Stack checker broken on PowerPC/virtex BSP - 4.7.99.1 or later

[Robert S. Grimes]

Chris Johns wrote:
> Robert S. Grimes wrote:
>>
>> I see you have changed cpukit/score/include/rtems/score/object.h a tiny
>> bit - is that the extent of this change?
>>
>
> Yes that is the fix. It is small but it stops the score writing past
> the end of the system object table. In other words it stops it
> corrupting memory.
>
Yes, but that is not the memory being corrupted!  I have applied just
the above mentioned patch to the 4.7.99.2 tarball, and the results are
the same.

I've narrowed it down to the invocation of this macro:

    #define Stack_check_Dope_stack(_stack) \
      memset((_stack)->area, BYTE_PATTERN, (_stack)->size)

In the suspect code, this translates to this:
     memset(0xe75c0, 0xa5, 0x2808);

Thus, it is attempting to set the area from 0xE75C0 to 0xE9DC8

This is the relevant output of the application build process - the .num
map file:

    000e0000 A stack.start
    000e8000 A IntrStack_start
    000e8000 A stack.end
    000ec000 A intrStack
    00100000 A _endloader
    00800000 A _HeapSize


A little fishy?  Yeah, but I don't know why...  Anyway, here is the
exception output:

    Exception handling initialization done
    opb_intc_init: mask = 0x7
    exception handler called for exception 7
         Next PC or Address of fault = A5A5A5A4
         Saved MSR = 0
         R0 = A5A5A5A5
         R1 = E7EB4
         R2 = C56D8
         R3 = 1
         R4 = A5
         R5 = 0
         R6 = FEFFFFFF
         R7 = D0000
         R8 = D327C
         R9 = E9DC8
         R10 = 1
         R11 = E9DC8
         R12 = 0
         R13 = FFFEA680
         R14 = FFFFFFFF
         R15 = FFFFFFFF
         R16 = FFFFFFFF
         R17 = FFFFFFFF
         R18 = FFFFFFFF
         R19 = FFFFFFFF
         R20 = FFFFFFFF
         R21 = FFFFFFFF
         R22 = FFFE0000
         R23 = FFFE0000
         R24 = 0
         R25 = D3154
         R26 = 1
         R27 = 0
         R28 = D0000
         R29 = D33FC
         R30 = E0F38
         R31 = A5A5A5A5
         CR = 39000033
         CTR = 0
         XER = E000007F
         LR = A5A5A5A5
         MSR = 0
         DAR = 0
    Stack Trace:
      IP: 0xA5A5A5A4, LR: 0xA5A5A5A5
    --^ 0x00000000


So it is clearly trying to execute code in the just-doped stack, though
I don't know why...

Anything else I should try?

-Bob