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

From: [email-masked] (Hanjun Guo)
Date: Thu, 23 Jun 2016 09:34:53 +0800

On 2016/6/22 22:51, Marc Zyngier wrote:
> 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 <[email-masked]>
>>>> ---
>>>>   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 <[email-masked]>
>>>> + *
>>>> + * 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

It needs to be free buffer.pointer.

>>
>> Would you mind to fix that (s/kfree/acpi_os_free) before merging ?
> Sure.

I tracked Marc's tree on git.kernel.org, it's  acpi_os_free(buffer.pointer) there so
my worry is gone :)

Thanks
Hanjun