Re: [PATCH v9 2/8] tpm: tpm_tis: Fix expected bit handling and send all bytes in one shot without last byte in exception
From: Jarkko Sakkinen <hidden>
Date: 2020-06-01 02:31:00
Also in:
linux-integrity, lkml
On Tue, May 26, 2020 at 05:16:52PM +0300, amirmizi6@gmail.com wrote:
From: Amir Mizinski <redacted> Incorrect implementation of send message was detected. We polled only TPM_STS.stsValid bit and then we single-checked the TPM_STS.expect bit value. TPM_STS.expected bit should be checked at the same time as TPM_STS.stsValid bit, and this should be repeated until timeout_A.
I don't understand what the first paragraph is trying to say. It does not conclude to anything. Please write instead soemthing that explains what is going on.
To detect a TPM_STS.expected bit reset, the "wait_for_tpm_stat" function is modified to "wait_for_tpm_stat_result". This function regularly reads the status register and check the bits defined by "mask" to reach the value defined in "mask_result".
Please remove this and explain instead how are you are changing the existing function.
quoted hunk ↗ jump to hunk
This correct implementation is required for using the new CRC calculation on I2C TPM command bytes or I2C TPM answer bytes. TPM_STS.expected bit is reset after all bytes are acquired and the CRC result is inserted in the dedicated register. It introduces a normal latency for TPM_STS.expected bit reset. Respectively, to send a message, as defined in TCG_DesignPrinciples_TPM2p0Driver_vp24_pubrev.pdf, all bytes should be sent in one shot instead of sending the last byte separately. Suggested-by: Benoit Houyere <redacted> Signed-off-by: Amir Mizinski <redacted> --- drivers/char/tpm/tpm_tis_core.c | 74 +++++++++++++++++------------------------ 1 file changed, 30 insertions(+), 44 deletions(-)diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 27c6ca0..c725b68 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c@@ -44,9 +44,10 @@ static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask, return false; } -static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask, - unsigned long timeout, wait_queue_head_t *queue, - bool check_cancel) +static int wait_for_tpm_stat_result(struct tpm_chip *chip, u8 mask, + u8 mask_result, unsigned long timeout, + wait_queue_head_t *queue, + bool check_cancel)
Please do not change the function name. /Jarkko