diff options
Diffstat (limited to 'drivers/char/tpm/tpm-chip.c')
-rw-r--r-- | drivers/char/tpm/tpm-chip.c | 196 |
1 files changed, 148 insertions, 48 deletions
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 252142524ff2..a0d9ac6b6cc9 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -29,33 +29,92 @@ #include "tpm.h" #include "tpm_eventlog.h" -static DECLARE_BITMAP(dev_mask, TPM_NUM_DEVICES); -static LIST_HEAD(tpm_chip_list); -static DEFINE_SPINLOCK(driver_lock); +DEFINE_IDR(dev_nums_idr); +static DEFINE_MUTEX(idr_lock); struct class *tpm_class; dev_t tpm_devt; -/* - * tpm_chip_find_get - return tpm_chip for a given chip number - * @chip_num the device number for the chip +/** + * tpm_try_get_ops() - Get a ref to the tpm_chip + * @chip: Chip to ref + * + * The caller must already have some kind of locking to ensure that chip is + * valid. This function will lock the chip so that the ops member can be + * accessed safely. The locking prevents tpm_chip_unregister from + * completing, so it should not be held for long periods. + * + * Returns -ERRNO if the chip could not be got. */ -struct tpm_chip *tpm_chip_find_get(int chip_num) +int tpm_try_get_ops(struct tpm_chip *chip) { - struct tpm_chip *pos, *chip = NULL; + int rc = -EIO; - rcu_read_lock(); - list_for_each_entry_rcu(pos, &tpm_chip_list, list) { - if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num) - continue; + get_device(&chip->dev); - if (try_module_get(pos->pdev->driver->owner)) { - chip = pos; - break; - } + down_read(&chip->ops_sem); + if (!chip->ops) + goto out_lock; + + if (!try_module_get(chip->dev.parent->driver->owner)) + goto out_lock; + + return 0; +out_lock: + up_read(&chip->ops_sem); + put_device(&chip->dev); + return rc; +} +EXPORT_SYMBOL_GPL(tpm_try_get_ops); + +/** + * tpm_put_ops() - Release a ref to the tpm_chip + * @chip: Chip to put + * + * This is the opposite pair to tpm_try_get_ops(). After this returns chip may + * be kfree'd. + */ +void tpm_put_ops(struct tpm_chip *chip) +{ + module_put(chip->dev.parent->driver->owner); + up_read(&chip->ops_sem); + put_device(&chip->dev); +} +EXPORT_SYMBOL_GPL(tpm_put_ops); + +/** + * tpm_chip_find_get() - return tpm_chip for a given chip number + * @chip_num: id to find + * + * The return'd chip has been tpm_try_get_ops'd and must be released via + * tpm_put_ops + */ +struct tpm_chip *tpm_chip_find_get(int chip_num) +{ + struct tpm_chip *chip, *res = NULL; + int chip_prev; + + mutex_lock(&idr_lock); + + if (chip_num == TPM_ANY_NUM) { + chip_num = 0; + do { + chip_prev = chip_num; + chip = idr_get_next(&dev_nums_idr, &chip_num); + if (chip && !tpm_try_get_ops(chip)) { + res = chip; + break; + } + } while (chip_prev != chip_num); + } else { + chip = idr_find_slowpath(&dev_nums_idr, chip_num); + if (chip && !tpm_try_get_ops(chip)) + res = chip; } - rcu_read_unlock(); - return chip; + + mutex_unlock(&idr_lock); + + return res; } /** @@ -68,12 +127,48 @@ static void tpm_dev_release(struct device *dev) { struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev); - spin_lock(&driver_lock); - clear_bit(chip->dev_num, dev_mask); - spin_unlock(&driver_lock); + mutex_lock(&idr_lock); + idr_remove(&dev_nums_idr, chip->dev_num); + mutex_unlock(&idr_lock); + kfree(chip); } + +/** + * tpm_class_shutdown() - prepare the TPM device for loss of power. + * @dev: device to which the chip is associated. + * + * Issues a TPM2_Shutdown command prior to loss of power, as required by the + * TPM 2.0 spec. + * Then, calls bus- and device- specific shutdown code. + * + * XXX: This codepath relies on the fact that sysfs is not enabled for + * TPM2: sysfs uses an implicit lock on chip->ops, so this could race if TPM2 + * has sysfs support enabled before TPM sysfs's implicit locking is fixed. + */ +static int tpm_class_shutdown(struct device *dev) +{ + struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev); + + if (chip->flags & TPM_CHIP_FLAG_TPM2) { + down_write(&chip->ops_sem); + tpm2_shutdown(chip, TPM2_SU_CLEAR); + chip->ops = NULL; + up_write(&chip->ops_sem); + } + /* Allow