linux-kernel - [PATCH v2 0/2] Introduce arch specific nmi enable, disable handlers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 13 Oct 2016 13:38:00 -0700
From:   Babu Moger <babu.moger@...cle.com>
To:     mingo@...nel.org, akpm@...ux-foundation.org, ak@...ux.intel.com,
        jkosina@...e.cz, baiyaowei@...s.chinamobile.com,
        dzickus@...hat.com, atomlin@...hat.com, uobergfe@...hat.com,
        tj@...nel.org, hidehiro.kawai.ez@...achi.com, johunt@...mai.com,
        davem@...emloft.net, sparclinux@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, sam@...nborg.org,
        babu.moger@...cle.com
Subject: [PATCH v2 0/2] Introduce arch specific nmi enable, disable handlers

During our testing we noticed that nmi watchdogs in sparc could not be disabled or
enabled dynamically using sysctl/proc interface. Sparc uses its own arch specific
nmi watchdogs. There is a sysctl and proc interface(proc/sys/kernel/nmi_watchdog)
to enable/disable nmi watchdogs. However, that is not working for sparc. There
is no interface to feed this parameter to arch specific nmi watchdogs.

These patches extend the same sysctl/proc interface to enable or disable
these arch specific nmi watchdogs dynamically. Introduced new functions
arch_watchdog_nmi_enable and arch_watchdog_nmi_disable which can be implemented
in arch specific handlers.
If you think there is a better way to do this. Please advice.

Tested on sparc. Compile tested on x86.

v2:
  a)Sam Ravnborg's comments about making the definitions visible.
  With the new approach we dont need those definitions((NMI_WATCHDOG_ENABLED,
  SOFT_WATCHDOG_ENABLED etc..) outside watchdog.c. So no action.

  b) Made changes per Don Zickus comments.
  Don, I could not use your patches as is. Reason is sparc does not define
  CONFIG_HARDLOCKUP_DETECTOR. So, defining default __weak function did not
  work for me. However, I have used your idea to define __weak functions
  arch_watchdog_nmi_enable and arch_watchdog_nmi_disable when CONFIG_HARDLOCKUP_DETECTOR
  is not defined. I feel this should have very less impact on the races you are
  concerned about. Please take a look. Feel free to suggest.

  Patch2 changes: I had to introduce new variable nmi_init_done to synchronize
  watchdog thread and kernel init thread.

v1:
 Initial version. Discussion thread here
 http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1245427.html

Babu Moger (2):
  watchdog: Introduce arch_watchdog_nmi_enable and
    arch_watchdog_nmi_disable
  sparc: Implement arch_watchdog_nmi_enable and
    arch_watchdog_nmi_disable

 arch/sparc/kernel/nmi.c |   41 +++++++++++++++++++++++++++++-
 kernel/watchdog.c       |   65 +++++++++++++++++++++++++++++++---------------
 2 files changed, 84 insertions(+), 22 deletions(-)