Do not torn down the system when getting invalid status from a TPM chip.
This can happen when panic-on-warn is used.

In addition, print out the value of TPM_STS.x instead of "invalid
status". In order to get the earlier benefits for forensics, also call
dump_stack().

Link: https://lore.kernel.org/keyrings/YKzlTR1AzUigShtZ@kroah.com/ (local)
Fixes: 55707d531af6 ("tpm_tis: Add a check for invalid status")
Cc: stable@vger.kernel.org
Cc: Hans de Goede <redacted>
Cc: Greg KH <redacted>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm_tis_core.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 55b9d3965ae1..514a481829c9 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c

@@ -202,7 +202,16 @@ static u8 tpm_tis_status(struct tpm_chip *chip)
 		 * acquired.  Usually because tpm_try_get_ops() hasn't
 		 * been called before doing a TPM operation.
 		 */
-		WARN_ONCE(1, "TPM returned invalid status\n");
+		dev_err_once(&chip->dev, "invalid TPM_STS.x 0x%02x, dumping stack for forensics\n",
+			     status);
+
+		/*
+		 * Dump stack for forensics, as invalid TPM_STS.x could be
+		 * potentially triggered by impaired tpm_try_get_ops() or
+		 * tpm_find_get_ops().
+		 */
+		dump_stack();
+
 		return 0;
 	}
 

-- 
2.31.1