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

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Date:   Fri, 14 Apr 2023 17:19:26 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        <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 4/14/2023 5:10 PM, Srinivas Kandagatla wrote:
> 
> 
> 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?

These regions are inside remoteproc memory carve-out.
like.

adsp_mem: memory@...00000 {
	reg = <0x0 0x85e00000 0x0 0x2100000>;
	no-map;
};



remoteproc_adsp: remoteproc@...00000 {
	compatible = "qcom,sm8450-adsp-pas";
	reg = <0 0x30000000 0 0x100>;
            ...
            ...
	memory-region = <&adsp_mem>; <==

-Mukesh
	
> 
> 
> --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