhancements (by Davidlohr Bueso)
- ... and misc other changes"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (63 commits)
jump_label/x86: Work around asm build bug on older/backported GCCs
locking, ARM, atomics: Define our SMP atomics in terms of _relaxed() operations
locking, include/llist: Use linux/atomic.h instead of asm/cmpxchg.h
locking/qrwlock: Make use of _{acquire|release|relaxed}() atomics
locking/qrwlock: Implement queue_write_unlock() using smp_store_release()
locking/lockref: Remove homebrew cmpxchg64_relaxed() macro definition
locking, asm-generic: Add _{relaxed|acquire|release}() variants for 'atomic_long_t'
locking, asm-generic: Rework atomic-long.h to avoid bulk code duplication
locking/atomics: Add _{acquire|release|relaxed}() variants of some atomic operations
locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic
locking/static_keys: Make verify_keys() static
jump label, locking/static_keys: Update docs
locking/static_keys: Provide a selftest
jump_label: Provide a self-test
s390/uaccess, locking/static_keys: employ static_branch_likely()
x86, tsc, locking/static_keys: Employ static_branch_likely()
locking/static_keys: Add selftest
locking/static_keys: Add a new static_key interface
locking/static_keys: Rework update logic
locking/static_keys: Add static_key_{en,dis}able() helpers
...
Pull irq updates from Thomas Gleixner:
"This updated pull request does not contain the last few GIC related
patches which were reported to cause a regression. There is a fix
available, but I let it breed for a couple of days first.
The irq departement provides:
- new infrastructure to support non PCI based MSI interrupts
- a couple of new irq chip drivers
- the usual pile of fixlets and updates to irq chip drivers
- preparatory changes for removal of the irq argument from interrupt
flow handlers
- preparatory changes to remove IRQF_VALID"
* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
irqchip/imx-gpcv2: IMX GPCv2 driver for wakeup sources
irqchip: Add bcm2836 interrupt controller for Raspberry Pi 2
irqchip: Add documentation for the bcm2836 interrupt controller
irqchip/bcm2835: Add support for being used as a second level controller
irqchip/bcm2835: Refactor handle_IRQ() calls out of MAKE_HWIRQ
PCI: xilinx: Fix typo in function name
irqchip/gic: Ensure gic_cpu_if_up/down() programs correct GIC instance
irqchip/gic: Only allow the primary GIC to set the CPU map
PCI/MSI: pci-xgene-msi: Consolidate chained IRQ handler install/remove
unicore32/irq: Prepare puv3_gpio_handler for irq argument removal
tile/pci_gx: Prepare trio_handle_level_irq for irq argument removal
m68k/irq: Prepare irq handlers for irq argument removal
C6X/megamode-pic: Prepare megamod_irq_cascade for irq argument removal
blackfin: Prepare irq handlers for irq argument removal
arc/irq: Prepare idu_cascade_isr for irq argument removal
sparc/irq: Use access helper irq_data_get_affinity_mask()
sparc/irq: Use helper irq_data_get_irq_handler_data()
parisc/irq: Use access helper irq_data_get_affinity_mask()
mn10300/irq: Use access helper irq_data_get_affinity_mask()
irqchip/i8259: Prepare i8259_irq_dispatch for irq argument removal
...
With all features in place, the ARC HS pct block can now be effectively
allowed to be probed/used
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* split off pmu info into singleton and per-cpu bits
* setup PMU on all cores
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
In times of ARC 700 performance counters didn't have support of
interrupt an so for ARC we only had support of non-sampling events.
Put simply only "perf stat" was functional.
Now with ARC HS we have support of interrupts in performance counters
which this change introduces support of.
ARC performance counters act in the following way in regard of
interrupts generation.
[1] A counter counts starting from value set in PCT_COUNT register pair
[2] Once counter reaches value set in PCT_INT_CNT interrupt is raised
Basic setup look like this:
[1] PCT_COUNT = 0;
[2] PCT_INT_CNT = __limit_value__;
[3] Enable interrupts for that counter and let it run
[4] Let counter reach its limit
[5] Handle interrupt when it happens
Note that PCT HW block is build in CPU core and so ints interrupt
line (which is basically OR of all counters IRQs) is wired directly to
top-level IRQC. That means do de-assert PCT interrupt it's required to
reset IRQs from all counters that have reached their limit values.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This generalization prepares for support of overflow interrupts.
