Message-ID: <c52e90e4-cab0-13b7-9658-1f730de6cf64@quicinc.com>
Date:   Mon, 11 Sep 2023 16:09:47 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     Bagas Sanjaya <bagasdotme@...il.com>, <corbet@....net>,
        <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <keescook@...omium.org>, <tony.luck@...el.com>,
        <gpiccoli@...lia.com>, <mathieu.poirier@...aro.org>,
        <catalin.marinas@....com>, <will@...nel.org>,
        <linus.walleij@...aro.org>, <andy.shevchenko@...il.com>,
        <vigneshr@...com>, <nm@...com>, <matthias.bgg@...il.com>,
        <kgene@...nel.org>, <alim.akhtar@...sung.com>,
        <bmasney@...hat.com>, <quic_tsoni@...cinc.com>
CC:     <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-hardening@...r.kernel.org>,
        <linux-remoteproc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-gpio@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
        <linux-samsung-soc@...r.kernel.org>, <kernel@...cinc.com>
Subject: Re: [PATCH v5 00/17] Add Qualcomm Minidump kernel driver related
 support



On 9/11/2023 2:22 PM, Bagas Sanjaya wrote:
> On Sun, Sep 10, 2023 at 01:46:01AM +0530, Mukesh Ojha wrote:
>> Hi All,
>>
>> This is to continuation from the conversation happened at v4
>>
>> https://lore.kernel.org/lkml/632c5b97-4a91-c3e8-1e6c-33d6c4f6454f@quicinc.com/
>>
>> https://lore.kernel.org/lkml/695133e6-105f-de2a-5559-555cea0a0462@quicinc.com/
>>
>> We have put abstract on LPC on this topic as well as initiated a mail thread
>> with other SoC vendors but did not get much traction on it.
>>
>> https://lore.kernel.org/lkml/0199db00-1b1d-0c63-58ff-03efae02cb21@quicinc.com/
>>
>> We explored most of possiblity present in kernel to address this issue[1] but
>> solution like kdump/fadump does not seems safe/secure/performant from our
>> perspective.
>>
>> Hence, with this series we tried to make the minidump kernel driver, simple
>> and tied with pstore frontends, so that it collects the present available
>> frontends data like dmesg, ftrace, pmsg, ftrace., Also, we will be working
>> towards enhancing generic pstore to capture more debug data which will be
>> helpful for first hand of debugging that can benefit both other pstore users
>> as well as us as minidump users.
>>
>> One of the proposal made here,
>> https://lore.kernel.org/lkml/1683561060-2197-1-git-send-email-quic_mojha@quicinc.com/
>>
>> Looking forward for your comments.
>>
>> Thanks,
>> Mukesh
>>
>> [1]
>> Minidump is a best effort mechanism to collect useful and predefined data
>> for first level of debugging on end user devices running on Qualcomm SoCs.
>> It is built on the premise that System on Chip (SoC) or subsystem part of
>> SoC crashes, due to a range of hardware and software bugs. Hence, the
>> ability to collect accurate data is only a best-effort. The data collected
>> could be invalid or corrupted, data collection itself could fail, and so on.
>>
>> Qualcomm devices in engineering mode provides a mechanism for generating
>> full system ramdumps for post mortem debugging. But in some cases it's
>> however not feasible to capture the entire content of RAM. The minidump
>> mechanism provides the means for selecting which snippets should be
>> included in the ramdump.
>>
>> The core of SMEM based minidump feature is part of Qualcomm's boot
>> firmware code. It initializes shared memory (SMEM), which is a part of
>> DDR and allocates a small section of SMEM to minidump table i.e also
>> called global table of content (G-ToC). Each subsystem (APSS, ADSP, ...)
>> has their own table of segments to be included in the minidump and all
>> get their reference from G-ToC. Each segment/region has some details
>> like name, physical address and it's size etc. and it could be anywhere
>> scattered in the DDR.
>>
>> Existing upstream Qualcomm remoteproc driver[1] already supports SMEM
>> based minidump feature for remoteproc instances like ADSP, MODEM, ...
>> where predefined selective segments of subsystem region can be dumped
>> as part of coredump collection which generates smaller size artifacts
>> compared to complete coredump of subsystem on crash.
>>
>> [1]
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/remoteproc/qcom_common.c#n142
>>
>> In addition to managing and querying the APSS minidump description,
>> the Linux driver maintains a ELF header in a segment. This segment
>> gets updated with section/program header whenever a new entry gets
>> registered.
>>
>> Changes in v5:
>>   - On suggestion from Pavan.k, to have single function call for minidump collection
>>     from remoteproc driver, separated the logic to have separate minidump file called
>>     qcom_rproc_minidump.c and also renamed the function from qcom_minidump() to
