Re: [PATCH V7 1/8] ACPI: I/O Remapping Table (IORT) initial support

[Marc Zyngier]

On 22/06/16 14:52, Tomasz Nowicki wrote:
> On 22.06.2016 15:25, Marc Zyngier wrote:
>> On 22/06/16 13:35, Tomasz Nowicki wrote:
>>> IORT shows representation of IO topology for ARM based systems.
>>> It describes how various components are connected together on
>>> parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec.
>>> http://infocenter.arm.com/help/topic/com.arm.doc.den0049b/DEN0049B_IO_Remapping_Table.pdf
>>>
>>> Initial support allows to detect IORT table presence and save its
>>> root pointer obtained through acpi_get_table(). The pointer validity
>>> depends on acpi_gbl_permanent_mmap because if acpi_gbl_permanent_mmap
>>> is not set while using IORT nodes we would dereference unmapped pointers.
>>>
>>> For the aforementioned reason call iort_table_detect() from acpi_init()
>>> which guarantees acpi_gbl_permanent_mmap to be set at that point.
>>>
>>> Add generic helpers which are helpful for scanning and retrieving
>>> information from IORT table content. List of the most important helpers:
>>> - iort_find_dev_node() finds IORT node for a given device
>>> - iort_node_map_rid() maps device RID and returns IORT node which provides
>>>    final translation
>>>
>>> Signed-off-by: Tomasz Nowicki <tn@xxxxxxxxxxxx>
>>> ---
>>>   drivers/acpi/Kconfig  |   3 +
>>>   drivers/acpi/Makefile |   1 +
>>>   drivers/acpi/bus.c    |   2 +
>>>   drivers/acpi/iort.c   | 217 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>>   include/linux/iort.h  |  30 +++++++
>>>   5 files changed, 253 insertions(+)
>>>   create mode 100644 drivers/acpi/iort.c
>>>   create mode 100644 include/linux/iort.h
>>>
>>> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
>>> index b7e2e77..848471f 100644
>>> --- a/drivers/acpi/Kconfig
>>> +++ b/drivers/acpi/Kconfig
>>> @@ -57,6 +57,9 @@ config ACPI_SYSTEM_POWER_STATES_SUPPORT
>>>   config ACPI_CCA_REQUIRED
>>>   	bool
>>>
>>> +config IORT_TABLE
>>> +	bool
>>> +
>>>   config ACPI_DEBUGGER
>>>   	bool "AML debugger interface"
>>>   	select ACPI_DEBUG
>>> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
>>> index 251ce85..c7c9b29 100644
>>> --- a/drivers/acpi/Makefile
>>> +++ b/drivers/acpi/Makefile
>>> @@ -82,6 +82,7 @@ obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
>>>   obj-$(CONFIG_ACPI_BGRT)		+= bgrt.o
>>>   obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
>>>   obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
>>> +obj-$(CONFIG_IORT_TABLE) 	+= iort.o
>>>
>>>   # processor has its own "processor." module_param namespace
>>>   processor-y			:= processor_driver.o
>>> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
>>> index 31e8da6..176c17d 100644
>>> --- a/drivers/acpi/bus.c
>>> +++ b/drivers/acpi/bus.c
>>> @@ -33,6 +33,7 @@
>>>   #ifdef CONFIG_X86
>>>   #include <asm/mpspec.h>
>>>   #endif
>>> +#include <linux/iort.h>
>>>   #include <linux/pci.h>
>>>   #include <acpi/apei.h>
>>>   #include <linux/dmi.h>
>>> @@ -1118,6 +1119,7 @@ static int __init acpi_init(void)
>>>   	}
>>>
>>>   	pci_mmcfg_late_init();
>>> +	iort_table_detect();
>>>   	acpi_scan_init();
>>>   	acpi_ec_init();
>>>   	acpi_debugfs_init();
>>> diff --git a/drivers/acpi/iort.c b/drivers/acpi/iort.c
>>> new file mode 100644
>>> index 0000000..fcfa008f
>>> --- /dev/null
>>> +++ b/drivers/acpi/iort.c
>>> @@ -0,0 +1,217 @@
>>> +/*
>>> + * Copyright (C) 2016, Semihalf
>>> + *	Author: Tomasz Nowicki <tn@xxxxxxxxxxxx>
