Re: [PATCH] MIPS: boot: Fix unaligned access with?? CONFIG_MIPS_RAW_APPENDED_DTB

[Paul Cercueil]

Hi Thomas,

Le mar. 29 déc. 2020 à 16:08, Thomas Bogendoerfer 
<tsbogend@xxxxxxxxxxxxxxxx> a écrit :
> On Mon, Dec 28, 2020 at 10:30:36PM +0000, Paul Cercueil wrote:
> >  Le lun. 28 déc. 2020 à 23:25, Thomas Bogendoerfer
> >  <tsbogend@xxxxxxxxxxxxxxxx> a écrit :
> >  > On Wed, Dec 16, 2020 at 11:39:56PM +0000, Paul Cercueil wrote:
> >  > >  The compressed payload is not necesarily 4-byte aligned, at 
> > least
> >  > > when
> >  > >  compiling with Clang. In that case, the 4-byte value appended 
> > to the
> >  > >  compressed payload that corresponds to the uncompressed kernel 
> > image
> >  > >  size must be read using get_unaligned_le().
> >  > >
> >  > >  This fixes Clang-built kernels not booting on MIPS (tested on a
> >  > > Ingenic
> >  > >  JZ4770 board).
> >  > >
> >  > >  Fixes: b8f54f2cde78 ("MIPS: ZBOOT: copy appended dtb to the 
> > end of
> >  > > the kernel")
> >  > >  Cc: <stable@xxxxxxxxxxxxxxx> # v4.7
> >  > >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  > >  ---
> >  > >   arch/mips/boot/compressed/decompress.c | 2 +-
> >  > >   1 file changed, 1 insertion(+), 1 deletion(-)
> >  > >
> >  > >  diff --git a/arch/mips/boot/compressed/decompress.c
> >  > > b/arch/mips/boot/compressed/decompress.c
> >  > >  index c61c641674e6..47c07990432b 100644
> >  > >  --- a/arch/mips/boot/compressed/decompress.c
> >  > >  +++ b/arch/mips/boot/compressed/decompress.c
> >  > >  @@ -117,7 +117,7 @@ void decompress_kernel(unsigned long
> >  > > boot_heap_start)
> >  > >   		dtb_size = fdt_totalsize((void *)&__appended_dtb);
> >  > >
> >  > >   		/* last four bytes is always image size in little endian */
> >  > >  -		image_size = le32_to_cpup((void *)&__image_end - 4);
> >  > >  +		image_size = get_unaligned_le32((void *)&__image_end - 4);
> >  >
> >  > gives me following error
> >  >
> >  > arch/mips/boot/compressed/decompress.c:120:16: error: implicit
> >  > declaration of function ‘get_unaligned_le32’
> >  > [-Werror=implicit-function-declaration]
> >  >    image_size = get_unaligned_le32((void *)&__image_end - 4);
> >  >
> >  > I've added
> >  >
> >  > #include <asm/unaligned.h>
> >  >
> >  > which fixes the compile error, but I'm wondering why the patch 
> > compiled
> >  > for you ?
> >
> >  No idea - but it does compile fine without the include here. 
> > Probably a
> >  defconfig difference.
>
> # CONFIG_KERNEL_LZO is not set
> # CONFIG_KERNEL_LZ4 is not set
>
> this makes the difference. Both decompress.c files include 
> asm/unaligned.h.
>
> I've added the #include, fixed the get_unaligned_le32 in the 
> description
> and applied it to mips-fixes.

Alright, great! Thanks!

Cheers,
-Paul