nios2: Module support

This patch adds support for loadable modules.
Signed-off-by: NLey Foon Tan <lftan@altera.com>

arch/nios2/kernel/module.c

+/*
+ * Kernel module support for Nios II.
+ *
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ *   Written by Wentao Xu <xuwentao@microtronix.com>
+ * Copyright (C) 2001, 2003 Rusty Russell
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License.  See the file COPYING in the main directory of this
+ * archive for more details.
+ */
+
+#include <linux/moduleloader.h>
+#include <linux/elf.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+
+#include <asm/pgtable.h>
+#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_free(struct module *mod, void *module_region)
+{
+	kfree(module_region);
+}
+
+int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
+			unsigned int symindex, unsigned int relsec,
+			struct module *mod)
+{
+	unsigned int i;
+	Elf32_Rela *rela = (void *)sechdrs[relsec].sh_addr;
+
+	pr_debug("Applying relocate section %u to %u\n", relsec,
+		 sechdrs[relsec].sh_info);
+
+	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
+		/* This is where to make the change */
+		uint32_t word;
+		uint32_t *loc
+			= ((void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+			   + rela[i].r_offset);
+		/* This is the symbol it is referring to.  Note that all
+		   undefined symbols have been resolved.  */
+		Elf32_Sym *sym
+			= ((Elf32_Sym *)sechdrs[symindex].sh_addr
+				+ ELF32_R_SYM(rela[i].r_info));
+		uint32_t v = sym->st_value + rela[i].r_addend;
+
+		pr_debug("reltype %d 0x%x name:<%s>\n",
+			ELF32_R_TYPE(rela[i].r_info),
+			rela[i].r_offset, strtab + sym->st_name);
+
+		switch (ELF32_R_TYPE(rela[i].r_info)) {
+		case R_NIOS2_NONE:
+			break;
+		case R_NIOS2_BFD_RELOC_32:
+			*loc += v;
+			break;
+		case R_NIOS2_PCREL16:
+			v -= (uint32_t)loc + 4;
+			if ((int32_t)v > 0x7fff ||
+				(int32_t)v < -(int32_t)0x8000) {
+				pr_err("module %s: relocation overflow\n",
+					mod->name);
+				return -ENOEXEC;
+			}
+			word = *loc;
+			*loc = ((((word >> 22) << 16) | (v & 0xffff)) << 6) |
+				(word & 0x3f);
+			break;
+		case R_NIOS2_CALL26:
+			if (v & 3) {
+				pr_err("module %s: dangerous relocation\n",
+					mod->name);
+				return -ENOEXEC;
+			}
+			if ((v >> 28) != ((uint32_t)loc >> 28)) {
+				pr_err("module %s: relocation overflow\n",
+					mod->name);
+				return -ENOEXEC;
+			}
+			*loc = (*loc & 0x3f) | ((v >> 2) << 6);
+			break;
+		case R_NIOS2_HI16:
+			word = *loc;
+			*loc = ((((word >> 22) << 16) |
+				((v >> 16) & 0xffff)) << 6) | (word & 0x3f);
+			break;
+		case R_NIOS2_LO16:
+			word = *loc;
+			*loc = ((((word >> 22) << 16) | (v & 0xffff)) << 6) |
+					(word & 0x3f);
+			break;
+		case R_NIOS2_HIADJ16:
+			{
+				Elf32_Addr word2;
+
+				word = *loc;
+				word2 = ((v >> 16) + ((v >> 15) & 1)) & 0xffff;
+				*loc = ((((word >> 22) << 16) | word2) << 6) |
+						(word & 0x3f);
+			}
+			break;
+
+		default:
+			pr_err("module %s: Unknown reloc: %u\n",
+				mod->name, ELF32_R_TYPE(rela[i].r_info));
+			return -ENOEXEC;
+		}
+	}
+
+	return 0;
+}
+
+int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+			struct module *me)
+{
+	flush_cache_all();
+	return 0;
+}