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Still puzzling over nasty stack corruption

Posted by Christian Koerber on August 14, 2006
Hi,
I'm still puzzling over my corrupted stack. I have tracked
the issue down until the portRESTORE_CONTEXT becomes expanded:

System Info:
- Atmel SAM7s256 64k RAM, 256k ROM
- Everything in ThUMB mode but startup, ARM7 parts of FreeRTOS
and possibly interrupts
- The stack of the first TASK is inspected with

void MemTrace( u32* adress, short nElements)
{
for( unsigned int i = 0; i < nElements; i++ )
TRACE("0x%lx + %d: 0x%lx\r\n", adress, i * 4, adress );
}

The stack looks fine after creation of the task.
The order of the functions which are called before the
first task is started is, to my knowledge:

Function File Mode Stack

vTaskStartScheduler() tasks.c THUMB OK
xPortStartScheduler() port.c THUMB OK
vPortISRStartFirstTask() portISR.c ARM ?
portRESTORE_CONTEXT portmacro.h ARM ?
vATaskMCP() Task_MCP.c THUMB NOK

Note that vPortISRStartFirstTask() is just expanding
the portRESTORE_CONTEXT assembler macro.

So directly before vPortISRStartFirstTask() the stack
looks like:

0x209e4c + 0: 0xa5a5a5a5
0x209e4c + 4: 0xa5a5a5a5
...
0x209e4c + 1924: 0xa5a5a5a5
0x209e4c + 1928: 0x0
0x209e4c + 1932: 0x3f
0x209e4c + 1936: 0x0
0x209e4c + 1940: 0x1010101
0x209e4c + 1944: 0x2020202
0x209e4c + 1948: 0x3030303
0x209e4c + 1952: 0x4040404
0x209e4c + 1956: 0x5050505
0x209e4c + 1960: 0x6060606
0x209e4c + 1964: 0x7070707
0x209e4c + 1968: 0x8080808
0x209e4c + 1972: 0x9090909
0x209e4c + 1976: 0x10101010
0x209e4c + 1980: 0x11111111
0x209e4c + 1984: 0x12121212
0x209e4c + 1988: 0x20a618
0x209e4c + 1992: 0xaaaaaaaa
0x209e4c + 1996: 0x10e035

I understand that the portRESTORE_CONTEXT macro does,
in this case, nothing else but start the first
task. Since all tasks but the one I'm inspecting were
suspended, execution should resume in this task.
The first thing I do in this task is looking at my
stack. Doing this must alter the stack to some degree
of course, but in, ahem, an ordered manner (sorry,
can't put it any better)?

Now the stack looks like this:

