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Subject[PATCH 07/12] platform/x86: dell-wmi-smbios: Use Dell WMI descriptor check
Date
The Dell WMI descriptor check is used as an indication that WMI
calls are safe to run both when used with the notification
ASL/GUID pair as well as the SMBIOS calling ASL/GUID pair.

As some code in dell-wmi-smbios is already a prerequisite for
dell-wmi, move the code for performing the descriptor check into
dell-wmi-smbios and let both drivers use it from there.

Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
---
drivers/platform/x86/dell-wmi-smbios.c | 78 ++++++++++++++++++++++++++++++++++
drivers/platform/x86/dell-wmi-smbios.h | 3 ++
drivers/platform/x86/dell-wmi.c | 75 +-------------------------------
3 files changed, 82 insertions(+), 74 deletions(-)

diff --git a/drivers/platform/x86/dell-wmi-smbios.c b/drivers/platform/x86/dell-wmi-smbios.c
index c3701fdadf7b..9deb851ff517 100644
--- a/drivers/platform/x86/dell-wmi-smbios.c
+++ b/drivers/platform/x86/dell-wmi-smbios.c
@@ -24,6 +24,7 @@
#include "dell-wmi-smbios.h"

#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
+#define DELL_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"

struct calling_interface_structure {
struct dmi_header header;
@@ -217,8 +218,81 @@ static const struct attribute_group smbios_attribute_group = {
.attrs = smbios_attrs,
};

+/*
+ * Descriptor buffer is 128 byte long and contains:
+ *
+ * Name Offset Length Value
+ * Vendor Signature 0 4 "DELL"
+ * Object Signature 4 4 " WMI"
+ * WMI Interface Version 8 4 <version>
+ * WMI buffer length 12 4 4096
+ */
+int dell_wmi_check_descriptor_buffer(struct wmi_device *wdev, u32 *version)
+{
+ union acpi_object *obj = NULL;
+ struct wmi_device *desc_dev;
+ u32 *desc_buffer;
+ int ret;
+
+ desc_dev = wmidev_get_other_guid(wdev, DELL_DESCRIPTOR_GUID);
+ if (!desc_dev) {
+ dev_err(&wdev->dev, "Dell WMI descriptor does not exist\n");
+ return -ENODEV;
+ }
+
+ obj = wmidev_block_query(desc_dev, 0);
+ if (!obj) {
+ dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");
+ ret = -EIO;
+ goto out;
+ }
+
+ if (obj->type != ACPI_TYPE_BUFFER) {
+ dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (obj->buffer.length != 128) {
+ dev_err(&wdev->dev,
+ "Dell descriptor buffer has invalid length (%d)\n",
+ obj->buffer.length);
+ if (obj->buffer.length < 16) {
+ ret = -EINVAL;
+ goto out;
+ }
+ }
+
+ desc_buffer = (u32 *)obj->buffer.pointer;
+
+ if (desc_buffer[0] != 0x4C4C4544 && desc_buffer[1] != 0x494D5720)
+ dev_warn(&wdev->dev, "Dell descriptor buffer has invalid signature (%*ph)\n",
+ 8, desc_buffer);
+
+ if (desc_buffer[2] != 0 && desc_buffer[2] != 1)
+ dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%d)\n",
+ desc_buffer[2]);
+
+ if (desc_buffer[3] != 4096)
+ dev_warn(&wdev->dev, "Dell descriptor buffer has invalid buffer length (%d)\n",
+ desc_buffer[3]);
+
+ *version = desc_buffer[2];
+ ret = 0;
+
+ dev_info(&wdev->dev, "Detected Dell WMI interface version %u\n",
+ *version);
+
+out:
+ kfree(obj);
+ put_device(&desc_dev->dev);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dell_wmi_check_descriptor_buffer);
+
static int dell_wmi_smbios_probe(struct wmi_device *wdev)
{
+ u32 interface_version;
int ret;

dmi_walk(find_tokens, NULL);
@@ -228,6 +302,10 @@ static int dell_wmi_smbios_probe(struct wmi_device *wdev)
return -ENODEV;
}

