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

On 2016/6/22 22:51, Marc Zyngier wrote:

On 22/06/16 14:52, Tomasz Nowicki wrote:

quoted

On 22.06.2016 15:25, Marc Zyngier wrote:

quoted

On 22/06/16 13:35, Tomasz Nowicki wrote:

quoted

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 <redacted>
---
  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.

quoted

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