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>

4 files changed, 28 insertions, 6 deletions

diff --git a/arch/arm/lib64/Makefile b/arch/arm/lib64/Makefile
index 77647128a5..4c0019fabe 100644
--- a/arch/arm/lib64/Makefile
+++ b/arch/arm/lib64/Makefile
@@ -2,7 +2,7 @@ obj-y += stacktrace.o
 obj-$(CONFIG_ARM_LINUX)	+= armlinux.o
 obj-y	+= div0.o
 obj-$(CONFIG_ARM_OPTIMZED_STRING_FUNCTIONS)	+= memcpy.o
-obj-$(CONFIG_ARM_OPTIMZED_STRING_FUNCTIONS)	+= memset.o
+obj-$(CONFIG_ARM_OPTIMZED_STRING_FUNCTIONS)	+= memset.o string.o
 extra-y += barebox.lds
 obj-pbl-y   += runtime-offset.o
 
diff --git a/arch/arm/lib64/memcpy.S b/arch/arm/lib64/memcpy.S
index cfed3191c5..a70e96ca29 100644
--- a/arch/arm/lib64/memcpy.S
+++ b/arch/arm/lib64/memcpy.S
@@ -67,8 +67,8 @@
 	stp \ptr, \regB, [\regC], \val
 	.endm
 
-	.weak memcpy
-ENTRY(memcpy)
+	.weak __arch_memcpy
+ENTRY(__arch_memcpy)
 #include "copy_template.S"
 	ret
-ENDPROC(memcpy)
+ENDPROC(__arch_memcpy)
diff --git a/arch/arm/lib64/memset.S b/arch/arm/lib64/memset.S
index 380a54097e..d17bcc6125 100644
--- a/arch/arm/lib64/memset.S
+++ b/arch/arm/lib64/memset.S
@@ -54,7 +54,7 @@ tmp3w		.req	w9
 tmp3		.req	x9
 
 	.weak memset
-ENTRY(memset)
+ENTRY(__arch_memset)
 	mov	dst, dstin	/* Preserve return value.  */
 	and	A_lw, val, #255
 	orr	A_lw, A_lw, A_lw, lsl #8
@@ -212,4 +212,4 @@ ENTRY(memset)
 	ands	count, count, zva_bits_x
 	b.ne	.Ltail_maybe_long
 	ret
-ENDPROC(memset)
+ENDPROC(__arch_memset)
diff --git a/arch/arm/lib64/string.c b/arch/arm/lib64/string.c
new file mode 100644
index 0000000000..cb26331527
--- /dev/null
+++ b/arch/arm/lib64/string.c
@@ -0,0 +1,22 @@
+#include <common.h>
+#include <asm/system.h>
+#include <string.h>
+
+void *__arch_memset(void *dst, int c, __kernel_size_t size);
+void *__arch_memcpy(void * dest, const void *src, size_t count);
+
+void *memset(void *dst, int c, __kernel_size_t size)
+{
+	if (likely(get_cr() & CR_M))
+		return __arch_memset(dst, c, size);
+
+	return __default_memset(dst, c, size);
+}
+
+void *memcpy(void * dest, const void *src, size_t count)
+{
+	if (likely(get_cr() & CR_M))
+		return __arch_memcpy(dest, src, count);
+
+	return __default_memcpy(dest, src, count);
+}
\ No newline at end of file