/* * 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). * * See Documentation/nommu-mmap.txt * * Copyright (c) 2004-2005 David Howells <dhowells@redhat.com> * Copyright (c) 2000-2003 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/file.h> #include <linux/highmem.h> #include <linux/pagemap.h> #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/ptrace.h> #include <linux/blkdev.h> #include <linux/backing-dev.h> #include <linux/mount.h> #include <linux/personality.h> #include <linux/security.h> #include <linux/syscalls.h> #include <asm/uaccess.h> #include <asm/tlb.h> #include <asm/tlbflush.h> void *high_memory; struct page *mem_map; unsigned long max_mapnr; unsigned long num_physpages; unsigned long askedalloc, realalloc; atomic_t vm_committed_space = ATOMIC_INIT(0); int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ int sysctl_overcommit_ratio = 50; /* default is 50% */ int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; int heap_stack_gap = 0; EXPORT_SYMBOL(mem_map); EXPORT_SYMBOL(sysctl_max_map_count); EXPORT_SYMBOL(sysctl_overcommit_memory); EXPORT_SYMBOL(sysctl_overcommit_ratio); EXPORT_SYMBOL(vm_committed_space); EXPORT_SYMBOL(__vm_enough_memory); /* list of shareable VMAs */ struct rb_root nommu_vma_tree = RB_ROOT; DECLARE_RWSEM(nommu_vma_sem); struct vm_operations_struct generic_file_vm_ops = { }; /* * 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; i_size_write(inode, offset); truncate_inode_pages(mapping, offset); goto out_truncate; do_expand: limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; if (limit != RLIM_INFINITY && offset > limit) goto out_sig; if (offset > inode->i_sb->s_maxbytes) goto out; i_size_write(inode, offset); out_truncate: if (inode->i_op && inode->i_op->truncate) inode->i_op->truncate(inode); return 0; out_sig: send_sig(SIGXFSZ, current, 0); out: return -EFBIG; } EXPORT_SYMBOL(vmtruncate); /* * 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; static struct vm_area_struct dummy_vma; for (i = 0; i < len; i++) { if (pages) { pages[i] = virt_to_page(start); if (pages[i]) page_cache_get(pages[i]); } if (vmas) vmas[i] = &dummy_vma; start += PAGE_SIZE; } return(i); } DEFINE_RWLOCK(vmlist_lock); struct vm_struct *vmlist; void vfree(void *addr) { kfree(addr); } void *__vmalloc(unsigned long size, unsigned int __nocast gfp_mask, pgprot_t prot) { /* * kmalloc doesn't like __GFP_HIGHMEM for some reason */ return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM); } struct page * vmalloc_to_page(void *addr) { return virt_to_page(addr); } unsigned long vmalloc_to_pfn(void *addr) { return page_to_pfn(virt_to_page(addr)); } 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, unsigned long flags, pgprot_t prot) { 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->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; } #ifdef DEBUG static void show_process_blocks(void) { struct vm_list_struct *vml; printk("Process blocks %d:", current->pid); for (vml = ¤t->mm->context.vmlist; vml; vml = vml->next) { printk(" %p: %p", vml, vml->vma); if (vml->vma) printk(" (%d @%lx #%d)", kobjsize((void *) vml->vma->vm_start), vml->vma->vm_start, atomic_read(&vml->vma->vm_usage)); printk(vml->next ? " ->" : ".