[PATCH] add the core mm/nommu file

This implements the mmu stuff for the mmuless cpus - a lot of it stubs
to avoid ifdefs in core code

mm/nommu.c

+/*
+ *  linux/mm/nommu.c
+ *
+ *  Replacement code for mm functions to support CPU's that don't
+ *  have any form of memory management unit (thus no virtual memory).
+ *
+ *  Copyright (c) 2000-2002 David McCullough <davidm@snapgear.com>
+ *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
+ *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/swap.h>
+#include <linux/smp_lock.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/blkdev.h>
+
+#include <asm/pgalloc.h>
+#include <asm/uaccess.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+
+void *high_memory;
+struct page *mem_map = NULL;
+unsigned long max_mapnr;
+unsigned long num_physpages;
+unsigned long askedalloc, realalloc;
+atomic_t vm_committed_space = ATOMIC_INIT(0);
+
+/*
+ * Handle all mappings that got truncated by a "truncate()"
+ * system call.
+ *
+ * NOTE! We have to be ready to update the memory sharing
+ * between the file and the memory map for a potential last
+ * incomplete page.  Ugly, but necessary.
+ */
+int vmtruncate(struct inode *inode, loff_t offset)
+{
+	struct address_space *mapping = inode->i_mapping;
+	unsigned long limit;
+
+	if (inode->i_size < offset)
+		goto do_expand;
+	inode->i_size = offset;
+
+	truncate_inode_pages(mapping, offset);
+	goto out_truncate;
+
+do_expand:
+	limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
+	if (limit != RLIM_INFINITY && offset > limit)
+		goto out_sig;
+	if (offset > inode->i_sb->s_maxbytes)
+		goto out;
+	inode->i_size = offset;
+
+out_truncate:
+	if (inode->i_op && inode->i_op->truncate) {
+		lock_kernel();
+		inode->i_op->truncate(inode);
+		unlock_kernel();
+	}
+	return 0;
+out_sig:
+	send_sig(SIGXFSZ, current, 0);
+out:
+	return -EFBIG;
+}
+
+/*
+ * Return the total memory allocated for this pointer, not
+ * just what the caller asked for.
+ *
+ * Doesn't have to be accurate, i.e. may have races.
+ */
+unsigned int kobjsize(const void *objp)
+{
+	struct page *page;
+
+	if (!objp || !((page = virt_to_page(objp))))
+		return 0;
+
+	if (PageSlab(page))
+		return ksize(objp);
+
+	BUG_ON(page->index < 0);
+	BUG_ON(page->index >= MAX_ORDER);
+
+	return (PAGE_SIZE << page->index);
+}
+
+/*
+ * The nommu dodgy version :-)
+ */
+int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+	unsigned long start, int len, int write, int force,
+	struct page **pages, struct vm_area_struct **vmas)
+{
+	int i;
+
+	for (i = 0; i < len; i++) {
+		if (pages) {
+			pages[i] = virt_to_page(start);
+			if (pages[i])
+				page_cache_get(pages[i]);
+		}
+		start += PAGE_SIZE;
+	}
+	return(i);
+}
+
+rwlock_t vmlist_lock = RW_LOCK_UNLOCKED;
+struct vm_struct *vmlist;
+
+void vfree(void *addr)
+{
+	kfree(addr);
+}
+
+void *__vmalloc(unsigned long size, int gfp_mask, pgprot_t prot)
+{
+	/*
+	 * kmalloc doesn't like __GFP_HIGHMEM for some reason
+	 */
+	return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM);
+}
+
+long vread(char *buf, char *addr, unsigned long count)
+{
+	memcpy(buf, addr, count);
+	return count;
+}
+
+long vwrite(char *buf, char *addr, unsigned long count)
+{
+	/* Don't allow overflow */
+	if ((unsigned long) addr + count < count)
+		count = -(unsigned long) addr;
+	
+	memcpy(addr, buf, count);
+	return(count);
+}
+
+/*
+ *	vmalloc  -  allocate virtually continguos memory
+ *
+ *	@size:		allocation size
+ *
+ *	Allocate enough pages to cover @size from the page level
+ *	allocator and map them into continguos kernel virtual space.