Hardware event counters on ARC work that way:
Each counter counts from programmed start value (set in
ARC_REG_PCT_COUNT) to a limit value (set in ARC_REG_PCT_INT_CNT) and
once limit value is reached this timer generates an interrupt.
Even though this hardware implementation allows for more flexibility,
in Linux kernel we decided to mimic behavior of other architectures
this way:
[1] Set limit value as half of counter's max value (to allow counter to
run after reaching it limit, see below for more explanation):
---------->8-----------
arc_pmu->max_period = (1ULL << counter_size) / 2 - 1ULL;
---------->8-----------
[2] Set start value as "arc_pmu->max_period - sample_period" and then
count up to the limit
Our event counters don't stop on reaching max value (the one we set in
ARC_REG_PCT_INT_CNT) but continue to count until kernel explicitly
stops each of them.
And setting a limit as half of counter capacity is done to allow
capturing of additional events in between moment when interrupt was
triggered until we're actually processing PMU interrupts. That way
we're trying to be more precise.
For example if we count CPU cycles we keep track of cycles while
running through generic IRQ handling code:
[1] We set counter period as say 100_000 events of type "crun"
[2] Counter reaches that limit and raises its interrupt
[3] Once we get in PMU IRQ handler we read current counter value from
ARC_REG_PCT_SNAP ans see there something like 105_000.
If counters stop on reaching a limit value then we would miss
additional 5000 cycles.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The number of counters in PCT can never be more than 32 (while
countable conditions could be 100+) for both ARCompact and ARCv2
And while at it update copyright dates.
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
When kernel's binary becomes large enough (32M and more) errors
may occur during the final linkage stage. It happens because
the build system uses short relocations for ARC by default.
This problem may be easily resolved by passing -mlong-calls
option to GCC to use long absolute jumps (j) instead of short
relative branchs (b).
But there are fragments of pure assembler code exist which use
branchs in inappropriate places and cause a linkage error because
of relocations overflow.
First of these fragments is .fixup insertion in futex.h and
unaligned.c. It inserts a code in the separate section (.fixup)
with branch instruction. It leads to the linkage error when
kernel becomes large.
Second of these fragments is calling scheduler's functions
(common kernel code) from entry.S of ARC's code. When kernel's
binary becomes large it may lead to the linkage error because
scheduler may occur far enough from ARC's code in the final
binary.
Signed-off-by: Yuriy Kolerov <yuriy.kolerov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
W/o hardware assisted atomic r-m-w the best we can do is to disable
preemption.
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC doesn't need the runtime detection of futex cmpxchg op
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Callers of cmpxchg_futex_value_locked() in futex code expect bimodal
return value:
!0 (essentially -EFAULT as failure)
0 (success)
Before this patch, the success return value was old value of futex,
which could very well be non zero, causing caller to possibly take the
failure path erroneously.
Fix that by returning 0 for success
(This fix was done back in 2011 for all upstream arches, which ARC
obviously missed)
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The atomic ops on futex need to provide the full barrier just like
regular atomics in kernel.
Also remove pagefault_enable/disable in futex_atomic_cmpxchg_inatomic()
as core code already does that
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
In case of ARCv2 CPU there're could be following configurations
that affect cache handling for data exchanged with peripherals
via DMA:
[1] Only L1 cache exists
[2] Both L1 and L2 exist, but no IO coherency unit
[3] L1, L2 caches and IO coherency unit exist
Current implementation takes care of [1] and [2].
Moreover support of [2] is implemented with run-time check
for SLC existence which is not super optimal.
This patch introduces support of [3] and rework of DMA ops
usage. Instead of doing run-time check every time a particular
DMA op is executed we'll have 3 different implementations of
DMA ops and select appropriate one during init.
