Any write with either dd or flashcp to a device driven by the spear_smi.c driver will pass through the spear_smi_cpy_toio() function. This function will get called for chunks of up to 256 bytes. If the amount of data is smaller, we may have a problem if the data length is not 4-byte aligned. In this situation, the kernel panics during the memcpy:
# dd if=/dev/urandom bs=1001 count=1 of=/dev/mtd6 spear_smi_cpy_toio [620] dest c9070000, src c7be8800, len 256 spear_smi_cpy_toio [620] dest c9070100, src c7be8900, len 256 spear_smi_cpy_toio [620] dest c9070200, src c7be8a00, len 256 spear_smi_cpy_toio [620] dest c9070300, src c7be8b00, len 233 Unhandled fault: external abort on non-linefetch (0x808) at 0xc90703e8 [...] PC is at memcpy+0xcc/0x330
Workaround this issue by using the alternate _memcpy_toio() method which at least does not present the same problem.
Fixes: f18dbbb1bfe0 ("mtd: ST SPEAr: Add SMI driver for serial NOR flash") Cc: stable@vger.kernel.org Suggested-by: Boris Brezillon boris.brezillon@collabora.com Signed-off-by: Miquel Raynal miquel.raynal@bootlin.com ---
Hello,
This patch could not be tested with a mainline kernel (only compiled) but was tested with a stable 4.14.x kernel. I have really no idea why memcpy fails in this situation that's why I propose this workaround but I bet there is something deeper not working.
Thanks, Miquèl
drivers/mtd/devices/spear_smi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mtd/devices/spear_smi.c b/drivers/mtd/devices/spear_smi.c index 986f81d2f93e..d888625a3244 100644 --- a/drivers/mtd/devices/spear_smi.c +++ b/drivers/mtd/devices/spear_smi.c @@ -614,7 +614,7 @@ static inline int spear_smi_cpy_toio(struct spear_smi *dev, u32 bank, ctrlreg1 = readl(dev->io_base + SMI_CR1); writel((ctrlreg1 | WB_MODE) & ~SW_MODE, dev->io_base + SMI_CR1);
- memcpy_toio(dest, src, len); + _memcpy_toio(dest, src, len);
writel(ctrlreg1, dev->io_base + SMI_CR1);