+ ret = dell_wmi_check_descriptor_buffer(wdev, &interface_version);
+ if (ret)
+ return ret;
+
buffer = (void *)__get_free_page(GFP_KERNEL);
if (!buffer) {
ret = -ENOMEM;
diff --git a/drivers/platform/x86/dell-wmi-smbios.h b/drivers/platform/x86/dell-wmi-smbios.h
index e6e9990bb2b7..0521ec5d437b 100644
--- a/drivers/platform/x86/dell-wmi-smbios.h
+++ b/drivers/platform/x86/dell-wmi-smbios.h
@@ -17,6 +17,8 @@
#ifndef _DELL_WMI_SMBIOS_H_
#define _DELL_WMI_SMBIOS_H_

+#include <linux/wmi.h>
+
struct notifier_block;

struct calling_interface_buffer {
@@ -54,5 +56,6 @@ enum dell_laptop_notifier_actions {
int dell_laptop_register_notifier(struct notifier_block *nb);
int dell_laptop_unregister_notifier(struct notifier_block *nb);
void dell_laptop_call_notifier(unsigned long action, void *data);
+int dell_wmi_check_descriptor_buffer(struct wmi_device *wdev, u32 *version);

#endif
diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index e8b4d412eabc..e7011792127f 100644
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -46,7 +46,6 @@ MODULE_DESCRIPTION("Dell laptop WMI hotkeys driver");
MODULE_LICENSE("GPL");

#define DELL_EVENT_GUID "9DBB5994-A997-11DA-B012-B622A1EF5492"
-#define DELL_DESCRIPTOR_GUID "8D9DDCBC-A997-11DA-B012-B622A1EF5492"

static bool wmi_requires_smbios_request;

@@ -617,78 +616,6 @@ static void dell_wmi_input_destroy(struct wmi_device *wdev)
input_unregister_device(priv->input_dev);
}

-/*
- * Descriptor buffer is 128 byte long and contains:
- *
- * Name Offset Length Value
- * Vendor Signature 0 4 "DELL"
- * Object Signature 4 4 " WMI"
- * WMI Interface Version 8 4 <version>
- * WMI buffer length 12 4 4096
- */
-static int dell_wmi_check_descriptor_buffer(struct wmi_device *wdev)
-{
- struct dell_wmi_priv *priv = dev_get_drvdata(&wdev->dev);
- union acpi_object *obj = NULL;
- struct wmi_device *desc_dev;
- u32 *buffer;
- int ret;
-
- desc_dev = wmidev_get_other_guid(wdev, DELL_DESCRIPTOR_GUID);
- if (!desc_dev) {
- dev_err(&wdev->dev, "Dell WMI descriptor does not exist\n");
- return -ENODEV;
- }
-
- obj = wmidev_block_query(desc_dev, 0);
- if (!obj) {
- dev_err(&wdev->dev, "failed to read Dell WMI descriptor\n");
- ret = -EIO;
- goto out;
- }
-
- if (obj->type != ACPI_TYPE_BUFFER) {
- dev_err(&wdev->dev, "Dell descriptor has wrong type\n");
- ret = -EINVAL;
- goto out;
- }
-
- if (obj->buffer.length != 128) {
- dev_err(&wdev->dev,
- "Dell descriptor buffer has invalid length (%d)\n",
- obj->buffer.length);
- if (obj->buffer.length < 16) {
- ret = -EINVAL;
- goto out;
- }
- }
-
- buffer = (u32 *)obj->buffer.pointer;
-
- if (buffer[0] != 0x4C4C4544 && buffer[1] != 0x494D5720)
- dev_warn(&wdev->dev, "Dell descriptor buffer has invalid signature (%*ph)\n",
- 8, buffer);
-
- if (buffer[2] != 0 && buffer[2] != 1)
- dev_warn(&wdev->dev, "Dell descriptor buffer has unknown version (%d)\n",
- buffer[2]);
-
- if (buffer[3] != 4096)
- dev_warn(&wdev->dev, "Dell descriptor buffer has invalid buffer length (%d)\n",
- buffer[3]);
-
- priv->interface_version = buffer[2];
- ret = 0;
-
- dev_info(&wdev->dev, "Detected Dell WMI interface version %u\n",
- priv->interface_version);
-
-out:
- kfree(obj);
- put_device(&desc_dev->dev);
- return ret;
-}
-
/*
* According to Dell SMBIOS documentation:
*
@@ -732,7 +659,7 @@ static int dell_wmi_probe(struct wmi_device *wdev)
return -ENOMEM;
dev_set_drvdata(&wdev->dev, priv);

- err = dell_wmi_check_descriptor_buffer(wdev);
+ err = dell_wmi_check_descriptor_buffer(wdev, &priv->interface_version);
if (err)
return err;

--
2.14.1
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