ARM: lib64: Make string functions aware of MMU configuration

Optimized version of memset() in memset.S if called as:

    memset(foo, 0, size)

will try to explicitly zero out data cache with:

    dc	zva, dst

which will result in Alignement Exception (DABT) if MMU is not
enabled.

For more info see:

    - C4.4.8 "DC ZVA, Data Cache Zero by VA"
    - D5.2.8 "The effects of disabling a stage of address translation"

in "ARM Architecture Reference Manual. ARMv8, for ARMv8-A architecture
profile"

In similar vein, using optimized version of memcpy() could lead to a
unaligned 16-byte write (using 'stp'), which is not allowed for
Device-nGnRnE type of memory (see D5.2.8) and would liead to
Alignement Exception.

To fix both problems expose non-optimized and optimzied versions of
the function and created a wrapper to dispatch the call to either one
based on if MMU is enabled or not.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 12 insertions, 6 deletions

diff --git a/lib/string.c b/lib/string.c
index f588933e81..717b59aa50 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -479,7 +479,6 @@ char *strswab(const char *s)
 }
 #endif
 
-#ifndef __HAVE_ARCH_MEMSET
 /**
  * memset - Fill a region of memory with the given value
  * @s: Pointer to the start of the area.
@@ -488,7 +487,7 @@ char *strswab(const char *s)
  *
  * Do not use memset() to access IO space, use memset_io() instead.
  */
-void * memset(void * s,int c,size_t count)
+void *__default_memset(void * s,int c,size_t count)
 {
 	char *xs = (char *) s;
 
@@ -497,10 +496,12 @@ void * memset(void * s,int c,size_t count)
 
 	return s;
 }
+EXPORT_SYMBOL(__default_memset);
+
+#ifndef __HAVE_ARCH_MEMSET
+void *memset(void *s, int c, size_t count) __alias(__default_memset);
 #endif
-EXPORT_SYMBOL(memset);
 
-#ifndef __HAVE_ARCH_MEMCPY
 /**
  * memcpy - Copy one area of memory to another
  * @dest: Where to copy to
@@ -510,7 +511,7 @@ EXPORT_SYMBOL(memset);
  * You should not use this function to access IO space, use memcpy_toio()
  * or memcpy_fromio() instead.
  */
-void * memcpy(void * dest,const void *src,size_t count)
+void *__default_memcpy(void * dest,const void *src,size_t count)
 {
 	char *tmp = (char *) dest, *s = (char *) src;
 
@@ -519,9 +520,14 @@ void * memcpy(void * dest,const void *src,size_t count)
 
 	return dest;
 }
-#endif
 EXPORT_SYMBOL(memcpy);
 
+#ifndef __HAVE_ARCH_MEMCPY
+void *memcpy(void * dest, const void *src, size_t count)
+	__alias(__default_memcpy);
+#endif
+
+
 #ifndef __HAVE_ARCH_MEMMOVE
 /**
  * memmove - Copy one area of memory to another