linux-kernel - [PATCH v10 2/4] tpm, tpm1-cmd: Use stack for trivial cases

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Message-Id: <20250921020804.1088824-3-jarkko@kernel.org>
Date: Sun, 21 Sep 2025 05:08:02 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Stefano Garzarella <sgarzare@...hat.com>,
	Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>,
	Peter Huewe <peterhuewe@....de>,
	Jarkko Sakkinen <jarkko@...nel.org>,
	Jason Gunthorpe <jgg@...pe.ca>,
	David Howells <dhowells@...hat.com>,
	Paul Moore <paul@...l-moore.com>,
	James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	linux-kernel@...r.kernel.org (open list),
	keyrings@...r.kernel.org (open list:KEYS/KEYRINGS),
	linux-security-module@...r.kernel.org (open list:SECURITY SUBSYSTEM)
Subject: [PATCH v10 2/4] tpm, tpm1-cmd: Use stack for trivial cases

From: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>

Use stack allocation for trivial "low-hanging fruit" sites, which are often
also critical code paths associated with probing and power management.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
---
 drivers/char/tpm/tpm1-cmd.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index ca3e7f9a105d..11c16ad9b2a7 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -323,19 +323,15 @@ unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
  */
 static int tpm1_startup(struct tpm_chip *chip)
 {
+	u8 buf_data[TPM_BUF_MIN_SIZE];
+	struct tpm_buf *buf = (struct tpm_buf *)buf_data;
 	int rc;
 
-	struct tpm_buf *buf __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	dev_info(&chip->dev, "starting up the TPM manually\n");
-
-	tpm_buf_init(buf, TPM_BUF_MAX_SIZE);
+	dev_info(&chip->dev, "TPM_Startup\n");
+	tpm_buf_init(buf, TPM_BUF_INT_SIZE);
 	tpm_buf_reset(buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
 	tpm_buf_append_u16(buf, TPM_ST_CLEAR);
-
-	rc = tpm_transmit_cmd(chip, buf, 0, "attempting to start the TPM");
+	rc = tpm_transmit_cmd(chip, buf, 0, "TPM_Startup");
 	return rc;
 }
 
-- 
2.39.5