Hi Mark

On 2/24/21 3:05 PM, Mark Kettenis wrote:

...

From: Patrice Chotard patrice.chotard@foss.st.com Date: Wed, 24 Feb 2021 13:47:55 +0100

To avoid "synchronous abort" in AARCH64 in case the "from" address is not aligned, replace memcpy_toio() and memcpy_fromio() by memcpy().

Signed-off-by: Patrice Chotard patrice.chotard@st.com Signed-off-by: Patrice Chotard patrice.chotard@foss.st.com

---

drivers/firmware/scmi/smt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

This doesnt really make sense. There is no guarantee that memcpy() doesn't do an unaligned load or store either.

Unaligned loads and stores from/to normal memory should just work on arm64, and memcpy_toio() and memcpy_fromio() make sure they don't do unaligned loads and stores from/to "IO" memory (in this case the shared memory buffer).

You are right. After further analysis, i understood why the "synchronous abort" occurs. At early stage, before U-Boot relocation, MMU is disabled and then all the "normal" memory space is not yet configured with MT_NORMAL type. In this situation, all 64bits accesses to a none 64 bits aligned pointer in "normal memory" triggers a synchronous abort.

Same accesses, with MMU configured (after U-Boot relocation), are OK.

I will propose a new patch which will update memcpy_from/toio() and forbid 64bits accesses to non aligned 64bits pointer in case MMU is not yet enabled.

Thanks

Patrice

...

diff --git a/drivers/firmware/scmi/smt.c b/drivers/firmware/scmi/smt.c index d25478796a..b001163b62 100644 --- a/drivers/firmware/scmi/smt.c +++ b/drivers/firmware/scmi/smt.c @@ -93,7 +93,7 @@ int scmi_write_msg_to_smt(struct udevice *dev, struct scmi_smt *smt, SMT_HEADER_PROTOCOL_ID(msg->protocol_id) | SMT_HEADER_MESSAGE_ID(msg->message_id);

• memcpy_toio(hdr->msg_payload, msg->in_msg, msg->in_msg_sz);

• memcpy(hdr->msg_payload, msg->in_msg, msg->in_msg_sz);

  return 0;

} @@ -124,7 +124,7 @@ int scmi_read_resp_from_smt(struct udevice *dev, struct scmi_smt *smt,

/* Get the data */ msg->out_msg_sz = hdr->length - sizeof(hdr->msg_header);

• memcpy_fromio(msg->out_msg, hdr->msg_payload, msg->out_msg_sz);

• memcpy(msg->out_msg, hdr->msg_payload, msg->out_msg_sz);

  return 0;

}

2.17.1