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

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Message-ID: <20180518223513.qh6wcckjp4sl7xwx@cantor>
Date:   Fri, 18 May 2018 15:35:13 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/4] tpm: migrate tpm2_probe() to use struct tpm_buf

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@...ux.intel.com>
>Acked-by: Jay Freyensee <why2jjj.linux@...il.com>

Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>

>---
> 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
>