ZynqMP and Versal crash clearing coherent cache memory with memset

[Chris Johns]

Hi,

I cannot run libbsd on real hardware because the cadence rx descriptor cache
coherent allocation crashes in `memset`. It is used to clear the memory.

The rtemsbsd allocator call optionally clears the memory and it seems the newlib
aarch64 memset code crashes when doing this. A basic loop with 8bit or 32bit
writes does not crash. The memset call happily clears an array in cached memory
with different offsets.

I have posted a patch to spcache01 that generates the crash on Versal and ZynqMP
hardware. The crash dump is:

test cache coherent allocation
clear cache coherent with memset: 0x1fe00050


*** FATAL ***
fatal source: 9 (RTEMS_FATAL_SOURCE_EXCEPTION)


X0   = 0x000000001fe00050 X17  = 0x000000000000000c
X1   = 0x0000000000000000 X18  = 0x00000000100007b0
X2   = 0x0000000000000110 X19  = 0x000000001fe00050
X3   = 0x000000001fe000c0 X20  = 0x000000001fdfff80
X4   = 0x000000001fe00250 X21  = 0x0000000010013ab0
X5   = 0x0000000000000004 X22  = 0x0000000000000000
X6   = 0x0000000000000001 X23  = 0x00000000ffffffff
X7   = 0x0000000000000000 X24  = 0x0000000010103140
X8   = 0x0000000000000000 X25  = 0x0000000000000000
X9   = 0xffffff80ffffffc8 X26  = 0x0000000000000000
X10  = 0x0000000000000000 X27  = 0x0000000000000000
X11  = 0x000000001010ca78 X28  = 0x0000000000000000
X12  = 0x0000000000000001 FP   = 0x000000001010cc30
X13  = 0x000000001fe00050 LR   = 0x0000000010001f94
X14  = 0x0000000000000000 SP   = 0x000000001010cc30
X15  = 0x0000000000000004 PC   = 0x00000000100125c0
X16  = 0x000000001000f700 DAIF = 0x00000000000003c0
VEC  = 0x0000000000000004 CPSR = 0x0000000060000005
ESR  = EC: 0b100101 IL: 0b1 ISS: 0b0000000000000000001100001
       Data Abort taken without a change in Exception level
FAR  = 0x000000001fe000c0
FPCR = 0x0000000000000000 FPSR = 0x0000000000000010

The Versal (A72) fails in exactly the same way. The allocated address is
0x1fe00050 and the FAR is 0x1fe000c0 so I am not sure if the "0xc0 - 0x50"
section is aligning the pointer to a larger word size for better performance and
that first part is OK but the different word size breaks.

Chris