Re: [PATCH v4 2/4] tpm: migrate tpm2_probe() to use struct tpm_buf

[Jerry Snitselaar]

On Mon Mar 26 18, Jarkko Sakkinen wrote:
> In order to make struct tpm_buf the first class object for constructing TPM
> commands, migrate tpm2_probe() to use it.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> Acked-by: Jay Freyensee <why2jjj.linux@xxxxxxxxx>

Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>

> ---
> drivers/char/tpm/tpm2-cmd.c | 37 +++++++++++++++++++++----------------
> 1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index 7665661d9230..7bffd0fd1dca 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -844,30 +844,35 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
>
> /**
>  * tpm2_probe() - probe TPM 2.0
> - * @chip: TPM chip to use
> + * @chip: a TPM chip to probe
>  *
> - * Return: < 0 error and 0 on success.
> + * Return: 0 on success,
> + *         -errno otherwise
>  *
> - * Send idempotent TPM 2.0 command and see whether TPM 2.0 chip replied based on
> - * the reply tag.
> + * Send an idempotent TPM 2.0 command and see whether there is TPM2 chip in the
> + * other end based on the response tag. The flag TPM_CHIP_FLAG_TPM2 is set if
> + * this is the case.
>  */
> int tpm2_probe(struct tpm_chip *chip)
> {
> -	struct tpm2_cmd cmd;
> +	struct tpm_output_header *out;
> +	struct tpm_buf buf;
> 	int rc;
>
> -	cmd.header.in = tpm2_get_tpm_pt_header;
> -	cmd.params.get_tpm_pt_in.cap_id = cpu_to_be32(TPM2_CAP_TPM_PROPERTIES);
> -	cmd.params.get_tpm_pt_in.property_id = cpu_to_be32(0x100);
> -	cmd.params.get_tpm_pt_in.property_cnt = cpu_to_be32(1);
> -
> -	rc = tpm_transmit_cmd(chip, NULL, &cmd, sizeof(cmd), 0, 0, NULL);
> -	if (rc <  0)
> +	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
> +	if (rc)
> 		return rc;
> -
> -	if (be16_to_cpu(cmd.header.out.tag) == TPM2_ST_NO_SESSIONS)
> -		chip->flags |= TPM_CHIP_FLAG_TPM2;
> -
> +	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
> +	tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
> +	tpm_buf_append_u32(&buf, 1);
> +	rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, 0, 0, NULL);
> +	/* We ignore TPM return codes on purpose. */
> +	if (rc >=  0) {
> +		out = (struct tpm_output_header *)buf.data;
> +		if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
> +			chip->flags |= TPM_CHIP_FLAG_TPM2;
> +	}
> +	tpm_buf_destroy(&buf);
> 	return 0;
> }
> EXPORT_SYMBOL_GPL(tpm2_probe);
> --
> 2.15.1