Streamline crash data access

Use correctly-typed external definition for the crash data region, and
eliminate unnecessary pointer indirection.

Results in a small ROM saving even with crash capture disabled, as there
was a pointer for the fault context store in either case. The pointer
isn't needed, as the context store location is fixed according to the
configuration flag.

Author: kjbracey

TESTS/mbed_platform/crash_reporting/main.cpp

@@ -36,7 +36,7 @@ static mbed_error_ctx saved_error_ctx = {0};
 void mbed_error_reboot_callback(mbed_error_ctx *error_context)
 {
 
-    TEST_ASSERT_EQUAL_UINT((uint32_t)error_context, ERROR_CONTEXT_LOCATION);
+    TEST_ASSERT_EQUAL_PTR(error_context, &MBED_CRASH_DATA);
     memcpy(&saved_error_ctx, error_context, sizeof(mbed_error_ctx));
     mbed_reset_reboot_error_info();
 

platform/source/TARGET_CORTEX_M/mbed_fault_handler.h renamed to platform/internal/mbed_fault_handler.h

@@ -18,11 +18,15 @@
 #ifndef MBED_FAULT_HANDLER_H
 #define MBED_FAULT_HANDLER_H
 
+#include "mbed_toolchain.h"
+#include "mbed_error.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 //Fault context struct
+#ifdef TARGET_CORTEX_M
 //WARNING: DO NOT CHANGE THIS STRUCT WITHOUT MAKING CORRESPONDING CHANGES in except.S files.
 //Offset of these registers are used by fault handler in except.S
 typedef struct {
@@ -48,13 +52,44 @@ typedef struct {
     uint32_t EXC_RETURN;
     uint32_t CONTROL;
 } mbed_fault_context_t;
+#elif defined TARGET_CORTEX_A
+// This is not currently used, but would be a plausible implementation
+typedef struct {
+    uint32_t R0_reg;
+    uint32_t R1_reg;
+    uint32_t R2_reg;
+    uint32_t R3_reg;
+    uint32_t R4_reg;
+    uint32_t R5_reg;
+    uint32_t R6_reg;
+    uint32_t R7_reg;
+    uint32_t R8_reg;
+    uint32_t R9_reg;
+    uint32_t R10_reg;
+    uint32_t R11_reg;
+    uint32_t R12_reg;
+    uint32_t SP_reg;
+    uint32_t LR_reg;
+    uint32_t PC_reg;
+    uint32_t CPSR;
+    uint32_t SP_usr;
+    uint32_t LR_usr;
+} mbed_fault_context_t;
+#else
+// Dummy for mbed_crash_data_t
+typedef struct {
+} mbed_fault_context_t;
+#endif
+
 
 //Fault type definitions
+#ifdef TARGET_CORTEX_M
 //WARNING: DO NOT CHANGE THESE VALUES WITHOUT MAKING CORRESPONDING CHANGES in except.S files.
 #define HARD_FAULT_EXCEPTION       (0x10) //Keep some gap between values for any future insertion/expansion
 #define MEMMANAGE_FAULT_EXCEPTION  (0x20)
 #define BUS_FAULT_EXCEPTION        (0x30)
 #define USAGE_FAULT_EXCEPTION      (0x40)
+#endif
 
 //This is a handler function called from Fault handler to print the error information out.
 //This runs in fault context and uses special functions(defined in mbed_fault_handler.c) to print the information without using C-lib support.
@@ -65,7 +100,7 @@ MBED_NORETURN void mbed_fault_handler(uint32_t fault_type, const mbed_fault_cont
  * @param  fault_context        Pointer to mbed_fault_context_t struct allocated by the caller. This is the mbed_fault_context_t info captured as part of the fatal exception which triggered the reboot.
  * @return                      0 or MBED_SUCCESS on success.
  *                              MBED_ERROR_INVALID_ARGUMENT in case of invalid error_info pointer
- *                              MBED_ERROR_ITEM_NOT_FOUND if no reboot context is currently captured by teh system
+ *                              MBED_ERROR_ITEM_NOT_FOUND if no reboot context is currently captured by the system
  *
  */
 mbed_error_status_t mbed_get_reboot_fault_context(mbed_fault_context_t *fault_context);

platform/source/TARGET_CORTEX_M/TOOLCHAIN_ARM/except.S

@@ -69,6 +69,9 @@ Fault_Handler\
         PROC
         EXPORT  Fault_Handler
 #if (DOMAIN_NS == 1)
+#if MBED_CONF_PLATFORM_CRASH_CAPTURE_ENABLED
+#define mbed_fault_context |Image$$RW_m_crash_data$$ZI$$Base|
+#endif
         IMPORT  mbed_fault_context
         IMPORT  mbed_fault_handler
 
