[PATCH v1 1/4] kexec: (bugfix) calc correct end address of memory ranges in device tree

[Russell King - ARM Linux]

On Wed, Jul 27, 2016 at 07:45:13PM -0300, Thiago Jung Bauermann wrote:
> Hello,
> 
> Am Dienstag, 19 Juli 2016, 23:28:13 schrieb Geoff Levand:
> > From: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > 
> > The end address of "reg" attribute in device tree's memory should be
> > inclusive.
> 
> Actually, there's a bug/inconsistency in kexec-tools right now.
> 
> crashdump-arm.c expect usablemem_rgns.ranges[i].end to be the last byte in 
> the range, but crashdump-powerpc.c, crashdump-ppc64.c and fs2dt.c expect it 
> to be the first byte after the range.

Well, ARM (and the generic code I introduced for mem_ranges) follows
what i386, ia64, mips, s390, and sh all do with struct memory_range
when used for crashdump.

It is extremely bad for a project to have a single structure used
inconsistently like this - even with generic helpers, you can't be
sure that the right helpers are used on the right structures, and
it will lead to off-by-one errors all over the place.  Just don't
pull crap like this, it's asking for trouble - settle on one way
and stick to it.

Given that the majority of architectures treat .end as inclusive, I
think ppc* and fs2dt need to conform to the convention establised by
the other architectures for this structure.

It's also interesting to note that crashdump-powerpc has this:

        /* On powerpc memory ranges in device-tree is denoted as start
         * and size rather than start and end, as is the case with
         * other architectures like i386 . Because of this when loading
         * the memory ranges in crashdump-elf.c the filesz calculation
         * [ end - start + 1 ] goes for a toss.
         *
         * To be in sync with other archs adjust the end value for
         * every crash memory range before calling the generic function
         */

        for (i = 0; i < nr_ranges; i++) {
                end = crash_memory_range[i].end - 1;
                crash_memory_range[i].end = end;
        }

to convert from powerpc end-exclusive to end-inclusive mode -
something that could be killed if it were to conform throughout
to the established convention.  Same goes for ppc64 too:

        /* On ppc64 memory ranges in device-tree is denoted as start
         * and size rather than start and end, as is the case with
         * other architectures like i386 . Because of this when loading
         * the memory ranges in crashdump-elf.c the filesz calculation
         * [ end - start + 1 ] goes for a toss.
         *
         * To be in sync with other archs adjust the end value for
         * every crash memory range before calling the generic function
         */

        for (i = 0; i < nr_ranges; i++) {
                end = crash_memory_range[i].end - 1;
                crash_memory_range[i].end = end;
        }

-- 
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