[PATCH AUTOSEL 4.19 196/237] wil6210: fix debugfs memory access alignment

[Sasha Levin <sashal@kernel.org>]

From: Ahmad Masri <amasri@codeaurora.org>

[ Upstream commit 84ec040d0fb25197584d28a0dedc355503cd19b9 ]

All wil6210 device memory access should be 4 bytes aligned. In io
blob wil6210 did not force alignment for read function, this caused
alignment fault on some platforms.
Fixing that by accessing all 4 lower bytes and return to host the
requested data.

Signed-off-by: Ahmad Masri <amasri@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/ath/wil6210/debugfs.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/ath/wil6210/debugfs.c b/drivers/net/wireless/ath/wil6210/debugfs.c
index 51c3330bc316f..12b8cb698f64d 100644
--- a/drivers/net/wireless/ath/wil6210/debugfs.c
+++ b/drivers/net/wireless/ath/wil6210/debugfs.c
@@ -662,10 +662,10 @@ static ssize_t wil_read_file_ioblob(struct file *file, char __user *user_buf,
 	enum { max_count = 4096 };
 	struct wil_blob_wrapper *wil_blob = file->private_data;
 	struct wil6210_priv *wil = wil_blob->wil;
-	loff_t pos = *ppos;
+	loff_t aligned_pos, pos = *ppos;
 	size_t available = wil_blob->blob.size;
 	void *buf;
-	size_t ret;
+	size_t unaligned_bytes, aligned_count, ret;
 	int rc;
 
 	if (test_bit(wil_status_suspending, wil_blob->wil->status) ||
@@ -683,7 +683,12 @@ static ssize_t wil_read_file_ioblob(struct file *file, char __user *user_buf,
 	if (count > max_count)
 		count = max_count;
 
-	buf = kmalloc(count, GFP_KERNEL);
+	/* set pos to 4 bytes aligned */
+	unaligned_bytes = pos % 4;
+	aligned_pos = pos - unaligned_bytes;
+	aligned_count = count + unaligned_bytes;
+
+	buf = kmalloc(aligned_count, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -694,9 +699,9 @@ static ssize_t wil_read_file_ioblob(struct file *file, char __user *user_buf,
 	}
 
 	wil_memcpy_fromio_32(buf, (const void __iomem *)
-			     wil_blob->blob.data + pos, count);
+			     wil_blob->blob.data + aligned_pos, aligned_count);
 
-	ret = copy_to_user(user_buf, buf, count);
+	ret = copy_to_user(user_buf, buf + unaligned_bytes, count);
 
 	wil_pm_runtime_put(wil);
 
-- 
2.20.1