/* * linux/mm/mmap.c * * Written by obz. */ #include <linux/stat.h> #include <linux/sched.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/shm.h> #include <linux/errno.h> #include <linux/mman.h> #include <linux/string.h> #include <linux/malloc.h> #include <linux/pagemap.h> #include <linux/swap.h> #include <asm/segment.h> #include <asm/system.h> #include <asm/pgtable.h> /* * description of effects of mapping type and prot in current implementation. * this is due to the limited x86 page protection hardware. The expected * behavior is in parens: * * map_type prot * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes * w: (no) no w: (no) no w: (yes) yes w: (no) no * x: (no) no x: (no) yes x: (no) yes x: (yes) yes * * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes * w: (no) no w: (no) no w: (copy) copy w: (no) no * x: (no) no x: (no) yes x: (no) yes x: (yes) yes * */ pgprot_t protection_map[16] = { __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 }; /* * Check that a process has enough memory to allocate a * new virtual mapping. */ static inline int vm_enough_memory(long pages) { /* * stupid algorithm to decide if we have enough memory: while * simple, it hopefully works in most obvious cases.. Easy to * fool it, but this should catch most mistakes. */ long freepages; freepages = buffermem >> PAGE_SHIFT; freepages += page_cache_size; if (freepages <= (MAP_NR(high_memory) >> 4) + 48) freepages >>= 1; freepages += nr_free_pages; freepages += nr_swap_pages; freepages -= MAP_NR(high_memory) >> 4; return freepages > pages; } asmlinkage unsigned long sys_brk(unsigned long brk) { unsigned long rlim; unsigned long newbrk, oldbrk; struct mm_struct *mm = current->mm; if (brk < mm->end_code) return mm->brk; newbrk = PAGE_ALIGN(brk); oldbrk = PAGE_ALIGN(mm->brk); if (oldbrk == newbrk) return mm->brk = brk; /* * Always allow shrinking brk */ if (brk <= mm->brk) { mm->brk = brk; do_munmap(newbrk, oldbrk-newbrk); return brk; } /* * Check against rlimit and stack.. */ rlim = current->rlim[RLIMIT_DATA].rlim_cur; if (rlim >= RLIM_INFINITY) rlim = ~0; if (brk - mm->end_code > rlim) return mm->brk; /* * Check against existing mmap mappings. */ if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) return mm->brk; /* * Check if we have enough memory.. */ if (!vm_enough_memory((newbrk-oldbrk) >> PAGE_SHIFT)) return mm->brk; /* * Ok, looks good - let it rip. */ if(do_mmap(NULL, oldbrk, newbrk-oldbrk, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, 0) != oldbrk) return mm->brk; 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 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 } unsigned long do_mmap(struct file * file, unsigned long addr, unsigned long len, unsigned long prot, unsigned long flags, unsigned long off) /* Przedziela pamięć na nowa strukturę typu vm_area_struct oraz następuje jej inicjalizowanie Zwalnia poprzednie obszary o zachodzących na siebie adresach Wywołuje funkcje charakterystyczną dla danego systemu plików i kończy inicjalizowanie struktury typu vm_area_struct Następnie struktura ta jest dostawiana do struktury zawierającej informacje o ramkach procesu. argumenty funkcji: file - określenie pliku, który ma być mapowany, Jeśli zostanie podane NULL to przydzielony segment nie będzie związany z żadnym plikiem (będzie "normalnym" segmentem) addr - adres w pamięci pod który chcemy mapować (jeśli podajemy konkretny adres flaga MAP_FIXED musi być ustawiona) Jesli zostanie podane NULL system sam przydzieli odpowiedni adres len - wielkość obszaru do przydzielenia prot, flags- flagi ochrony i dzielenia zdefiniowane w pliku asm/mmap.h off - offset w pliku. Jeśli pamięć ma