linux-hardening - Re: [PATCH v2 6/6] remoterproc: qcom: refactor to leverage exported minidump symbol

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Date:   Fri, 14 Apr 2023 12:40:58 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Mukesh Ojha <quic_mojha@...cinc.com>, agross@...nel.org,
        andersson@...nel.org, konrad.dybcio@...aro.org, corbet@....net,
        keescook@...omium.org, tony.luck@...el.com, gpiccoli@...lia.com,
        catalin.marinas@....com, will@...nel.org
Cc:     linux-arm-msm@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 6/6] remoterproc: qcom: refactor to leverage exported
 minidump symbol



On 14/04/2023 12:14, Mukesh Ojha wrote:
> 
> 
> On 4/14/2023 4:14 PM, Srinivas Kandagatla wrote:
>>
>>
>> On 22/03/2023 13:30, Mukesh Ojha wrote:
>>> qcom_minidump driver provides qcom_minidump_subsystem_desc()
>>> exported API which other driver can use it query subsystem
>>> descriptor. Refactor qcom_minidump() to use this symbol.
>>>
>>> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
>>> ---
>>>   drivers/remoteproc/qcom_common.c | 13 ++-----------
>>>   1 file changed, 2 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/remoteproc/qcom_common.c 
>>> b/drivers/remoteproc/qcom_common.c
>>> index 88fc984..240e9f7 100644
>>> --- a/drivers/remoteproc/qcom_common.c
>>> +++ b/drivers/remoteproc/qcom_common.c
>>> @@ -94,19 +94,10 @@ void qcom_minidump(struct rproc *rproc, unsigned 
>>> int minidump_id,
>>>   {
>>>       int ret;
>>>       struct minidump_subsystem *subsystem;
>>> -    struct minidump_global_toc *toc;
>>> -    /* Get Global minidump ToC*/
>>> -    toc = qcom_smem_get(QCOM_SMEM_HOST_ANY, SBL_MINIDUMP_SMEM_ID, 
>>> NULL);
>>> -
>>> -    /* check if global table pointer exists and init is set */
>>> -    if (IS_ERR(toc) || !toc->status) {
>>> -        dev_err(&rproc->dev, "Minidump TOC not found in SMEM\n");
>>> +    subsystem = qcom_minidump_subsystem_desc(minidump_id);
>>> +    if (IS_ERR(subsystem))
>>>           return;
>>
>> Sorry If I am missing something but I got lost looking at the below 
>> code snippet in drivers/remoteproc/qcom_common.c
>>
>>
>> -------------------->cut<-----------------------------
>>      subsystem = qcom_minidump_subsystem_desc(minidump_id);
>>      if (IS_ERR(subsystem))
>>          return;
>>
>>      /**
>>       * Collect minidump if SS ToC is valid and segment table
>>       * is initialized in memory and encryption status is set.
>>       */
>>      if (subsystem->regions_baseptr == 0 ||
>>          le32_to_cpu(subsystem->status) != 1 ||
>>          le32_to_cpu(subsystem->enabled) != MINIDUMP_SS_ENABLED ||
>>          le32_to_cpu(subsystem->encryption_status) != 
>> MINIDUMP_SS_ENCR_DONE) {
>>          dev_err(&rproc->dev, "Minidump not ready, skipping\n");
>>          return;
>>      }
>> -------------------->cut<-----------------------------
>>
>> where does "subsystem->regions_baseptr" for this ADSP minidump 
>> descriptor get set?
> 
> Other co-processor such as adsp/cdsp/Mpss has their own way of 
> registering their region/segment (mostly they are static known
> regions) with minidump global infra and which could be happening
> from firmware side .
If its happening from firmware side, then that ram phys address range 
should be reserved from kernel usage I guess.

Do you have more details on where exactly is this reserved from within 
linux kernel?


--srini

> 
> 
> -Mukesh
> 
>>
>>
>> --srini
>>
>>> -    }
>>> -
>>> -    /* Get subsystem table of contents using the minidump id */
>>> -    subsystem = &toc->subsystems[minidump_id];
>>>       /**
>>>        * Collect minidump if SS ToC is valid and segment table