As for IOC support for it we need:
[a] Implement empty DMA ops because IOC takes care of cache
coherency with DMAed data
[b] Route dma_alloc_coherent() via dma_alloc_noncoherent()
This is required to make IOC work in first place and also
serves as optimization as LD/ST to coherent buffers can be
srviced from caches w/o going all the way to memory
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
[vgupta:
-Added some comments about IOC gains
-Marked dma ops as static,
-Massaged changelog a bit]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The increment of delay counter was 2 instructions:
Arithmatic Shfit Left (ASL) + set to 1 on overflow
This can be done in 1 using ROtate Left (ROL)
Suggested-by: Nigel Topham <ntopham@synopsys.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
KGDB fails to build after f51e2f1911 ("ARC: make sure instruction_pointer()
returns unsigned value")
The hack to force one specific reg to unsigned backfired. There's no
reason to keep the regs signed after all.
| CC arch/arc/kernel/kgdb.o
|../arch/arc/kernel/kgdb.c: In function 'kgdb_trap':
| ../arch/arc/kernel/kgdb.c:180:29: error: lvalue required as left operand of assignment
| instruction_pointer(regs) -= BREAK_INSTR_SIZE;
Reported-by: Yuriy Kolerov <yuriy.kolerov@synopsys.com>
Fixes: f51e2f1911 ("ARC: make sure instruction_pointer() returns unsigned value")
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The previous commit for delayed retry of SCOND needs some fine tuning
for spin locks.
The backoff from delayed retry in conjunction with spin looping of lock
itself can potentially cause the delay counter to reach high values.
So to provide fairness to any lock operation, after a lock "seems"
available (i.e. just before first SCOND try0, reset the delay counter
back to starting value of 1
Essentially reset delay to 1 for a new spin-wait-loop-acquire cycle.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This is to workaround the llock/scond livelock
HS38x4 could get into a LLOCK/SCOND livelock in case of multiple overlapping
coherency transactions in the SCU. The exclusive line state keeps rotating
among contenting cores leading to a never ending cycle. So break the cycle
by deferring the retry of failed exclusive access (SCOND). The actual delay
needed is function of number of contending cores as well as the unrelated
coherency traffic from other cores. To keep the code simple, start off with
small delay of 1 which would suffice most cases and in case of contention
double the delay. Eventually the delay is sufficient such that the coherency
pipeline is drained, thus a subsequent exclusive access would succeed.
Link: http://lkml.kernel.org/r/1438612568-28265-1-git-send-email-vgupta@synopsys.com
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
With LLOCK/SCOND, the rwlock counter can be atomically updated w/o need
for a guarding spin lock.
This in turn elides the EXchange instruction based spinning which causes
the cacheline transition to exclusive state and concurrent spinning
across cores would cause the line to keep bouncing around.
LLOCK/SCOND based implementation is superior as spinning on LLOCK keeps
the cacheline in shared state.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Current spin_lock uses EXchange instruction to implement the atomic test
and set of lock location (reads orig value and ST 1). This however forces
the cacheline into exclusive state (because of the ST) and concurrent
loops in multiple cores will bounce the line around between cores.
Instead, use LLOCK/SCOND to implement the atomic test and set which is
better as line is in shared state while lock is spinning on LLOCK
The real motivation of this change however is to make way for future
changes in atomics to implement delayed retry (with backoff).
Initial experiment with delayed retry in atomics combined with orig
EX based spinlock was a total disaster (broke even LMBench) as
struct sock has a cache line sharing an atomic_t and spinlock. The
tight spinning on lock, caused the atomic retry to keep backing off
such that it would never finish.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This reduces the diff in forth-coming patches and also helps understand
better the incremental changes to inline asm.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Extended testing of quad core configuration revealed that this fix was
insufficient. Specifically LTP open posix shm_op/23-1 would cause the
hardware livelock in llock/scond loop in update_cpu_load_active()
So remove this and make way for a proper workaround
This reverts commit a5c8b52abe.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
With HS 2.1 release, the peripheral space register no longer contains
the uncached space specifics, causing the kernel to panic early on.
So read the newer NON VOLATILE AUX register to get that info.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The irq argument of most interrupt flow handlers is unused or merily
used instead of a local variable. The handlers which need the irq
argument can retrieve the irq number from the irq descriptor.
Search and update was done with coccinelle and the invaluable help of
Julia Lawall.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Vineet Gupta <vgupta@synopsys.com>
Move the now generic definitions of atomic_{set,clear}_mask() into
linux/atomic.h to avoid endless and pointless repetition.
Also, provide an atomic_andnot() wrapper for those few archs that can
implement that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Implement atomic logic ops -- atomic_{or,xor,and}.
These will replace the atomic_{set,clear}_mask functions that are
available on some archs.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Implement atomic logic ops -- atomic_{or,xor,and}.
