[PATCH v11 4/8] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()"

From: amirmizi6@gmail.com
To: Eyal.Cohen@nuvoton.com, jarkko.sakkinen@linux.intel.com,
	oshrialkoby85@gmail.com, alexander.steffen@infineon.com,
	robh+dt@kernel.org,
	"benoit.houyere@st.com--to=mark.rutland"@arm.com,
	peterhuewe@gmx.de, christophe-h.richard@st.com, jgg@ziepe.ca,
	arnd@arndb.de, gregkh@linuxfoundation.org
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-integrity@vger.kernel.org, oshri.alkoby@nuvoton.com,
	tmaimon77@gmail.com, gcwilson@us.ibm.com, kgoldman@us.ibm.com,
	Dan.Morav@nuvoton.com, oren.tanami@nuvoton.com,
	shmulik.hager@nuvoton.com, amir.mizinski@nuvoton.com,
	Amir Mizinski <amirmizi6@gmail.com>
Subject: [PATCH v11 4/8] tpm: tpm_tis: Rewrite "tpm_tis_req_canceled()"
Date: Thu, 18 Jun 2020 16:43:39 +0300	[thread overview]
Message-ID: <20200618134344.243537-5-amirmizi6@gmail.com> (raw)
In-Reply-To: <20200618134344.243537-1-amirmizi6@gmail.com>

From: Amir Mizinski <amirmizi6@gmail.com>

Using this function while reading/writing data resulted in an aborted
operation.
After investigating the issue according to the TCG TPM Profile (PTP)
Specifications, I found that "request to cancel" should occur only if
TPM_STS.commandReady bit is lit.
Note that i couldn't find a case where the present condition
(in the linux kernel) is valid, so I'm removing the case for
"TPM_VID_WINBOND" since we have no need for it.

Also, the default comparison is wrong. Only cmdReady bit needs to be
compared instead of the full lower status register byte.

Fixes: 1f866057291f (tpm: Fix cancellation of TPM commands (polling mode))
Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
---
 drivers/char/tpm/tpm_tis_core.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 14ffee4..2636ec7 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -699,13 +699,11 @@ static bool tpm_tis_req_canceled(struct tpm_chip *chip, u8 status)
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 
 	switch (priv->manufacturer_id) {
-	case TPM_VID_WINBOND:
-		return ((status == TPM_STS_VALID) ||
-			(status == (TPM_STS_VALID | TPM_STS_COMMAND_READY)));
 	case TPM_VID_STM:
 		return (status == (TPM_STS_VALID | TPM_STS_COMMAND_READY));
 	default:
-		return (status == TPM_STS_COMMAND_READY);
+		return ((status & TPM_STS_COMMAND_READY) ==
+			TPM_STS_COMMAND_READY);
 	}
 }
 
-- 
2.7.4

