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

    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


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