linux-kernel - [PATCH 0/5] Support hld based on Pseudo-NMI for arm64

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Date:   Sat, 12 Feb 2022 18:43:44 +0800
From:   Lecopzer Chen <lecopzer.chen@...iatek.com>
To:     <linux-kernel@...r.kernel.org>
CC:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>, <davem@...emloft.net>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "Marc Zyngier" <maz@...nel.org>,
        Julien Thierry <jthierry@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Wang Qing <wangqing@...o.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Xiaoming Ni <nixiaoming@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-perf-users@...r.kernel.org>, <sparclinux@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <sumit.garg@...aro.org>,
        <kernelfans@...il.com>, <lecopzer.chen@...iatek.com>,
        <yj.chiang@...iatek.com>
Subject: [PATCH 0/5] Support hld based on Pseudo-NMI for arm64

As we already used hld internally for arm64 since 2020, there still
doesn't have a proper commit on the upstream and we badly need it.

This serise rebase on 5.17-rc3 from [1] and the origin author is
Pingfan Liu <kernelfans@...il.com>
Sumit Garg <sumit.garg@...aro.org>

[1] wasn't reviewed for its patch v3, I'll take over the further development
for this.


Qoute from [1]:

Hard lockup detector is helpful to diagnose unpaired irq enable/disable.
But the current watchdog framework can not cope with arm64 hw perf event
easily.

On arm64, when lockup_detector_init()->watchdog_nmi_probe(), PMU is not
ready until device_initcall(armv8_pmu_driver_init).  And it is deeply
integrated with the driver model and cpuhp. Hence it is hard to push the
initialization of armv8_pmu_driver_init() before smp_init().

But it is easy to take an opposite approach by enabling watchdog_hld to
get the capability of PMU async. 
The async model is achieved by expanding watchdog_nmi_probe() with
-EBUSY, and a re-initializing work_struct which waits on a
wait_queue_head.

[1] https://lore.kernel.org/lkml/20211014024155.15253-1-kernelfans@gmail.com/


Lecopzer Chen (2):
  kernel/watchdog: remove WATCHDOG_DEFAULT
  kernel/watchdog: change watchdog_nmi_enable() to void

Pingfan Liu (2):
  kernel/watchdog_hld: Ensure CPU-bound context when creating hardlockup
    detector event
  kernel/watchdog: Adapt the watchdog_hld interface for async model

Sumit Garg (1):
  arm64: Enable perf events based hard lockup detector

 arch/arm64/Kconfig               |  2 ++
 arch/arm64/kernel/Makefile       |  1 +
 arch/arm64/kernel/perf_event.c   | 11 ++++--
 arch/arm64/kernel/watchdog_hld.c | 36 +++++++++++++++++++
 arch/sparc/kernel/nmi.c          |  8 ++---
 drivers/perf/arm_pmu.c           |  5 +++
 include/linux/nmi.h              | 11 +++++-
 include/linux/perf/arm_pmu.h     |  2 ++
 kernel/watchdog.c                | 61 ++++++++++++++++++++++++++++----
 kernel/watchdog_hld.c            |  8 ++++-
 10 files changed, 131 insertions(+), 14 deletions(-)
 create mode 100644 arch/arm64/kernel/watchdog_hld.c

-- 
2.25.1