\n"); } } #endif /* DEBUG */ static inline struct vm_area_struct *find_nommu_vma(unsigned long start) { struct vm_area_struct *vma; struct rb_node *n = nommu_vma_tree.rb_node; while (n) { vma = rb_entry(n, struct vm_area_struct, vm_rb); if (start < vma->vm_start) n = n->rb_left; else if (start > vma->vm_start) n = n->rb_right; else return vma; } return NULL; } static void add_nommu_vma(struct vm_area_struct *vma) { struct vm_area_struct *pvma; struct address_space *mapping; struct rb_node **p = &nommu_vma_tree.rb_node; struct rb_node *parent = NULL; /* add the VMA to the mapping */ if (vma->vm_file) { mapping = vma->vm_file->f_mapping; flush_dcache_mmap_lock(mapping); vma_prio_tree_insert(vma, &mapping->i_mmap); flush_dcache_mmap_unlock(mapping); } /* add the VMA to the master list */ while (*p) { parent = *p; pvma = rb_entry(parent, struct vm_area_struct, vm_rb); if (vma->vm_start < pvma->vm_start) { p = &(*p)->rb_left; } else if (vma->vm_start > pvma->vm_start) { p = &(*p)->rb_right; } else { /* mappings are at the same address - this can only * happen for shared-mem chardevs and shared file * mappings backed by ramfs/tmpfs */ BUG_ON(!(pvma->vm_flags & VM_SHARED)); if (vma < pvma) p = &(*p)->rb_left; else if (vma > pvma) p = &(*p)->rb_right; else BUG(); } } rb_link_node(&vma->vm_rb, parent, p); rb_insert_color(&vma->vm_rb, &nommu_vma_tree); } static void delete_nommu_vma(struct vm_area_struct *vma) { struct address_space *mapping; /* remove the VMA from the mapping */ if (vma->vm_file) { mapping = vma->vm_file->f_mapping; flush_dcache_mmap_lock(mapping); vma_prio_tree_remove(vma, &mapping->i_mmap); flush_dcache_mmap_unlock(mapping); } /* remove from the master list */ rb_erase(&vma->vm_rb, &nommu_vma_tree); } /* * determine whether a mapping should be permitted and, if so, what sort of * mapping we're capable of supporting */ static int validate_mmap_request(struct file *file, unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long pgoff, unsigned long *_capabilities) { unsigned long capabilities; unsigned long reqprot = prot; int ret; /* do the simple checks first */ if (flags & MAP_FIXED || addr) { printk(KERN_DEBUG "%d: Can't do fixed-address/overlay mmap of RAM\n", current->pid); return -EINVAL; } if ((flags & MAP_TYPE) != MAP_PRIVATE && (flags & MAP_TYPE) != MAP_SHARED) return -EINVAL; if (PAGE_ALIGN(len) == 0) return addr; if (len > TASK_SIZE) return -EINVAL; /* offset overflow? */ if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) return -EINVAL; if (file) { /* validate file mapping requests */ struct address_space *mapping; /* files must support mmap */ if (!file->f_op || !file->f_op->mmap) return -ENODEV; /* work out if what we've got could possibly be shared * - we support chardevs that provide their own "memory" * - we support files/blockdevs that are memory backed */ mapping = file->f_mapping; if (!mapping) mapping = file->f_dentry->d_inode->i_mapping; capabilities = 0; if (mapping && mapping->backing_dev_info) capabilities = mapping->backing_dev_info->capabilities; if (!capabilities) { /* no explicit capabilities set, so assume some * defaults */ switch (file->f_dentry->d_inode->i_mode & S_IFMT) { case S_IFREG: case S_IFBLK: capabilities = BDI_CAP_MAP_COPY; break; case S_IFCHR: capabilities = BDI_CAP_MAP_DIRECT | BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP; break; default: return -EINVAL; } } /* eliminate any capabilities that we can't support on this * device */ if (!file->f_op->get_unmapped_area) capabilities &= ~BDI_CAP_MAP_DIRECT; if (!file->f_op->read) capabilities &= ~BDI_CAP_MAP_COPY; if (flags & MAP_SHARED) { /* do checks for writing, appending and locking */ if ((prot & PROT_WRITE) && !(file->f_mode & FMODE_WRITE)) return -EACCES; if (IS_APPEND(file->f_dentry->d_inode) && (file->f_mode & FMODE_WRITE)) return -EACCES; if (locks_verify_locked(file->f_dentry->d_inode)) return -EAGAIN; if (!(capabilities & BDI_CAP_MAP_DIRECT)) return -ENODEV; if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) ) { printk("MAP_SHARED not completely supported on !MMU\n"); return -EINVAL; } /* we mustn't privatise shared mappings */ capabilities &= ~BDI_CAP_MAP_COPY; } else { /* we're going to read the file into private memory we * allocate */ if (!