[PATCH] powerpc: Unify mem= handling

We currently do mem= handling in three seperate places. And as benh pointed out
I wrote two of them. Now that we parse command line parameters earlier we can
clean this mess up.

Moving the parsing out of prom_init means the device tree might be allocated
above the memory limit. If that happens we'd have to move it. As it happens
we already have logic to do that for kdump, so just genericise it.

This also means we might have reserved regions above the memory limit, if we
do the bootmem allocator will blow up, so we have to modify
lmb_enforce_memory_limit() to truncate the reserves as well.

Tested on P5 LPAR, iSeries, F50, 44p. Tested moving device tree on P5 and
44p and F50.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/kexec.h

@@ -31,9 +31,10 @@
 #define KEXEC_ARCH KEXEC_ARCH_PPC
 #endif
 
+#ifndef __ASSEMBLY__
+
 #ifdef CONFIG_KEXEC
 
-#ifndef __ASSEMBLY__
 #ifdef __powerpc64__
 /*
  * This function is responsible for capturing register states if coming
@@ -123,8 +124,16 @@ extern int default_machine_kexec_prepare(struct kimage *image);
 extern void default_machine_crash_shutdown(struct pt_regs *regs);
 
 extern void machine_kexec_simple(struct kimage *image);
+extern int overlaps_crashkernel(unsigned long start, unsigned long size);
+
+#else /* !CONFIG_KEXEC */
+
+static inline int overlaps_crashkernel(unsigned long start, unsigned long size)
+{
+	return 0;
+}
 
-#endif /* ! __ASSEMBLY__ */
 #endif /* CONFIG_KEXEC */
+#endif /* ! __ASSEMBLY__ */
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_KEXEC_H */