Cortex-M4 堆栈中的代码执行

Question

我正在尝试将代码从代码内存复制到堆栈，然后使用堆栈中的代码执行。我正在使用以下功能

;Personal Function
IMPORT extfunc
EXPORT func
func
LDR R0,=extfunc;Function  in C 
LDR R1,=0x00000000;Counter for Counting instructions when i make code generic
PUSH {LR};For nested call       
ADD R3,SP,#0x00;move 
SUB SP,#0x10;As stack grows upwards, we just make space for 10 instructions for testing
ADD R5,SP,#0x0;Where we branch after copying
LOOP
LDR SP,[R0];Load in stack instruction
ADD R1,R1,#0x01;instruction count
ADD R0,#0x04;next C instruction address 
ADD SP,#0x04;next instruction address
CMP R1,#0x10;Copy 10 instructions
BLT LOOP
ADD R0,PC,#0x0C;Get ready for branching
ADD LR,R0,#0x00;LR prepared
ADD PC,R5,#0x00;GO
ADD SP,R3,#0x00;When we return restore the SP
POP {LR}
BX LR

但我收到以下错误

startup_XMC4500.s(335): error: A1477E: This register combination results in UNPREDICTABLE behaviour

startup_XMC4500.s(336): error: A1477E: This register combination results in UNPREDICTABLE behaviour

显然你不能将 PC 移动到在运行时间计算的任意地址，谁能告诉我这个问题的解决方法？

Answer 1

事实证明，您不能通过添加具有某些值的寄存器并将它们存储回来来操作特殊寄存器，您必须使用显式加载或存储指令..

Cortex-M4 堆栈中的代码执行

Code execution in Stack in Cortex-M4

assembly

stack

arm

runtime