> > As I am bit concerned with performance why require nops there? Add a > > byte count number >= requested thats boundary of next instruction. When > > lifepatching for return you need to copy this followed by jump back to next > > instruction. Then gcc could fill that with instructions that don't > > depend on address, fill with nops as trivial first implementation. > > > > Would that be possible? > > So instead of placing NOPs to be overwritten you intend to simply overwrite > the existing code after > making a backup of it?
This is how Linux k/uprobes work. But it only works for a subset of instructions and is fairly complicated because you need a complete decoder that is able to adjust any program counter relative data offsets. Having a patch area is far easier and more reliable. -Andi -- a...@linux.intel.com -- Speaking for myself only
