Merge patch series "Fix boot failure due to misaligned DMA buffer"
Nam Cao <namcao@linutronix.de> says:
We observed the following sporadic boot failure while booting from MMC
device:
=> boot
CACHE: Misaligned operation at range [9efa25f8, 9efa27f8]
CACHE: Misaligned operation at range [9efa25f8, 9efa27f8]
CACHE: Misaligned operation at range [9efa25f8, 9efa27f8]
CACHE: Misaligned operation at range [9efa25f8, 9efa27f8]
** Booting bootflow 'mmc@2194000.bootdev.part_1' with extlinux
Ignoring unknown command: �D���D��
Boot failed (err=-14)
The reason is because while allocating buffer to read a file from MMC,
alignment of 1 byte is used. Thus, the buffer doesn't work for performing
DMA, and garbage data is read.
While looking at this issue, I also noticed that if no alignment specified
(align=0) then fs_read_alloc() is documented to use the default. But the
default is no alignment. Therefore, other users of fs_read_alloc() which
specify align=0 may be broken as well.
The first patch changes extlinux_read_bootflow() to use proper buffer
alignment for DMA.
The second patch changes the default alignment of fs_read_alloc() to be
DMA-suitable, to fix other potential bugs.
diff --git a/boot/bootmeth_extlinux.c b/boot/bootmeth_extlinux.c
index be8fbf4..c6ae6df 100644
--- a/boot/bootmeth_extlinux.c
+++ b/boot/bootmeth_extlinux.c
@@ -8,6 +8,7 @@
#define LOG_CATEGORY UCLASS_BOOTSTD
+#include <asm/cache.h>
#include <bootdev.h>
#include <bootflow.h>
#include <bootmeth.h>
@@ -159,7 +160,7 @@
return log_msg_ret("try", ret);
size = bflow->size;
- ret = bootmeth_alloc_file(bflow, 0x10000, 1);
+ ret = bootmeth_alloc_file(bflow, 0x10000, ARCH_DMA_MINALIGN);
if (ret)
return log_msg_ret("read", ret);
diff --git a/fs/fs.c b/fs/fs.c
index 1afa0fb..21a23ef 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -23,6 +23,7 @@
#include <time.h>
#include <ubifs_uboot.h>
#include <btrfs.h>
+#include <asm/cache.h>
#include <asm/global_data.h>
#include <asm/io.h>
#include <div64.h>
@@ -1001,6 +1002,9 @@
char *buf;
int ret;
+ if (!align)
+ align = ARCH_DMA_MINALIGN;
+
buf = memalign(align, size + 1);
if (!buf)
return log_msg_ret("buf", -ENOMEM);
diff --git a/include/fs.h b/include/fs.h
index 6372756..2474880 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -325,7 +325,7 @@
*
* @fname: Filename to read
* @size: Size of file to read (must be correct!)
- * @align: Alignment to use for memory allocation (0 for default)
+ * @align: Alignment to use for memory allocation (0 for default: ARCH_DMA_MINALIGN)
* @bufp: On success, returns the allocated buffer with the nul-terminated file
* in it
* Return: 0 if OK, -ENOMEM if out of memory, -EIO if read failed