Bad memory access in GUI_Init()

Hello,

Recently, I encountered an annoying issue causing freezing.
It seems like dereferencing a null pointer.
Please refer to the image below:

It appears to happen in a call to LCD_INIT->GUI_SelectLayer->GUI_SelectLCD->LCD_UpdateColorIndices->LCD_SetColorIndex.
Within that function r1 is loaded from a location with an offset of 0x3C, so probably a structure member.
The content is loaded in r1, but is zero. The next instruction (see yellow arrow) stores r0 back to location zero and thus overwriting the initial stackpointer.

I checked the soruce code:

void LCD_SetColorIndex(unsigned PixelIndex) {
  if (GUI_pContext->DrawMode & LCD_DRAWMODE_REV) {
    LCD__SetBkColorIndex(PixelIndex);
  } else {
    LCD__SetColorIndex(PixelIndex);
  }
}

#define LCD__SetBkColorIndex(Index) (*GUI_pContext->LCD_pBkColorIndex = Index)
#define LCD__SetColorIndex(Index)   (*GUI_pContext->LCD_pColorIndex   = Index)
#define LCD__GetBkColorIndex()      (*GUI_pContext->LCD_pBkColorIndex)
#define LCD__GetColorIndex()        (*GUI_pContext->LCD_pColorIndex)

From the image, you can get that: the value of GUI_pContext->LCD_pColorIndex is null!
So, any solutions? Please save me!

My project using:
1) i.MX RT1050
2) KEIL RTX OS2
3) emWin v5.48j

PS:
To catch this, I set ITCM read only to MPU.

Thanks,
Kenmux

Hi Sven,

Today I step into the vary functions.

First, the values in the struct pointed by GUI_pContext seems okay after first initial:

But, after calling GUI_LOCK() in the function GUI_SelectLayer() all cleared to 0:

by this:

GUI_pContext = &_pSave[TaskNo].Context;

It seems a context switching occurred.
Then this pointer GUI_pContext->LCD_pColorIndex (its value is 0) is dereferenced.

Hi Sven,

I check the project over and over again and still the same story.
For I step into this issue using the source codes, so it should not be the library.

If I set ITCM read write to MPU, then the code runs well.
(Yes, this bad memory access occurred, too.)

For the address of ITCM start from 0x00000000, and we decide to put crucial code to it.
So this issue makes the code crashing from the very beginning.

Attached's the config file & OS specific file.
I've removed the file header for the license info.

I also check the two tasks: system tick task, background task, and they're running well.
Before the function GUI_SelectLayer() being called, the two tasks run several times.

So what should be the problem? Any ideas?

Thanks,
Kenmux

Hi Sven,

It's MIMXRT1052.
The project is built with Keil μVision5.

Attached is the code for config MPU.

Thanks,
Kenmux

Hi Sven,

Okay, I see. Thanks for your work though.

Regards,
Kenmux