Date: Thu, 15 Sep 2022 10:43:47 +0200 From: Kristof Provost <kp@FreeBSD.org> To: Lee MATTHEWS <Lee.MATTHEWS.external@stormshield.eu> Cc: freebsd-drivers@freebsd.org Subject: Re: Tracing userland calls through to a driver Message-ID: <7C93934E-7DF5-44FC-93B5-331AE3490189@FreeBSD.org> In-Reply-To: <484f6c4f5a2840daafaeda4943f22793@stormshield.eu> References: <484f6c4f5a2840daafaeda4943f22793@stormshield.eu>
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On 15 Sep 2022, at 10:37, Lee MATTHEWS wrote:
> I am trying to debug some GPIO issues on FreeBSD 10.3.
>
That’s an unsupported version (unless you meant 12.3), so the first
thing to do is to see if your issue is still present in main.
> I'd like to know if it is possible to know what process in userland
> (via a process id) has called a method in the driver.
>
> So for example, in the driver, the functions are bound via DEVMETHOD
> like :
>
>
> static device_method_t winbond_gpio_methods[] = {
> /* Device interface */
> ...
> DEVMETHOD(gpio_pin_set, winbond_gpio_pin_set),
> DEVMETHOD(gpio_pin_get, winbond_gpio_pin_get),
> ...
> DEVMETHOD_END
> };
>
>
> When the function winbond_gpio_pin_get() is called, how can I know
> what called this?
>
>
For things like this I’d either look at truss(1), which will tell you
what system calls the user space process called, or Dtrace.
Something like `dtrace -n fbt::winbond_gpio_pin_set:entry { stack(); }`
should give you a pointer already.
Dtrace can take a bit of effort to learn, but it’s generally well
worth it. The wiki has some initial hints:
https://wiki.freebsd.org/DTrace
Best regards,
Kristof
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<head>
<meta http-equiv=3D"Content-Type" content=3D"text/xhtml; charset=3Dutf-8"=
>
</head>
<body><div style=3D"font-family: sans-serif;"><div class=3D"markdown" sty=
le=3D"white-space: normal;">
<p dir=3D"auto">On 15 Sep 2022, at 10:37, Lee MATTHEWS wrote:</p>
</div><div class=3D"plaintext" style=3D"white-space: normal;"><blockquote=
style=3D"margin: 0 0 5px; padding-left: 5px; border-left: 2px solid #136=
BCE; color: #136BCE;"><p dir=3D"auto">I am trying to debug some GPIO issu=
es on FreeBSD 10.3.</p>
<br></blockquote></div>
<div class=3D"markdown" style=3D"white-space: normal;">
<p dir=3D"auto">That=E2=80=99s an unsupported version (unless you meant 1=
2.3), so the first thing to do is to see if your issue is still present i=
n main.</p>
</div><div class=3D"plaintext" style=3D"white-space: normal;"><blockquote=
style=3D"margin: 0 0 5px; padding-left: 5px; border-left: 2px solid #136=
BCE; color: #136BCE;"><p dir=3D"auto">I'd like to know if it is possible =
to know what process in userland (via a process id) has called a method i=
n the driver.</p>
<p dir=3D"auto">So for example, in the driver, the functions are bound vi=
a DEVMETHOD like :</p>
<p dir=3D"auto">static device_method_t winbond_gpio_methods[] =3D {
<br>
/* Device interface */
<br>
=2E..
<br>
DEVMETHOD(gpio_pin_set, winbond_gpio_pin_set),
<br>
DEVMETHOD(gpio_pin_get, winbond_gpio_pin_get),
<br>
=2E..
<br>
DEVMETHOD_END
<br>
};</p>
<p dir=3D"auto">When the function winbond_gpio_pin_get() is called, how c=
an I know what called this?</p>
<br></blockquote></div>
<div class=3D"markdown" style=3D"white-space: normal;">
<p dir=3D"auto">For things like this I=E2=80=99d either look at truss(1),=
which will tell you what system calls the user space process called, or =
Dtrace.</p>
<p dir=3D"auto">Something like <code>dtrace -n fbt::winbond_gpio_pin_set:=
entry { stack(); }</code> should give you a pointer already.<br>
Dtrace can take a bit of effort to learn, but it=E2=80=99s generally well=
worth it. The wiki has some initial hints: <a href=3D"https://wiki.freeb=
sd.org/DTrace">https://wiki.freebsd.org/DTrace</a></p>;
<p dir=3D"auto">Best regards,<br>
Kristof</p>
</div></div></body>
</html>
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