On 01/12/2013 09:06 AM, Oleg Nesterov wrote: > On 01/10, Josh Stone wrote: >> and for uretprobes we want the original return address. > > Yes, Anton's v2 does this. > > But. Don't you also need to know the address of function we are going > to return from? > > Probably you do not, uprobe_consumer should know which function (but > not vaddr) it probes, but please confirm.
Right, this is fine. The main reason we need a fixed-up IP is to have a consistent user state for unwinding and evaluating other related DWARF expressions. Setting regs->ip to the entry address of the function we just returned from would actually be harmful, as it would be completely lying about the current execution point, and the rest of the register and memory state wouldn't match that point either. Maybe it would be useful if regs->ip reflected the address of the RET instruction we just executed, but only if e.g. regs->sp also got rewound accordingly. Since I don't think this is possible, just setting regs->ip to the return target is good enough. Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