These will replace the atomic_{set,clear}_mask functions that are
available on some archs.
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
There are configurations which may not have LDD/STD
Signed-off-by: Claudiu Zissulescu <claziss@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Being highly configurable core ARC HS among other features might be
configured with or without DIV_REM_OPTION (hardware divider).
That option when enabled adds following instructions: div, divu, rem, remu.
By default ARC HS38 has this option enabled. So we add here possibility
to disable usage of hardware divider by compiler.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Migrate arc driver to the new 'set-state' interface provided by
clockevents core, the earlier 'set-mode' interface is marked obsolete
now.
This also enables us to implement callbacks for new states of clockevent
devices, for example: ONESHOT_STOPPED.
Cc: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Commit 2ae416b142 ("mm: new mm hook framework") introduced an empty
header file (mm-arch-hooks.h) for every architecture, even those which
doesn't need to define mm hooks.
As suggested by Geert Uytterhoeven, this could be cleaned through the use
of a generic header file included via each per architecture
asm/include/Kbuild file.
The PowerPC architecture is not impacted here since this architecture has
to defined the arch_remap MM hook.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently instruction_pointer() returns pt_regs->ret and so return value
is of type "long", which implicitly stands for "signed long".
While that's perfectly fine when dealing with 32-bit values if return
value of instruction_pointer() gets assigned to 64-bit variable sign
extension may happen.
And at least in one real use-case it happens already.
In perf_prepare_sample() return value of perf_instruction_pointer()
(which is an alias to instruction_pointer() in case of ARC) is assigned
to (struct perf_sample_data)->ip (which type is "u64").
And what we see if instuction pointer points to user-space application
that in case of ARC lays below 0x8000_0000 "ip" gets set properly with
leading 32 zeros. But if instruction pointer points to kernel address
space that starts from 0x8000_0000 then "ip" is set with 32 leadig
"f"-s. I.e. id instruction_pointer() returns 0x8100_0000, "ip" will be
assigned with 0xffff_ffff__8100_0000. Which is obviously wrong.
In particular that issuse broke output of perf, because perf was unable
to associate addresses like 0xffff_ffff__8100_0000 with anything from
/proc/kallsyms.
That's what we used to see:
----------->8----------
6.27% ls [unknown] [k] 0xffffffff8046c5cc
2.96% ls libuClibc-0.9.34-git.so [.] memcpy
2.25% ls libuClibc-0.9.34-git.so [.] memset
1.66% ls [unknown] [k] 0xffffffff80666536
1.54% ls libuClibc-0.9.34-git.so [.] 0x000224d6
1.18% ls libuClibc-0.9.34-git.so [.] 0x00022472
----------->8----------
With that change perf output looks much better now:
----------->8----------
8.21% ls [kernel.kallsyms] [k] memset
3.52% ls libuClibc-0.9.34-git.so [.] memcpy
2.11% ls libuClibc-0.9.34-git.so [.] malloc
1.88% ls libuClibc-0.9.34-git.so [.] memset
1.64% ls [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
1.41% ls [kernel.kallsyms] [k] __d_lookup_rcu
----------->8----------
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: arc-linux-dev@synopsys.com
Cc: stable@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
The IRQCHIP_DECLARE macro migrated to 'include/linux/irqchip.h'.
See commit 91e20b5040
("irqchip: Move IRQCHIP_DECLARE macro to include/linux/irqchip.h").
This patch removes the inclusions of private header 'drivers/irqchip/irqchip.h'
and if necessary replaces them with inclusions of 'include/linux/irqchip.h'.
Signed-off-by: Joel Porquet <joel@porquet.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARCompact/ARCv2 ISA provide that any instructions which deals with
bitpos/count operand ASL, LSL, BSET, BCLR, BMSK .... will only consider
lower 5 bits. i.e. auto-clamp the pos to 0-31.
ARC Linux bitops exploited this fact by NOT explicitly masking out upper
bits for @nr operand in general, saving a bunch of AND/BMSK instructions
in generated code around bitops.
While this micro-optimization has worked well over years it is NOT safe
as shifting a number with a value, greater than native size is
"undefined" per "C" spec.
