Commit 72fd50e1 authored Sep 02, 2016 by Jarkko Sakkinen

tpm_crb: fix crb_req_canceled behavior



The req_canceled() callback is used by tpm_transmit() periodically to
check whether the request has been canceled while it is receiving a
response from the TPM.

The TPM_CRB_CTRL_CANCEL register was cleared already in the crb_cancel
callback, which has two consequences:

* Cancel might not happen.
* req_canceled() always returns zero.

A better place to clear the register is when starting to send a new
command. The behavior of TPM_CRB_CTRL_CANCEL is described in the
section 5.5.3.6 of the PTP specification.

CC: stable@vger.kernel.org
Fixes: 30fc8d13 ("tpm: TPM 2.0 CRB Interface")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

parent 0c541332

drivers/char/tpm/tpm_crb.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -142,6 +142,11 @@ static int crb_send(struct tpm_chip chip, u8 buf, size_t len)
		struct crb_priv *priv = dev_get_drvdata(&chip->dev);
		int rc = 0;

		/* Zero the cancel register so that the next command will not get
		* canceled.
		*/
		iowrite32(0, &priv->cca->cancel);

		if (len > ioread32(&priv->cca->cmd_size)) {
		dev_err(&chip->dev,
		"invalid command count value %x %zx\n",
		@@ -175,8 +180,6 @@ static void crb_cancel(struct tpm_chip *chip)

		if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
		dev_err(&chip->dev, "ACPI Start failed\n");

		iowrite32(0, &priv->cca->cancel);
		}

		static bool crb_req_canceled(struct tpm_chip *chip, u8 status)