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
  ...

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/arc/include/asm/spinlock.h b/arch/arc/include/asm/spinlock.h
index b6a8c2d..e1651df 100644
--- a/arch/arc/include/asm/spinlock.h
+++ b/arch/arc/include/asm/spinlock.h
@@ -22,24 +22,46 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
 {
 	unsigned int tmp = __ARCH_SPIN_LOCK_LOCKED__;
 
+	/*
+	 * This smp_mb() is technically superfluous, we only need the one
+	 * after the lock for providing the ACQUIRE semantics.
+	 * However doing the "right" thing was regressing hackbench
+	 * so keeping this, pending further investigation
+	 */
+	smp_mb();
+
 	__asm__ __volatile__(
 	"1:	ex  %0, [%1]		\n"
 	"	breq  %0, %2, 1b	\n"
 	: "+&r" (tmp)
 	: "r"(&(lock->slock)), "ir"(__ARCH_SPIN_LOCK_LOCKED__)
 	: "memory");
+
+	/*
+	 * ACQUIRE barrier to ensure load/store after taking the lock
+	 * don't "bleed-up" out of the critical section (leak-in is allowed)
+	 * http://www.spinics.net/lists/kernel/msg2010409.html
+	 *
+	 * ARCv2 only has load-load, store-store and all-all barrier
+	 * thus need the full all-all barrier
+	 */
+	smp_mb();
 }
 
 static inline int arch_spin_trylock(arch_spinlock_t *lock)
 {
 	unsigned int tmp = __ARCH_SPIN_LOCK_LOCKED__;
 
+	smp_mb();
+
 	__asm__ __volatile__(
 	"1:	ex  %0, [%1]		\n"
 	: "+r" (tmp)
 	: "r"(&(lock->slock))
 	: "memory");
 
+	smp_mb();
+
 	return (tmp == __ARCH_SPIN_LOCK_UNLOCKED__);
 }
 
@@ -47,12 +69,22 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
 {
 	unsigned int tmp = __ARCH_SPIN_LOCK_UNLOCKED__;
 
+	/*
+	 * RELEASE barrier: given the instructions avail on ARCv2, full barrier
+	 * is the only option
+	 */
+	smp_mb();
+
 	__asm__ __volatile__(
 	"	ex  %0, [%1]		\n"
 	: "+r" (tmp)
 	: "r"(&(lock->slock))
 	: "memory");
 
+	/*
+	 * superfluous, but keeping for now - see pairing version in
+	 * arch_spin_lock above
+	 */
 	smp_mb();
 }