Re: [PATCH V7 1/8] ACPI: I/O Remapping Table (IORT) initial support
From: Marc Zyngier
Date: Wed Jun 22 2016 - 09:25:52 EST
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.
*/
Thanks,
M.
--
Jazz is not dead. It just smells funny...