(capabilities & BDI_CAP_MAP_COPY)) return -ENODEV; /* we don't permit a private writable mapping to be * shared with the backing device */ if (prot & PROT_WRITE) capabilities &= ~BDI_CAP_MAP_DIRECT; } /* handle executable mappings and implied executable * mappings */ if (file->f_vfsmnt->mnt_flags & MNT_NOEXEC) { if (prot & PROT_EXEC) return -EPERM; } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { /* handle implication of PROT_EXEC by PROT_READ */ if (current->personality & READ_IMPLIES_EXEC) { if (capabilities & BDI_CAP_EXEC_MAP) prot |= PROT_EXEC; } } else if ((prot & PROT_READ) && (prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP) ) { /* backing file is not executable, try to copy */ capabilities &= ~BDI_CAP_MAP_DIRECT; } } else { /* anonymous mappings are always memory backed and can be * privately mapped */ capabilities = BDI_CAP_MAP_COPY; /* handle PROT_EXEC implication by PROT_READ */ if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) prot |= PROT_EXEC; } /* allow the security API to have its say */ ret = security_file_mmap(file, reqprot, prot, flags); if (ret < 0) return ret; /* looks okay */ *_capabilities = capabilities; return 0; } /* * we've determined that we can make the mapping, now translate what we * now know into VMA flags */ static unsigned long determine_vm_flags(struct file *file, unsigned long prot, unsigned long flags, unsigned long capabilities) { unsigned long vm_flags; vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; /* vm_flags |= mm->def_flags; */ if (!(capabilities & BDI_CAP_MAP_DIRECT)) { /* attempt to share read-only copies of mapped file chunks */ if (file && !(prot & PROT_WRITE)) vm_flags |= VM_MAYSHARE; } else { /* overlay a shareable mapping on the backing device or inode * if possible - used for chardevs, ramfs/tmpfs/shmfs and * romfs/cramfs */ if (flags & MAP_SHARED) vm_flags |= VM_MAYSHARE | VM_SHARED; else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0) vm_flags |= VM_MAYSHARE; } /* refuse to let anyone share private mappings with this process if * it's being traced - otherwise breakpoints set in it may interfere * with another untraced process */ if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED)) vm_flags &= ~VM_MAYSHARE; return vm_flags; } /* * set up a shared mapping on a file */ static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len) { int ret; ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); if (ret != -ENOSYS) return ret; /* getting an ENOSYS error indicates that direct mmap isn't * possible (as opposed to tried but failed) so we'll fall * through to making a private copy of the data and mapping * that if we can */ return -ENODEV; } /* * set up a private mapping or an anonymous shared mapping */ static int do_mmap_private(struct vm_area_struct *vma, unsigned long len) { void *base; int ret; /* invoke the file's mapping function so that it can keep track of * shared mappings on devices or memory * - VM_MAYSHARE will be set if it may attempt to share */ if (vma->vm_file) { ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); if (ret != -ENOSYS) { /* shouldn't return success if we're not sharing */ BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE)); return ret; /* success or a real error */ } /* getting an ENOSYS error indicates that direct mmap isn't * possible (as opposed to tried but failed) so we'll try to * make a private copy of the data and map that instead */ } /* allocate some memory to hold the mapping * - note that this may not return a page-aligned address if the object * we're allocating is smaller than a page */ base = kmalloc(len, GFP_KERNEL); if (!base) goto enomem; vma->vm_start = (unsigned long) base; vma->vm_end = vma->vm_start + len; vma->vm_flags |= VM_MAPPED_COPY; #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 (vma->vm_file) { /* read the contents of a file into the copy */ mm_segment_t old_fs; loff_t fpos; fpos = vma->vm_pgoff; fpos <<= PAGE_SHIFT; old_fs = get_fs(); set_fs(KERNEL_DS); ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); set_fs(old_fs); if (ret < 0) goto error_free; /* clear the last little bit */ if (ret < len) memset(base + ret, 0, len - ret); } else { /* if it's an anonymous mapping, then just clear it */ memset(base, 0, len); } return 0; error_free: kfree(base); vma->vm_start = 0; return ret; enomem: printk("Allocation of length %lu from process %d failed\n", len, current->pid); show_free_areas(); return -ENOMEM; } /* * handle mapping creation for uClinux */ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long pgoff) { struct vm_list_struct *vml = NULL; struct vm_area_struct *vma = NULL; struct rb_node *rb; unsigned long capabilities, vm_flags; void *result; int ret; /* decide whether we should attempt the mapping, and if so what sort of * mapping */ ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, &capabilities); if (ret < 0) return ret; /* we've determined that we can make the mapping, now translate what we * now know into VMA flags */ vm_flags = determine_vm_flags(file, prot, flags, capabilities); /* we're going to need to record the mapping if it works */ vml = kmalloc(sizeof(struct vm_list_struct), GFP_KERNEL); if (!vml) goto error_getting_vml; memset(vml, 0, sizeof(*vml)); down_write(&nommu_vma_sem); /* if we want to share, we need to check for VMAs created by other * mmap() calls that overlap with our proposed mapping * - we can only share with an exact match on most regular files * - shared mappings on character devices and memory backed files are * permitted to overlap inexactly as far as we are concerned for in * these cases, sharing is handled in the driver or filesystem rather * than here */ if (vm_flags & VM_MAYSHARE) { unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; unsigned long vmpglen; for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) { vma = rb_entry(rb, struct vm_area_struct, vm_rb); if (!(vma->vm_flags & VM_MAYSHARE)) continue; /* search for overlapping mappings on the same file */ if (vma->vm_file->f_dentry->d_inode != file->f_dentry->d_inode) continue; if (vma->vm_pgoff >= pgoff + pglen) continue; vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1; vmpglen >>= PAGE_SHIFT; if (pgoff >= vma->vm_pgoff + vmpglen) continue; /* handle inexactly overlapping matches between mappings */ if (vma->vm_pgoff != pgoff || vmpglen != pglen) { if (!(capabilities & BDI_CAP_MAP_DIRECT)) goto sharing_violation; continue; } /* we've found a VMA we can share */ atomic_inc(&vma->vm_usage); vml->vma = vma; result = (void *) vma->vm_start; goto shared; } vma = NULL; /* obtain the address at which to make a shared mapping * - this is the hook for quasi-memory character devices to * tell us the location of a shared mapping */ if (file && file->f_op->get_unmapped_area) { addr = file->f_op->get_unmapped_area(file, addr, len, pgoff, flags); if (IS_ERR((void *) addr)) { ret = addr; if (ret != (unsigned long) -ENOSYS) goto error; /* the driver refused to tell us where to site * the mapping so we'll have to attempt to copy * it */ ret = (unsigned long) -ENODEV; if (!