From: linux@armlinux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v1 1/4] kexec: (bugfix) calc correct end address of memory ranges in device tree
Date: Fri, 29 Jul 2016 09:27:14 +0100 [thread overview]
Message-ID: <20160729082714.GA1041@n2100.armlinux.org.uk> (raw)
In-Reply-To: <1860371.lT9GInp2C3@hactar>
On Thu, Jul 28, 2016 at 08:54:55PM -0300, Thiago Jung Bauermann wrote:
> Am Donnerstag, 28 Juli 2016, 00:23:31 schrieb Russell King - ARM Linux:
> > 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.
>
> Agreed. Personally, I prefer base address and size because it's unambiguous.
> But as long as just one convention is used and the structure and helpers
> make it clear which one they expect, it doesn't matter that much.
Indeed.
> > 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.
>
> So do valid_memory_range and find_memory_range in kexec/kexec.c, which
> assume struct memory_range is end-exclusive too. I'm not sure about
> locate_hole, it seems to assume end-inclusive but it does have a line saying
> "size = end - start".
Unfortunately, valid_memory_range() is a mess of doing this one way and
the other:
send = sstart + segment->memsz - 1;
return valid_memory_range(info, sstart, send);
...
last = base + memsz -1;
if (!valid_memory_range(info, base, last)) {
So, callers of valid_memory_range pass a start and inclusive end address
to valid_memory_range(), and the end address becomes "send" in this
function.
/* Check to see if we are fully contained */
if ((mstart <= sstart) && (mend >= send)) {
So, this also points to an inclusive end address for mend, but the
preceding line has:
&& mend == info->memory_range[i+1].start
which doesn't, so this is buggy because it inconsistently treats the
end address as inclusive vs exclusive.
find_memory_range() looks like end-exclusive.
locate_hole() in one place treats it as end-inclusive while doing the
merge, and end-exclusive while looking for a hole.
So, these functions are a mess and need fixing.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
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next prev parent reply other threads:[~2016-07-29 8:27 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-19 23:28 [PATCH v1 0/4] arm64 kexec-tools patches Geoff Levand
2016-07-19 23:28 ` [PATCH v1 1/4] kexec: (bugfix) calc correct end address of memory ranges in device tree Geoff Levand
2016-07-27 22:45 ` Thiago Jung Bauermann
2016-07-27 23:23 ` Russell King - ARM Linux
2016-07-28 23:54 ` Thiago Jung Bauermann
2016-07-29 8:27 ` Russell King - ARM Linux [this message]
2016-07-29 17:12 ` Geoff Levand
2016-07-29 17:23 ` Russell King - ARM Linux
2016-08-01 4:52 ` AKASHI Takahiro
2016-09-06 0:29 ` Memory range end be inclusive or exclusive? " AKASHI Takahiro
2016-10-31 8:50 ` AKASHI Takahiro
2016-11-07 8:17 ` Simon Horman
2016-07-19 23:28 ` [PATCH v1 2/4] kexec: Add common device tree routines Geoff Levand
2016-07-22 7:19 ` AKASHI Takahiro
2016-07-27 18:11 ` Geoff Levand
2016-07-19 23:28 ` [PATCH v1 4/4] arm64: Add support for binary image files Geoff Levand
2016-07-19 23:28 ` [PATCH v1 3/4] arm64: Add arm64 kexec support Geoff Levand
2016-07-20 15:39 ` Mark Rutland
2016-07-20 19:19 ` Geoff Levand
2016-07-21 10:31 ` Mark Rutland
2016-07-21 10:50 ` Robin Murphy
2016-07-21 21:49 ` Geoff Levand
2016-07-22 4:08 ` Pratyush Anand
2016-07-22 5:33 ` AKASHI Takahiro
2016-07-22 9:54 ` Mark Rutland
2016-07-22 10:03 ` Robin Murphy
2016-07-22 13:56 ` Pratyush Anand
2016-07-22 17:59 ` Robin Murphy
2016-07-25 21:56 ` Geoff Levand
2016-07-20 17:53 ` Pratyush Anand
2016-07-20 20:33 ` Geoff Levand
2016-07-20 20:54 ` [PATCH v1.2 " Geoff Levand
2016-07-22 7:12 ` AKASHI Takahiro
2016-07-26 0:37 ` Geoff Levand
2016-07-25 14:28 ` Ruslan Bilovol
2016-07-25 20:50 ` Geoff Levand
2016-07-26 1:36 ` Ruslan Bilovol
2016-07-26 8:16 ` AKASHI Takahiro
2016-07-26 21:26 ` Ruslan Bilovol
2016-07-26 21:54 ` Geoff Levand
2016-07-20 4:30 ` [PATCH v1 0/4] arm64 kexec-tools patches AKASHI Takahiro
2016-07-26 23:05 ` Simon Horman
2016-07-27 5:57 ` AKASHI Takahiro
2016-07-28 18:09 ` Geoff Levand
2016-07-29 0:31 ` Simon Horman
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