0x209e4c + 0: 0xa5a5a5a5
0x209e4c + 4: 0xa5a5a5a5
...
0x209e4c + 132: 0xa5a5a5a5
0x209e4c + 136: 0x2
0x209e4c + 140: 0x78
0x209e4c + 144: 0x113f59
0x209e4c + 148: 0x2004e8
0x209e4c + 152: 0xa5a5a5a5
0x209e4c + 156: 0x20a450
0x209e4c + 160: 0x78
0x209e4c + 164: 0x20a5d0
0x209e4c + 168: 0x6
0x209e4c + 172: 0x20a408
0x209e4c + 176: 0x2
0x209e4c + 180: 0x20a3a8
0x209e4c + 184: 0x121443
0x209e4c + 188: 0x11278d
0x209e4c + 192: 0x121443
0x209e4c + 196: 0x11307b
0x209e4c + 200: 0xa5a5a5a5
0x209e4c + 204: 0x2004ec
0x209e4c + 208: 0x0
0x209e4c + 212: 0x20a407
0x209e4c + 216: 0x10
0x209e4c + 220: 0x16
0x209e4c + 224: 0x0
0x209e4c + 228: 0xffffffff
0x209e4c + 232: 0x1217a8
0x209e4c + 236: 0x0
0x209e4c + 240: 0xffffffff
0x209e4c + 244: 0x20a5d0
0x209e4c + 248: 0xa5a5a5a5
...
0x209e4c + 1360: 0xa5a5a5a5
0x209e4c + 1364: 0x121441
0x209e4c + 1368: 0x2
0x209e4c + 1372: 0x20a407
0x209e4c + 1376: 0x6
0x209e4c + 1380: 0xa5a5a5a5
...
0x209e4c + 1456: 0xa5a5a5a5
0x209e4c + 1460: 0x35613561
0x209e4c + 1464: 0x31363533
0x209e4c + 1468: 0x20a3a0
0x209e4c + 1472: 0x0
0x209e4c + 1476: 0x0
0x209e4c + 1480: 0xa5a5a5a5
0x209e4c + 1484: 0xa5a5a5a5
0x209e4c + 1488: 0xa5a5a5a5
0x209e4c + 1492: 0xa5a5a5a5
0x209e4c + 1496: 0xa5a5a5a5
0x209e4c + 1500: 0xa5a5a5
0x209e4c + 1504: 0x8080808
0x209e4c + 1508: 0x9090909
0x209e4c + 1512: 0x10101010
0x209e4c + 1516: 0x11111111
0x209e4c + 1520: 0x121430
0x209e4c + 1524: 0x209e4c
0x209e4c + 1528: 0x1f4
0x209e4c + 1532: 0x7070707
0x209e4c + 1536: 0x113463
0x209e4c + 1540: 0x20a4cf
0x209e4c + 1544: 0xa5a5a5a5
0x209e4c + 1548: 0x7fffffe2
0x209e4c + 1552: 0xffff0208
0x209e4c + 1556: 0x20a4b4
0x209e4c + 1560: 0x7fffffff
0x209e4c + 1564: 0xa5a5a5a5
...
0x209e4c + 1628: 0xa5a5a5a5
0x209e4c + 1632: 0x197
0x209e4c + 1636: 0x10efb9
0x209e4c + 1640: 0x30327830
0x209e4c + 1644: 0x63346539
0x209e4c + 1648: 0x31202b20
0x209e4c + 1652: 0x3a383436
0x209e4c + 1656: 0x33783020
0x209e4c + 1660: 0x33383733
0x209e4c + 1664: 0xd333337
0x209e4c + 1668: 0xa5a50000
0x209e4c + 1672: 0xa5a5a5a5
...
0x209e4c + 1856: 0xa5a5a5a5
0x209e4c + 1860: 0x38
0x209e4c + 1864: 0x36
0x209e4c + 1868: 0x34
0x209e4c + 1872: 0x3a
0x209e4c + 1876: 0x40
0x209e4c + 1880: 0x4016
0x209e4c + 1884: 0x0
0x209e4c + 1888: 0x3a0c
0x209e4c + 1892: 0x0
0x209e4c + 1896: 0x20a5c4
0x209e4c + 1900: 0x1da
0x209e4c + 1904: 0x110407
0x209e4c + 1908: 0x121430
0x209e4c + 1912: 0x209e4c
0x209e4c + 1916: 0x778
0x209e4c + 1920: 0x778
0x209e4c + 1924: 0x4040404
0x209e4c + 1928: 0x5050505
0x209e4c + 1932: 0x6060606
0x209e4c + 1936: 0x10e03f
0x209e4c + 1940: 0x2020202
0x209e4c + 1944: 0x3030303
0x209e4c + 1948: 0x4040404
0x209e4c + 1952: 0x5050505
0x209e4c + 1956: 0x6060606
0x209e4c + 1960: 0x7070707
0x209e4c + 1964: 0x8080808
0x209e4c + 1968: 0x9090909
0x209e4c + 1972: 0x10101010
0x209e4c + 1976: 0x4040404
0x209e4c + 1980: 0x5050505
0x209e4c + 1984: 0x6060606
0x209e4c + 1988: 0x7070707
0x209e4c + 1992: 0xaaaaaaaa
0x209e4c + 1996: 0x10e035

I am clueless abou what is going on here.
To me it looks as if something was
hijacking my stack, but I have not the
slightest hint who could be this.
Any advices are appreciated.

regards,

Christian







RE: Still puzzling over nasty stack corruption

Posted by Richard on August 14, 2006
Which compiler are you using?

Can you zip up your project and send it to me? Use the email address from the FreeRTOS.org contact WEB page ( r __dot~ barry *AT* freertos ~dot org) rather than the sourceforge email address, otherwise the attachment will get stripped off.

Regards.


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