Re: [PATCH v3 12/18] soc: qcom: Register pstore frontend region with minidump

From: Luca Stefani <luca.stefani.ge1@gmail.com>
To: Mukesh Ojha <quic_mojha@quicinc.com>,
	agross@kernel.org, andersson@kernel.org,
	konrad.dybcio@linaro.org, corbet@lwn.net, keescook@chromium.org,
	tony.luck@intel.com, gpiccoli@igalia.com,
	catalin.marinas@arm.com, will@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org,
	linus.walleij@linaro.org, linux-gpio@vger.kernel.org,
	srinivas.kandagatla@linaro.org
Cc: linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v3 12/18] soc: qcom: Register pstore frontend region with minidump
Date: Tue, 9 May 2023 17:45:54 +0200	[thread overview]
Message-ID: <e59064e1-a826-1b90-fed4-29b0cabb1a87@gmail.com> (raw)
In-Reply-To: <1683133352-10046-13-git-send-email-quic_mojha@quicinc.com>

FYI the following comments also apply to the downstream driver, as the 
same bogus logic is implemented.

On 03/05/23 19:02, Mukesh Ojha wrote:

> Since qcom_pstore_minidump driver creates platform device
> for qualcomm devices, so it knows the physical addresses
> of the frontend region now. Let's register the regions
> with qcom_minidump driver.
>
> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
> ---
>   drivers/soc/qcom/qcom_pstore_minidump.c | 80 ++++++++++++++++++++++++++++++++-
>   1 file changed, 79 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soc/qcom/qcom_pstore_minidump.c b/drivers/soc/qcom/qcom_pstore_minidump.c
> index 8d58500..c2bba4e 100644
> --- a/drivers/soc/qcom/qcom_pstore_minidump.c
> +++ b/drivers/soc/qcom/qcom_pstore_minidump.c
> @@ -11,6 +11,8 @@
>   #include <linux/pstore_ram.h>
>   #include <soc/qcom/qcom_minidump.h>
>   
> +#define QCOM_PSTORE_TYPE_MAX	4
Unused
> +
>   struct qcom_ramoops_config {
>   	unsigned long	record_size;
>   	unsigned long	console_size;
> @@ -24,6 +26,11 @@ struct qcom_ramoops_config {
>   struct qcom_ramoops_dd {
>   	struct ramoops_platform_data qcom_ramoops_pdata;
>   	struct platform_device *ramoops_pdev;
> +	struct device *dev;
> +	struct qcom_apss_minidump_region *record_region;

In the pstore driver record_size is used to split the KDMESG region into 
different chunks.

There's no "record" region anywhere in RAM that should be preserved, it 
should instead be the dmesg_region.

> +	struct qcom_apss_minidump_region *console_region;
> +	struct qcom_apss_minidump_region *pmsg_region;
> +	struct qcom_apss_minidump_region *ftrace_region;
>   };
>   
>   static struct qcom_ramoops_config default_ramoops_config = {
> @@ -35,6 +42,64 @@ static struct qcom_ramoops_config default_ramoops_config = {
>   };
>   
>   static struct qcom_ramoops_dd *qcom_rdd;
> +
> +static int
> +__qcom_ramoops_minidump_region_register(struct qcom_apss_minidump_region *md_region,
> +					const char *name, phys_addr_t phys_addr,
> +					unsigned long size)
> +{
> +	int ret;
> +
> +	if (!size)
> +		return 0;
> +
> +	md_region = devm_kzalloc(qcom_rdd->dev, sizeof(*md_region), GFP_KERNEL);
> +	if (!md_region)
> +		return -ENOMEM;
> +
> +	strlcpy(md_region->name, name, sizeof(md_region->name));
> +	md_region->phys_addr = phys_addr;
> +	md_region->virt_addr = phys_to_virt(phys_addr);
> +	md_region->size = size;
> +	ret = qcom_apss_minidump_region_register(md_region);
> +	if (ret)
> +		dev_err(qcom_rdd->dev,
> +			"failed to add %s in minidump: err: %d\n", name, ret);
> +
> +	return ret;
> +}
> +
> +static int
> +qcom_ramoops_minidump_region_register(struct ramoops_platform_data *qcom_ramoops_data)
> +{
> +	phys_addr_t phys_addr;
> +	int ret = 0;
> +
> +	phys_addr = qcom_ramoops_data->mem_address;
> +	ret = __qcom_ramoops_minidump_region_register(qcom_rdd->record_region,
> +			"KDMESG", phys_addr, qcom_ramoops_data->record_size);