bus- and device-specific code to run. Note: since chip->ops + * is NULL, more-specific shutdown code will not be able to issue TPM + * commands. + */ + if (dev->bus && dev->bus->shutdown) + dev->bus->shutdown(dev); + else if (dev->driver && dev->driver->shutdown) + dev->driver->shutdown(dev); + return 0; +} + + /** * tpmm_chip_alloc() - allocate a new struct tpm_chip instance * @dev: device to which the chip is associated @@ -88,37 +183,35 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev, const struct tpm_class_ops *ops) { struct tpm_chip *chip; + int rc; chip = kzalloc(sizeof(*chip), GFP_KERNEL); if (chip == NULL) return ERR_PTR(-ENOMEM); mutex_init(&chip->tpm_mutex); - INIT_LIST_HEAD(&chip->list); + init_rwsem(&chip->ops_sem); chip->ops = ops; - spin_lock(&driver_lock); - chip->dev_num = find_first_zero_bit(dev_mask, TPM_NUM_DEVICES); - spin_unlock(&driver_lock); - - if (chip->dev_num >= TPM_NUM_DEVICES) { + mutex_lock(&idr_lock); + rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL); + mutex_unlock(&idr_lock); + if (rc < 0) { dev_err(dev, "No available tpm device numbers\n"); kfree(chip); - return ERR_PTR(-ENOMEM); + return ERR_PTR(rc); } - - set_bit(chip->dev_num, dev_mask); + chip->dev_num = rc; scnprintf(chip->devname, sizeof(chip->devname), "tpm%d", chip->dev_num); - chip->pdev = dev; - dev_set_drvdata(dev, chip); chip->dev.class = tpm_class; + chip->dev.class->shutdown = tpm_class_shutdown; chip->dev.release = tpm_dev_release; - chip->dev.parent = chip->pdev; + chip->dev.parent = dev; #ifdef CONFIG_ACPI chip->dev.groups = chip->groups; #endif @@ -133,7 +226,7 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev, device_initialize(&chip->dev); cdev_init(&chip->cdev, &tpm_fops); - chip->cdev.owner = chip->pdev->driver->owner; + chip->cdev.owner = dev->driver->owner; chip->cdev.kobj.parent = &chip->dev.kobj; devm_add_action(dev, (void (*)(void *)) put_device, &chip->dev); @@ -167,6 +260,11 @@ static int tpm_add_char_device(struct tpm_chip *chip) return rc; } + /* Make the chip available. */ + mutex_lock(&idr_lock); + idr_replace(&dev_nums_idr, chip, chip->dev_num); + mutex_unlock(&idr_lock); + return rc; } @@ -174,6 +272,16 @@ static void tpm_del_char_device(struct tpm_chip *chip) { cdev_del(&chip->cdev); device_del(&chip->dev); + + /* Make the chip unavailable. */ + mutex_lock(&idr_lock); + idr_replace(&dev_nums_idr, NULL, chip->dev_num); + mutex_unlock(&idr_lock); + + /* Make the driver uncallable. */ + down_write(&chip->ops_sem); + chip->ops = NULL; + up_write(&chip->ops_sem); } static int tpm1_chip_register(struct tpm_chip *chip) @@ -228,17 +336,11 @@ int tpm_chip_register(struct tpm_chip *chip) if (rc) goto out_err; - /* Make the chip available. */ - spin_lock(&driver_lock); - list_add_tail_rcu(&chip->list, &tpm_chip_list); - spin_unlock(&driver_lock); - chip->flags |= TPM_CHIP_FLAG_REGISTERED; if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) { - rc = __compat_only_sysfs_link_entry_to_kobj(&chip->pdev->kobj, - &chip->dev.kobj, - "ppi"); + rc = __compat_only_sysfs_link_entry_to_kobj( + &chip->dev.parent->kobj, &chip->dev.kobj, "ppi"); if (rc && rc != -ENOENT) { tpm_chip_unregister(chip); return rc; @@ -259,6 +361,9 @@ EXPORT_SYMBOL_GPL(tpm_chip_register); * Takes the chip first away from the list of available TPM chips and then * cleans up all the resources reserved by tpm_chip_register(). * + * Once this function returns the driver call backs in 'op's will not be + * running and will no longer start. + * * NOTE: This function should be only called before deinitializing chip * resources. */ @@ -267,13 +372,8 @@ void tpm_chip_unregister(struct tpm_chip *chip) if (!(chip->flags & TPM_CHIP_FLAG_REGISTERED)) return; - spin_lock(&driver_lock); - list_del_rcu(&chip->list); - spin_unlock(&driver_lock); - synchronize_rcu(); - if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) - sysfs_remove_link(&chip->pdev->kobj, "ppi"); + sysfs_remove_link(&chip->dev.parent->kobj, "ppi"); tpm1_chip_unregister(chip); tpm_del_char_device(chip); |