tpm: fix raciness of PPI interface lookup
[cascardo/linux.git] / drivers / char / tpm / tpm_ppi.c
index 61dcc80..af48c56 100644 (file)
@@ -1,3 +1,22 @@
+/*
+ * Copyright (C) 2012-2014 Intel Corporation
+ *
+ * Authors:
+ * Xiaoyan Zhang <xiaoyan.zhang@intel.com>
+ * Jiang Liu <jiang.liu@linux.intel.com>
+ * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
+ *
+ * Maintained by: <tpmdd-devel@lists.sourceforge.net>
+ *
+ * This file contains implementation of the sysfs interface for PPI.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+
 #include <linux/acpi.h>
 #include "tpm.h"
 
@@ -12,7 +31,6 @@
 #define PPI_TPM_REQ_MAX                22
 #define PPI_VS_REQ_START       128
 #define PPI_VS_REQ_END         255
-#define PPI_VERSION_LEN                3
 
 static const u8 tpm_ppi_uuid[] = {
        0xA6, 0xFA, 0xDD, 0x3D,
@@ -22,45 +40,22 @@ static const u8 tpm_ppi_uuid[] = {
        0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
 };
 
-static char tpm_ppi_version[PPI_VERSION_LEN + 1];
-static acpi_handle tpm_ppi_handle;
-
-static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
-                               void **return_value)
-{
-       union acpi_object *obj;
-
-       if (!acpi_check_dsm(handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
-                           1 << TPM_PPI_FN_VERSION))
-               return AE_OK;
-
-       /* Cache version string */
-       obj = acpi_evaluate_dsm_typed(handle, tpm_ppi_uuid,
-                                     TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
-                                     NULL, ACPI_TYPE_STRING);
-       if (obj) {
-               strlcpy(tpm_ppi_version, obj->string.pointer,
-                       PPI_VERSION_LEN + 1);
-               ACPI_FREE(obj);
-       }
-
-       *return_value = handle;
-
-       return AE_CTRL_TERMINATE;
-}
-
 static inline union acpi_object *
-tpm_eval_dsm(int func, acpi_object_type type, union acpi_object *argv4)
+tpm_eval_dsm(acpi_handle ppi_handle, int func, acpi_object_type type,
+            union acpi_object *argv4)
 {
-       BUG_ON(!tpm_ppi_handle);
-       return acpi_evaluate_dsm_typed(tpm_ppi_handle, tpm_ppi_uuid,
-                                      TPM_PPI_REVISION_ID, func, argv4, type);
+       BUG_ON(!ppi_handle);
+       return acpi_evaluate_dsm_typed(ppi_handle, tpm_ppi_uuid,
+                                      TPM_PPI_REVISION_ID,
+                                      func, argv4, type);
 }
 
 static ssize_t tpm_show_ppi_version(struct device *dev,
                                    struct device_attribute *attr, char *buf)
 {
-       return scnprintf(buf, PAGE_SIZE, "%s\n", tpm_ppi_version);
+       struct tpm_chip *chip = dev_get_drvdata(dev);
+
+       return scnprintf(buf, PAGE_SIZE, "%s\n", chip->ppi_version);
 }
 
 static ssize_t tpm_show_ppi_request(struct device *dev,
@@ -68,8 +63,10 @@ static ssize_t tpm_show_ppi_request(struct device *dev,
 {
        ssize_t size = -EINVAL;
        union acpi_object *obj;
+       struct tpm_chip *chip = dev_get_drvdata(dev);
 
-       obj = tpm_eval_dsm(TPM_PPI_FN_GETREQ, ACPI_TYPE_PACKAGE, NULL);
+       obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETREQ,
+                          ACPI_TYPE_PACKAGE, NULL);
        if (!obj)
                return -ENXIO;
 
@@ -103,14 +100,15 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
        int func = TPM_PPI_FN_SUBREQ;
        union acpi_object *obj, tmp;
        union acpi_object argv4 = ACPI_INIT_DSM_ARGV4(1, &tmp);
+       struct tpm_chip *chip = dev_get_drvdata(dev);
 
        /*
         * the function to submit TPM operation request to pre-os environment
         * is updated with function index from SUBREQ to SUBREQ2 since PPI
         * version 1.1
         */
-       if (acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
-                          1 << TPM_PPI_FN_SUBREQ2))
+       if (acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
+                          TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_SUBREQ2))
                func = TPM_PPI_FN_SUBREQ2;
 
        /*
@@ -119,7 +117,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
         * string/package type. For PPI version 1.0 and 1.1, use buffer type
         * for compatibility, and use package type since 1.2 according to spec.
         */
-       if (strcmp(tpm_ppi_version, "1.2") < 0) {
+       if (strcmp(chip->ppi_version, "1.2") < 0) {
                if (sscanf(buf, "%d", &req) != 1)
                        return -EINVAL;
                argv4.type = ACPI_TYPE_BUFFER;
@@ -131,7 +129,8 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
                        return -EINVAL;
        }
 
