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Merge patch series "Fix boot failure due to misaligned DMA buffer"

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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.
This commit is contained in:
Tom Rini 2024-11-18 08:24:06 -06:00
commit 0e6432e19f
3 changed files with 7 additions and 2 deletions
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3
boot/bootmeth_extlinux.c
View file

@ -8,6 +8,7 @@
#define LOG_CATEGORY UCLASS_BOOTSTD #define LOG_CATEGORY UCLASS_BOOTSTD
#include <asm/cache.h>
#include <bootdev.h> #include <bootdev.h>
#include <bootflow.h> #include <bootflow.h>
#include <bootmeth.h> #include <bootmeth.h>
@ -159,7 +160,7 @@ static int extlinux_read_bootflow(struct udevice *dev, struct bootflow *bflow)
return log_msg_ret("try", ret); return log_msg_ret("try", ret);
size = bflow->size; size = bflow->size;
ret = bootmeth_alloc_file(bflow, 0x10000, 1); ret = bootmeth_alloc_file(bflow, 0x10000, ARCH_DMA_MINALIGN);
if (ret) if (ret)
return log_msg_ret("read", ret); return log_msg_ret("read", ret);

4
fs/fs.c
View file

@ -23,6 +23,7 @@
#include <time.h> #include <time.h>
#include <ubifs_uboot.h> #include <ubifs_uboot.h>
#include <btrfs.h> #include <btrfs.h>
#include <asm/cache.h>
#include <asm/global_data.h> #include <asm/global_data.h>
#include <asm/io.h> #include <asm/io.h>
#include <div64.h> #include <div64.h>
@ -1001,6 +1002,9 @@ int fs_read_alloc(const char *fname, ulong size, uint align, void **bufp)
char *buf; char *buf;
int ret; int ret;
if (!align)
align = ARCH_DMA_MINALIGN;
buf = memalign(align, size + 1); buf = memalign(align, size + 1);
if (!buf) if (!buf)
return log_msg_ret("buf", -ENOMEM); return log_msg_ret("buf", -ENOMEM);

2
include/fs.h
View file

@ -325,7 +325,7 @@ int do_fs_types(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[]);
* *
* @fname: Filename to read * @fname: Filename to read
* @size: Size of file to read (must be correct!) * @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 * @bufp: On success, returns the allocated buffer with the nul-terminated file
* in it * in it
* Return: 0 if OK, -ENOMEM if out of memory, -EIO if read failed * Return: 0 if OK, -ENOMEM if out of memory, -EIO if read failed