On Fri, Dec 22, 2023 at 07:51:44PM +0000, Alexander Graf wrote: > With ftrace in KHO, we are creating an ABI between old kernel and new > kernel about the state that they transfer. To ensure that we document > that state and catch any breaking change, let's add its schema to the > common devicetree bindings. This way, we can quickly reason about the > state that gets passed. Why so much data in DT rather than putting all this information into memory in your own data structure and DT just has a single property pointing to that? That's what is done with every other blob of data passed by kexec. > > Signed-off-by: Alexander Graf <graf@xxxxxxxxxx> > --- > .../bindings/kho/ftrace/ftrace-array.yaml | 46 +++++++++++++++ > .../bindings/kho/ftrace/ftrace-cpu.yaml | 56 +++++++++++++++++++ > .../bindings/kho/ftrace/ftrace.yaml | 48 ++++++++++++++++ > 3 files changed, 150 insertions(+) > create mode 100644 Documentation/devicetree/bindings/kho/ftrace/ftrace-array.yaml > create mode 100644 Documentation/devicetree/bindings/kho/ftrace/ftrace-cpu.yaml > create mode 100644 Documentation/devicetree/bindings/kho/ftrace/ftrace.yaml > > diff --git a/Documentation/devicetree/bindings/kho/ftrace/ftrace-array.yaml b/Documentation/devicetree/bindings/kho/ftrace/ftrace-array.yaml > new file mode 100644 > index 000000000000..9960fefc292d > --- /dev/null > +++ b/Documentation/devicetree/bindings/kho/ftrace/ftrace-array.yaml > @@ -0,0 +1,46 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/kho/ftrace/ftrace-array.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Ftrace trace array > + > +maintainers: > + - Alexander Graf <graf@xxxxxxxxxx> > + > +properties: > + compatible: > + enum: > + - ftrace,array-v1 > + > + trace_flags: > + $ref: /schemas/types.yaml#/definitions/uint32 > + description: > + Bitmap of all the trace flags that were enabled in the trace array at the > + point of serialization. > + > +# Subnodes will be of type "ftrace,cpu-v1", one each per CPU This can be expressed as a schema. > +additionalProperties: true > + > +required: > + - compatible > + - trace_flags > + > +examples: > + - | > + ftrace { > + compatible = "ftrace-v1"; > + events = <1 1 2 2 3 3>; > + > + global_trace { > + compatible = "ftrace,array-v1"; > + trace_flags = < 0x3354601 >; > + > + cpu0 { > + compatible = "ftrace,cpu-v1"; > + cpu = < 0x00 >; > + mem = < 0x101000000ULL 0x38ULL 0x101000100ULL 0x1000ULL 0x101000038ULL 0x38ULL 0x101002000ULL 0x1000ULL>; > + }; > + }; > + }; > diff --git a/Documentation/devicetree/bindings/kho/ftrace/ftrace-cpu.yaml b/Documentation/devicetree/bindings/kho/ftrace/ftrace-cpu.yaml > new file mode 100644 > index 000000000000..58c715e93f37 > --- /dev/null > +++ b/Documentation/devicetree/bindings/kho/ftrace/ftrace-cpu.yaml > @@ -0,0 +1,56 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/kho/ftrace/ftrace-cpu.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Ftrace per-CPU ring buffer contents > + > +maintainers: > + - Alexander Graf <graf@xxxxxxxxxx> > + > +properties: > + compatible: > + enum: > + - ftrace,cpu-v1 > + > + cpu: > + $ref: /schemas/types.yaml#/definitions/uint32 'cpu' is already a defined property of type 'phandle'. While we can have multiple types for a given property name, best practice is to avoid that. The normal way to refer to a CPU would be a phandle to the CPU node, but I can see that might not make sense here. "CPU numbers" on arm64 are 64-bit values as well as they are the CPU's MPIDR value. > + description: > + CPU number of the CPU that this ring buffer belonged to when it was > + serialized. > + > + mem: Too vague. Make the property name indicate what's in the memory. > + $ref: /schemas/types.yaml#/definitions/uint32-array > + description: > + Array of { u64 phys_addr, u64 len } elements that describe a list of ring > + buffer pages. Each page consists of two elements. The first element > + describes the location of the struct buffer_page that contains metadata > + for a given ring buffer page, such as the ring's head indicator. The > + second element points to the ring buffer data page which contains the raw > + trace data. > + > +additionalProperties: false > + > +required: > + - compatible > + - cpu > + - mem > + > +examples: > + - | > + ftrace { > + compatible = "ftrace-v1"; > + events = <1 1 2 2 3 3>; > + > + global_trace { > + compatible = "ftrace,array-v1"; > + trace_flags = < 0x3354601 >; > + > + cpu0 { > + compatible = "ftrace,cpu-v1"; > + cpu = < 0x00 >; > + mem = < 0x101000000ULL 0x38ULL 0x101000100ULL 0x1000ULL 0x101000038ULL 0x38ULL 0x101002000ULL 0x1000ULL>; > + }; > + }; > + }; > diff --git a/Documentation/devicetree/bindings/kho/ftrace/ftrace.yaml b/Documentation/devicetree/bindings/kho/ftrace/ftrace.yaml > new file mode 100644 > index 000000000000..b87a64843af3 > --- /dev/null > +++ b/Documentation/devicetree/bindings/kho/ftrace/ftrace.yaml > @@ -0,0 +1,48 @@ > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/kho/ftrace/ftrace.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Ftrace core data > + > +maintainers: > + - Alexander Graf <graf@xxxxxxxxxx> > + > +properties: > + compatible: > + enum: > + - ftrace-v1 > + > + events: Again, too vague. > + $ref: /schemas/types.yaml#/definitions/uint32-array > + description: > + Array of { u32 crc, u32 type } elements. Each element contains a unique > + identifier for an event, followed by the identifier that this event had > + in the previous kernel's trace buffers. > + > +# Other child nodes will be of type "ftrace,array-v1". Each of which describe > +# a trace buffer > +additionalProperties: true > + > +required: > + - compatible > + - events > + > +examples: > + - | > + ftrace { This should go under /chosen. Show that here. Start the example with '/{' to do that and not add the usual boilerplate we add when extracting the examples. Also, we don't need 3 examples. Just do 1 complete example here. > + compatible = "ftrace-v1"; > + events = <1 1 2 2 3 3>; > + > + global_trace { > + compatible = "ftrace,array-v1"; > + trace_flags = < 0x3354601 >; > + > + cpu0 { > + compatible = "ftrace,cpu-v1"; > + cpu = < 0x00 >; > + mem = < 0x101000000ULL 0x38ULL 0x101000100ULL 0x1000ULL 0x101000038ULL 0x38ULL 0x101002000ULL 0x1000ULL>; > + }; > + }; > + }; > -- > 2.40.1 > > > > > Amazon Development Center Germany GmbH > Krausenstr. 38 > 10117 Berlin > Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss > Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B > Sitz: Berlin > Ust-ID: DE 289 237 879 > > >
