!234 用户态异常处理，进程退出时恢复系统正常运行的过程依赖编译器行为，存在风险

Merge pull request !234 from zhushengle/exc

arch/arm/arm/src/include/los_exc_pri.h

@@ -40,11 +40,6 @@ extern "C" {
 #endif /* __cplusplus */
 #endif /* __cplusplus */
 
-STATIC INLINE VOID OsSetCurrCpuSp(UINTPTR regSp)
-{
-    __asm__ __volatile__("mov sp, %0" :: "r"(regSp));
-}
-
 #define OS_SYSTEM_NORMAL        0
 #define OS_SYSTEM_EXC_CURR_CPU  1
 #define OS_SYSTEM_EXC_OTHER_CPU 2

arch/arm/arm/src/los_exc.c

@@ -525,7 +525,7 @@ VOID OsDumpContextMem(const ExcContext *excBufAddr)
     }
 }
 
-STATIC VOID OsExcRestore(UINTPTR taskStackPointer)
+STATIC VOID OsExcRestore(VOID)
 {
     UINT32 currCpuID = ArchCurrCpuid();
 
@@ -536,8 +536,6 @@ STATIC VOID OsExcRestore(UINTPTR taskStackPointer)
     OsPercpuGet()->excFlag = CPU_RUNNING;
 #endif
     OsPercpuGet()->taskLockCnt = 0;
-
-    OsSetCurrCpuSp(taskStackPointer);
 }
 
 STATIC VOID OsUserExcHandle(ExcContext *excBufAddr)
@@ -564,8 +562,6 @@ STATIC VOID OsUserExcHandle(ExcContext *excBufAddr)
 #endif
     runProcess->processStatus &= ~OS_PROCESS_FLAG_EXIT;
 
-    OsExcRestore(excBufAddr->SP);
-
 #if (LOSCFG_KERNEL_SMP == YES)
 #ifdef LOSCFG_FS_VFS
     OsWakeConsoleSendTask();
@@ -577,6 +573,9 @@ STATIC VOID OsUserExcHandle(ExcContext *excBufAddr)
 #endif
     OsProcessExitCodeSignalSet(runProcess, SIGUSR2);
 
+    /* Exception handling All operations should be kept prior to that operation */
+    OsExcRestore();
+
     /* kill user exc process */
     LOS_Exit(OS_PRO_EXIT_OK);
 
@@ -962,7 +961,7 @@ STATIC VOID OsWaitOtherCoresHandleExcEnd(UINT32 currCpuID)
     }
 }
 
-STATIC VOID OsCheckAllCpuStatus(UINTPTR taskStackPointer)
+STATIC VOID OsCheckAllCpuStatus(VOID)
 {
     UINT32 currCpuID = ArchCurrCpuid();
     UINT32 ret, target;
@@ -982,7 +981,7 @@ STATIC VOID OsCheckAllCpuStatus(UINTPTR taskStackPointer)
     } else if (g_excFromUserMode[currCpuID] == TRUE) {
         if (OsCurrProcessGet()->processID == g_currHandleExcPID) {
             LOS_SpinUnlock(&g_excSerializerSpin);
-            OsExcRestore(taskStackPointer);
+            OsExcRestore();
             while (1) {
                 ret = LOS_TaskSuspend(OsCurrTaskGet()->taskID);
                 PrintExcInfo("%s supend task :%u failed: 0x%x\n", __FUNCTION__, OsCurrTaskGet()->taskID, ret);
@@ -1010,12 +1009,11 @@ STATIC VOID OsCheckAllCpuStatus(UINTPTR taskStackPointer)
 }
 #endif
 
-STATIC VOID OsCheckCpuStatus(UINTPTR taskStackPointer)
+STATIC VOID OsCheckCpuStatus(VOID)
 {
 #if (LOSCFG_KERNEL_SMP == YES)
-    OsCheckAllCpuStatus(taskStackPointer);
+    OsCheckAllCpuStatus();
 #else
-    (VOID)taskStackPointer;
     g_currHandleExcCpuID = ArchCurrCpuid();
 #endif
 }
@@ -1036,7 +1034,7 @@ LITE_OS_SEC_TEXT VOID STATIC OsExcPriorDisposal(ExcContext *excBufAddr)
         g_excFromUserMode[ArchCurrCpuid()] = FALSE;
     }
 
-    OsCheckCpuStatus(excBufAddr->SP);
+    OsCheckCpuStatus();
 
     if (g_excFromUserMode[ArchCurrCpuid()] == TRUE) {
         while (1) {

arch/arm/arm/src/los_hw_exc.S

@@ -371,6 +371,13 @@ _osExceptDispatch:
 
     MOV     R1, SP
 
+#ifdef LOSCFG_KERNEL_VM
+    LDR     R2, [SP, #(19 * 4)]                              @ Get CPSR
+    AND     R2, R2, #CPSR_MASK_MODE                          @ Interrupted mode
+    CMP     R2, #CPSR_USER_MODE                              @ User mode
+    BEQ     _osExceptionGetSP
+#endif
+
     EXC_SP_SET __exc_stack_top, OS_EXC_STACK_SIZE, R6, R7
 
     MRC     P15, 0, R4, C0, C0, 5