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

[Tomasz Nowicki <tn@semihalf.com>]

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@semihalf.com>
>> ---
>>   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@semihalf.com>
>> + *
>> + * 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 ?

Thanks,
Tomasz