[PATCH 3/5] mtd: cfi-flash: use I/O accessors for reads/writes of MMIO regions

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

The memcpy() routine can use post-indexed memory access instructions
on ARM that would trigger data aborts under KVM.

To fix this, use memcpy_fromio/memcpy_toio or the (read|write)[bwlq]
family of functions, as these are safe to call on MMIO addresses.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/mtd/nor/cfi_flash.c |  2 +-
 drivers/mtd/nor/cfi_flash.h | 15 ++++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nor/cfi_flash.c b/drivers/mtd/nor/cfi_flash.c
index 2cb3d5538fbd..ea2373a01827 100644
--- a/drivers/mtd/nor/cfi_flash.c
+++ b/drivers/mtd/nor/cfi_flash.c
@@ -892,7 +892,7 @@ static int cfi_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
 {
 	struct flash_info *info = container_of(mtd, struct flash_info, mtd);
 
-	memcpy(buf, info->base + from, len);
+	memcpy_fromio(buf, info->base + from, len);
 	*retlen = len;
 
 	return 0;
diff --git a/drivers/mtd/nor/cfi_flash.h b/drivers/mtd/nor/cfi_flash.h
index 5d3053f97156..a80a979f8c0f 100644
--- a/drivers/mtd/nor/cfi_flash.h
+++ b/drivers/mtd/nor/cfi_flash.h
@@ -260,7 +260,11 @@ static inline void flash_write32(u32 value, void *addr)
 
 static inline void flash_write64(u64 value, void *addr)
 {
-	memcpy((void *)addr, &value, 8);
+#if BITS_PER_LONG >= 64
+	__raw_writeq(value, addr);
+#else
+	memcpy_toio(addr, &value, 8);
+#endif
 }
 
 static inline u8 flash_read8(void *addr)
@@ -280,8 +284,13 @@ static inline u32 flash_read32(void *addr)
 
 static inline u64 flash_read64(void *addr)
 {
-	/* No architectures currently implement readq() */
-	return *(volatile u64 *)addr;
+	u64 value;
+#if BITS_PER_LONG >= 64
+	value = __raw_readq(addr);
+#else
+	memcpy_fromio(&value, addr, 8);
+#endif
+	return value;
 }
 
 /*
-- 
2.39.5