być dzielona to offset musi być wielokrotnościa rozmiaru strony Zwracany jest przydzielony adres lub odpowiedni kod błędu (<0) EINVAL - niewłaściwy argument EAGAIN - spróbuj ponownie EACCES - dostęp zabroniony ETXTBSY - plik tekstowo zajęty ENOMEM - brak pamięci ENODEV - nie ma takiego urządzenia */ { struct mm_struct * mm = current->mm; struct vm_area_struct * vma; if ((len = PAGE_ALIGN(len)) == 0) return addr; /*PAGE_ALIGN(len) zwraca len gdy (len mod PAGE_SIZE == 0) wpp (PAGE_SIZE*((len div PAGE_SIZE) + 1) PAGE_SIZE - rozmiar strony */ if (len > TASK_SIZE || addr > TASK_SIZE-len) return -EINVAL; /* próba przydzielenia za dużej liczby pamięci lub w niewłaściwym obszarze */ /* offset overflow? */ if (off + len < off) return -EINVAL; /* mlock MCL_FUTURE? */ if (mm->def_flags & VM_LOCKED) { unsigned long locked = mm->locked_vm << PAGE_SHIFT; locked += len; if (locked > current->rlim[RLIMIT_MEMLOCK].rlim_cur) return -EAGAIN; } /* * 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. */ if (file != NULL) {/*sprawdzenie praw dostępu*/ switch (flags & MAP_TYPE) { case MAP_SHARED: /*obszar dzielony */ if ((prot & PROT_WRITE) && !(file->f_mode & 2)) return -EACCES; /*błąd dostępu */ /* PROT_WRITE - strona może być modyfikowana*/ /* * make sure there are no mandatory locks on the file. */ if (locks_verify_locked(file->f_inode)) return -EAGAIN;/* spróbuj ponownie */ /* fall through */ case MAP_PRIVATE:/*obszar niedzielony*/ if (!(file->f_mode & 1)) return -EACCES;/*błąd dostępu*/ break; default: return -EINVAL;/*niewłaściwy argument*/ } if (flags & MAP_DENYWRITE) { if (file->f_inode->i_writecount > 0) return -ETXTBSY;/*plik tekstowo zajęty */ } } else if ((flags & MAP_TYPE) != MAP_PRIVATE) return -EINVAL; /* * obtain the address to map to. we verify (or select) it and ensure * that it represents a valid section of the address space. */ if (flags & MAP_FIXED) {/*podaliśmy konkretny adres */ if (addr & ~PAGE_MASK) return -EINVAL; } else {/*przydzielamy adres obszaru o długosci len */ addr = get_unmapped_area(addr, len); if (!addr) return -ENOMEM;/*brak pamięci*/ } /* * determine the object being mapped and call the appropriate * specific mapper. the address has already been validated, but * not unmapped, but the maps are removed from the list. */ if (file && (!file->f_op || !file->f_op->mmap)) return -ENODEV;/*plik nie ma zdefinowanej struktury używanej przy wymianie dotyczącej urządzenia na jakim znajduje się plik */ vma = (struct vm_area_struct *)kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); if (!vma) return -ENOMEM; /* inicjalizowanie vma */ vma->vm_mm = mm; vma->vm_start = addr; vma->vm_end = addr + len; vma->vm_flags = vm_flags(prot,flags) | mm->def_flags; if (file) { if (file->f_mode & 1) vma->vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; if (flags & MAP_SHARED) { vma->vm_flags |= VM_SHARED | VM_MAYSHARE; /* * This looks strange, but when we don't have the file open * for writing, we can demote the shared mapping to a simpler * private mapping. That also takes care of a security hole * with ptrace() writing to a shared mapping without write * permissions. * * We leave the VM_MAYSHARE bit on, just to get correct output * from /proc/xxx/maps.. */ if (!