Oleg> Now, to continue the tracee, gdb does not restore the Oleg> original instruction. Instead, it Oleg> - writes this insn into _start code Oleg> - changes regs->ip to point to this insn Oleg> - does single-step to execute this insn Oleg> - changes regs->ip again
This is what is done for non-stop. I believe it is called "displaced stepping" in gdb. I think eventually we would like it if uprobes did this work, instead of gdb doing it. Presumably that would yield better performance. E.g., if we have a thread-specific breakpoint, then other threads hitting that breakpoint could simply do the displaced stepping via uprobes, and not report a breakpoint hit to gdb at all. For all-stop, breakpoints are handled differently, though I don't remember how offhand. Tom
