On 17:28-20240130, Dhruva Gole wrote:

The ti_sci driver in U-Boot has support for secure_msg as part of it's do_xfer function. This let's U-boot send secure messages during boot up.

The protocol to send such secure messages is described as part of the struct ti_sci_secure_msg_hdr. As part of this, there are 2 fields for checksum and reserved that occupy the first 4 bytes of any secure message. This is called as the secure_hdr.

As of now, the secure_hdr needs to be 0 init-ed before sending secure messages. However the existing code was never putting the zero-inited vars into the secure_buf, leading to possibility of the first 4 bytes of secure_buf being possibly garbage.

Fix this by initialising the secure_hdr itself to the secure_buf location, thus when we make secure_hdr members 0, it automatically ensures the first 4 bytes of secure_buf are 0.

Fixes: 32cd25128bd849 ("firmware: Add basic support for TI System Control Interface (TI SCI)") Cc: Nishanth Menon nm@ti.com Cc: Andrew Davis afd@ti.com Cc: Manorit Chawdhry m-chawdhry@ti.com Signed-off-by: Dhruva Gole d-gole@ti.com

---

drivers/firmware/ti_sci.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c index 6e9f93e9a302..49d2696a6d09 100644 --- a/drivers/firmware/ti_sci.c +++ b/drivers/firmware/ti_sci.c @@ -236,21 +236,21 @@ static int ti_sci_do_xfer(struct ti_sci_info *info, { struct k3_sec_proxy_msg *msg = &xfer->tx_message; u8 secure_buf[info->desc->max_msg_size];

• struct ti_sci_secure_msg_hdr secure_hdr;

• struct ti_sci_secure_msg_hdr *secure_hdr = (struct ti_sci_secure_msg_hdr *)secure_buf; int ret;

  if (info->is_secure) { /* ToDo: get checksum of the entire message */

• secure_hdr.checksum = 0;
  

• secure_hdr.reserved = 0;
  

I was thinking originally just adding memcpy(secure_buf, secure_hdr, sizeof(secure_hdr)) would save all the churn.. but anyways.. we save allocating secure_hdr struct.. not a big saving, but better code anyways..

• memcpy(&secure_buf[sizeof(secure_hdr)], xfer->tx_message.buf,
  

• secure_hdr->checksum = 0;
  

• secure_hdr->reserved = 0;
  

• memcpy(&secure_buf[sizeof(struct ti_sci_secure_msg_hdr)], xfer->tx_message.buf,
    xfer->tx_message.len);
  

here and below:

s/sizeof(var)/sizeof(*var) instead of sizeof(struct ... ) is probably all the change we need? rather than converting it to sizeof(struct ..)? same below. this would allow (theoretically), that the structure name to change for secure_hdr and there would be less churn? not that it matters here.. just a style thing..

Either way:

Reviewed-by: Nishanth Menon nm@ti.com

xfer->tx_message.buf = (u32 *)secure_buf;

• xfer->tx_message.len += sizeof(secure_hdr);
  

• xfer->tx_message.len += sizeof(struct ti_sci_secure_msg_hdr);
  
  

  if (xfer->rx_len)

• 	xfer->rx_len += sizeof(secure_hdr);
  

• 	xfer->rx_len += sizeof(struct ti_sci_secure_msg_hdr);
  

  }

  /* Send the message */

-- 2.34.1

On 17:28-20240130, Dhruva Gole wrote:

Add a comment to explain the code under is_secure condition of ti_sci_do_xfer. This will help avoid confusion amongst people who may in future touch upon this code.

Signed-off-by: Dhruva Gole d-gole@ti.com

drivers/firmware/ti_sci.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c index 49d2696a6d09..d969470b5221 100644 --- a/drivers/firmware/ti_sci.c +++ b/drivers/firmware/ti_sci.c @@ -239,6 +239,12 @@ static int ti_sci_do_xfer(struct ti_sci_info *info, struct ti_sci_secure_msg_hdr *secure_hdr = (struct ti_sci_secure_msg_hdr *)secure_buf; int ret;

• /*

• * The reason why we need the is_secure code is because of boot R5.
  

• * boot R5 starts off in "secure mode" when it hands off from Boot
  

• * ROM over to the Secondary bootloader. The initial set of calls
  

• * we have to make need to be on a secure pipe.
  

• */
  

  if (info->is_secure) { /* ToDo: get checksum of the entire message */ secure_hdr->checksum = 0;

-- 2.34.1

Reviewed-by: Nishanth Menon nm@ti.com