+ *
+ *	For tight cotrol over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+void *vmalloc(unsigned long size)
+{
+       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
+}
+
+/*
+ *	vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
+ *
+ *	@size:		allocation size
+ *
+ *	Allocate enough 32bit PA addressable pages to cover @size from the
+ *	page level allocator and map them into continguos kernel virtual space.
+ */
+void *vmalloc_32(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
+}
+
+void *vmap(struct page **pages, unsigned int count)
+{
+	BUG();
+	return NULL;
+}
+
+void vunmap(void *addr)
+{
+	BUG();
+}
+
+/*
+ *  sys_brk() for the most part doesn't need the global kernel
+ *  lock, except when an application is doing something nasty
+ *  like trying to un-brk an area that has already been mapped
+ *  to a regular file.  in this case, the unmapping will need
+ *  to invoke file system routines that need the global lock.
+ */
+asmlinkage unsigned long sys_brk(unsigned long brk)
+{
+	struct mm_struct *mm = current->mm;
+
+	if (brk < mm->end_code || brk < mm->start_brk || brk > mm->context.end_brk)
+		return mm->brk;
+
+	if (mm->brk == brk)
+		return mm->brk;
+
+	/*
+	 * Always allow shrinking brk
+	 */
+	if (brk <= mm->brk) {
+		mm->brk = brk;
+		return brk;
+	}
+
+	/*
+	 * Ok, looks good - let it rip.
+	 */
+	return mm->brk = brk;
+}
+
+/*
+ * Combine the mmap "prot" and "flags" argument into one "vm_flags" used
+ * internally. Essentially, translate the "PROT_xxx" and "MAP_xxx" bits
+ * into "VM_xxx".
+ */
+static inline unsigned long calc_vm_flags(unsigned long prot, unsigned long flags)
+{
+#define _trans(x,bit1,bit2) \
+((bit1==bit2)?(x&bit1):(x&bit1)?bit2:0)
+
+	unsigned long prot_bits, flag_bits;
+	prot_bits =
+		_trans(prot, PROT_READ, VM_READ) |
+		_trans(prot, PROT_WRITE, VM_WRITE) |
+		_trans(prot, PROT_EXEC, VM_EXEC);
+	flag_bits =
+		_trans(flags, MAP_GROWSDOWN, VM_GROWSDOWN) |
+		_trans(flags, MAP_DENYWRITE, VM_DENYWRITE) |
+		_trans(flags, MAP_EXECUTABLE, VM_EXECUTABLE);
+	return prot_bits | flag_bits;
+#undef _trans
+}
+
+#ifdef DEBUG
+static void show_process_blocks(void)
+{
+	struct mm_tblock_struct * tblock, *tmp;
+	
+	printk("Process blocks %d:", current->pid);
+	
+	tmp = current->mm->context.tblock;
+	while (tmp) {
+		printk(" %p: %p", tmp, tmp->rblock);
+		if (tmp->rblock)
+			printk(" (%d @%p #%d)", kobjsize(tmp->rblock->kblock),
+				tmp->rblock->kblock, tmp->rblock->refcount);
+		if (tmp->next)
+			printk(" ->");
+		else
+			printk(".");
+		tmp = tmp->next;
+	}
+	printk("\n");
+}
+#endif /* DEBUG */
+
+unsigned long do_mmap_pgoff(
+	struct file * file,
+	unsigned long addr,
+	unsigned long len,
+	unsigned long prot,
+	unsigned long flags,
+	unsigned long pgoff)
+{
+	void * result;
+	struct mm_tblock_struct * tblock;
+	unsigned int vm_flags;
+
+	/*
+	 * Get the !CONFIG_MMU specific checks done first
+	 */
+	if ((flags & MAP_SHARED) && (prot & PROT_WRITE) && (file)) {
+		printk("MAP_SHARED not supported (cannot write mappings to disk)\n");
+		return -EINVAL;
+	}
+	
+	if ((prot & PROT_WRITE) && (flags & MAP_PRIVATE)) {
+		printk("Private writable mappings not supported\n");
+		return -EINVAL;
+	}
+	
+	/*
+	 *	now all the standard checks
+	 */
+	if (file && (!file->f_op || !file->f_op->mmap))
+		return -ENODEV;
+
+	if (PAGE_ALIGN(len) == 0)
+		return addr;
+
+	if (len > TASK_SIZE)
+		return -EINVAL;
+
+	/* offset overflow? */
+	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
+		return -EINVAL;
+
+	/* Do simple checking here so the lower-level routines won't have
+	 * to. we assume access permissions have been handled by the open
+	 * of the memory object, so we don't do any here.