So as it turns outm EZChip ran into this eventually, in their massive
muti-core SMP build with 64 cpus. There was a test_bit() inside a loop
from 63 to 0 and gcc was weirdly optimizing away the first iteration
(so it was really adhering to standard by implementing undefined behaviour
vs. removing all the iterations which were phony i.e. (1 << [63..32])
| for i = 63 to 0
| X = ( 1 << i )
| if X == 0
| continue
So fix the code to do the explicit masking at the expense of generating
additional instructions. Fortunately, this can be mitigated to a large
extent as gcc has SHIFT_COUNT_TRUNCATED which allows combiner to fold
masking into shift operation itself. It is currently not enabled in ARC
gcc backend, but could be done after a bit of testing.
Fixes STAR 9000866918 ("unsafe "undefined behavior" code in kernel")
Reported-by: Noam Camus <noamc@ezchip.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
With up-to-date FPGA builds ARC cores are supposed to correctly operate
even with 90 MHz clock (which is a target frequency for AXS103 release).
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: arc-linux-dev@synopsys.com
Added the x86 implementation of word-at-a-time to the
generic version, which previously only supported big-endian.
Omitted the x86-specific load_unaligned_zeropad(), which in
any case is also not present for the existing BE-only
implementation of a word-at-a-time, and is only used under
CONFIG_DCACHE_WORD_ACCESS.
Added as a "generic-y" to the Kbuilds of all architectures
that didn't previously have it.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
With this nsim standlone / OSCI have working irq affinity - AXS103 still
needs some work as IDU is not visible in intc hierarchy yet !
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
alloc_pages_exact() get gfp flags and handle zero'ing already
And while it, fix the case where ioremap fails: return rightaway.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC kernels have historically been built with -O3, despite top level
Makefile defaulting to -O2. This was facilitated by implicitly ordering
of arch makefile include AFTER top level assigned -O2.
An upstream fix to top level a1c48bb160 ("Makefile: Fix unrecognized
cross-compiler command line options") changed the ordering, making ARC
-O3 defunct.
Fix that by NOT relying on any ordering whatsoever and use the proper
arch override facility now present in kbuild (ARCH_*FLAGS)
Depends-on: ("kbuild: Allow arch Makefiles to override {cpp,ld,c}flags")
Suggested-by: Michal Marek <mmarek@suse.cz>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
SLC maintenance ops need to be serialized by software as there is no
inherent buffering / quequing of aux commands. It can silently ignore a
new aux operation if previous one is still ongoing (SLC_CTRL_BUSY)
So gaurd the SLC op using a spin lock
The spin lock doesn't seem to be contended even in heavy workloads such
as iperf. On FPGA @ 75 MHz.
[1] Before this change:
============================================================
# iperf -c 10.42.0.1
------------------------------------------------------------
Client connecting to 10.42.0.1, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[ 3] local 10.42.0.110 port 38935 connected with 10.42.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 48.4 MBytes 40.6 Mbits/sec
============================================================
[2] After this change:
============================================================
# iperf -c 10.42.0.1
------------------------------------------------------------
Client connecting to 10.42.0.1, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[ 3] local 10.42.0.243 port 60248 connected with 10.42.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 47.5 MBytes 39.8 Mbits/sec
# iperf -c 10.42.0.1
------------------------------------------------------------
Client connecting to 10.42.0.1, TCP port 5001
TCP window size: 43.8 KByte (default)
------------------------------------------------------------
[ 3] local 10.42.0.243 port 60249 connected with 10.42.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 54.9 MBytes 46.0 Mbits/sec
============================================================
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: arc-linux-dev@synopsys.com
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Pull more vfs updates from Al Viro:
"Assorted VFS fixes and related cleanups (IMO the most interesting in
that part are f_path-related things and Eric's descriptor-related
stuff). UFS regression fixes (it got broken last cycle). 9P fixes.
fs-cache series, DAX patches, Jan's file_remove_suid() work"
[ I'd say this is much more than "fixes and related cleanups". The
file_table locking rule change by Eric Dumazet is a rather big and
fundamental update even if the patch isn't huge. - Linus ]
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits)
9p: cope with bogus responses from server in p9_client_{read,write}
p9_client_write(): avoid double p9_free_req()
9p: forgetting to cancel request on interrupted zero-copy RPC
dax: bdev_direct_access() may sleep
block: Add support for DAX reads/writes to block devices
dax: Use copy_from_iter_nocache
dax: Add block size note to documentation
fs/file.c: __fget() and dup2() atomicity rules
fs/file.c: don't acquire files->file_lock in fd_install()
fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation
vfs: avoid creation of inode number 0 in get_next_ino
namei: make set_root_rcu() return void
make simple_positive() public
ufs: use dir_pages instead of ufs_dir_pages()
pagemap.h: move dir_pages() over there
remove the pointless include of lglock.h
fs: cleanup slight list_entry abuse
xfs: Correctly lock inode when removing suid and file capabilities
fs: Call security_ops->inode_killpriv on truncate
fs: Provide function telling whether file_remove_privs() will do anything
...
