From: Linus Walleij <linus.walleij@linaro.org>
To: psodagud@codeaurora.org
Cc: Stephen Boyd <sboyd@codeaurora.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-arm-msm@vger.kernel.org
Subject: Re: protected pins and debugfs
Date: Thu, 4 Oct 2018 10:34:03 +0200 [thread overview]
Message-ID: <CACRpkdazxOt0E0J8D763_Mc5RVxpYTrfNgHYkMVQB+GVi1S9Hw@mail.gmail.com> (raw)
In-Reply-To: <9aec322678417753fe4022691f4bfdbe@codeaurora.org>
On Wed, Oct 3, 2018 at 2:38 PM Sodagudi Prasad <psodagud@codeaurora.org> wrote:
> This is regarding the protected pins configuration reading and printing
> from non-secure operating systems.
I do not think anyone with security in mind should have debugfs
enabled. But maybe that is beside the point.
> GPIO framework is checking whether pin is in use(flag FLAG_REQUESTED) or
> not in gpiolib_dbg_show().
>
> If GPIO chip drivers are overriding the dbg_show callback, drivers are
> not checking whether a pin is really in use or not to print
> configuration details.
> if (chip->dbg_show)
> chip->dbg_show(s, chip);
> else
> gpiolib_dbg_show(s, gdev);
Ah that is right. Because some drivers can inspect all pins whether they
are requested or not.
> Can we use a simple/common solution like below? It will check whether a
> pin is in use or not before printing configuration data with the help of
> gpiochip_is_requested().
In the msm case I think maybe you want to inspect the valid_mask
instead, so you display debugfs info for all pins you can inspect
in hardware but avoid the "invalid" ones which I half-guess is used
by ACPI in your case.
Yours,
Linus Walleij
next prev parent reply other threads:[~2018-10-04 8:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 12:38 protected pins and debugfs Sodagudi Prasad
2018-10-04 8:34 ` Linus Walleij [this message]
2018-10-08 6:04 ` Stephen Boyd
2018-10-10 19:40 ` Sodagudi Prasad
2018-10-17 2:00 ` Sodagudi Prasad
2018-10-17 7:28 ` Stephen Boyd
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