ARM: qcom: Fix SCM interface for big-endian kernels

The secure environment only runs in little-endian mode, so any buffers shared with the secure environment should have their contents converted to little-endian. We also mark such elements with __le32 to allow sparse to catch such problems.

Signed-off-by Stephen Boyd <[email protected]>

---

Changes since v1:
* Rebased onto Kumar's qcom/soc branch

drivers/soc/qcom/scm-boot.c | 8 ++++----
drivers/soc/qcom/scm.c | 30 ++++++++++++++++--------------

2 files changed, 20 insertions(+), 18 deletions(-)

drivers/soc/qcom/scm-boot.c +0 -0

index 1822b13bbc10..af16fcc8d5cb 100644

drivers/soc/qcom/scm-boot.c +2 -2

 	} cmd;
 
-	cmd.addr = addr;
-	cmd.flags = flags;
+	cmd.addr = cpu_to_le32(addr);
+	cmd.flags = cpu_to_le32(flags);
 	return scm_call(SCM_SVC_BOOT, SCM_BOOT_ADDR,
 			&cmd, sizeof(cmd), NULL, 0);
 }

drivers/soc/qcom/scm.c +13 -11

index 2e98d80e2387..3e724b8af485 100644
@@ -62,11 +62,11 @@ static DEFINE_MUTEX(scm_lock);
 * to access the buffers in a safe manner.
 */
 struct scm_command {
-	u32	len;
-	u32	buf_offset;
-	u32	resp_hdr_offset;
-	u32	id;
-	u32	buf[0];
+	__le32 len;
+	__le32 buf_offset;
+	__le32 resp_hdr_offset;
+	__le32 id;
+	__le32 buf[0];
 };
 
 /**

@@ -76,9 +76,9 @@ struct scm_command {
 * @is_complete: indicates if the command has finished processing
 */
 struct scm_response {
-	u32	len;
-	u32	buf_offset;
-	u32	is_complete;
+	__le32 len;
+	__le32 buf_offset;
+	__le32 is_complete;
 };
 
 /**

@@ -96,12 +96,14 @@ static struct scm_command *alloc_scm_command(size_t cmd_size, size_t resp_size)
 	struct scm_command *cmd;
 	size_t len = sizeof(*cmd) + sizeof(struct scm_response) + cmd_size +
 		resp_size;
+	u32 offset;
 
 	cmd = kzalloc(PAGE_ALIGN(len), GFP_KERNEL);
 	if (cmd) {
-		cmd->len = len;
-		cmd->buf_offset = offsetof(struct scm_command, buf);
-		cmd->resp_hdr_offset = cmd->buf_offset + cmd_size;
+		cmd->len = cpu_to_le32(len);
+		offset = offsetof(struct scm_command, buf);
+		cmd->buf_offset = cpu_to_le32(offset);
+		cmd->resp_hdr_offset = cpu_to_le32(offset + cmd_size);
 	}
 	return cmd;
 }

@@ -126,7 +128,7 @@ static inline void free_scm_command(struct scm_command *cmd)

static inline struct scm_response *scm_command_to_response(
const struct scm_command *cmd)
{

drivers/soc/qcom/scm.c +1 -1

-	return (void *)cmd + cmd->resp_hdr_offset;
+	return (void *)cmd + le32_to_cpu(cmd->resp_hdr_offset);

}

/**

drivers/soc/qcom/scm.c +2 -2

@@ -148,7 +150,7 @@ static inline void *scm_get_command_buffer(const struct scm_command *cmd)
 */
 static inline void *scm_get_response_buffer(const struct scm_response *rsp)
 {
-	return (void *)rsp + rsp->buf_offset;
+	return (void *)rsp + le32_to_cpu(rsp->buf_offset);
 }
 
 static int scm_remap_error(int err)

@@ -260,7 +262,7 @@ int scm_call(u32 svc_id, u32 cmd_id, const void *cmd_buf, size_t cmd_len,
 	if (!cmd)
 		return -ENOMEM;
 
-	cmd->id = (svc_id << 10) | cmd_id;
+	cmd->id = cpu_to_le32((svc_id << 10) | cmd_id);
 	if (cmd_buf)
 		memcpy(scm_get_command_buffer(cmd), cmd_buf, cmd_len);
 

Signature · 7 lines

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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Quoted 15 lines · Stephen Boyd

The secure environment only runs in little-endian mode, so any buffers shared with the secure environment should have their contents converted to little-endian. We also mark such elements with __le32 to allow sparse to catch such problems.

Signed-off-by Stephen Boyd <[email protected]>

---

Changes since v1:
* Rebased onto Kumar's qcom/soc branch

drivers/soc/qcom/scm-boot.c | 8 ++++----
drivers/soc/qcom/scm.c | 30 ++++++++++++++++--------------

2 files changed, 20 insertions(+), 18 deletions(-)

drivers/soc/qcom/scm-boot.c line 31

Quoted 12 lines

drivers/soc/qcom/scm-boot.c +2 -2

index 1822b13bbc10..af16fcc8d5cb 100644
@@ -27,12 +27,12 @@
 int scm_set_boot_addr(u32 addr, int flags)
 {
 	struct {
-		unsigned int flags;
-		phys_addr_t  addr;
+		__le32 flags;
+		__le32 addr;

How does this work? How can we go from phys_addr_t back to __le32 on LPAE or 64-bit systems?