nios2: define virtual address space for modules

nios2 uses kmalloc() to implement module_alloc() because CALL26/PCREL26
cannot reach all of vmalloc address space.

Define module space as 32MiB below the kernel base and switch nios2 to
use vmalloc for module allocations.

Suggested-by: Thomas Gleixner <[e-mail]>
Acked-by: Dinh Nguyen <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Signed-off-by: Mike Rapoport (IBM) <[e-mail]>
Signed-off-by: Luis Chamberlain <[e-mail]>

arch/nios2/include/asm/pgtable.h

···
 #include <asm-generic/pgtable-nopmd.h>
 
 #define VMALLOC_START		CONFIG_NIOS2_KERNEL_MMU_REGION_BASE
-#define VMALLOC_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
+#define VMALLOC_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - SZ_32M - 1)
+
+#define MODULES_VADDR		(CONFIG_NIOS2_KERNEL_REGION_BASE - SZ_32M)
+#define MODULES_END		(CONFIG_NIOS2_KERNEL_REGION_BASE - 1)
 
 struct mm_struct;
 

arch/nios2/kernel/module.c

···
 
 #include <asm/cacheflush.h>
 
-/*
- * Modules should NOT be allocated with kmalloc for (obvious) reasons.
- * But we do it for now to avoid relocation issues. CALL26/PCREL26 cannot reach
- * from 0x80000000 (vmalloc area) to 0xc00000000 (kernel) (kmalloc returns
- * addresses in 0xc0000000)
- */
 void *module_alloc(unsigned long size)
 {
-	if (size == 0)
-		return NULL;
-	return kmalloc(size, GFP_KERNEL);
-}
-
-/* Free memory returned from module_alloc */
-void module_memfree(void *module_region)
-{
-	kfree(module_region);
+	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));
 }
 
 int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,