4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx>
commit 47016b341fc3b3fd4909e058c6fa38f165b53646 upstream.
The current Cadence QSPI driver caused a kernel panic when loading
a Root Filesystem from QSPI. The problem was caused by reading more
bytes than needed because the QSPI operated on 4 bytes at a time.
<snip>
[ 7.947754] spi_nor_read[1048]:from 0x037cad74, len 1 [bfe07fff]
[ 7.956247] cqspi_read[910]:offset 0x58502516, buffer=bfe07fff
[ 7.956247]
[ 7.966046] Unable to handle kernel paging request at virtual
address bfe08002
[ 7.973239] pgd = eebfc000
[ 7.975931] [bfe08002] *pgd=2fffb811, *pte=00000000, *ppte=00000000
</snip>
Notice above how only 1 byte needed to be read but by reading 4 bytes
into the end of a mapped page, an unrecoverable page fault occurred.
This patch uses a temporary buffer to hold the 4 bytes read and then
copies only the bytes required into the buffer. A min() function is
used to limit the length to prevent buffer overflows.
Request testing of this patch on other platforms. This was tested
on the Intel Arria10 SoCFPGA DevKit.
Fixes: 0cf1725676a97fc8 ("mtd: spi-nor: cqspi: Fix build on arches missing readsl/writesl")
Signed-off-by: Thor Thayer <thor.thayer@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Marek Vasut <marek.vasut@xxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/mtd/spi-nor/cadence-quadspi.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
--- a/drivers/mtd/spi-nor/cadence-quadspi.c
+++ b/drivers/mtd/spi-nor/cadence-quadspi.c
@@ -495,7 +495,9 @@ static int cqspi_indirect_read_execute(s
void __iomem *reg_base = cqspi->iobase;
void __iomem *ahb_base = cqspi->ahb_base;
unsigned int remaining = n_rx;
+ unsigned int mod_bytes = n_rx % 4;
unsigned int bytes_to_read = 0;
+ u8 *rxbuf_end = rxbuf + n_rx;
int ret = 0;
writel(remaining, reg_base + CQSPI_REG_INDIRECTRDBYTES);
@@ -523,11 +525,24 @@ static int cqspi_indirect_read_execute(s
}
while (bytes_to_read != 0) {
+ unsigned int word_remain = round_down(remaining, 4);
+
bytes_to_read *= cqspi->fifo_width;
bytes_to_read = bytes_to_read > remaining ?
remaining : bytes_to_read;
- ioread32_rep(ahb_base, rxbuf,
- DIV_ROUND_UP(bytes_to_read, 4));
+ bytes_to_read = round_down(bytes_to_read, 4);
+ /* Read 4 byte word chunks then single bytes */
+ if (bytes_to_read) {
+ ioread32_rep(ahb_base, rxbuf,
+ (bytes_to_read / 4));
+ } else if (!word_remain && mod_bytes) {
+ unsigned int temp = ioread32(ahb_base);
+
+ bytes_to_read = mod_bytes;
+ memcpy(rxbuf, &temp, min((unsigned int)
+ (rxbuf_end - rxbuf),
+ bytes_to_read));
+ }
rxbuf += bytes_to_read;
remaining -= bytes_to_read;
bytes_to_read = cqspi_get_rd_sram_level(cqspi);
