arm: implement safe reads by intercepting the data abort handler.

Implement functions to read from a memory location and indicate
failure in case this is not possible. Since we do not have a MMU,
intercept the data abort handler and simply return when the abort
comes from the safe read routines.

Change-Id: I08f2e59898dcac893319a8150d4cf626f3adabbd
Reviewed-on: http://gerrit.rockbox.org/207
Reviewed-by: Marcin Bukat <marcin.bukat@gmail.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/lib/unwarminder/backtrace.c b/lib/unwarminder/backtrace.c
index 4e1609137c..294b7f66f4 100644
--- a/lib/unwarminder/backtrace.c
+++ b/lib/unwarminder/backtrace.c
@@ -23,6 +23,7 @@
  ***************************************************************************/
 
 #include "backtrace.h"
+#include "safe_read.h"
 
 /***************************************************************************
  * Prototypes
@@ -86,20 +87,17 @@ static Boolean CliReport(void *data, Int32 address)
 
 static Boolean CliReadW(const Int32 a, Int32 *v)
 {
-    *v = *(Int32 *)a;
-    return TRUE;
+    return safe_read32((uint32_t *)a, (uint32_t *)v);
 }
 
 static Boolean CliReadH(const Int32 a, Int16 *v)
 {
-    *v = *(Int16 *)a;
-    return TRUE;
+    return safe_read16((void *)a, (uint16_t *)v);
 }
 
 static Boolean CliReadB(const Int32 a, Int8 *v)
 {
-    *v = *(Int8 *)a;
-    return TRUE;
+    return safe_read8((void *)a, (uint8_t *)v);
 }
 
 Boolean CliInvalidateW(const Int32 a)