Re: [PATCH V7 1/8] ACPI: I/O Remapping Table (IORT) initial support
From: Hanjun Guo
Date: Wed Jun 22 2016 - 21:36:56 EST
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 <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
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