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

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Date:	Tue, 29 Sep 2015 09:02:33 +0300
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org,
	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	Peter Huewe <peterhuewe@....de>,
	Marcel Selhorst <tpmdd@...horst.net>,
	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Subject: [PATCH] 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 Broxton platform HW will abort the read operation, which
causes the CPU to fill the read 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.

Reported-by: Imran Desai <imran.desai@...el.com>
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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