+	 */
+	vm_flags = calc_vm_flags(prot,flags) /* | mm->def_flags */ | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
+
+	/*
+	 * determine the object being mapped and call the appropriate
+	 * specific mapper. 
+	 */
+	if (file) {
+		struct vm_area_struct vma;
+		int error;
+
+		if (!file->f_op)
+			return -ENODEV;
+
+		vma.vm_start = addr;
+		vma.vm_end = addr + len;
+		vma.vm_flags = vm_flags;
+		vma.vm_pgoff = pgoff;
+
+#ifdef MAGIC_ROM_PTR
+		/* First, try simpler routine designed to give us a ROM pointer. */
+
+		if (file->f_op->romptr && !(prot & PROT_WRITE)) {
+			error = file->f_op->romptr(file, &vma);
+#ifdef DEBUG
+			printk("romptr mmap returned %d, start 0x%.8x\n", error,
+					vma.vm_start);
+#endif
+			if (!error)
+				return vma.vm_start;
+			else if (error != -ENOSYS)
+				return error;
+		} else
+#endif /* MAGIC_ROM_PTR */
+		/* Then try full mmap routine, which might return a RAM pointer,
+		   or do something truly complicated. */
+		   
+		if (file->f_op->mmap) {
+			error = file->f_op->mmap(file, &vma);
+				   
+#ifdef DEBUG
+			printk("mmap mmap returned %d /%x\n", error, vma.vm_start);
+#endif
+			if (!error)
+				return vma.vm_start;
+			else if (error != -ENOSYS)
+				return error;
+		} else
+			return -ENODEV; /* No mapping operations defined */
+
+		/* An ENOSYS error indicates that mmap isn't possible (as opposed to
+		   tried but failed) so we'll fall through to the copy. */
+	}
+
+	tblock = (struct mm_tblock_struct *)
+                        kmalloc(sizeof(struct mm_tblock_struct), GFP_KERNEL);
+	if (!tblock) {
+		printk("Allocation of tblock for %lu byte allocation from process %d failed\n", len, current->pid);
+		show_free_areas();
+		return -ENOMEM;
+	}
+
+	tblock->rblock = (struct mm_rblock_struct *)
+			kmalloc(sizeof(struct mm_rblock_struct), GFP_KERNEL);
+
+	if (!tblock->rblock) {
+		printk("Allocation of rblock for %lu byte allocation from process %d failed\n", len, current->pid);
+		show_free_areas();
+		kfree(tblock);
+		return -ENOMEM;
+	}
+
+	result = kmalloc(len, GFP_KERNEL);
+	if (!result) {
+		printk("Allocation of length %lu from process %d failed\n", len,
+				current->pid);
+		show_free_areas();
+		kfree(tblock->rblock);
+		kfree(tblock);
+		return -ENOMEM;
+	}
+
+	tblock->rblock->refcount = 1;
+	tblock->rblock->kblock = result;
+	tblock->rblock->size = len;
+	
+	realalloc += kobjsize(result);
+	askedalloc += len;
+
+#ifdef WARN_ON_SLACK	
+	if ((len+WARN_ON_SLACK) <= kobjsize(result))
+		printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n", len, current->pid, kobjsize(result)-len);
+#endif
+	
+	if (file) {
+		int error;
+		mm_segment_t old_fs = get_fs();
+		set_fs(KERNEL_DS);
+		error = file->f_op->read(file, (char *) result, len, &file->f_pos);
+		set_fs(old_fs);
+		if (error < 0) {
+			kfree(result);
+			kfree(tblock->rblock);
+			kfree(tblock);
+			return error;
+		}
+		if (error < len)
+			memset(result+error, '\0', len-error);
+	} else {
+		memset(result, '\0', len);
+	}
+
+	realalloc += kobjsize(tblock);
+	askedalloc += sizeof(struct mm_tblock_struct);
+
+	realalloc += kobjsize(tblock->rblock);
+	askedalloc += sizeof(struct mm_rblock_struct);
+
+	tblock->next = current->mm->context.tblock.next;
+	current->mm->context.tblock.next = tblock;
+
+#ifdef DEBUG
+	printk("do_mmap:\n");
+	show_process_blocks();
+#endif	  
+
+	return (unsigned long)result;
+}
+
+int do_munmap(struct mm_struct * mm, unsigned long addr, size_t len)
+{
+	struct mm_tblock_struct * tblock, *tmp;
+
+#ifdef MAGIC_ROM_PTR
+	/*
+	 * For efficiency's sake, if the pointer is obviously in ROM,
+	 * don't bother walking the lists to free it.
