Introduce new exception handling framework
This patch introduces the reworked exception handling logic which lays
the foundation for accessing runtime services in later patches. The
type of an exception has a greater say in the way it is
handled. SP_EL3 is used as the stack pointer for:
1. Determining the type of exception and handling the unexpected ones
on the exception stack
2. Saving and restoring the essential general purpose and system
register state after exception entry and prior to exception exit.
SP_EL0 is used as the stack pointer for handling runtime service
requests e.g. SMCs. A new structure for preserving general purpose
register state has been added to the 'cpu_context' structure. All
assembler ensures that it does not use callee saved registers
(x19-x29). The C runtime preserves them across functions calls. Hence
EL3 code does not have to save and restore them explicitly.
Since the exception handling framework has undergone substantial change,
the changes have been kept in separate files to aid readability. These
files will replace the existing ones in subsequent patches.
Change-Id: Ice418686592990ff7a4260771e8d6676e6c8c5ef
diff --git a/include/runtime_svc.h b/include/runtime_svc.h
index db8fd29..3ee043e 100644
--- a/include/runtime_svc.h
+++ b/include/runtime_svc.h
@@ -143,7 +143,8 @@
* Constants to allow the assembler access a runtime service
* descriptor
*/
-#define SIZEOF_RT_SVC_DESC 32
+#define RT_SVC_SIZE_LOG2 5
+#define SIZEOF_RT_SVC_DESC (1 << RT_SVC_SIZE_LOG2)
#define RT_SVC_DESC_INIT 16
#define RT_SVC_DESC_HANDLE 24
@@ -156,6 +157,13 @@
#ifndef __ASSEMBLY__
+/* Various flags passed to SMC handlers */
+#define SMC_FROM_SECURE (0 << 0)
+#define SMC_FROM_NON_SECURE (1 << 0)
+
+#define is_caller_non_secure(_f) (!!(_f & SMC_FROM_NON_SECURE))
+#define is_caller_secure(_f) (!(is_caller_non_secure(_f)))
+
/* Prototype for runtime service initializing function */
typedef int32_t (*rt_svc_init)(void);
@@ -288,7 +296,7 @@
* of the structure are the same.
* 2. ensure that the assembler and the compiler see the initialisation
* routine at the same offset.
- * 2. ensure that the assembler and the compiler see the handler
+ * 3. ensure that the assembler and the compiler see the handler
* routine at the same offset.
*/
CASSERT((sizeof(rt_svc_desc) == SIZEOF_RT_SVC_DESC), \