[PATCH v3 1/2] dt-bindings: ramoops: Inherit reserve memory property

[PATCH v3 1/2] dt-bindings: ramoops: Inherit reserve memory property

[Mukesh Ojha]

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 an environment where it is preferred the
region to be dynamically allocated at runtime, as opposed to
being fixed at compile time.

So, update the ramoops binding by inheriting some reserve memory
property to allocate the ramoops region dynamically.

Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
---
Changes in v3:
 - Fixed yaml error and updated commit text as per comment.

Change in v2:
  - Added this patch as per changes going to be done in patch 3/3

 .../bindings/reserved-memory/ramoops.yaml          | 34 ++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml b/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml
index 0391871..8741626 100644
--- a/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml
+++ b/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml
@@ -10,7 +10,8 @@ description: |
   ramoops provides persistent RAM storage for oops and panics, so they can be
   recovered after a reboot. This is a child-node of "/reserved-memory", and
   is named "ramoops" after the backend, rather than "pstore" which is the
-  subsystem.
+  subsystem. This region can be reserved both statically or dynamically by
+  using appropriate property in device tree.
 
   Parts of this storage may be set aside for other persistent log buffers, such
   as kernel log messages, or for optional ECC error-correction data.  The total
@@ -112,7 +113,13 @@ unevaluatedProperties: false
 
 required:
   - compatible
-  - reg
+
+oneOf:
+  - required:
+      - reg
+
+  - required:
+      - size
 
 anyOf:
   - required: [record-size]
@@ -142,3 +149,26 @@ examples:
             };
         };
     };
+
+  - |
+    / {
+        compatible = "foo";
+        model = "foo";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        reserved-memory {
+            #address-cells = <1>;
+            #size-cells = <1>;
+            ranges;
+
+            ramoops: ramoops_region {
+                compatible = "ramoops";
+                alloc-ranges = <0x00000000 0xffffffff>;
+                size = <0x0 0x10000>;       /* 64kB */
+                console-size = <0x8000>;    /* 32kB */
+                record-size = <0x400>;      /*  1kB */
+                ecc-size = <16>;
+            };
+        };
+    };
-- 
2.7.4

[PATCH v3 2/2] pstore/ram: Rework logic for detecting ramoops

[Mukesh Ojha]

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 an environment where it is preferred the region to be dynamically
allocated at runtime, as opposed to being fixed at compile time.

Also, some of the platforms might be still expecting dedicated
memory region for ramoops node where the region is known beforehand
and platform_get_resource() is used in that case.

So, add logic to detect the start and size of the ramoops memory
region by looking up reserved memory region with of_reserved_mem_lookup()
api when platform_get_resource() fails also update the ramoops
documentation,

Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com> 
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
---
Changes in v3:
 - Merged 2/3 and 3/3 into one.
   https://lore.kernel.org/lkml/1673611126-13803-2-git-send-email-quic_mojha@quicinc.com/
   https://lore.kernel.org/lkml/1673611126-13803-3-git-send-email-quic_mojha@quicinc.com/

Changes in v2:
 - Addressed the comments made by kees and Guilherme in v1.

 Documentation/admin-guide/ramoops.rst | 25 ++++++++++++++++++++++---
 fs/pstore/ram.c                       | 18 +++++++++++++-----
 2 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/Documentation/admin-guide/ramoops.rst b/Documentation/admin-guide/ramoops.rst
index e9f8514..f701fab 100644
--- a/Documentation/admin-guide/ramoops.rst
+++ b/Documentation/admin-guide/ramoops.rst
@@ -16,8 +16,9 @@ survive after a restart.
 Ramoops concepts
 ----------------
 
-Ramoops uses a predefined memory area to store the dump. The start and size
-and type of the memory area are set using three variables:
+Ramoops uses both predefined and dynamically memory area to store the dump.
+The start and size and type of the memory area are set using three
+variables:
 
   * ``mem_address`` for the start
   * ``mem_size`` for the size. The memory size will be rounded down to a
@@ -70,7 +71,8 @@ Setting the ramoops parameters can be done in several different manners:
 
