On Tue, Jul 28, 2009 at 04:11:57PM +0800, Liu Yu-B13201 wrote: > > On Sat, Jul 25, 2009 at 04:40:12PM +0800, Liu Yu wrote: > > > For example booke has a code template for > > > jumping to and returning from interrupt handlers: > > > > > > bl transfer > > > .long handler_addr > > > .long ret_addr > > > > > > when call transfer, it never return but > > > in transfer assembly code it will read the handler_addr > > > and ultimately call the handler. > > > Gdb doesn't know that and treat it as a normal function call. > > > so gdb put a software breakpoint instruction at handler_addr, > > > in order to get trap there when return from transfer. > > > > > > Then guest will read software breakpoint as handler_addr > > and jump to there.. > > > > > > I'm not sure if x86 suffer this kind of issue. > > > Is there any way to avoid this? > > > > You would need to modify GDB to recognize this sort of case with the > > skip_trampoline_code gdbarch method. > > Hmm.. I am not a gdb expert. > But even gdb can recognize this pattern, is it safe to skip it?
The code doesn't get skipped. skip_trampoline_code is a hook for telling GDB "this function doesn't return in the normal way: here's where execution will resume once this function finishes." That way GDB can place the software breakpoint in the correct location: in this case, at the address handler_addr. -Nathan -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
