arm: define speculation barrier
Jeetesh Burman [Wed, 14 Feb 2018 06:20:57 +0000 (11:20 +0530)]
The instruction sequency "dsb sy" followed by "isb" functions as
a speculation barrier, which prevents the instructions after that
from being speculatively executed.

bug 2039126

Change-Id: I898aab771ff82b26b08214a06814d2e6e78969a7
Signed-off-by: Bo Yan <byan@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1618222
Signed-off-by: James Huang <jamehuang@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1650093
Signed-off-by: Jeetesh Burman <jburman@nvidia.com>
(cherry picked from commit f125c60045878513902cac4a084fde9a516eb3e2)
Reviewed-on: https://git-master.nvidia.com/r/1660771
GVS: Gerrit_Virtual_Submit
Reviewed-by: Bibek Basu <bbasu@nvidia.com>

arch/arm/include/asm/barrier.h

index b00ef07..6af46bf 100644 (file)
@@ -79,5 +79,9 @@ do {                                                                  \
 
 #define set_mb(var, value)     do { var = value; smp_mb(); } while (0)
 
+#define speculation_barrier()                                           \
+       asm volatile(   "dsb sy\n"                                      \
+               "isb\n" : : : "memory")
+
 #endif /* !__ASSEMBLY__ */
 #endif /* __ASM_BARRIER_H */