Commit cacc6e22 authored by Mario Limonciello's avatar Mario Limonciello Committed by Linus Torvalds
Browse files

tpm: Add a helper for checking hwrng enabled 



The same checks are repeated in three places to decide whether to use
hwrng.  Consolidate these into a helper.

Also this fixes a case that one of them was missing a check in the
cleanup path.

Fixes: 554b841d ("tpm: Disable RNG for all AMD fTPMs")
Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 22883973

drivers/char/tpm/tpm-chip.c

+14 −5
Original line number Diff line number Diff line
@@ -521,10 +521,20 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) 
	return tpm_get_random(chip, data, max);

}



static bool tpm_is_hwrng_enabled(struct tpm_chip *chip)

{

	if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))

		return false;

	if (tpm_is_firmware_upgrade(chip))

		return false;

	if (chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED)

		return false;

	return true;

}



static int tpm_add_hwrng(struct tpm_chip *chip)

{

	if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip) ||

	    chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED)

	if (!tpm_is_hwrng_enabled(chip))

		return 0;



	snprintf(chip->hwrng_name, sizeof(chip->hwrng_name),
@@ -629,7 +639,7 @@ int tpm_chip_register(struct tpm_chip *chip) 
	return 0;



out_hwrng:

	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip))

	if (tpm_is_hwrng_enabled(chip))

		hwrng_unregister(&chip->hwrng);

out_ppi:

	tpm_bios_log_teardown(chip);
@@ -654,8 +664,7 @@ EXPORT_SYMBOL_GPL(tpm_chip_register); 
void tpm_chip_unregister(struct tpm_chip *chip)

{

	tpm_del_legacy_sysfs(chip);

	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) &&

	    !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))

	if (tpm_is_hwrng_enabled(chip))

		hwrng_unregister(&chip->hwrng);

	tpm_bios_log_teardown(chip);

	if (chip->flags & TPM_CHIP_FLAG_TPM2 && !tpm_is_firmware_upgrade(chip))