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Subject: Re: [PATCH] pstore/ram: Rework logic for detecting ramoops reserved
 memory region
To:     keescook@chromium.org, anton@enomsg.org, ccross@android.com,
        tony.luck@intel.com, linux-kernel@vger.kernel.org
Cc:     "Isaac J. Manjarres" <isaacm@codeaurora.org>
References: <1624619838-2578-1-git-send-email-mojha@codeaurora.org>
From:   Mukesh Ojha <mojha@codeaurora.org>
Message-ID: <26681678-ac97-9fae-44bb-957f1edd5dd8@codeaurora.org>
Date:   Mon, 5 Jul 2021 16:09:50 +0530
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Hi Kees,

Could  you please review this ?

-Mukesh

On 6/25/2021 4:47 PM, Mukesh Ojha wrote:
> From: "Isaac J. Manjarres" <isaacm@codeaurora.org>
>
> The reserved memory region for ramoops is assumed to be at a fixed
> and known location when read from the devicetree. This is not desirable
> in environments where it is preferred for the region to be dynamically
> allocated at runtime, as opposed to it being fixed at compile time.
>
> Change the logic for detecting the start and size of the ramoops
> memory region by looking up the reserved memory region instead of
> using platform_get_resource(), which assumes that the location
> of the memory is known ahead of time.
>
> Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
> Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>
> ---
>   fs/pstore/ram.c | 11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index fefe3d3..5f90455 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -21,6 +21,7 @@
>   #include <linux/pstore_ram.h>
>   #include <linux/of.h>
>   #include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
>   #include "internal.h"
>   
>   #define RAMOOPS_KERNMSG_HDR "===="
> @@ -633,21 +634,21 @@ static int ramoops_parse_dt(struct platform_device *pdev,
>   {
>   	struct device_node *of_node = pdev->dev.of_node;
>   	struct device_node *parent_node;
> -	struct resource *res;
> +	struct reserved_mem *rmem;
>   	u32 value;
>   	int ret;
>   
>   	dev_dbg(&pdev->dev, "using Device Tree\n");
>   
> -	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (!res) {
> +	rmem = of_reserved_mem_lookup(of_node);
> +	if (!rmem) {
>   		dev_err(&pdev->dev,
>   			"failed to locate DT /reserved-memory resource\n");
>   		return -EINVAL;
>   	}
>   
> -	pdata->mem_size = resource_size(res);
> -	pdata->mem_address = res->start;
> +	pdata->mem_size = rmem->size;
> +	pdata->mem_address = rmem->base;
>   	/*
>   	 * Setting "unbuffered" is deprecated and will be ignored if
>   	 * "mem_type" is also specified.