ramips: lzma-loader: fix O32 ABI conformance

According to the calling convention of the o32 ABI the
caller function must reserve stack space for $a0-$a3
registers in case the callee needs to save its arguments.

The assembly startup code does not reserve stack space
for these registers thus when the main C function needs
to save its arguments, that will cause a stack overflow.

Fix the assembly code to reserve stack space for the
registers to avoid that.

Untested. It seems that the lzma-loader is not used at all?

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

SVN-Revision: 49062

target/linux/ramips/image/lzma-loader/src/head.S

@@ -109,6 +109,9 @@ __bss_check:
 	/* Setup new "C" stack */
 	la	sp, _stack
 
+	/* reserve stack space for a0-a3 registers */
+	subu	sp, 16
+
 	/* jump to the decompressor routine */
 	la	t0, loader_main
 	jr	t0