powerpc/64: Fix flush_(d|i)cache_range() called from modules

commit 8f5f525d upstream.

When the kernel is compiled to use 64bit ABIv2 the _GLOBAL() macro does
not include a global entry point. A function's global entry point is
used when the function is called from a different TOC context and in the
kernel this typically means a call from a module into the vmlinux (or
vice-versa).

There are a few exported asm functions declared with _GLOBAL() and
calling them from a module will likely crash the kernel since any TOC
relative load will yield garbage.

flush_icache_range() and flush_dcache_range() are both exported to
modules, and use the TOC, so must use _GLOBAL_TOC().

Fixes: 721aeaa9 ("powerpc: Build little endian ppc64 kernel with ABIv2")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/powerpc/kernel/misc_64.S

@@ -65,7 +65,7 @@ PPC64_CACHES:
  *   flush all bytes from start through stop-1 inclusive
  */
 
-_GLOBAL(flush_icache_range)
+_GLOBAL_TOC(flush_icache_range)
 BEGIN_FTR_SECTION
 	PURGE_PREFETCHED_INS
 	blr
@@ -117,7 +117,7 @@ _ASM_NOKPROBE_SYMBOL(flush_icache_range)
  *
  *    flush all bytes from start to stop-1 inclusive
  */
-_GLOBAL(flush_dcache_range)
+_GLOBAL_TOC(flush_dcache_range)
 
 /*
  * Flush the data cache to memory