From: Arnd Bergmann <arnd@arndb.de>
To: Jerry Hoemann <jerry.hoemann@hpe.com>
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>,
Guenter Roeck <linux@roeck-us.net>,
linux-watchdog@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
rwright@hpe.com, maurice.a.saldivar@hpe.com,
Ingo Molnar <mingo@kernel.org>,
marcus.folkesson@gmail.com, Josh Poimboeuf <jpoimboe@redhat.com>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH v5 2/9] watchdog/hpwdt: Remove legacy NMI sourcing.
Date: Mon, 26 Feb 2018 15:11:01 +0100 [thread overview]
Message-ID: <CAK8P3a1A5d52g-3Wgs1xP3P=dT6K0RVjmamfqAi9vE5TT=mo3g@mail.gmail.com> (raw)
In-Reply-To: <20180226032227.14615-3-jerry.hoemann@hpe.com>
On Mon, Feb 26, 2018 at 4:22 AM, Jerry Hoemann <jerry.hoemann@hpe.com> wrote:
> Gen8 and prior Proliant systems supported the "CRU" interface
> to firmware. This interfaces allows linux to "call back" into firmware
> to source the cause of an NMI. This feature isn't fully utilized
> as the actual source of the NMI isn't printed, the driver only
> indicates that the source couldn't be determined when the call
> fails.
>
> With the advent of Gen9, iCRU replaces the CRU. The call back
> feature is no longer available in firmware. To be compatible and
> not attempt to call back into firmware on system not supporting CRU,
> the SMBIOS table is consulted to determine if it is safe to
> make the call back or not.
>
> This results in about half of the driver code being devoted
> to either making CRU calls or determing if it is safe to make
> CRU calls. As noted, the driver isn't really using the results of
> the CRU calls.
>
> Furthermore, as a consequence of the Spectre security issue, the
> BIOS/EFI calls are being wrapped into Spectre-disabling section.
> Removing the call back in hpwdt_pretimeout assists in this effort.
>
> As the CRU sourcing of the NMI isn't required for handling the
> NMI and there are security concerns with making the call back, remove
> the legacy (pre Gen9) NMI sourcing and the DMI code to determine if
> the system had the CRU interface.
>
> Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
This avoids a warning in mainline kernels, so that's great:
drivers/watchdog/hpwdt.o: warning: objtool: .text+0x24: indirect call
found in RETPOLINE build
I wonder what we do about stable kernels. Are both this patch and the patch
that added the objtool warning message candidates for backports to
stable kernels?
Arnd
next prev parent reply other threads:[~2018-02-26 14:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-26 3:22 [PATCH v5 0/9] watchdog/hpwdt: Update driver to use watchdog core Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 1/9] watchdog/hpwdt: Update Module info and copyright Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 2/9] watchdog/hpwdt: Remove legacy NMI sourcing Jerry Hoemann
2018-02-26 14:11 ` Arnd Bergmann [this message]
2018-02-26 14:32 ` Guenter Roeck
2018-02-27 1:02 ` Jerry Hoemann
2018-02-27 1:29 ` Guenter Roeck
2018-02-28 19:45 ` Jerry Hoemann
2018-03-02 4:42 ` Guenter Roeck
2018-02-26 3:22 ` [PATCH v5 3/9] watchdog/hpwdt: Update nmi_panic message Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 4/9] watchdog/hpwdt: Modify to use watchdog core Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 5/9] watchdog/hpwdt: condition early return of NMI handler on iLO5 Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 6/9] watchdog/hpwdt: remove allow_kdump module parameter Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 7/9] watchdog/hpwdt: Programable Pretimeout NMI Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 8/9] watchdog/hpwdt: Add dynamic debug Jerry Hoemann
2018-02-26 3:22 ` [PATCH v5 9/9] watchdog/hpwdt: Update driver version Jerry Hoemann
2018-03-02 4:42 ` [PATCH v5 0/9] watchdog/hpwdt: Update driver to use watchdog core Guenter Roeck
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAK8P3a1A5d52g-3Wgs1xP3P=dT6K0RVjmamfqAi9vE5TT=mo3g@mail.gmail.com' \
--to=arnd@arndb.de \
--cc=jerry.hoemann@hpe.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-watchdog@vger.kernel.org \
--cc=linux@roeck-us.net \
--cc=marcus.folkesson@gmail.com \
--cc=maurice.a.saldivar@hpe.com \
--cc=mingo@kernel.org \
--cc=rwright@hpe.com \
--cc=stable@vger.kernel.org \
--cc=wim@linux-watchdog.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).