Merge tag 'arc-v4.2-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

Pull ARC fixes from Vineet Gupta:
 - Makefile changes (top-level+ARC) reinstates -O3 builds (regression
   since 3.16)
 - IDU intc related fixes, IRQ affinity
 - patch to make bitops safer for ARC
 - perf fix from Alexey to remove signed PC braino
 - Futex backend gets llock/scond support

* tag 'arc-v4.2-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARCv2: support HS38 releases
  ARC: make sure instruction_pointer() returns unsigned value
  ARC: slightly refactor macros for boot logging
  ARC: Add llock/scond to futex backend
  arc:irqchip: prepare for drivers/irqchip/irqchip.h removal
  ARC: Make ARC bitops "safer" (add anti-optimization)
  ARCv2: [axs103] bump CPU frequency from 75 to 90 MHZ
  ARCv2: intc: IDU: Fix potential race in installing a chained IRQ handler
  ARCv2: intc: IDU: support irq affinity
  ARC: fix unused var wanring
  ARC: Don't memzero twice in dma_alloc_coherent for __GFP_ZERO
  ARC: Override toplevel default -O2 with -O3
  kbuild: Allow arch Makefiles to override {cpp,ld,c}flags
  ARCv2: guard SLC DMA ops with spinlock
  ARC: Kconfig: better way to disable ARC_HAS_LLSC for ARC_CPU_750D

2 files changed, 12 insertions, 4 deletions

diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index b29d62e..1cd6695 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -468,10 +468,18 @@ static void __ic_line_inv_vaddr(unsigned long paddr, unsigned long vaddr,
 noinline void slc_op(unsigned long paddr, unsigned long sz, const int op)
 {
 #ifdef CONFIG_ISA_ARCV2
+	/*
+	 * SLC is shared between all cores and concurrent aux operations from
+	 * multiple cores need to be serialized using a spinlock
+	 * A concurrent operation can be silently ignored and/or the old/new
+	 * operation can remain incomplete forever (lockup in SLC_CTRL_BUSY loop
+	 * below)
+	 */
+	static DEFINE_SPINLOCK(lock);
 	unsigned long flags;
 	unsigned int ctrl;
 
-	local_irq_save(flags);
+	spin_lock_irqsave(&lock, flags);
 
 	/*
 	 * The Region Flush operation is specified by CTRL.RGN_OP[11..9]
@@ -504,7 +512,7 @@ noinline void slc_op(unsigned long paddr, unsigned long sz, const int op)
 
 	while (read_aux_reg(ARC_REG_SLC_CTRL) & SLC_CTRL_BUSY);
 
-	local_irq_restore(flags);
+	spin_unlock_irqrestore(&lock, flags);
 #endif
 }
 
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index 74a637a..57706a9 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -60,8 +60,8 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
 
 	/* This is kernel Virtual address (0x7000_0000 based) */
 	kvaddr = ioremap_nocache((unsigned long)paddr, size);
-	if (kvaddr != NULL)
-		memset(kvaddr, 0, size);
+	if (kvaddr == NULL)
+		return NULL;
 
 	/* This is bus address, platform dependent */
 	*dma_handle = (dma_addr_t)paddr;