Merge third patchbomb from Andrew Morton:
- the rest of MM
- scripts/gdb updates
- ipc/ updates
- lib/ updates
- MAINTAINERS updates
- various other misc things
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (67 commits)
genalloc: rename of_get_named_gen_pool() to of_gen_pool_get()
genalloc: rename dev_get_gen_pool() to gen_pool_get()
x86: opt into HAVE_COPY_THREAD_TLS, for both 32-bit and 64-bit
MAINTAINERS: add zpool
MAINTAINERS: BCACHE: Kent Overstreet has changed email address
MAINTAINERS: move Jens Osterkamp to CREDITS
MAINTAINERS: remove unused nbd.h pattern
MAINTAINERS: update brcm gpio filename pattern
MAINTAINERS: update brcm dts pattern
MAINTAINERS: update sound soc intel patterns
MAINTAINERS: remove website for paride
MAINTAINERS: update Emulex ocrdma email addresses
bcache: use kvfree() in various places
libcxgbi: use kvfree() in cxgbi_free_big_mem()
target: use kvfree() in session alloc and free
IB/ehca: use kvfree() in ipz_queue_{cd}tor()
drm/nouveau/gem: use kvfree() in u_free()
drm: use kvfree() in drm_free_large()
cxgb4: use kvfree() in t4_free_mem()
cxgb3: use kvfree() in cxgb_free_mem()
...
ARCv2 is the next generation ISA from Synopsys and basis for the
HS3{4,6,8} families of processors which retain the traditional ARC mantra of
low power and configurability and are now more performant and feature rich.
HS38x is a 10 stage pipeline core which supports MMU (with huge pages) and
SMP (upto 4 cores) among other features.
+ www.synopsys.com/dw/ipdir.php?ds=arc-hs38-processor
+ http://news.synopsys.com/2014-10-14-New-DesignWare-ARC-HS38-Processor-Doubles-Performance-for-Embedded-Linux-Applications
+ http://www.embedded.com/electronics-news/4435975/Synopsys-ARC-HS38-core-gives-2X-boost-to-Linux-based-apps
- Support for ARC SDP (Software Development platform): Main Board + CPU Cards
= AXS101: CPU Card with ARC700 in silicon @ 700 MHz
= AXS103: CPU Card with HS38x in FPGA
- Refactoring of ARCompact port to accomodate new ARCv2 ISA
- Miscll updates/cleanups
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Merge tag 'arc-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc
Pull ARC architecture updates from Vineet Gupta:
- support for HS38 cores based on ARCv2 ISA
ARCv2 is the next generation ISA from Synopsys and basis for the
HS3{4,6,8} families of processors which retain the traditional ARC mantra of
low power and configurability and are now more performant and feature rich.
HS38x is a 10 stage pipeline core which supports MMU (with huge pages) and
SMP (upto 4 cores) among other features.