(file->f_mode & 2)) vma->vm_flags &= ~(VM_MAYWRITE | VM_SHARED); } } else vma->vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; vma->vm_page_prot = protection_map[vma->vm_flags & 0x0f]; vma->vm_ops = NULL; vma->vm_offset = off; vma->vm_inode = NULL; vma->vm_pte = 0; do_munmap(addr, len); /* Clear old maps */ /* Check against address space limit. */ if ((mm->total_vm << PAGE_SHIFT) + len > current->rlim[RLIMIT_AS].rlim_cur) { kfree(vma); return -ENOMEM; } /* Private writable mapping? Check memory availability.. */ if ((vma->vm_flags & (VM_SHARED | VM_WRITE)) == VM_WRITE) { if (!vm_enough_memory(len >> PAGE_SHIFT)) { kfree(vma); return -ENOMEM; } } if (file) { /* zakończenie inicjalizowania struktury vma, mmap wykonuje się zależnie od systemu plików z którego pochodzi "file" */ int error = file->f_op->mmap(file->f_inode, file, vma); if (error) { kfree(vma); return error; } } flags = vma->vm_flags; insert_vm_struct(mm, vma); /* łączenie segmentów - możliwe, że nasze vma zazębia się początkiem lub końcem z jakimś innym vma z którym można go połączyć */ merge_segments(mm, vma->vm_start, vma->vm_end); /* merge_segments might have merged our vma, so we can't use it any more */ mm->total_vm += len >> PAGE_SHIFT; if (flags & VM_LOCKED) { unsigned long start = addr; mm->locked_vm += len >> PAGE_SHIFT; do { char c = get_user((char *) start); len -= PAGE_SIZE; start += PAGE_SIZE; __asm__ __volatile__("": :"r" (c)); } while (len > 0); } return addr; } /* * Get an address range which is currently unmapped. * For mmap() without MAP_FIXED and shmat() with addr=0. * Return value 0 means ENOMEM. */ unsigned long get_unmapped_area(unsigned long addr, unsigned long len) /* Zwraca adres obszaru pod który możemy wstawić strukturę vma lub 0 gdy bład */ { struct vm_area_struct * vmm; if (len > TASK_SIZE) return 0; /* nie można przydzielić wiecej niż wynosi limit */ if (!addr) addr = TASK_SIZE / 3; addr = PAGE_ALIGN(addr); /* PAGE_ALIGN(addr)=addr gdy (addr mod PAGE_SIZE)==0 =PAGE_SIZE*(addr div PAGE_SIZE +1) PAGE_SIZE - rozmiar strony */ for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) { /* At this point: (!vmm || addr < vmm->vm_end). */ if (TASK_SIZE - len < addr) return 0; /* przekroczyliśmy zakres */ if (!vmm || addr + len <= vmm->vm_start) /* zmieściliśmy się w luce pomiędzy dwoma strukturami vma */ return addr; addr = vmm->vm_end; } } /* * Searching a VMA in the linear list task->mm->mmap is horribly slow. * Use an AVL (Adelson-Velskii and Landis) tree to speed up this search * from O(n) to O(log n), where n is the number of VMAs of the task * (typically around 6, but may reach 3000 in some cases). * Written by Bruno Haible <haible@ma2s2.mathematik.uni-karlsruhe.de>. */ /* We keep the list and tree sorted by address. */ #define vm_avl_key vm_end #define vm_avl_key_t unsigned long /* typeof(vma->avl_key) */ /* * task->mm->mmap_avl is the AVL tree corresponding to task->mm->mmap * or, more exactly, its root. * A vm_area_struct has the following fields: * vm_avl_left left son of a tree node * vm_avl_right right son of a tree node * vm_avl_height 1+max(heightof(left),heightof(right)) * The empty tree is represented as NULL. */ /* Since the trees are balanced, their height will never be large. */ #define avl_maxheight 41 /* why this? a small exercise */ #define heightof(tree) ((tree) == avl_empty ? 0 : (tree)->vm_avl_height) /* * Consistency and balancing rules: * 1. tree->vm_avl_height == 1+max(heightof(tree->vm_avl_left),heightof(tree->vm_avl_right)) * 2. abs( heightof(tree->vm_avl_left) - heightof(tree->vm_avl_right) ) <= 1 * 3. foreach node in tree->vm_avl_left: node->vm_avl_key <= tree->vm_avl_key, * foreach node in tree->vm_avl_right: node->vm_avl_key >= tree->vm_avl_key. */ /* Look up the nodes at the left and at the right of a given node. */ static inline void avl_neighbours (struct vm_area_struct * node, struct vm_area_struct * tree, struct vm_area_struct ** to_the_left, struct vm_area_struct ** to_the_right) { vm_avl_key_t key = node->vm_avl_key; *to_the_left = *to_the_right = NULL; for (;;) { if (tree == avl_empty) { printk("avl_neighbours: node not found in the tree\n"); return; } if (key == tree->vm_avl_key) break; if (key < tree->vm_avl_key) { *to_the_right = tree; tree = tree->vm_avl_left; } else { *to_the_left = tree; tree = tree->vm_avl_right; } } if (tree != node) { printk("avl_neighbours: node not exactly found in the tree\n"); return; } if (tree->vm_avl_left != avl_empty) { struct vm_area_struct * node; for (node = tree->vm_avl_left; node->vm_avl_right != avl_empty; node = node->vm_avl_right) continue; *to_the_left = node; } if (tree->vm_avl_right != avl_empty) { struct vm_area_struct * node; for (node = tree->vm_avl_right; node->vm_avl_left != avl_empty; node = node->vm_avl_left) continue; *to_the_right = node; } if ((*to_the_left && ((*to_the_left)->vm_next != node)) || (node->vm_next != *to_the_right)) printk("avl_neighbours: tree inconsistent with list\n"); } /* * Rebalance a tree. * After inserting or deleting a node of a tree we have a sequence of subtrees * nodes[0]..nodes[k-1] such that * nodes[0] is the root and nodes[i+1] = nodes[i]->{vm_avl_left|vm_avl_right}. */ static inline void avl_rebalance (struct vm_area_struct *** nodeplaces_ptr, int count) { for ( ; count > 0 ; count--) { struct vm_area_struct ** nodeplace = *--nodeplaces_ptr; struct vm_area_struct * node = *nodeplace; struct vm_area_struct * nodeleft = node->vm_avl_left; struct vm_area_struct * noderight = node->vm_avl_right; int heightleft = heightof(nodeleft); int heightright = heightof(noderight); if (heightright + 1 < heightleft) { /* */ /* * */ /* / \ */ /* n+2 n */ /* */ struct vm_area_struct * nodeleftleft = nodeleft->vm_avl_left; struct vm_area_struct * nodeleftright = nodeleft->vm_avl_right; int heightleftright = heightof(nodeleftright); if (heightof(nodeleftleft) >= heightleftright) { /* */ /* * n+2|n+3 */ /* / \ / \ */ /* n+2 n --> / n+1|n+2 */ /* / \ | / \ */ /* n+1 n|n+1 n+1 n|n+1 n */ /* */ node->vm_avl_left = nodeleftright; nodeleft->vm_avl_right = node; nodeleft->vm_avl_height = 1 + (node->vm_avl_height = 1 + heightleftright); *nodeplace = nodeleft; } else { /* */ /* * n+2 */ /* / \ / \ */ /* n+2 n --> n+1 n+1 */ /* / \ / \ / \ */ /* n n+1 n L R n */ /* / \ */ /* L R */ /* */ nodeleft->vm_avl_right = nodeleftright->vm_avl_left; node->vm_avl_left = nodeleftright->vm_avl_right; nodeleftright->vm_avl_left = nodeleft; nodeleftright->vm_avl_right = node; nodeleft->vm_avl_height = node->vm_avl_height = heightleftright; nodeleftright->vm_avl_height = heightleft; *nodeplace = nodeleftright; } } else if (heightleft + 1 < heightright) { /* similar to the above, just interchange 'left' <--> 'right' */ struct vm_area_struct * noderightright = noderight->vm_avl_right; struct vm_area_struct * noderightleft = noderight->vm_avl_left; int heightrightleft = heightof(noderightleft); if (heightof(noderightright) >= heightrightleft) { node->vm_avl_right = noderightleft; noderight->vm_avl_left = node; noderight->vm_avl_height = 1 + (node->vm_avl_height = 1 + heightrightleft); *nodeplace = noderight; } else { noderight->vm_avl_left = noderightleft->vm_avl_right; node->vm_avl_right = noderightleft->vm_avl_left; noderightleft->vm_avl_right = noderight; noderightleft->vm_avl_left = node; noderight->vm_avl_height = node->vm_avl_height = heightrightleft; noderightleft->vm_avl_height = heightright; *nodeplace = noderightleft; } } else { int height = (heightleft<heightright ? heightright : heightleft) + 1; if (height == node->vm_avl_height) break; node->vm_avl_height = height; } } } /* Insert a node into a tree. */ static inline void avl_insert (struct vm_area_struct * new_node, struct vm_area_struct ** ptree) { vm_avl_key_t key = new_node->vm_avl_key; struct vm_area_struct ** nodeplace = ptree; struct vm_area_struct ** stack[avl_maxheight]; int stack_count = 0; struct vm_area_struct *** stack_ptr = &stack[0]; /* = &stack[stackcount] */ for (;;) { struct vm_area_struct * node = *nodeplace; if (node == avl_empty) break; *stack_ptr++ = nodeplace; stack_count++; if (key < node->vm_avl_key) nodeplace = &node->vm_avl_left; else nodeplace = &node->vm_avl_right; } new_node->vm_avl_left = avl_empty; new_node->vm_avl_right = avl_empty; new_node->vm_avl_height = 1; *nodeplace = new_node; avl_rebalance(stack_ptr,stack_count); } /* Insert a node into a tree, and * return the node to the left of it and the node to the right of it. */ static inline void avl_insert_neighbours (struct vm_area_struct * new_node, struct vm_area_struct ** ptree, struct vm_area_struct ** to_the_left, struct vm_area_struct ** to_the_right) { vm_avl_key_t key = new_node->vm_avl_key; struct vm_area_struct ** nodeplace = ptree; struct vm_area_struct ** stack[avl_maxheight]; int stack_count = 0; struct vm_area_struct *** stack_ptr = &stack[0]; /* = &stack[stackcount] */ *to_the_left = *to_the_right = NULL; for (;;) { struct vm_area_struct * node = *nodeplace; if (node == avl_empty) break; *stack_ptr++ = nodeplace; stack_count++; if (key < node->vm_avl_key) { *to_the_right = node; nodeplace = &node->vm_avl_left; } else { *to_the_left = node; nodeplace = &node->vm_avl_right; } } new_node->vm_avl_left = avl_empty; new_node->vm_avl_right = avl_empty; new_node->vm_avl_height = 1; *nodeplace = new_node; avl_rebalance(stack_ptr,stack_count); } /* Removes a node out of a tree. */ static inline void avl_remove (struct vm_area_struct * node_to_delete, struct vm_area_struct ** ptree) { vm_avl_key_t key = node_to_delete->vm_avl_key; struct vm_area_struct ** nodeplace = ptree; struct vm_area_struct ** stack[avl_maxheight]; int stack_count = 0; struct vm_area_struct *** stack_ptr = &stack[0]; /* = &stack[stackcount] */ struct vm_area_struct ** nodeplace_to_delete; for (;;) { struct vm_area_struct * node = *nodeplace; if (node == avl_empty) { /* what? node_to_delete not found in tree? */ printk("avl_remove: node to delete not found in tree\n"); return; } *stack_ptr++ = nodeplace; stack_count++; if (key == node->vm_avl_key) break; if (key < node->vm_avl_key) nodeplace = &node->vm_avl_left; else nodeplace = &node->vm_avl_right; } nodeplace_to_delete = nodeplace; /* Have to remove node_to_delete = *nodeplace_to_delete. */ if (node_to_delete->vm_avl_left == avl_empty) { *nodeplace_to_delete = node_to_delete->vm_avl_right; stack_ptr--; stack_count--; } else { struct vm_area_struct *** stack_ptr_to_delete = stack_ptr; struct vm_area_struct ** nodeplace = &node_to_delete->vm_avl_left; struct vm_area_struct * node; for (;;) { node = *nodeplace; if (node->vm_avl_right == avl_empty) break; *stack_ptr++ = nodeplace; stack_count++; nodeplace = &node->vm_avl_right; } *nodeplace = node->vm_avl_left; /* node replaces node_to_delete */ node->vm_avl_left = node_to_delete->vm_avl_left; node->vm_avl_right = node_to_delete->vm_avl_right; node->vm_avl_height = node_to_delete->vm_avl_height; *nodeplace_to_delete = node; /* replace node_to_delete */ *stack_ptr_to_delete = &node->vm_avl_left; /* replace &node_to_delete->vm_avl_left */ } avl_rebalance(stack_ptr,stack_count); } #ifdef DEBUG_AVL /* print a list */ static void printk_list (struct vm_area_struct * vma) { printk("["); while (vma) { printk("%08lX-%08lX", vma->vm_start, vma->vm_end); vma = vma->vm_next; if (!vma) break; printk(" "); } printk("]"); } /* print a tree */ static void printk_avl (struct vm_area_struct * tree) { if (tree != avl_empty) { printk("("); if (tree->vm_avl_left != avl_empty) { printk_avl(tree->vm_avl_left); printk("<"); } printk("%08lX-%08lX", tree->vm_start, tree->vm_end); if (tree->vm_avl_right != avl_empty) { printk(">"); printk_avl(tree->vm_avl_right); } printk(")"); } } static char *avl_check_point = "somewhere"; /* check a tree's consistency and balancing */ static void avl_checkheights (struct vm_area_struct * tree) { int h, hl, hr; if (tree == avl_empty) return; avl_checkheights(tree->vm_avl_left); avl_checkheights(tree->vm_avl_right); h = tree->vm_avl_height; hl = heightof(tree->vm_avl_left); hr = heightof(tree->vm_avl_right); if ((h == hl+1) && (hr <= hl) && (hl <= hr+1)) return; if ((h == hr+1) && (hl <= hr) && (hr <= hl+1)) return; printk("%s: avl_checkheights: heights inconsistent\n",avl_check_point); } /* check that all values stored in a tree are < key */ static void avl_checkleft (struct vm_area_struct * tree, vm_avl_key_t key) { if (tree == avl_empty) return; avl_checkleft(tree->vm_avl_left,key); avl_checkleft(tree->vm_avl_right,key); if (tree->vm_avl_key < key) return; printk("%s: avl_checkleft: left key %lu >= top key %lu\n",avl_check_point,tree->vm_avl_key,key); } /* check that all values stored in a tree are > key */ static void avl_checkright (struct vm_area_struct * tree, vm_avl_key_t key) { if (tree == avl_empty) return; avl_checkright(tree->vm_avl_left,key); avl_checkright(tree->vm_avl_right,key); if (tree->vm_avl_key > key) return; printk("%s: avl_checkright: right key %lu <= top key %lu\n",avl_check_point,tree->vm_avl_key,key); } /* check that all values are properly increasing */ static void avl_checkorder (struct vm_area_struct * tree) { if (tree == avl_empty) return; avl_checkorder(tree->vm_avl_left); avl_checkorder(tree->vm_avl_right); avl_checkleft(tree->vm_avl_left,tree->vm_avl_key); avl_checkright(tree->vm_avl_right,tree->vm_avl_key); } /* all checks */ static void avl_check (struct task_struct * task, char *caller) { avl_check_point = caller; /* printk("task \"%s\", %s\n",task->comm,caller); */ /* printk("task \"%s\" list: ",task->comm); printk_list(task->mm->mmap); printk("\n"); */ /* printk("task \"%s\" tree: ",task->comm); printk_avl(task->mm->mmap_avl); printk("\n"); */ avl_checkheights(task->mm->mmap_avl); avl_checkorder(task->mm->mmap_avl); } #endif /* * Normal function to fix up a mapping * This function is the default for when an area has no specific * function. This may be used as part of a more specific routine. * This function works out what part of an area is affected and * adjusts the mapping information. Since the actual page * manipulation is done in do_mmap(), none need be done here, * though it would probably be more appropriate. * * By the time this function is called, the area struct has been * removed from the process mapping list, so it needs to be * reinserted if necessary. * * The 4 main cases are: * Unmapping the whole area * Unmapping from the start of the segment to a point in it * Unmapping from an intermediate point to the end * Unmapping between to intermediate points, making a hole. * * Case 4 involves the creation of 2 new areas, for each side of * the hole. */ static void unmap_fixup(struct vm_area_struct *area, unsigned long addr, size_t len) { struct vm_area_struct *mpnt; unsigned long end = addr + len; if (addr < area->vm_start || addr >= area->vm_end || end <= area->vm_start || end > area->vm_end || end < addr) /* czy podane dane są poprawne */ { printk("unmap_fixup: area=%lx-%lx, unmap %lx-%lx!!