+	 */
+	if (is_in_rom(addr))
+		return 0;
+#endif
+
+#ifdef DEBUG
+	printk("do_munmap:\n");
+#endif
+
+	tmp = &mm->context.tblock; /* dummy head */
+	while ((tblock=tmp->next) && tblock->rblock &&
+			tblock->rblock->kblock != (void*)addr) 
+		tmp = tblock;
+		
+	if (!tblock) {
+		printk("munmap of non-mmaped memory by process %d (%s): %p\n",
+				current->pid, current->comm, (void*)addr);
+		return -EINVAL;
+	}
+	if (tblock->rblock) {
+		if (!--tblock->rblock->refcount) {
+			if (tblock->rblock->kblock) {
+				realalloc -= kobjsize(tblock->rblock->kblock);
+				askedalloc -= tblock->rblock->size;
+				kfree(tblock->rblock->kblock);
+			}
+			
+			realalloc -= kobjsize(tblock->rblock);
+			askedalloc -= sizeof(struct mm_rblock_struct);
+			kfree(tblock->rblock);
+		}
+	}
+	tmp->next = tblock->next;
+	realalloc -= kobjsize(tblock);
+	askedalloc -= sizeof(struct mm_tblock_struct);
+	kfree(tblock);
+
+#ifdef DEBUG
+	show_process_blocks();
+#endif	  
+
+	return -EINVAL;
+}
+
+/* Release all mmaps. */
+void exit_mmap(struct mm_struct * mm)
+{
+	struct mm_tblock_struct *tmp;
+
+	if (!mm)
+		return;
+
+#ifdef DEBUG
+	printk("Exit_mmap:\n");
+#endif
+
+	while((tmp = mm->context.tblock.next)) {
+		if (tmp->rblock) {
+			if (!--tmp->rblock->refcount) {
+				if (tmp->rblock->kblock) {
+					realalloc -= kobjsize(tmp->rblock->kblock);
+					askedalloc -= tmp->rblock->size;
+					kfree(tmp->rblock->kblock);
+				}
+				realalloc -= kobjsize(tmp->rblock);
+				askedalloc -= sizeof(struct mm_rblock_struct);
+				kfree(tmp->rblock);
+			}
+			tmp->rblock = 0;
+		}
+		mm->context.tblock.next = tmp->next;
+		realalloc -= kobjsize(tmp);
+		askedalloc -= sizeof(struct mm_tblock_struct);
+		kfree(tmp);
+	}
+
+#ifdef DEBUG
+	show_process_blocks();
+#endif	  
+}
+
+asmlinkage long sys_munmap(unsigned long addr, size_t len)
+{
+	int ret;
+	struct mm_struct *mm = current->mm;
+
+	down_write(&mm->mmap_sem);
+	ret = do_munmap(mm, addr, len);
+	up_write(&mm->mmap_sem);
+	return ret;
+}
+
+unsigned long do_brk(unsigned long addr, unsigned long len)
+{
+	return -ENOMEM;
+}
+
+struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
+{
+	return NULL;
+}
+
+unsigned long get_unmapped_area(struct file *file, unsigned long addr,
+	unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	return -ENOMEM;
+}
+
+void pte_chain_init(void)
+{
+}