On Sat, Apr 27, 2019 at 12:06:38PM +0200, Nicolai Stange wrote: > ftrace_int3_handler()'s context is different from the interrupted call > instruction's one, obviously. In order to be able to emulate the call > within the original context, make ftrace_int3_handler() set its iret > frame's ->ip to some helper stub. Upon return from the trap, this stub will > then mimic the call by pushing the the return address onto the stack and > issuing a jmp to the target address. As describe above, the jmp target > will be either of ftrace_ops_list_func() or ftrace_regs_caller(). Provide > one such stub implementation for each of the two cases. Yuck; I'd much rather we get that static_call() stuff sorted such that text_poke() and poke_int3_handler() can do CALL emulation. Given all the back and forth, I think the solution where we shift pt_regs a bit to allow the emulated PUSH is a viable solution; eg. I think we collectively hated it least.
