Messages in this thread | | | Date | Fri, 22 Jul 2016 06:49:01 +0900 | From | Byungchul Park <> | Subject | Re: [PATCH 15/19] x86/dumpstack: convert show_trace_log_lvl() to the new unwinder |
| |
On Thu, Jul 21, 2016 at 04:21:52PM -0500, Josh Poimboeuf wrote: > Convert show_trace_log_lvl() to the new unwinder. dump_trace() has been > deprecated. > > show_trace_log_lvl() is special compared to other users of the unwinder. > It's the only place where both reliable *and* unreliable addresses are > needed. With frame pointers enabled, most stack walking code doesn't > want to know about unreliable addresses. But in this case, when we're > dumping the stack to the console because something presumably went > wrong, the unreliable addresses are useful: > > - They show stale data on the stack which can provide useful clues. > > - If something goes wrong with the unwinder, or if frame pointers are > corrupt or missing, all the stack addresses still get shown. > > So in order to show all addresses on the stack, and at the same time > figure out which addresses are reliable, we have to do the scanning and > the unwinding in parallel. > > The scanning is done with the help of get_stack_info() to traverse the > stacks. The unwinding is done separately by the new unwinder. > > In theory we could simplify show_trace_log_lvl() by instead pushing some > of this logic into the unwind code. But then we would need some kind of > "fake" frame logic in the unwinder which would add a lot of complexity > and wouldn't be worth it in order to support only one user. > > Another benefit of this approach is that once we have a DWARF unwinder, > we should be able to just plug it in with minimal impact to this code. > > Another change here is that callers of show_trace_log_lvl() don't need > to provide the 'bp' argument. The unwinder already finds the relevant > frame pointer by unwinding until it reaches the first frame after the > provided stack pointer.
Hello,
You seem to have changed a lot of code with which I dealt in another patch. I might be supposed to wait until yours will be done. I need to check yours at first anyway.
| |