For this we need to:
- Use the correct undefined instruction
- Leave space on the exception stack to emulate the push instruction with 16 registers
- Call dtrace_invop_jump_addr iff it's set and we are called from kernel context
- Pass the details of the push, pop, and branch instructions to the code emulating them
- Emulate said instructions
With this I am able to use probes like:
dtrace -n 'fbt::free:return { stack (); }'and:
dtrace -n 'fbt::malloc:entry { stack (); }'on my ARM board.