powerpc: Use MODULES_VADDR if defined

In order to allow allocation of modules outside of vmalloc space,
use MODULES_VADDR and MODULES_END when MODULES_VADDR is defined.

Redefine module_alloc() when MODULES_VADDR defined.
Unmap corresponding KASAN shadow memory.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7ecf5fff1eef67d450e73fc412b6ec3818483d75.1593428200.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/module.c

@@ -86,3 +86,14 @@ int module_finalize(const Elf_Ehdr *hdr,
 
 	return 0;
 }
+
+#ifdef MODULES_VADDR
+void *module_alloc(unsigned long size)
+{
+	BUILD_BUG_ON(TASK_SIZE > MODULES_VADDR);
+
+	return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, GFP_KERNEL,
+				    PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
+				    __builtin_return_address(0));
+}
+#endif