+ www.synopsys.com/dw/ipdir.php?ds=arc-hs38-processor
+ http://news.synopsys.com/2014-10-14-New-DesignWare-ARC-HS38-Processor-Doubles-Performance-for-Embedded-Linux-Applications
+ http://www.embedded.com/electronics-news/4435975/Synopsys-ARC-HS38-core-gives-2X-boost-to-Linux-based-apps
- support for ARC SDP (Software Development platform): Main Board + CPU Cards
= AXS101: CPU Card with ARC700 in silicon @ 700 MHz
= AXS103: CPU Card with HS38x in FPGA
- refactoring of ARCompact port to accomodate new ARCv2 ISA
- misc updates/cleanups
* tag 'arc-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (72 commits)
ARC: Fix build failures for ARCompact in linux-next after ARCv2 support
ARCv2: Allow older gcc to cope with new regime of ARCv2/ARCompact support
ARCv2: [vdk] dts files and defconfig for HS38 VDK
ARCv2: [axs103] Support ARC SDP FPGA platform for HS38x cores
ARC: [axs101] Prepare for AXS103
ARCv2: [nsim*hs*] Support simulation platforms for HS38x cores
ARCv2: All bits in place, allow ARCv2 builds
ARCv2: SLC: Handle explcit flush for DMA ops (w/o IO-coherency)
ARCv2: STAR 9000837815 workaround hardware exclusive transactions livelock
ARC: Reduce bitops lines of code using macros
ARCv2: barriers
arch: conditionally define smp_{mb,rmb,wmb}
ARC: add smp barriers around atomics per Documentation/atomic_ops.txt
ARC: add compiler barrier to LLSC based cmpxchg
ARCv2: SMP: intc: IDU 2nd level intc for dynamic IRQ distribution
ARCv2: SMP: clocksource: Enable Global Real Time counter
ARCv2: SMP: ARConnect debug/robustness
ARCv2: SMP: Support ARConnect (MCIP) for Inter-Core-Interrupts et al
ARC: make plat_smp_ops weak to allow over-rides
ARCv2: clocksource: Introduce 64bit local RTC counter
...
This replaces the plain loop over the sglist array with for_each_sg()
macro which consists of sg_next() function calls. Since arc doesn't
select ARCH_HAS_SG_CHAIN, it is not necessary to use for_each_sg() in
order to loop over each sg element. But this can help find problems with
drivers that do not properly initialize their sg tables when
CONFIG_DEBUG_SG is enabled.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-no-ll64 is specific to ARCv2 ISA, and is obviously not supported by
older ARC gcc - in this case the one hosted by linux-next sanity build
service.
Ensure that it doesn't get included for ISA_ARCOMPACT
Reported-by: Guenter Roeck <private@roeck-us.net>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Pull asm/scatterlist.h removal from Jens Axboe:
"We don't have any specific arch scatterlist anymore, since parisc
finally switched over. Kill the include"
* 'for-4.2/sg' of git://git.kernel.dk/linux-block:
remove scatterlist.h generation from arch Kbuild files
remove <asm/scatterlist.h>
CRIU is recreating the process memory layout by remapping the checkpointee
memory area on top of the current process (criu). This includes remapping
the vDSO to the place it has at checkpoint time.
However some architectures like powerpc are keeping a reference to the
vDSO base address to build the signal return stack frame by calling the
vDSO sigreturn service. So once the vDSO has been moved, this reference
is no more valid and the signal frame built later are not usable.
This patch serie is introducing a new mm hook framework, and a new
arch_remap hook which is called when mremap is done and the mm lock still
hold. The next patch is adding the vDSO remap and unmap tracking to the
powerpc architecture.
This patch (of 3):
This patch introduces a new set of header file to manage mm hooks:
- per architecture empty header file (arch/x/include/asm/mm-arch-hooks.h)
- a generic header (include/linux/mm-arch-hooks.h)
The architecture which need to overwrite a hook as to redefine it in its
header file, while architecture which doesn't need have nothing to do.
The default hooks are defined in the generic header and are used in the
case the architecture is not defining it.
In a next step, mm hooks defined in include/asm-generic/mm_hooks.h should
be moved here.
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- CONFIG_ARC_UBOOT_SUPPORT to handle arguments passed in r0, r1, r2
- CONFIG_DEVTMPFS_MOUNT for mouting rootfs since it uses external cpio
for rootfs
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Ruud Derwig <rderwig@synopsys.com>
[vgupta: folded the Main baord DT files for smp/up into one]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
To avoid duplicating the MB DTS file, move the MB intc entry into cpu
card specific file
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
L2 cache on ARCHS processors is called SLC (System Level Cache)
For working DMA (in absence of hardware assisted IO Coherency) we need
to manage SLC explicitly when buffers transition between cpu and
controllers.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
A quad core SMP build could get into hardware livelock with concurrent
LLOCK/SCOND. Workaround that by adding a PREFETCHW which is serialized by
SCU (System Coherency Unit). It brings the cache line in Exclusive state
and makes others invalidate their lines. This gives enough time for
winner to complete the LLOCK/SCOND, before others can get the line back.
The prefetchw in the ll/sc loop is not nice but this is the only
software workaround for current version of RTL.
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Vineet Gupta