Re: DTrace - capturing two userspace strack frames on top of system call

From: Mark Johnston <markj_at_freebsd.org>
Date: Tue, 24 Jan 2023 16:15:46 UTC 
On Mon, Jan 23, 2023 at 04:54:05PM -0500, Martin Cracauer wrote:
> Mark Johnston wrote on Mon, Jan 23, 2023 at 11:52:12AM -0500: 
> > On Sun, Jan 22, 2023 at 10:04:50PM -0500, Martin Cracauer wrote:
> > > Actually the error only appears on arm64 for me.  I moved the script
> > > to amd64 and it works as I thought.
> > 
> > Support for userspace tracing on arm64 is definitely less mature than on
> > amd64, so this isn't too surprising, unfortunately.
> > 
> > Is the problem reproducible with a trivial program compiled with
> > -fno-omit-frame-pointer?
> 
> Yes:
> $ gcc -O2 -fno-omit-frame-pointer -Wall -Werror -o crasparse crasparse.c
> # dtrace -n 'syscall::write*:entry /arg1/ { @traces[ustack()] = count(); }' -c ./crasparse
> dtrace: error on enabled probe ID 1 (ID 57136: syscall:freebsd:writev:entry): invalid address (0x0) in action #2
> [...]
> 
> Should I make a bugzilla entry out of this?

Yes please, that would be helpful.