ARM: Eliminate decompressor -Dstatic= PIC hack

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: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 7 insertions, 1 deletions

diff --git a/arch/arm/boot/compressed/vmlinux.lds.in b/arch/arm/boot/compressed/vmlinux.lds.in
index a5924b9b88bd..7ca9ecff652f 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.in
+++ b/arch/arm/boot/compressed/vmlinux.lds.in
@@ -14,6 +14,13 @@ SECTIONS
   /DISCARD/ : {
     *(.ARM.exidx*)
     *(.ARM.extab*)
+    /*
+     * Discard any r/w data - this produces a link error if we have any,
+     * which is required for PIC decompression.  Local data generates
+     * GOTOFF relocations, which prevents it being relocated independently
+     * of the text/got segments.
+     */
+    *(.data)
   }
 
   . = TEXT_START;
@@ -40,7 +47,6 @@ SECTIONS
   .got			: { *(.got) }
   _got_end = .;
   .got.plt		: { *(.got.plt) }
-  .data			: { *(.data) }
   _edata = .;
 
   . = BSS_START;