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

From: Jarkko Sakkinen
Date: Tue Sep 29 2015 - 02:02:55 EST

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@xxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
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,
if (!priv->cmd) {

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