-       obj = tpm_eval_dsm(func, ACPI_TYPE_INTEGER, &argv4);
+       obj = tpm_eval_dsm(chip->acpi_dev_handle, func, ACPI_TYPE_INTEGER,
+                          &argv4);
        if (!obj) {
                return -ENXIO;
        } else {
@@ -157,6 +156,7 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
                .buffer.length = 0,
                .buffer.pointer = NULL
        };
+       struct tpm_chip *chip = dev_get_drvdata(dev);
 
        static char *info[] = {
                "None",
@@ -171,9 +171,10 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
         * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
         * compatibility, define params[3].type as buffer, if PPI version < 1.2
         */
-       if (strcmp(tpm_ppi_version, "1.2") < 0)
+       if (strcmp(chip->ppi_version, "1.2") < 0)
                obj = &tmp;
-       obj = tpm_eval_dsm(TPM_PPI_FN_GETACT, ACPI_TYPE_INTEGER, obj);
+       obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETACT,
+                          ACPI_TYPE_INTEGER, obj);
        if (!obj) {
                return -ENXIO;
        } else {
@@ -196,8 +197,10 @@ static ssize_t tpm_show_ppi_response(struct device *dev,
        acpi_status status = -EINVAL;
        union acpi_object *obj, *ret_obj;
        u64 req, res;
+       struct tpm_chip *chip = dev_get_drvdata(dev);
 
-       obj = tpm_eval_dsm(TPM_PPI_FN_GETRSP, ACPI_TYPE_PACKAGE, NULL);
+       obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETRSP,
+                          ACPI_TYPE_PACKAGE, NULL);
        if (!obj)
                return -ENXIO;
 
@@ -248,7 +251,8 @@ cleanup:
        return status;
 }
 
-static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
+static ssize_t show_ppi_operations(acpi_handle dev_handle, char *buf, u32 start,
+                                  u32 end)
 {
        int i;
        u32 ret;
@@ -264,14 +268,15 @@ static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
                "User not required",
        };
 
-       if (!acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
+       if (!acpi_check_dsm(dev_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
                            1 << TPM_PPI_FN_GETOPR))
                return -EPERM;
 
        tmp.integer.type = ACPI_TYPE_INTEGER;
        for (i = start; i <= end; i++) {
                tmp.integer.value = i;
-               obj = tpm_eval_dsm(TPM_PPI_FN_GETOPR, ACPI_TYPE_INTEGER, &argv);
+               obj = tpm_eval_dsm(dev_handle, TPM_PPI_FN_GETOPR,
+                                  ACPI_TYPE_INTEGER, &argv);
                if (!obj) {
                        return -ENOMEM;
                } else {
@@ -291,14 +296,20 @@ static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
                                           struct device_attribute *attr,
                                           char *buf)
 {
-       return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
+       struct tpm_chip *chip = dev_get_drvdata(dev);
+
+       return show_ppi_operations(chip->acpi_dev_handle, buf, 0,
+                                  PPI_TPM_REQ_MAX);
 }
 
 static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
                                          struct device_attribute *attr,
                                          char *buf)
 {
-       return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
+       struct tpm_chip *chip = dev_get_drvdata(dev);
+
+       return show_ppi_operations(chip->acpi_dev_handle, buf, PPI_VS_REQ_START,
+                                  PPI_VS_REQ_END);
 }
 
 static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
@@ -323,16 +334,38 @@ static struct attribute_group ppi_attr_grp = {
        .attrs = ppi_attrs
 };
 
-int tpm_add_ppi(struct kobject *parent)
+int tpm_add_ppi(struct tpm_chip *chip)
 {
-       /* Cache TPM ACPI handle and version string */
-       acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
-                           ppi_callback, NULL, NULL, &tpm_ppi_handle);
-       return tpm_ppi_handle ? sysfs_create_group(parent, &ppi_attr_grp) : 0;
+       union acpi_object *obj;
+       int rc;
+
+       if (!chip->acpi_dev_handle)
+               return 0;
+
+       if (!acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
+                           TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_VERSION))
+               return 0;
+
+       /* Cache PPI version string. */
+       obj = acpi_evaluate_dsm_typed(chip->acpi_dev_handle, tpm_ppi_uuid,
+                                     TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
+                                     NULL, ACPI_TYPE_STRING);
+       if (obj) {
+               strlcpy(chip->ppi_version, obj->string.pointer,
+                       sizeof(chip->ppi_version));
+               ACPI_FREE(obj);
+       }
+
+       rc = sysfs_create_group(&chip->dev->kobj, &ppi_attr_grp);
+
+       if (!rc)
+               chip->flags |= TPM_CHIP_FLAG_PPI;
+
+       return rc;
 }
 
-void tpm_remove_ppi(struct kobject *parent)
+void tpm_remove_ppi(struct tpm_chip *chip)
 {
-       if (tpm_ppi_handle)
-               sysfs_remove_group(parent, &ppi_attr_grp);
+       if (chip->flags & TPM_CHIP_FLAG_PPI)
+               sysfs_remove_group(&chip->dev->kobj, &ppi_attr_grp);
 }