注解汇编代码如何保存任务上下文

    百万汉字注解 + 百篇博客分析 => 挖透鸿蒙内核源码
    https://weharmony.gitee.io

arch/arm/arm/src/include/los_hw_pri.h

@@ -51,7 +51,7 @@ extern "C" {
 
 /* The size of this structure must be smaller than or equal to the size specified by OS_TSK_STACK_ALIGN (16 bytes). */
 typedef struct { //参考OsTaskSchedule来理解
-#if !defined(LOSCFG_ARCH_FPU_DISABLE)
+#if !defined(LOSCFG_ARCH_FPU_DISABLE) //支持浮点运算
     UINT64 D[FP_REGS_NUM]; /* D0-D31 */
     UINT32 regFPSCR;       /* FPSCR */
     UINT32 regFPEXC;       /* FPEXC */

arch/arm/arm/src/los_dispatch.S

@@ -134,12 +134,12 @@ LDM/STR架构中{∧}为可选后缀,当指令为LDM且寄存器列表中包含R
 /* macros to save and restore fpu regs */ 
 .macro PUSH_FPU_REGS reg1 /* 保存fpu寄存器 */ 
 #if !defined(LOSCFG_ARCH_FPU_DISABLE) @FPU使能
-    VMRS    \reg1, FPEXC
-    PUSH    {\reg1}
-    VMRS    \reg1, FPSCR
-    PUSH    {\reg1}
+    VMRS    \reg1, FPEXC 	
+    PUSH    {\reg1}			@对应TaskContext->regFPEXC
+    VMRS    \reg1, FPSCR	
+    PUSH    {\reg1}			@对应TaskContext->regFPSCR
 #if defined(LOSCFG_ARCH_FPU_VFP_D32)
-    VPUSH   {D16-D31}
+    VPUSH   {D16-D31}		@对应TaskContext->D
 #endif
     VPUSH   {D0-D15}
 #endif
@@ -200,14 +200,14 @@ OsTaskSchedule:			/*任务调度,OsTaskSchedule的目的是将寄存器值按Tas
     PUSH_FPU_REGS   R2	/*保存fpu寄存器*/
 
     /* store sp on running task */
-    STR     SP, [R1] @在运行的任务栈中保存SP,即runTask->stackPointer = sp
+    STR     SP, [R1] @在运行的任务栈中保存SP,即*runTask->stackPointer = sp
 
 OsTaskContextLoad: @加载上下文
     /* clear the flag of ldrex */ @LDREX 可从内存加载数据,如果物理地址有共享TLB属性，则LDREX会将该物理地址标记为由当前处理器独占访问，并且会清除该处理器对其他任何物理地址的任何独占访问标记。
     CLREX @清除ldrex指令的标记
 
     /* switch to new task's sp */
-    LDR     SP, [R0] @ 即:sp = new task->stackPointer
+    LDR     SP, [R0] @ 即:sp =  *task->stackPointer
 
     /* restore fpu registers */
     POP_FPU_REGS    R2 @恢复fpu寄存器,这里用了汇编宏R2是宏的参数

arch/arm/arm/src/los_hw.c

@@ -74,7 +74,7 @@ VOID OsTaskEntrySetupLoopFrame(UINT32 arg0)
                  "\tpop {fp, pc}\n");
 }
 #endif
-//任务栈初始化,非常重要的函数
+//内核态运行栈初始化
 LITE_OS_SEC_TEXT_INIT VOID *OsTaskStackInit(UINT32 taskID, UINT32 stackSize, VOID *topStack, BOOL initFlag)
 {
     UINT32 index = 1;
@@ -83,7 +83,7 @@ LITE_OS_SEC_TEXT_INIT VOID *OsTaskStackInit(UINT32 taskID, UINT32 stackSize, VOI
     if (initFlag == TRUE) {
         OsStackInit(topStack, stackSize);
     }
-    taskContext = (TaskContext *)(((UINTPTR)topStack + stackSize) - sizeof(TaskContext));//注意看上下文将存放在栈的底部
+    taskContext = (TaskContext *)(((UINTPTR)topStack + stackSize) - sizeof(TaskContext));//上下文存放在栈的底部
 
     /* initialize the task context */ //初始化任务上下文
 #ifdef LOSCFG_GDB
@@ -94,10 +94,10 @@ LITE_OS_SEC_TEXT_INIT VOID *OsTaskStackInit(UINT32 taskID, UINT32 stackSize, VOI
     taskContext->LR = (UINTPTR)OsTaskExit;  /* LR should be kept, to distinguish it's THUMB or ARM instruction */
     taskContext->resved = 0x0;
     taskContext->R[0] = taskID;             /* R0 */
-    taskContext->R[index++] = 0x01010101;   /* R1, 0x01010101 : reg initialed magic word */
+    taskContext->R[index++] = 0x01010101;   /* R1, 0x01010101 : reg initialed magic word */ //0x55
     for (; index < GEN_REGS_NUM; index++) {//R2 - R12的初始化很有意思,为什么要这么做？
         taskContext->R[index] = taskContext->R[index - 1] + taskContext->R[1]; /* R2 - R12 */
-    }
+    }//R[2]=R[2]<<1=0xAA
 
