Wire up support for the XZ decompressor
Signed-off-by: NImre Kaloz <kaloz@openwrt.org>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

If decompress() returns an error without calling error(), we must
not attempt to boot the resulting kernel.
Signed-off-by: NNicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: NShawn Guo <shawn.guo@linaro.org>
Tested-by: NTony Lindgren <tony@atomide.com>

This patch allows using a kernel image compressed with LZMA on ARM.
Extracting the image is fairly slow, but it might be useful on machines
with a very limited amount of storage, as the size benefit is quite
significant (about 25% smaller with LZMA compared to GZIP)
Tested-by: NMartin Michlmayr <tbm@cyrius.com>
Tested-by: NPaulius Zaleckas <paulius.zaleckas@gmail.com>
Signed-off-by: NAlbin Tonnerre <albin.tonnerre@free-electrons.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This defines STATIC_RW_DATA, which prevents the read/write malloc
management data being declared with a static attribute.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

We used to build decompressors with -Dstatic= to avoid any local data
being generated.  The problem is that local data generates GOTOFF
relocations, which means we can't relocate the data relative to the
text segment.

Global data, on the other hand, goes through the GOT, and can be
relocated anywhere.

Unfortunately, with the new decompressors, this presents a problem
since they declare static data within functions, and this leads to
stack overflow.

Fix this by separating out the decompressor code into a separate file,
and removing 'static' from BSS data in misc.c.

Also, discard the .data section - this means that should we end up
with read/write initialized data, the decompressor will fail to link
and the problem will be obvious.
Acked-by: NNicolas Pitre <nico@fluxnic.net>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>