Re: [PATCH v2 05/11] firewall: introduce stm32_firewall framework

[Gatien CHEVALLIER <gatien.chevallier@foss.st.com>]

On 7/26/23 12:19, Simon Horman wrote:
> On Tue, Jul 25, 2023 at 06:40:58PM +0200, Gatien Chevallier wrote:
>> Introduce a STM32 firewall framework that offers to firewall consumers
>> different firewall services such as the ability to check their access
>> rights against their firewall controller(s).
>>
>> The STM32 firewall framework offers a generic API for STM32 firewall
>> controllers that is defined in their drivers to best fit the
>> specificity of each firewall.
>>
>> There are various types of firewalls:
>> -Peripheral firewalls that filter accesses to peripherals
>> -Memory firewalls that filter accesses to memories or memory regions
>> -No type for undefined type of firewall
>>
>> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
> 
> ...
> 
>> diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c
> 
> ...
> 
>> +int stm32_firewall_populate_bus(struct stm32_firewall_controller *firewall_controller)
>> +{
>> +	struct stm32_firewall *firewalls;
>> +	struct device_node *child;
>> +	struct device *parent;
>> +	unsigned int i;
>> +	int len;
>> +	int err;
>> +
>> +	parent = firewall_controller->dev;
>> +
>> +	dev_dbg(parent, "Populating %s system bus\n", dev_name(firewall_controller->dev));
>> +
>> +	for_each_available_child_of_node(dev_of_node(parent), child) {
>> +		/* The feature-domains property is mandatory for firewall bus devices */
>> +		len = of_count_phandle_with_args(child, "feature-domains", "#feature-domain-cells");
>> +		if (len <= 0)
> 
> Coccinelle says that, due to breaking out of a
> for_each_available_child_of_node() loop, a call to of_node_put()
> is needed here
> 

Hi Simon,

Thank you, I already sent a V3 correcting the patch ordering issue. I
will implement this for V4.

>> +			return -EINVAL;
>> +
>> +		firewalls = kcalloc(len, sizeof(*firewalls), GFP_KERNEL);
>> +		if (!firewalls)
> 
> And here.
> 

ditto

>> +			return -ENOMEM;
>> +
>> +		err = stm32_firewall_get_firewall(child, firewalls, (unsigned int)len);
>> +		if (err) {
>> +			kfree(firewalls);
> 
> And here.
> 

ditto

>> +			return err;
>> +		}
>> +
>> +		for (i = 0; i < len; i++) {
>> +			if (firewall_controller->grant_access(firewall_controller,
>> +							      firewalls[i].firewall_id)) {
>> +				/*
>> +				 * Peripheral access not allowed or not defined.
>> +				 * Mark the node as populated so platform bus won't probe it
>> +				 */
>> +				of_node_set_flag(child, OF_POPULATED);
>> +				dev_err(parent, "%s: Device driver will not be probed\n",
>> +					child->full_name);
>> +			}
>> +		}
>> +
>> +		kfree(firewalls);
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(stm32_firewall_populate_bus);
> 
>> diff --git a/drivers/bus/stm32_firewall.h b/drivers/bus/stm32_firewall.h
> 
> ...
> 
>> +/**
>> + * struct stm32_firewall_controller - Information on firewall controller supplying services
>> + *
>> + * @name			Name of the firewall controller
> 
> kernel-doc complains that name and the other fields of
> struct stm32_firewall_controller are not documented.
> I believe this is because a ':' is needed after the name of
> the parameter (in this case 'name').
> 
>   * @name:			Name of the firewall controller
> 
> Likewise, elsewhere.
> 

I will implement it in V4, thank you.

>> + * @dev				Device reference of the firewall controller
>> + * @mmio			Base address of the firewall controller
>> + * @entry			List entry of the firewall controller list
>> + * @type			Type of firewall
>> + * @max_entries			Number of entries covered by the firewall
>> + * @grant_access		Callback used to grant access for a device access against a
>> + *				firewall controller
>> + * @release_access		Callback used to release resources taken by a device when access was
>> + *				granted
>> + * @grant_memory_range_access	Callback used to grant access for a device to a given memory region
>> + */
>> +struct stm32_firewall_controller {
>> +	const char *name;
>> +	struct device *dev;
>> +	void __iomem *mmio;
>> +	struct list_head entry;
>> +	unsigned int type;
>> +	unsigned int max_entries;
>> +
>> +	int (*grant_access)(struct stm32_firewall_controller *ctrl, u32 id);
>> +	void (*release_access)(struct stm32_firewall_controller *ctrl, u32 id);
>> +	int (*grant_memory_range_access)(struct stm32_firewall_controller *ctrl, phys_addr_t paddr,
>> +					 size_t size);
>> +};
>> +
>> +/**
>> + * int stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall
> 
> kernel-doc seems unhappy about the presence of 'int' on this line.
> 
>   * stm32_firewall_controller_register - Register a firewall controller to the STM32 firewall
> 
> Likewise, elsewhere.
> 

Yes, I will remove the type in V4.

>> + *					    framework
>> + * @firewall_controller		Firewall controller to register
>> + *
>> + * Returns 0 in case of success or -ENODEV if no controller was given.
>> + */
>> +int stm32_firewall_controller_register(struct stm32_firewall_controller *firewall_controller);
> 
> ...
> 
>> diff --git a/include/linux/bus/stm32_firewall_device.h b/include/linux/bus/stm32_firewall_device.h
>> new file mode 100644
>> index 000000000000..9bdc4060154c
>> --- /dev/null
>> +++ b/include/linux/bus/stm32_firewall_device.h
>> @@ -0,0 +1,140 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (C) 2023, STMicroelectronics - All Rights Reserved
>> + */
>> +
>> +#ifndef STM32_FIREWALL_DEVICE_H
>> +#define STM32_FIREWALL_DEVICE_H
>> +
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/types.h>
>> +
>> +#define STM32_FIREWALL_MAX_EXTRA_ARGS		5
>> +
>> +/* Opaque reference to stm32_firewall_controller */
>> +struct stm32_firewall_controller;
>> +
>> +/**
>> + * stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.
> 
> kernel-doc seems unhappy about the absence of struct on this line.
> 
>   * struct stm32_firewall - Information on a device's firewall. Each device can have more than one firewall.
> 

Yes, I will add the struct in V4.

>> + *
>> + * @firewall_ctrl		Pointer referencing a firewall controller of the device. It is
>> + *				opaque so a device cannot manipulate the controller's ops or access
>> + *				the controller's data
>> + * @extra_args			Extra arguments that are implementation dependent
>> + * @entry			Name of the firewall entry
>> + * @extra_args_size		Number of extra arguments
>> + * @firewall_id			Firewall ID associated the device for this firewall controller
>> + */
>> +struct stm32_firewall {
>> +	struct stm32_firewall_controller *firewall_ctrl;
>> +	u32 extra_args[STM32_FIREWALL_MAX_EXTRA_ARGS];
>> +	const char *entry;
>> +	size_t extra_args_size;
>> +	u32 firewall_id;
>> +};
> 
> ...
> 
Best regards,
Gatien