You can't use record_size here as it's not the actual size of the dmesg 
region.

The size is calculated in fs/pstore/ram.c as mem_size - console_size - 
ftrace_size - pmsg_size, where mem_size is the size on the ramoops 
memory region in the devicetree.

Since the actual size is never exposed by the pstore driver you have to 
re-purpose the same logic in this driver, hoping it never changes.

> +	if (ret)
> +		return ret;
> +
> +	phys_addr += qcom_ramoops_data->record_size;
> +	ret = __qcom_ramoops_minidump_region_register(qcom_rdd->console_region,
> +			"KCONSOLE", phys_addr, qcom_ramoops_data->console_size);
> +	if (ret)
> +		return ret;
> +
> +	phys_addr += qcom_ramoops_data->console_size;
> +	ret = __qcom_ramoops_minidump_region_register(qcom_rdd->pmsg_region,
> +			"KPMSG", phys_addr, qcom_ramoops_data->pmsg_size);
> +	if (ret)
> +		return ret;
> +
> +	phys_addr += qcom_ramoops_data->pmsg_size;
> +	ret = __qcom_ramoops_minidump_region_register(qcom_rdd->ftrace_region,
> +			"KFTRACE", phys_addr, qcom_ramoops_data->ftrace_size);
> +
> +	return ret;
> +}
> +
>   static int qcom_ramoops_probe(struct platform_device *pdev)
>   {
>   	struct device_node *of_node = pdev->dev.of_node;
> @@ -59,6 +124,7 @@ static int qcom_ramoops_probe(struct platform_device *pdev)
>   	if (!qcom_rdd)
>   		return -ENOMEM;
>   
> +	qcom_rdd->dev = &pdev->dev;
>   	cfg = of_device_get_match_data(&pdev->dev);
>   	if (!cfg) {
>   		dev_err(&pdev->dev, "failed to get supported matched data\n");
> @@ -81,13 +147,25 @@ static int qcom_ramoops_probe(struct platform_device *pdev)
>   		ret = PTR_ERR(qcom_rdd->ramoops_pdev);
>   		dev_err(&pdev->dev, "could not create platform device: %ld\n", ret);
>   		qcom_rdd->ramoops_pdev = NULL;
> +		return ret;
>   	}
>   
> -	return ret;
> +	return qcom_ramoops_minidump_region_register(pdata);
>   }
>   
>   static int qcom_ramoops_remove(struct platform_device *pdev)
>   {
> +	struct ramoops_platform_data *pdata;
> +
> +	pdata = &qcom_rdd->qcom_ramoops_pdata;
> +	if (pdata->record_size)
> +		qcom_apss_minidump_region_unregister(qcom_rdd->record_region);
> +	if (pdata->console_size)
> +		qcom_apss_minidump_region_unregister(qcom_rdd->console_region);
> +	if (pdata->pmsg_size)
> +		qcom_apss_minidump_region_unregister(qcom_rdd->pmsg_region);
> +	if (pdata->ftrace_size)
> +		qcom_apss_minidump_region_unregister(qcom_rdd->ftrace_region);
>   	platform_device_unregister(qcom_rdd->ramoops_pdev);
>   	qcom_rdd->ramoops_pdev = NULL;
>   

Regards,

Luca Stefani