>>     qcom_rproc_minidump(); however, dropped his suggestion about rework on lazy deletion
>>     during region unregister in this series, will pursue it in next series.
>>
>>   - To simplify the minidump driver, removed the complication for frontend and different
>>     backend from Greg suggestion, will pursue this once main driver gets mainlined.
>>
>>   - Move the dynamic ramoops region allocation from Device tree approach to command line
>>     approch with the introduction command line parsing and memblock reservation during
>>     early boot up; Not added documentation about it yet, will add if it gets positive
>>     response.
>>
>>   - Exporting linux banner from kernel to make minidump build also as module, however,
>>     minidump is a debug module and should be kernel built to get most debug information
>>     from kernel.
>>
>>   - Tried to address comments given on dload patch series.
>>
>> Changes in v4: https://lore.kernel.org/lkml/1687955688-20809-1-git-send-email-quic_mojha@quicinc.com/
>>   - Redesigned the driver and divided the driver into front end and backend (smem) so
>>     that any new backend can be attached easily to avoid code duplication.
>>   - Patch reordering as per the driver and subsystem to easier review of the code.
>>   - Removed minidump specific code from remoteproc to minidump smem based driver.
>>   - Enabled the all the driver as modules.
>>   - Address comments made on documentation and yaml and Device tree file [Krzysztof/Konrad]
>>   - Address comments made qcom_pstore_minidump driver and given its Device tree
>>     same set of properties as ramoops. [Luca/Kees]
>>   - Added patch for MAINTAINER file.
>>   - Include defconfig change as one patch as per [Krzysztof] suggestion.
>>   - Tried to remove the redundant file scope variables from the module as per [Krzysztof] suggestion.
>>   - Addressed comments made on dload mode patch v6 version
>>     https://lore.kernel.org/lkml/1680076012-10785-1-git-send-email-quic_mojha@quicinc.com/
>>
>> Changes in v3: https://lore.kernel.org/lkml/1683133352-10046-1-git-send-email-quic_mojha@quicinc.com/
>>   - Addressed most of the comments by Srini on v2 and refactored the minidump driver.
>>      - Added platform device support
>>      - Unregister region support.
>>   - Added update region for clients.
>>   - Added pending region support.
>>   - Modified the documentation guide accordingly.
>>   - Added qcom_pstore_ramdump client driver which happen to add ramoops platform
>>     device and also registers ramoops region with minidump.
>>   - Added download mode patch series with this minidump series.
>>      https://lore.kernel.org/lkml/1680076012-10785-1-git-send-email-quic_mojha@quicinc.com/
>>
>> Changes in v2: https://lore.kernel.org/lkml/1679491817-2498-1-git-send-email-quic_mojha@quicinc.com/
>>   - Addressed review comment made by [quic_tsoni/bmasney] to add documentation.
>>   - Addressed comments made by [srinivas.kandagatla]
>>   - Dropped pstore 6/6 from the last series, till i get conclusion to get pstore
>>     region in minidump.
>>   - Fixed issue reported by kernel test robot.
>>
>> Changes in v1: https://lore.kernel.org/lkml/1676978713-7394-1-git-send-email-quic_mojha@quicinc.com/
>>
>> Testing of the patches has been done on sm8450 target after enabling config like
>> CONFIG_PSTORE_RAM and CONFIG_PSTORE_CONSOLE and once the device boots up.
>>
>>   echo mini > /sys/module/qcom_scm/parameters/download_mode
>>
>> Try crashing it via devmem2 0xf11c000(this is known to create xpu violation and
>> and put the device in download mode) on command prompt.
>>
>> Default storage type is set to via USB, so minidump would be downloaded with the
>> help of x86_64 machine (running PCAT tool) attached to Qualcomm device which has
>> backed minidump boot firmware support.
>>
>> This will make the device go to download mode and collect the minidump on to the
>> attached x86 machine running the Qualcomm PCAT tool(This comes as part Qualcomm
>> package manager kit).
>>
>> After that we will see a bunch of predefined registered region as binary blobs files
>> starts with md_* downloaded on the x86 machine on given location in PCAT tool from
>> the target device, more about this can be found in qualcomm minidump guide patch.
>>
> 
> I tried to apply this series on top of 535a265d7f0dd50 (as suggested by
> `b4 am -l -g`), but it conflicts on patch [04/17]. Please specify the
> exact base commit or another series for which this series is based on.

Apologies !
I just realized, it was 6.5-rc7, but let me rebase version of the series;

Sorry, for all the reviewed done so far, i will definitely take care of 
them or reply.

-Mukesh
> 
> Thanks.
> 

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