ARM: 6385/1: setup: detect aliasing I-cache when D-cache is non-aliasing

Currently, the Kernel assumes that if a CPU has a non-aliasing D-cache
then the I-cache is also non-aliasing. This may not be true on ARM cores
from v6 onwards, which may have aliasing I-caches but non-aliasing
D-caches.

This patch adds a cpu_has_aliasing_icache function, which is called from
cacheid_init and adds CACHEID_VIPT_I_ALIASING to the cacheid when
appropriate. A utility macro, icache_is_vipt_aliasing(), is also
provided.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/arm/include/asm/cachetype.h b/arch/arm/include/asm/cachetype.h
index d3a4c2cb9f2f..c023db09fcc1 100644
--- a/arch/arm/include/asm/cachetype.h
+++ b/arch/arm/include/asm/cachetype.h
@@ -6,6 +6,7 @@
 #define CACHEID_VIPT_ALIASING           (1 << 2)
 #define CACHEID_VIPT                    (CACHEID_VIPT_ALIASING|CACHEID_VIPT_NONALIASING)
 #define CACHEID_ASID_TAGGED             (1 << 3)
+#define CACHEID_VIPT_I_ALIASING         (1 << 4)
 
 extern unsigned int cacheid;
 
@@ -14,15 +15,18 @@ extern unsigned int cacheid;
 #define cache_is_vipt_nonaliasing()     cacheid_is(CACHEID_VIPT_NONALIASING)
 #define cache_is_vipt_aliasing()        cacheid_is(CACHEID_VIPT_ALIASING)
 #define icache_is_vivt_asid_tagged()    cacheid_is(CACHEID_ASID_TAGGED)
+#define icache_is_vipt_aliasing()       cacheid_is(CACHEID_VIPT_I_ALIASING)
 
 /*
  * __LINUX_ARM_ARCH__ is the minimum supported CPU architecture
  * Mask out support which will never be present on newer CPUs.
  * - v6+ is never VIVT
- * - v7+ VIPT never aliases
+ * - v7+ VIPT never aliases on D-side
  */
 #if __LINUX_ARM_ARCH__ >= 7
-#define __CACHEID_ARCH_MIN      (CACHEID_VIPT_NONALIASING | CACHEID_ASID_TAGGED)
+#define __CACHEID_ARCH_MIN      (CACHEID_VIPT_NONALIASING |\
+                                 CACHEID_ASID_TAGGED |\
+                                 CACHEID_VIPT_I_ALIASING)
 #elif __LINUX_ARM_ARCH__ >= 6
 #define __CACHEID_ARCH_MIN      (~CACHEID_VIVT)
 #else