Dumping Registers in PPC

Question

I'm trying to dump the value of r5 so that I can see what var_A0 data is. I am trying to dump in PPC since I'm using UART debugging on the XBox 360 console,
EX): I'm trying to figure out what the value of var_A0 is

addi      r5, r1, 0x110+var_A0

Code im using is ::

PrintKey:
    lis     %r29, -0x8000
    ori     %r29, %r29, 0x100
    sldi    %r3, %r29, 32
    ori     %r3, %r3, 0x247C  # 0x800001000000247C
    li      %r4, 0x80
    bl      printAddress
printAddress:
    mr      %r30, %r3
    mr      %r11, %r4           # text size
    mtctr   %r11

But this only print the physical code in the HV not the Registers Data

Answer 1

There are a few things you'll need to sort out here:

The printAddress function looks like it takes an address in r3, and a size in r4, then (presumably) prints the contents of memory at that address. We have no way of telling how that printing is done, as the code to do that is missing from your question.

Consequently, you probably don't want to use printAddress to display the value of r5. You could probably adapt the actual printing code (which is missing) to just print the contents of a register, rather than memory.

However: the actual thing you want to find out (the value of var_A0) is likely to be determined at compile time (or at least during final link - is this binary statically linked?). Check the disassembled code, and/or check for dynamic relocation entries if this is a dynamic executable.

Alternatively, you could use printAddress to print the contents of the memory containing the addi instruction, then manually decode the instruction to determine the immediate value used in the addi.