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify it
>>> + * under the terms and conditions of the GNU General Public License,
>>> + * version 2, as published by the Free Software Foundation.
>>> + *
>>> + * This program is distributed in the hope it will be useful, but WITHOUT
>>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>>> + * more details.
>>> + *
>>> + * This file implements early detection/parsing of I/O mapping
>>> + * reported to OS through firmware via I/O Remapping Table (IORT)
>>> + * IORT document number: ARM DEN 0049A
>>> + */
>>> +
>>> +#define pr_fmt(fmt)	"ACPI: IORT: " fmt
>>> +
>>> +#include <linux/iort.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/pci.h>
>>> +
>>> +typedef acpi_status (*iort_find_node_callback)
>>> +	(struct acpi_iort_node *node, void *context);
>>> +
>>> +/* Root pointer to the mapped IORT table */
>>> +static struct acpi_table_header *iort_table;
>>> +
>>> +static struct acpi_iort_node *
>>> +iort_scan_node(enum acpi_iort_node_type type,
>>> +	       iort_find_node_callback callback, void *context)
>>> +{
>>> +	struct acpi_iort_node *iort_node, *iort_end;
>>> +	struct acpi_table_iort *iort;
>>> +	int i;
>>> +
>>> +	/* Get the first IORT node */
>>> +	iort = (struct acpi_table_iort *)iort_table;
>>> +	iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort,
>>> +				 iort->node_offset);
>>> +	iort_end = ACPI_ADD_PTR(struct acpi_iort_node, iort_table,
>>> +				iort_table->length);
>>> +
>>> +	for (i = 0; i < iort->node_count; i++) {
>>> +		if (WARN_TAINT(iort_node >= iort_end, TAINT_FIRMWARE_WORKAROUND,
>>> +			       "IORT node pointer overflows, bad table!\n"))
>>> +			return NULL;
>>> +
>>> +		if (iort_node->type == type) {
>>> +			if (ACPI_SUCCESS(callback(iort_node, context)))
>>> +				return iort_node;
>>> +		}
>>> +
>>> +		iort_node = ACPI_ADD_PTR(struct acpi_iort_node, iort_node,
>>> +					 iort_node->length);
>>> +	}
>>> +
>>> +	return NULL;
>>> +}
>>> +
>>> +static acpi_status
>>> +iort_match_node_callback(struct acpi_iort_node *node, void *context)
>>> +{
>>> +	struct device *dev = context;
>>> +
>>> +	switch (node->type) {
>>> +	case ACPI_IORT_NODE_NAMED_COMPONENT: {
>>> +		struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>>> +		struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
>>> +		struct acpi_iort_named_component *ncomp;
>>> +
>>> +		if (!adev)
>>> +			break;
>>> +
>>> +		ncomp = (struct acpi_iort_named_component *)node->node_data;
>>> +
>>> +		if (ACPI_FAILURE(acpi_get_name(adev->handle,
>>> +					       ACPI_FULL_PATHNAME, &buffer))) {
>>> +			dev_warn(dev, "Can't get device full path name\n");
>>> +		} else {
>>> +			int match;
>>> +
>>> +			match = !strcmp(ncomp->device_name, buffer.pointer);
>>> +			kfree(buffer.pointer);
>>
>> Why did you change this to a naked kfree? The ACPI code clearly states:
>>
>> /*
>>   * Allocate a new buffer. We directectly call acpi_os_allocate here to
>>   * purposefully bypass the (optionally enabled) internal allocation
>>   * tracking mechanism since we only want to track internal
>>   * allocations. Note: The caller should use acpi_os_free to free this
>>   * buffer created via ACPI_ALLOCATE_BUFFER.
>>   */
> 
> Yes we should use symmetric free function to acpi_os_allocate here, 
> which means acpi_os_free should be used here.
> 
> My main motivation was to free buffer.pointer instead of &buffer
> 
> Would you mind to fix that (s/kfree/acpi_os_free) before merging ?

Sure.

	M.
-- 
Jazz is not dead. It just smells funny...