Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

[linux-2.6-microblaze.git] / arch / arm64 / include / asm / barrier.h

diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h
index 5a8367a..2175ec0 100644 (file)
--- a/arch/arm64/include/asm/barrier.h
+++ b/arch/arm64/include/asm/barrier.h
@@ -26,10 +26,6 @@
 #define tsb_csync()    asm volatile("hint #18" : : : "memory")
 #define csdb()         asm volatile("hint #20" : : : "memory")
 
-#define spec_bar()     asm volatile(ALTERNATIVE("dsb nsh\nisb\n",              \
-                                                SB_BARRIER_INSN"nop\n",        \
-                                                ARM64_HAS_SB))
-
 #ifdef CONFIG_ARM64_PSEUDO_NMI
 #define pmr_sync()                                             \
        do {                                                    \
@@ -71,6 +67,25 @@ static inline unsigned long array_index_mask_nospec(unsigned long idx,
        return mask;
 }
 
+/*
+ * Ensure that reads of the counter are treated the same as memory reads
+ * for the purposes of ordering by subsequent memory barriers.
+ *
+ * This insanity brought to you by speculative system register reads,
+ * out-of-order memory accesses, sequence locks and Thomas Gleixner.
+ *
+ * http://lists.infradead.org/pipermail/linux-arm-kernel/2019-February/631195.html
+ */
+#define arch_counter_enforce_ordering(val) do {                                \
+       u64 tmp, _val = (val);                                          \
+                                                                       \
+       asm volatile(                                                   \
+       "       eor     %0, %1, %1\n"                                   \
+       "       add     %0, sp, %0\n"                                   \
+       "       ldr     xzr, [%0]"                                      \
+       : "=r" (tmp) : "r" (_val));                                     \
+} while (0)
+
 #define __smp_mb()     dmb(ish)
 #define __smp_rmb()    dmb(ishld)
 #define __smp_wmb()    dmb(ishst)