\n", area->vm_start, area->vm_end, addr, end); return; } /* Od całkowitej liczby stron odejmujemy liczbę stron jaką mamy usunąć */ area->vm_mm->total_vm -= len >> PAGE_SHIFT; if (area->vm_flags & VM_LOCKED) area->vm_mm->locked_vm -= len >> PAGE_SHIFT; /* Unmapping the whole area */ /* Obszar który chcemy usunąć jest równy obszarowi zajętemu przez area */ if (addr == area->vm_start && end == area->vm_end) { if (area->vm_ops && area->vm_ops->close) area->vm_ops->close(area); if (area->vm_inode) iput(area->vm_inode); return; } /* Work out to one of the ends */ /* Obszar do usunięcia jest końcem area */ if (end == area->vm_end) area->vm_end = addr; else /* Obszar do usunięcia jest początkiem area */ if (addr == area->vm_start) { area->vm_offset += (end - area->vm_start); area->vm_start = end; } else { /* Obszar do usunięcia rozdziela area na dwa vma */ /* Unmapping a hole: area->vm_start < addr <= end < area->vm_end */ /* Add end mapping -- leave beginning for below */ mpnt = (struct vm_area_struct *)kmalloc(sizeof(*mpnt), GFP_KERNEL); if (!mpnt) return; *mpnt = *area; mpnt->vm_offset += (end - area->vm_start); mpnt->vm_start = end; if (mpnt->vm_inode) mpnt->vm_inode->i_count++; if (mpnt->vm_ops && mpnt->vm_ops->open) mpnt->vm_ops->open(mpnt); area->vm_end = addr; /* Truncate area */ insert_vm_struct(current->mm, mpnt); } /* construct whatever mapping is needed */ /* ewentualne dodawanie drugiego mpnt (w przypadku usuwania ze środka vma */ mpnt = (struct vm_area_struct *)kmalloc(sizeof(*mpnt), GFP_KERNEL); if (!mpnt) return; *mpnt = *area; if (mpnt->vm_ops && mpnt->vm_ops->open) mpnt->vm_ops->open(mpnt); if (area->vm_ops && area->vm_ops->close) { area->vm_end = area->vm_start; area->vm_ops->close(area); } insert_vm_struct(current->mm, mpnt); } asmlinkage int sys_munmap(unsigned long addr, size_t len) { return do_munmap(addr, len); } /* * Munmap is split into 2 main parts -- this part which finds * what needs doing, and the areas themselves, which do the * work. This now handles partial unmappings. * Jeremy Fitzhardine <jeremy@sw.oz.au> */ int do_munmap(unsigned long addr, size_t len) /* argumenty: addr - adres obszaru do odłączenia len - wielkość obszaru do odłączenia zawraca 0 gdy wszystko odbyło się pomyślnie liczbe<0 gdy wystapił błąd - (zdefiniowane w errno.h) niektóre zaś opisane w funkcji do_mmap */ { struct vm_area_struct *mpnt, *prev, *next, **npp, *free; if ((addr & ~PAGE_MASK) || addr > TASK_SIZE || len > TASK_SIZE-addr) return -EINVAL; /* niewłaściwy argument */ if ((len = PAGE_ALIGN(len)) == 0) return 0; /* nie chcemy nic zmieniać więc wychodzimy */ /* PAGE_ALIGN(len)=addr gdy (len mod PAGE_SIZE)==0 =PAGE_SIZE*(len div PAGE_SIZE +1) PAGE_SIZE - rozmiar strony */ /* * Check if this memory area is ok - put it on the temporary * list if so.. The checks here are pretty simple -- * every area affected in some way (by any overlap) is put * on the list. If nothing is put on, nothing is affected. */ mpnt = find_vma(current->mm, addr); /* find_vma wyszukuje pierwszego vma który spełnia addr<vm_end NULL jeśli takiego nie ma */ if (!mpnt) return 0; avl_neighbours(mpnt, current->mm->mmap_avl, &prev, &next); /* we have prev->vm_next == mpnt && mpnt->vm_next = next */ /* and addr < mpnt->vm_end */ npp = (prev ? &prev->vm_next : ¤t->mm->mmap); free = NULL; /* wstawianie na listę free, vma do usunięcia znajdujące się w przedziale (addr, addr+len) */ for ( ; mpnt && mpnt->vm_start < addr+len; mpnt = *npp) { *npp = mpnt->vm_next; mpnt->vm_next = free; free = mpnt; /* wstawiliśmy już na listę więc możemy usunąć mpnt z AVL */ avl_remove(mpnt, ¤t->mm->mmap_avl); } /* nic nie wstawiono więc nic nię można usunąć */ if (free == NULL) return 0; /* * Ok - we have the memory areas we should free on the 'free' list, * so release them, and unmap the