 #ifdef LOSCFG_INTERWORK_THUMB // 16位模式
     taskContext->regPSR = PSR_MODE_SVC_THUMB; /* CPSR (Enable IRQ and FIQ interrupts, THUMNB-mode) */
@@ -127,7 +127,7 @@ LITE_OS_SEC_TEXT VOID OsUserCloneParentStack(LosTaskCB *childTaskCB, LosTaskCB *
     (VOID)memcpy_s(childTaskCB->stackPointer, sizeof(TaskContext), cloneStack, sizeof(TaskContext));//直接把任务上下文拷贝了一份
     context->R[0] = 0;//R0寄存器为0
 }
-//用户任务使用栈初始化
+//用户态运行栈初始化
 LITE_OS_SEC_TEXT_INIT VOID OsUserTaskStackInit(TaskContext *context, TSK_ENTRY_FUNC taskEntry, UINTPTR stack)
 {
     LOS_ASSERT(context != NULL);

kernel/base/core/los_task.c

@@ -762,12 +762,12 @@ LITE_OS_SEC_TEXT_INIT STATIC VOID OsTaskCBInitBase(LosTaskCB *taskCB,
                                                    const VOID *topStack,
                                                    const TSK_INIT_PARAM_S *initParam)
 {
-    taskCB->stackPointer = (VOID *)stackPtr;
+    taskCB->stackPointer = (VOID *)stackPtr;//内核态SP位置
     taskCB->args[0]      = initParam->auwArgs[0]; /* 0~3: just for args array index */
     taskCB->args[1]      = initParam->auwArgs[1];
     taskCB->args[2]      = initParam->auwArgs[2];
     taskCB->args[3]      = initParam->auwArgs[3];
-    taskCB->topOfStack   = (UINTPTR)topStack;	//内核态栈顶位置
+    taskCB->topOfStack   = (UINTPTR)topStack;	//内核态栈起始位置
     taskCB->stackSize    = initParam->uwStackSize;//
     taskCB->priority     = initParam->usTaskPrio;
     taskCB->taskEntry    = initParam->pfnTaskEntry;
@@ -809,7 +809,7 @@ LITE_OS_SEC_TEXT_INIT STATIC UINT32 OsTaskCBInit(LosTaskCB *taskCB, const TSK_IN
     SCHEDULER_LOCK(intSave);
     processCB = OS_PCB_FROM_PID(initParam->processID);//通过ID获取PCB ,单核进程数最多64个
     taskCB->processID = processCB->processID;//进程-线程的父子关系绑定
-    mode = processCB->processMode;//调度方式同步process
+    mode = processCB->processMode;//模式方式同步process
     LOS_ListTailInsert(&(processCB->threadSiblingList), &(taskCB->threadList));//挂入进程的线程链表
     if (mode == OS_USER_MODE) {//用户模式
         taskCB->userArea = initParam->userParam.userArea;
@@ -887,7 +887,7 @@ LITE_OS_SEC_TEXT_INIT UINT32 LOS_TaskCreateOnly(UINT32 *taskID, TSK_INIT_PARAM_S
         goto LOS_ERREND_REWIND_TCB;
     }
 	//OsTaskStackAlloc 只在LOS_TaskCreateOnly中被调用,此处是分配任务在内核态栈空间 
-    OsTaskStackAlloc(&topStack, initParam->uwStackSize, pool);//为任务栈分配空间
+    OsTaskStackAlloc(&topStack, initParam->uwStackSize, pool);//为任务分配内核态栈空间
     if (topStack == NULL) {
         errRet = LOS_ERRNO_TSK_NO_MEMORY;
         goto LOS_ERREND_REWIND_SYNC;

kernel/base/include/los_task_pri.h

@@ -145,7 +145,7 @@ extern SPIN_LOCK_S g_taskSpin;//任务自旋锁
  *
  * The time for waiting for an event to occur expires.
  */
-#define OS_TASK_STATUS_TIMEOUT      0x0040U
+#define OS_TASK_STATUS_TIMEOUT      0x0040U	//任务超时
 
 /**
  * @ingroup los_task
@@ -294,13 +294,13 @@ extern SPIN_LOCK_S g_taskSpin;//任务自旋锁
 #define OS_TCB_NAME_LEN 32
 
 typedef struct {
-    VOID            *stackPointer;      /**< Task stack pointer */	//用于保存任务上下文TaskContext *context
+    VOID            *stackPointer;      /**< Task stack pointer */	//内核态栈指针,SP位置,切换任务时先保存上下文并指向TaskContext位置.
     UINT16          taskStatus;         /**< Task status */			//各种状态标签，可以拥有多种标签，按位标识
     UINT16          priority;           /**< Task priority */		//任务优先级[0:31],默认是31级
     UINT16          policy;				//任务的调度方式(三种 .. LOS_SCHED_RR )
     UINT16          timeSlice;          /**< Remaining time slice *///剩余时间片
-    UINT32          stackSize;          /**< Task stack size */		//非用户模式下栈大小
-    UINTPTR         topOfStack;         /**< Task stack top */		//非用户模式下的栈顶 bottom = top + size
+    UINT32          stackSize;          /**< Task stack size */		//内核态栈大小
+    UINTPTR         topOfStack;         /**< Task stack top */		//内核态栈顶 bottom = top + size
     UINT32          taskID;             /**< Task ID */				//任务ID，任务池本质是一个大数组，ID就是数组的索引，默认 < 128
     TSK_ENTRY_FUNC  taskEntry;          /**< Task entrance function */	//任务执行入口函数
     VOID            *joinRetval;        /**< pthread adaption */	//用来存储join线程的返回值

zzz/git/push.sh

 git add -A
-git commit -m  '注解汇编代码如何保持任务上下文
+git commit -m  '注解汇编代码如何保存任务上下文
     百万汉字注解 + 百篇博客分析 => 挖透鸿蒙内核源码
     https://weharmony.gitee.io
 '