Re: [PATCH] arm64: fix address fault during mapping fdt region

On Mon, Aug 01, 2016 at 09:17:09PM +0800, zijun_hu wrote:

On 08/01/2016 07:24 PM, Mark Rutland wrote:

quoted

On Mon, Aug 01, 2016 at 06:59:50PM +0800, zijun_hu wrote:

quoted

2，it is more portable; we only need to call fdt_check_header() and don't
care about fdt header filed layout; moreover,fdt module is another independent
module and arm64 only uses it and should not depend on more details of fdt
such as size and magic fields locate within the first MIN_FDT_ALIGN bytes;
the decision whether a fdt header is corrupted should be left to fdt team

While it's true that we assume knowledge of the FDT format, and ideally
we'd leave this to common code, we do so regardless by requiring the
header size. So both approaches assume details regarding the FDT format.

okay, the only thing my solution is depends on is the fdt header struct name
which maybe remain unchanged in further fdt source modification
regardless of fields layout or position or header size;

by the way, my solution only maps more one SWAPPER_BLOCK_SIZE at extreme condition
(offset + sizeof(struct fdt_header)) > SWAPPER_BLOCK_SIZE, it can occurs very rarely,
even it happens, it is no matter due to the fast mapping operations

That all said, ard.biesheuvel's can resolves address fault too, you can decide which
solution to used, maybe ask fdt team for some advisements

As a member of the "fdt team" (at least for bindings and the spec), I'm
happy with Ard's patch. ;)

Regardless, many thanks for the report, and the proposed fix!

Thanks,
Mark.