@@ -82,7 +85,6 @@ Fault_Handler\
 
 Fault_Handler_Continue
         LDR     R7,=mbed_fault_context
-        LDR     R7,[R7]
         LDMIA   R6!,{R0-R3}
         STMIA   R7!,{R0-R3}             ; Capture R0..R3
         POP     {R0-R3}
@@ -110,8 +112,7 @@ Fault_Handler_Continue2
         MRS     R6,CONTROL
         STMIA   R7!,{R0,R1,R5,R6}       ; Capture PSP,MSP,EXC_RETURN,CONTROL
         MOV     R0,R12
-        MOVS    R1,R7
-        SUBS    R1,#21*4
+        LDR     R1,=mbed_fault_context
         BL      mbed_fault_handler      ; mbed_fault_handler does not return
 #else
         B       .

platform/source/TARGET_CORTEX_M/TOOLCHAIN_GCC/except.S

@@ -104,6 +104,10 @@ UsageFault_Handler:
 
 Fault_Handler:
 #if (DOMAIN_NS == 1)
+#if MBED_CONF_PLATFORM_CRASH_CAPTURE_ENABLED
+#define mbed_fault_context __CRASH_DATA_RAM_START__
+#endif
+
         MOV     R12,R3
         PUSH    {R4-R7}
         ADD     R6,SP,#16
@@ -114,7 +118,6 @@ Fault_Handler:
 
 Fault_Handler_Continue:
         LDR     R7,=mbed_fault_context
-        LDR     R7,[R7]
         LDMIA   R6!,{R0-R3}
         STMIA   R7!,{R0-R3}             // Capture R0..R3
         POP     {R0-R3}
@@ -143,8 +146,7 @@ Fault_Handler_Continue2:
         MRS     R6,CONTROL
         STMIA   R7!,{R0,R1,R5,R6}       // Capture PSP,MSP,EXC_RETURN,CONTROL
         MOV     R0,R12
-        MOV     R1,R7
-        SUBS    R1,R1,#21*4
+        LDR     R1,=mbed_fault_context
         BL      mbed_fault_handler      // mbed_fault_handler does not return
 #else
         B       .

platform/source/TARGET_CORTEX_M/TOOLCHAIN_IAR/except.S

@@ -63,6 +63,9 @@ UsageFault_Handler
 Fault_Handler
         EXPORT  Fault_Handler
 #if (DOMAIN_NS == 1)
+#if MBED_CONF_PLATFORM_CRASH_CAPTURE_ENABLED
+#define mbed_fault_context __CRASH_DATA_RAM_START__
+#endif
         IMPORT  mbed_fault_context
         IMPORT  mbed_fault_handler
 
@@ -76,7 +79,6 @@ Fault_Handler
 
 Fault_Handler_Continue
         LDR     R7,=mbed_fault_context
-        LDR     R7,[R7]
         LDMIA   R6!,{R0-R3}
         STMIA   R7!,{R0-R3}             ; Capture R0..R3
         POP     {R0-R3}
@@ -104,8 +106,7 @@ Fault_Handler_Continue2
         MRS     R6,CONTROL
         STMIA   R7!,{R0,R1,R5,R6}       ; Capture PSP,MSP,EXC_RETURN,CONTROL
         MOV     R0,R12
-        MOVS    R1,R7
-        SUBS    R1,#21*4
+        LDR     R1,=mbed_fault_context
         BL      mbed_fault_handler      ; mbed_fault_handler does not return
 #else
         B       .

platform/source/TARGET_CORTEX_M/mbed_fault_handler.c

@@ -34,11 +34,9 @@
 void print_context_info(void);
 
 #if MBED_CONF_PLATFORM_CRASH_CAPTURE_ENABLED
-//Global for populating the context in exception handler
-mbed_fault_context_t *const mbed_fault_context = (mbed_fault_context_t *)(FAULT_CONTEXT_LOCATION);
+#define mbed_fault_context MBED_CRASH_DATA.fault.context
 #else
-mbed_fault_context_t fault_context;
-mbed_fault_context_t *const mbed_fault_context = &fault_context;
+mbed_fault_context_t mbed_fault_context;
 #endif
 
 extern bool mbed_error_in_progress;
@@ -94,16 +92,16 @@ MBED_NOINLINE void print_context_info(void)
 {
     //Context Regs
     for (int i = 0; i < 13; i++) {
-        mbed_error_printf("\nR%-4d: %08" PRIX32, i, ((uint32_t *)(mbed_fault_context))[i]);
+        mbed_error_printf("\nR%-4d: %08" PRIX32, i, (&mbed_fault_context.R0_reg)[i]);
     }
 
     mbed_error_printf("\nSP   : %08" PRIX32
                       "\nLR   : %08" PRIX32
                       "\nPC   : %08" PRIX32
                       "\nxPSR : %08" PRIX32
                       "\nPSP  : %08" PRIX32
-                      "\nMSP  : %08" PRIX32, mbed_fault_context->SP_reg, mbed_fault_context->LR_reg, mbed_fault_context->PC_reg,
-                      mbed_fault_context->xPSR, mbed_fault_context->PSP, mbed_fault_context->MSP);
+                      "\nMSP  : %08" PRIX32, mbed_fault_context.SP_reg, mbed_fault_context.LR_reg, mbed_fault_context.PC_reg,
+                      mbed_fault_context.xPSR, mbed_fault_context.PSP, mbed_fault_context.MSP);
 
