Date: Wed, 24 Oct 2018 20:26:21 +0300 From: Lev Serebryakov <lev@FreeBSD.org> To: Ryan Stone <rysto32@gmail.com> Cc: freebsd-hackers@freebsd.org, Conrad Meyer <cse.cem@gmail.com>, Alan Somers <asomers@freebsd.org> Subject: Re: What is wrong with dtrace's stack()? Message-ID: <eab6fa6a-a702-dda1-9d21-d249b8446978@FreeBSD.org> In-Reply-To: <CAFMmRNzSAVfGywx%2BPfkQ1Oq1Lt3c53FFQpxDagnkdN=AYQqBCA@mail.gmail.com> References: <170994671.20181021201021@serebryakov.spb.ru> <CAG6CVpVCe-8OVU%2BKEyAh8swFSAjRshNcNLN0tjAS3W8bZxyrTA@mail.gmail.com> <475670271.20181022003734@serebryakov.spb.ru> <CAOtMX2goztCYJXM72WNR711DEBEKAGk1zFHF=NpE4UiVAF2bAQ@mail.gmail.com> <234d745d-37a9-9610-15b9-0f5cd5af21bf@FreeBSD.org> <b30f2080-1037-1752-60fb-6d22e28ce90d@FreeBSD.org> <CAFMmRNz35Ay82NcMnUkSAvpyU5p2m9ykiji1xXcbEanH9A2H%2Bw@mail.gmail.com> <168122586.20181024003412@serebryakov.spb.ru> <CAFMmRNxbu=V6F9LW_6oWeQzws%2B1-UhETC%2BWWGMFGKAoH-5Ajjw@mail.gmail.com> <c7e9aa2f-8efa-6f48-d4b1-3705928803b2@FreeBSD.org> <CAFMmRNzSAVfGywx%2BPfkQ1Oq1Lt3c53FFQpxDagnkdN=AYQqBCA@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
This is an OpenPGP/MIME signed message (RFC 4880 and 3156)
--7BrRdxDYahHwCnPlh3S6ZYNNhCexDf7a6
Content-Type: multipart/mixed; boundary="U3JEUfUuyBAemrdoU3tZDIQLpBBTsohOn";
protected-headers="v1"
From: Lev Serebryakov <lev@FreeBSD.org>
Reply-To: lev@FreeBSD.org
To: Ryan Stone <rysto32@gmail.com>
Cc: freebsd-hackers@freebsd.org, Conrad Meyer <cse.cem@gmail.com>,
Alan Somers <asomers@freebsd.org>
Message-ID: <eab6fa6a-a702-dda1-9d21-d249b8446978@FreeBSD.org>
Subject: Re: What is wrong with dtrace's stack()?
References: <170994671.20181021201021@serebryakov.spb.ru>
<CAG6CVpVCe-8OVU+KEyAh8swFSAjRshNcNLN0tjAS3W8bZxyrTA@mail.gmail.com>
<475670271.20181022003734@serebryakov.spb.ru>
<CAOtMX2goztCYJXM72WNR711DEBEKAGk1zFHF=NpE4UiVAF2bAQ@mail.gmail.com>
<234d745d-37a9-9610-15b9-0f5cd5af21bf@FreeBSD.org>
<b30f2080-1037-1752-60fb-6d22e28ce90d@FreeBSD.org>
<CAFMmRNz35Ay82NcMnUkSAvpyU5p2m9ykiji1xXcbEanH9A2H+w@mail.gmail.com>
<168122586.20181024003412@serebryakov.spb.ru>
<CAFMmRNxbu=V6F9LW_6oWeQzws+1-UhETC+WWGMFGKAoH-5Ajjw@mail.gmail.com>
<c7e9aa2f-8efa-6f48-d4b1-3705928803b2@FreeBSD.org>
<CAFMmRNzSAVfGywx+PfkQ1Oq1Lt3c53FFQpxDagnkdN=AYQqBCA@mail.gmail.com>
In-Reply-To: <CAFMmRNzSAVfGywx+PfkQ1Oq1Lt3c53FFQpxDagnkdN=AYQqBCA@mail.gmail.com>
--U3JEUfUuyBAemrdoU3tZDIQLpBBTsohOn
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable
On 24.10.2018 20:14, Ryan Stone wrote:
> ia32_pause() is an inline function. How does dtrace map instruction
> pointers to symbol names? Is it getting that mapping from some CTF
> data, and is that CTF data aware of inline functions?
It looks like plausable explanation, but why sometimes it pick-up
"middle layer" like this:
kernel`ia32_pause+0x6
kernel`tcp_usr_send+0x131
kernel`sosend_generic+0xf61
And sometimes doesn't:
kernel`ia32_pause+0x7
kernel`sosend_generic+0xf61
As I said, these stacks are equivalent, I've proved it (ok, it is not
mathematical proof, of course) with custom SDT probes around this
"`tcp_usr_send+0x131" place.
--=20
// Lev Serebryakov
--U3JEUfUuyBAemrdoU3tZDIQLpBBTsohOn--
--7BrRdxDYahHwCnPlh3S6ZYNNhCexDf7a6
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"
-----BEGIN PGP SIGNATURE-----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=kTcY
-----END PGP SIGNATURE-----
--7BrRdxDYahHwCnPlh3S6ZYNNhCexDf7a6--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?eab6fa6a-a702-dda1-9d21-d249b8446978>