s390: claim efficient unaligned access

most unaligned accesses are reasonable efficient (no kernel emulation)
on s390, let's announce it

This also
- removes the ubsan false positives for unaligned accesses on s390 with
  default config
- uses simpler arithmetic in several functions in several other areas
  of the kernel like ethernet frame classification

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index e751fe25d6ab..f4989fb4ac8d 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -137,6 +137,7 @@ config S390
         select HAVE_DMA_API_DEBUG
         select HAVE_DYNAMIC_FTRACE
         select HAVE_DYNAMIC_FTRACE_WITH_REGS
+        select HAVE_EFFICIENT_UNALIGNED_ACCESS
         select HAVE_EXIT_THREAD
         select HAVE_FTRACE_MCOUNT_RECORD
         select HAVE_FUNCTION_GRAPH_TRACER