  B. Use Device Tree bindings, as described in
  ``Documentation/devicetree/bindings/reserved-memory/ramoops.yaml``.
- For example::
+
+ Example of statically reserved ramoops region::
 
 	reserved-memory {
 		#address-cells = <2>;
@@ -85,6 +87,23 @@ Setting the ramoops parameters can be done in several different manners:
 		};
 	};
 
+ Example of dynamically reserved ramoops region::
+
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		ramoops@8f000000 {
+			compatible = "ramoops";
+			alloc-ranges = <0x00000000 0xffffffff>;
+			size = <0 0x100000>;
+			record-size = <0x4000>;
+			console-size = <0x4000>;
+		};
+	};
+
+
  C. Use a platform device and set the platform data. The parameters can then
  be set through that platform data. An example of doing that is:
 
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index ade66db..17c9f46 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -20,6 +20,7 @@
 #include <linux/compiler.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
 
 #include "internal.h"
 #include "ram_internal.h"
@@ -643,6 +644,7 @@ static int ramoops_parse_dt(struct platform_device *pdev,
 {
 	struct device_node *of_node = pdev->dev.of_node;
 	struct device_node *parent_node;
+	struct reserved_mem *rmem;
 	struct resource *res;
 	u32 value;
 	int ret;
@@ -651,13 +653,19 @@ static int ramoops_parse_dt(struct platform_device *pdev,
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
-		dev_err(&pdev->dev,
-			"failed to locate DT /reserved-memory resource\n");
-		return -EINVAL;
+		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 = rmem->size;
+		pdata->mem_address = rmem->base;
+	} else {
+		pdata->mem_size = resource_size(res);
+		pdata->mem_address = res->start;
 	}
 
-	pdata->mem_size = resource_size(res);
-	pdata->mem_address = res->start;
 	/*
 	 * Setting "unbuffered" is deprecated and will be ignored if
 	 * "mem_type" is also specified.
-- 
2.7.4

Re: [PATCH v3 1/2] dt-bindings: ramoops: Inherit reserve memory property

[Krzysztof Kozlowski]

On 27/01/2023 16:10, Mukesh Ojha wrote:
> 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 an environment where it is preferred the
> region to be dynamically allocated at runtime, as opposed to
> being fixed at compile time.
> 
> So, update the ramoops binding by inheriting some reserve memory
> property to allocate the ramoops region dynamically.
> 
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
> ---
> Changes in v3:
>  - Fixed yaml error and updated commit text as per comment.
> 
> Change in v2:
>   - Added this patch as per changes going to be done in patch 3/3
> 
>  .../bindings/reserved-memory/ramoops.yaml          | 34 ++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml b/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml
> index 0391871..8741626 100644
> --- a/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml
> +++ b/Documentation/devicetree/bindings/reserved-memory/ramoops.yaml
> @@ -10,7 +10,8 @@ description: |
>    ramoops provides persistent RAM storage for oops and panics, so they can be
>    recovered after a reboot. This is a child-node of "/reserved-memory", and
>    is named "ramoops" after the backend, rather than "pstore" which is the
> -  subsystem.
> +  subsystem. This region can be reserved both statically or dynamically by
> +  using appropriate property in device tree.
>  
>    Parts of this storage may be set aside for other persistent log buffers, such
>    as kernel log messages, or for optional ECC error-correction data.  The total
> @@ -112,7 +113,13 @@ unevaluatedProperties: false
>  
>  required:
>    - compatible
> -  - reg
> +
> +oneOf:
> +  - required:
> +      - reg
> +
> +  - required:
> +      - size
>  
>  anyOf:
>    - required: [record-size]
> @@ -142,3 +149,26 @@ examples:
>              };
>          };
>      };
> +
> +  - |
> +    / {
> +        compatible = "foo";
> +        model = "foo";
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +
> +        reserved-memory {
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +            ranges;
> +
> +            ramoops: ramoops_region {

This is a friendly reminder during the review process.

It seems my previous comments were not fully addressed. Maybe my
feedback got lost between the quotes, maybe you just forgot to apply it.
Please go back to the previous discussion and either implement all
requested changes or keep discussing them.

Thank you.

Best regards,
Krzysztof