Hi Vignesh,
On 11/14/18 6:00 AM, Vignesh R wrote:
Hi,
On 13/11/18 11:02 PM, thor.thayer@xxxxxxxxxxxxxxx wrote:
From: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx>
The current Cadence QSPI driver caused a kernel panic sporadically
when writing to QSPI. The problem was caused by writing more bytes
than needed because the QSPI operated on 4 bytes at a time.
<snip>
[ 11.202044] Unable to handle kernel paging request at virtual address bffd3000
[ 11.209254] pgd = e463054d
[ 11.211948] [bffd3000] *pgd=2fffb811, *pte=00000000, *ppte=00000000
[ 11.218202] Internal error: Oops: 7 [#1] SMP ARM
[ 11.222797] Modules linked in:
[ 11.225844] CPU: 1 PID: 1317 Comm: systemd-hwdb Not tainted 4.17.7-d0c45cd44a8f
[ 11.235796] Hardware name: Altera SOCFPGA Arria10
[ 11.240487] PC is at __raw_writesl+0x70/0xd4
[ 11.244741] LR is at cqspi_write+0x1a0/0x2cc
</snip>
On a page boundary limit the number of bytes copied from the tx buffer
to remain within the page.
This patch uses a temporary buffer to hold the 4 bytes to write and then
copies only the bytes required from the tx buffer. A min() function is
used to limit the length to prevent buffer indexing overflows.
Reported-by: Adrian Amborzewicz <adrian.ambrozewicz@xxxxxxxxx>
Signed-off-by: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx>
---
drivers/mtd/spi-nor/cadence-quadspi.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/spi-nor/cadence-quadspi.c b/drivers/mtd/spi-nor/cadence-quadspi.c
index d846428ef038..3659d94b4d2f 100644
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -644,9 +644,23 @@ static int cqspi_indirect_write_execute(struct spi_nor *nor, loff_t to_addr,
ndelay(cqspi->wr_delay);
while (remaining > 0) {
+ size_t write_words, mod_bytes;
+
write_bytes = remaining > page_size ? page_size : remaining;
- iowrite32_rep(cqspi->ahb_base, txbuf,
- DIV_ROUND_UP(write_bytes, 4));
+ write_words = write_bytes / 4;
+ mod_bytes = write_bytes % 4;
+ /* Write 4 bytes at a time then single bytes. */
+ if (write_words) {
+ iowrite32_rep(cqspi->ahb_base, txbuf, write_words);
+ txbuf += (write_words * 4);
+ }
+ if (mod_bytes) {
+ unsigned int temp = 0xFFFFFFFF;
+
+ memcpy(&temp, txbuf, min(sizeof(temp), mod_bytes));
Sorry, I dont understand why min() is required here since:
mod_bytes = write_bytes % 4;
Doesn't that ensure mod_bytes < sizeof(temp)?
Yes, good point. I was being overly cautious with the memcpy buffers. I
will re-spin and re-submit. Thanks!
+ iowrite32(temp, cqspi->ahb_base);
+ txbuf += mod_bytes;
+ }
if (!wait_for_completion_timeout(&cqspi->transfer_complete,
msecs_to_jiffies(CQSPI_TIMEOUT_MS))) {
@@ -655,7 +669,6 @@ static int cqspi_indirect_write_execute(struct spi_nor *nor, loff_t to_addr,
goto failwr;
}
- txbuf += write_bytes;
remaining -= write_bytes;
if (remaining > 0)
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