Copy function to RAM and call it with function pointer

Question

Hello, 
 
 I am trying to copy the function to RAM and then call it using a function pointer like below: 
 It forced a system restart and it should have encountered an error. 
 Can you please help me deal with it? Thanks in advance! 
 uint8_t ram_func(uint8_t data_in)
{
 data_in++;
 return data_in;
}
/*---------------------------------------------------------------*/
int main() {
 typedef uint8_t (*func_ptr)(uint8_t);
 uint8_t func_buffer[256];
 memset(func_buffer, 0, 256);
 // Copy the machine code of func into func_buffer
 memcpy(&func_buffer, (uint8_t*)ram_func, 255);

 // Create a function pointer and cast the buffer address to it
 func_ptr fp = (func_ptr)func_buffer;

 // Call the function through the function pointer
 uint8_t data_out = fp(3);

 printf("Result = %d
", data_out);
 return 0;
}

hmolesworth · Answer

Same code, but also returning a value on stack in case something was amiss there; seems ok: 
 uint8_t ram_func(uint8_t data_in)
{
 data_in++;
 return data_in;
}
static uint8_t RamFuncTestSub(void) {
 typedef uint8_t (*func_ptr)(uint8_t);
 uint32_t func_buffer[64];
 // Copy the machine code of func into func_buffer
 uint32_t *pRAM=func_buffer;
 uint32_t *pCode=(uint32_t *)((uint32_t)&ram_func & 0xFFFFFFFEUL);
 for (uint32_t i=0UL; i<sizeof(func_buffer)/sizeof(func_buffer[0]); i++)
 {
 *pRAM++ = *pCode++;
 }
 // Create a function pointer and cast the buffer address to it, remember Thumb Mode
 uint32_t *pfunc_buffer = (uint32_t*)(((uint32_t)func_buffer) | 0x00000001UL);
 func_ptr fp = (func_ptr)pfunc_buffer;
 // Test code function to verify that works
 uint8_t data_out1 = ram_func(2);
 // Call the function through the function pointer
 uint8_t data_out2 = fp(3);
 return data_out2;
}
static void RamFuncTest(void) {
 //printf("start

");
 uint8_t result = RamFuncTestSub();
 //printf("Result = %d
", result);
 while(1) ;
} 
 I even tested with buffer on stack; all ok.