(capabilities & BDI_CAP_MAP_COPY)) goto error; capabilities &= ~BDI_CAP_MAP_DIRECT; } } } /* we're going to need a VMA struct as well */ vma = kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); if (!vma) goto error_getting_vma; memset(vma, 0, sizeof(*vma)); INIT_LIST_HEAD(&vma->anon_vma_node); atomic_set(&vma->vm_usage, 1); if (file) get_file(file); vma->vm_file = file; vma->vm_flags = vm_flags; vma->vm_start = addr; vma->vm_end = addr + len; vma->vm_pgoff = pgoff; vml->vma = vma; /* set up the mapping */ if (file && vma->vm_flags & VM_SHARED) ret = do_mmap_shared_file(vma, len); else ret = do_mmap_private(vma, len); if (ret < 0) goto error; /* okay... we have a mapping; now we have to register it */ result = (void *) vma->vm_start; if (vma->vm_flags & VM_MAPPED_COPY) { realalloc += kobjsize(result); askedalloc += len; } realalloc += kobjsize(vma); askedalloc += sizeof(*vma); current->mm->total_vm += len >> PAGE_SHIFT; add_nommu_vma(vma); shared: realalloc += kobjsize(vml); askedalloc += sizeof(*vml); vml->next = current->mm->context.vmlist; current->mm->context.vmlist = vml; up_write(&nommu_vma_sem); if (prot & PROT_EXEC) flush_icache_range((unsigned long) result, (unsigned long) result + len); #ifdef DEBUG printk("do_mmap:\n"); show_process_blocks(); #endif return (unsigned long) result; error: up_write(&nommu_vma_sem); kfree(vml); if (vma) { fput(vma->vm_file); kfree(vma); } return ret; sharing_violation: up_write(&nommu_vma_sem); printk("Attempt to share mismatched mappings\n"); kfree(vml); return -EINVAL; error_getting_vma: up_write(&nommu_vma_sem); kfree(vml); printk("Allocation of vml for %lu byte allocation from process %d failed\n", len, current->pid); show_free_areas(); return -ENOMEM; error_getting_vml: printk("Allocation of vml for %lu byte allocation from process %d failed\n", len, current->pid); show_free_areas(); return -ENOMEM; } /* * handle mapping disposal for uClinux */ static void put_vma(struct vm_area_struct *vma) { if (vma) { down_write(&nommu_vma_sem); if (atomic_dec_and_test(&vma->vm_usage)) { delete_nommu_vma(vma); if (vma->vm_ops && vma->vm_ops->close) vma->vm_ops->close(vma); /* IO memory and memory shared directly out of the pagecache from * ramfs/tmpfs mustn't be released here */ if (vma->vm_flags & VM_MAPPED_COPY) { realalloc -= kobjsize((void *) vma->vm_start); askedalloc -= vma->vm_end - vma->vm_start; kfree((void *) vma->vm_start); } realalloc -= kobjsize(vma); askedalloc -= sizeof(*vma); if (vma->vm_file) fput(vma->vm_file); kfree(vma); } up_write(&nommu_vma_sem); } } int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len) { struct vm_list_struct *vml, **parent; unsigned long end = addr + len; #ifdef DEBUG printk("do_munmap:\n"); #endif for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) if ((*parent)->vma->vm_start == addr && (*parent)->vma->vm_end == end) goto found; printk("munmap of non-mmaped memory by process %d (%s): %p\n", current->pid, current->comm, (void *) addr); return -EINVAL; found: vml = *parent; put_vma(vml->vma); *parent = vml->next; realalloc -= kobjsize(vml); askedalloc -= sizeof(*vml); kfree(vml); mm->total_vm -= len >> PAGE_SHIFT; #ifdef DEBUG show_process_blocks(); #endif return 0; } /* Release all mmaps. */ void exit_mmap(struct mm_struct * mm) { struct vm_list_struct *tmp; if (mm) { #ifdef DEBUG printk("Exit_mmap:\n"); #endif mm->total_vm = 0; while ((tmp = mm->context.vmlist)) { mm->context.vmlist = tmp->next; put_vma(tmp->vma); realalloc -= kobjsize(tmp); askedalloc -= sizeof(*tmp); 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; } /* * Expand (or shrink) an existing mapping, potentially moving it at the * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) * * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise * This option implies MREMAP_MAYMOVE. * * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable */ unsigned long do_mremap(unsigned long addr, unsigned long old_len, unsigned long new_len, unsigned long flags, unsigned long new_addr) { struct vm_list_struct *vml = NULL; /* insanity checks first */ if (new_len == 0) return (unsigned long) -EINVAL; if (flags & MREMAP_FIXED && new_addr != addr) return (unsigned long) -EINVAL; for (vml = current->mm->context.vmlist; vml; vml = vml->next) if (vml->vma->vm_start == addr) goto found; return (unsigned long) -EINVAL; found: if (vml->vma->vm_end != vml->vma->vm_start + old_len) return (unsigned long) -EFAULT; if (vml->vma->vm_flags & VM_MAYSHARE) return (unsigned long) -EPERM; if (new_len > kobjsize((void *) addr)) return (unsigned long) -ENOMEM; /* all checks complete - do it */ vml->vma->vm_end = vml->vma->vm_start + new_len; askedalloc -= old_len; askedalloc += new_len; return vml->vma->vm_start; } /* * Look up the first VMA which satisfies addr < vm_end, NULL if none */ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) { struct vm_list_struct *vml; for (vml = mm->context.vmlist; vml; vml = vml->next) if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end) return vml->vma; return NULL; } EXPORT_SYMBOL(find_vma); struct page * follow_page(struct mm_struct *mm, unsigned long addr, int write) { return NULL; } struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) { return NULL; } int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, unsigned long to, unsigned long size, pgprot_t prot) { return -EPERM; } void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) { } unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { return -ENOMEM; } void arch_unmap_area(struct mm_struct *mm, unsigned long addr) { } void update_mem_hiwater(struct task_struct *tsk) { unsigned long rss = get_mm_counter(tsk->mm, rss); if (likely(tsk->mm)) { if (tsk->mm->hiwater_rss < rss) tsk->mm->hiwater_rss = rss; if (tsk->mm->hiwater_vm < tsk->mm->total_vm) tsk->mm->hiwater_vm = tsk->mm->total_vm; } } void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows) { } /* * Check that a process has enough memory to allocate a new virtual * mapping. 0 means there is enough memory for the allocation to * succeed and -ENOMEM implies there is not. * * We currently support three overcommit policies, which are set via the * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting * * Strict overcommit modes added 2002 Feb 26 by Alan Cox. * Additional code 2002 Jul 20 by Robert Love. * * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. * * Note this is a helper function intended to be used by LSMs which * wish to use this logic. */ int __vm_enough_memory(long pages, int cap_sys_admin) { unsigned long free, allowed; vm_acct_memory(pages); /* * Sometimes we want to use more memory than we have */ if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) return 0; if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { unsigned long n; free = get_page_cache_size(); free += nr_swap_pages; /* * Any slabs which are created with the * SLAB_RECLAIM_ACCOUNT flag claim to have contents * which are reclaimable, under pressure. The dentry * cache and most inode caches should fall into this */ free += atomic_read(&slab_reclaim_pages); /* * Leave the last 3% for root */ if (!cap_sys_admin) free -= free / 32; if (free > pages) return 0; /* * nr_free_pages() is very expensive on large systems, * only call if we're about to fail. */ n = nr_free_pages(); if (!cap_sys_admin) n -= n / 32; free += n; if (free > pages) return 0; vm_unacct_memory(pages); return -ENOMEM; } allowed = totalram_pages * sysctl_overcommit_ratio / 100; /* * Leave the last 3% for root */ if (!cap_sys_admin) allowed -= allowed / 32; allowed += total_swap_pages; /* Don't let a single process grow too big: leave 3% of the size of this process for other processes */ allowed -= current->mm->total_vm / 32; /* * cast `allowed' as a signed long because vm_committed_space * sometimes has a negative value */ if (atomic_read(&vm_committed_space) < (long)allowed) return 0; vm_unacct_memory(pages); return -ENOMEM; } int in_gate_area_no_task(unsigned long addr) { return 0; }