[lldb-dev] Is there a way to inspect signaled stack?

Eugene Birukov via lldb-dev lldb-dev at lists.llvm.org
Mon Nov 16 09:41:06 PST 2015


You are right, it does work - sorry for false alarm.

> From: labath at google.com
> Date: Mon, 16 Nov 2015 11:26:10 +0000
> Subject: Re: [lldb-dev] Is there a way to inspect signaled stack?
> To: eugenebi at hotmail.com
> CC: lldb-dev at lists.llvm.org
> 
> Hi Eugene,
> 
> the libc signal trampoline should have .eh_frame unwind info (I am
> assuming this is x86_64 btw), and last time I looked at it, it seemed
> that it should be able to handle sigaltstack(). However, I have never
> tested this, so it's quite possible there is still some bug hidden
> there. Could you file a bug with a small repro case and attach the
> output of (thread backtrace) with logging enabled (log enable lldb
> unwind). We'll try to look at it.
> 
> thanks,
> pl
> 
> 
> On 13 November 2015 at 19:22, Eugene Birukov via lldb-dev
> <lldb-dev at lists.llvm.org> wrote:
> > Hi,
> >
> > I am running on Ubuntu Linux. I am using a custom debugger built upon LLDB
> > C++ API using version 3.7.
> >
> > The target program issues a lot of "legitimate" SIGSEGV signals that it
> > handles itself. Its signal handler runs on a separate stack (it uses
> > sigaltstack() and SA_ONSTACK). Now, sometimes a bug in the program causes
> > SIGSEGV that the handler cannot deal with and it crashes. Now, when I load
> > the core, I see stack frames for the signal handler stack, but what I really
> > need are frames for the signaled stack.
> >
> > Of course, I have access to siginfo_t and ucontext_t, so I can try to use
> > some unwind library, but that approach is far from ideal - the LLDB already
> > has the unwinder. So, what should I do to get the set of SBFrame's that I
> > can query about local variables, etc.? I mean, something like .cxr command
> > in Windbg would be really handy...
> >
> > Thanks,
> > Eugene
> >
> > _______________________________________________
> > lldb-dev mailing list
> > lldb-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
> >
 		 	   		  
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