linux-kernel - [PATCH v3] tpm, tpm_crb: fix unaligned read of the command buffer address

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Message-Id: <1442336740-9383-1-git-send-email-jarkko.sakkinen@linux.intel.com>
Date:	Tue, 15 Sep 2015 20:05:40 +0300
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Subject: [PATCH v3] tpm, tpm_crb: fix unaligned read of the command buffer address

The command buffer address must be read with exactly two 32-bit reads.
Otherwise, on some HW platforms, it seems that HW will abort the read
operation, which causes CPU to fill the read bytes with 1's. Therefore,
we cannot rely on memcpy_fromio() but must call ioread32() two times
instead.

Also, this matches the PC Client Platform TPM Profile specification,
which defines command buffer address with two 32-bit fields.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
 drivers/char/tpm/tpm_crb.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index b4564b6..c09b370 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -68,7 +68,8 @@ struct crb_control_area {
 	u32 int_enable;
 	u32 int_sts;
 	u32 cmd_size;
-	u64 cmd_pa;
+	u32 cmd_pa_low;
+	u32 cmd_pa_high;
 	u32 rsp_size;
 	u64 rsp_pa;
 } __packed;
@@ -263,8 +264,8 @@ static int crb_acpi_add(struct acpi_device *device)
 		return -ENOMEM;
 	}
 
-	memcpy_fromio(&pa, &priv->cca->cmd_pa, 8);
-	pa = le64_to_cpu(pa);
+	pa = ((u64) le32_to_cpu(ioread32(&priv->cca->cmd_pa_high)) << 32) +
+		(u64) le32_to_cpu(ioread32(&priv->cca->cmd_pa_low));
 	priv->cmd = devm_ioremap_nocache(dev, pa,
 					 ioread32(&priv->cca->cmd_size));
 	if (!priv->cmd) {
-- 
2.5.0

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