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tpm: Add a helper for checking hwrng enabled

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commit cacc6e22932f373a91d7be55a9b992dc77f4c59b upstream.

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: 554b841d4703 ("tpm: Disable RNG for all AMD fTPMs")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mario Limonciello 2023-08-07 23:12:29 -05:00 committed by Greg Kroah-Hartman
parent d8a7d6136c
commit ccb1700ed6
1 changed files with 14 additions and 5 deletions
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19
drivers/char/tpm/tpm-chip.c
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@ -518,10 +518,20 @@ 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),
@ -626,7 +636,7 @@ 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);
@ -651,8 +661,7 @@ 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))