     //Capture CPUID to get core/cpu info
     mbed_error_printf("\nCPUID: %08" PRIX32, SCB->CPUID);
@@ -129,12 +127,12 @@ MBED_NOINLINE void print_context_info(void)
 #endif
 
     //Print Mode
-    if (mbed_fault_context->EXC_RETURN & 0x8) {
+    if (mbed_fault_context.EXC_RETURN & 0x8) {
         mbed_error_printf("\nMode : Thread");
         //Print Priv level in Thread mode - We capture CONTROL reg which reflects the privilege.
         //Note that the CONTROL register captured still reflects the privilege status of the
         //thread mode eventhough we are in Handler mode by the time we capture it.
-        if (mbed_fault_context->CONTROL & 0x1) {
+        if (mbed_fault_context.CONTROL & 0x1) {
             mbed_error_printf("\nPriv : User");
         } else {
             mbed_error_printf("\nPriv : Privileged");
@@ -144,7 +142,7 @@ MBED_NOINLINE void print_context_info(void)
         mbed_error_printf("\nPriv : Privileged");
     }
     //Print Return Stack
-    if (mbed_fault_context->EXC_RETURN & 0x4) {
+    if (mbed_fault_context.EXC_RETURN & 0x4) {
         mbed_error_printf("\nStack: PSP");
     } else {
         mbed_error_printf("\nStack: MSP");
@@ -158,7 +156,7 @@ mbed_error_status_t mbed_get_reboot_fault_context(mbed_fault_context_t *fault_co
     if (fault_context == NULL) {
         return MBED_MAKE_ERROR(MBED_MODULE_PLATFORM, MBED_ERROR_CODE_INVALID_ARGUMENT);
     }
-    memcpy(fault_context, mbed_fault_context, sizeof(mbed_fault_context_t));
+    *fault_context = mbed_fault_context;
     status = MBED_SUCCESS;
 #endif
     return status;

platform/source/mbed_crash_data_offsets.h

@@ -17,6 +17,9 @@
 #ifndef MBED_CRASH_DATA_INFO_H
 #define MBED_CRASH_DATA_INFO_H
 
+#include "platform/internal/mbed_fault_handler.h"
+#include "platform/mbed_error.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -25,25 +28,28 @@ extern "C" {
 /** \ingroup mbed-os-internal */
 /** \addtogroup platform-internal-api */
 /** @{*/
+// Any changes here must be reflected in except.S if they affect the fault handler.
+// The fault context is first to keep it simple for the assembler.
+typedef struct mbed_crash_data {
+    union {
+        mbed_fault_context_t context;
+        int pad[32];
+    } fault;
+    union {
+        mbed_error_ctx context;
+        int pad[32];
+    } error;
+} mbed_crash_data_t;
+
 #if defined(__ARMCC_VERSION)
-extern uint32_t Image$$RW_m_crash_data$$ZI$$Base[];
-extern uint32_t Image$$RW_m_crash_data$$ZI$$Size;
-#define __CRASH_DATA_RAM_START__    Image$$RW_m_crash_data$$ZI$$Base
+#define MBED_CRASH_DATA Image$$RW_m_crash_data$$ZI$$Base
 #elif defined(__ICCARM__)
-extern uint32_t __CRASH_DATA_RAM_START__[];
-extern uint32_t __CRASH_DATA_RAM_END__[];
+#define MBED_CRASH_DATA __CRASH_DATA_RAM_START__
 #elif defined(__GNUC__)
-extern uint32_t __CRASH_DATA_RAM_START__[];
-extern uint32_t __CRASH_DATA_RAM_END__[];
-#endif /* defined(__CC_ARM) */
+#define MBED_CRASH_DATA __CRASH_DATA_RAM_START__
+#endif
 
-/* Offset definitions for context capture */
-#define FAULT_CONTEXT_OFFSET    (0x0)
-#define FAULT_CONTEXT_SIZE      (0x80 / 4)    //32 words(128 bytes) for Fault Context
-#define ERROR_CONTEXT_OFFSET    (FAULT_CONTEXT_OFFSET + FAULT_CONTEXT_SIZE)
-#define ERROR_CONTEXT_SIZE      (0x80 / 4)    //32 words(128 bytes) bytes for Error Context
-#define FAULT_CONTEXT_LOCATION  (__CRASH_DATA_RAM_START__ + FAULT_CONTEXT_OFFSET)
-#define ERROR_CONTEXT_LOCATION  (__CRASH_DATA_RAM_START__ + ERROR_CONTEXT_OFFSET)
+extern mbed_crash_data_t MBED_CRASH_DATA;
 /**@}*/
 #endif