page range.. * If the one of the segments is only being partially unmapped, * it will put new vm_area_struct(s) into the address space. */ do { unsigned long st, end; mpnt = free; free = free->vm_next; /* usuwanie mpnt z list inode i i_mmap */ remove_shared_vm_struct(mpnt); st = addr < mpnt->vm_start ? mpnt->vm_start : addr; end = addr+len; end = end > mpnt->vm_end ? mpnt->vm_end : end; if (mpnt->vm_ops && mpnt->vm_ops->unmap) mpnt->vm_ops->unmap(mpnt, st, end-st); //usuwanie stron o adresach z przedziału (st, end-st) zap_page_range(current->mm, st, end-st); unmap_fixup(mpnt, st, end-st); kfree(mpnt); } while (free); /* dopóki są jeszcze jakieś elementy do usunięcia */ /* we could zap the page tables here too.. */ return 0; } /* Build the AVL tree corresponding to the VMA list. */ void build_mmap_avl(struct mm_struct * mm) { struct vm_area_struct * vma; mm->mmap_avl = NULL; for (vma = mm->mmap; vma; vma = vma->vm_next) avl_insert(vma, &mm->mmap_avl); } /* Release all mmaps. */ void exit_mmap(struct mm_struct * mm) /* usuwa wszystkie mapowania plików */ { struct vm_area_struct * mpnt; mpnt = mm->mmap; mm->mmap = NULL; mm->mmap_avl = NULL; mm->rss = 0; mm->total_vm = 0; mm->locked_vm = 0; while (mpnt) { struct vm_area_struct * next = mpnt->vm_next; if (mpnt->vm_ops) { if (mpnt->vm_ops->unmap) mpnt->vm_ops->unmap(mpnt, mpnt->vm_start, mpnt->vm_end-mpnt->vm_start); if (mpnt->vm_ops->close) mpnt->vm_ops->close(mpnt); } remove_shared_vm_struct(mpnt); /* usuwanie stron o adresach z podanego przedziału */ zap_page_range(mm, mpnt->vm_start, mpnt->vm_end-mpnt->vm_start); if (mpnt->vm_inode) iput(mpnt->vm_inode); kfree(mpnt); mpnt = next; } } /* * Insert vm structure into process list sorted by address * and into the inode's i_mmap ring. */ void insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vmp) /* wstawianie vmp do listy vm-ów procesu sortowanej względem adresów oraz do listy i_mmap węzła inode */ { struct vm_area_struct *share; struct inode * inode; #if 0 /* equivalent, but slow */ struct vm_area_struct **p, *mpnt; p = &mm->mmap; while ((mpnt = *p) != NULL) { if (mpnt->vm_start > vmp->vm_start) break; if (mpnt->vm_end > vmp->vm_start) printk("insert_vm_struct: overlapping memory areas\n"); p = &mpnt->vm_next; } vmp->vm_next = mpnt; *p = vmp; #else struct vm_area_struct * prev, * next; avl_insert_neighbours(vmp, &mm->mmap_avl, &prev, &next); if ((prev ? prev->vm_next : mm->mmap) != next) printk("insert_vm_struct: tree inconsistent with list\n"); if (prev) prev->vm_next = vmp; else mm->mmap = vmp; vmp->vm_next = next; #endif inode = vmp->vm_inode; if (!inode) return; /* insert vmp into inode's circular share list */ if ((share = inode->i_mmap)) { vmp->vm_next_share = share->vm_next_share; vmp->vm_next_share->vm_prev_share = vmp; share->vm_next_share = vmp; vmp->vm_prev_share = share; } else inode->i_mmap = vmp->vm_next_share = vmp->vm_prev_share = vmp; } /* * Remove one vm structure from the inode's i_mmap ring. */ void remove_shared_vm_struct(struct vm_area_struct *mpnt) /* Usuwanie mpnt z listy i_mmap */ { struct inode * inode = mpnt->vm_inode; if (!inode) return; if (mpnt->vm_next_share == mpnt) { if (inode->i_mmap != mpnt) printk("Inode i_mmap ring corrupted\n"); inode->i_mmap = NULL; return; } if (inode->i_mmap == mpnt) inode->i_mmap = mpnt->vm_next_share; mpnt->vm_prev_share->vm_next_share = mpnt->vm_next_share; mpnt->vm_next_share->vm_prev_share = mpnt->vm_prev_share; } /* * Merge the list of memory segments if possible. * Redundant vm_area_structs are freed. * This assumes that the list is ordered by address. * We don't need to traverse the entire list, only those segments * which intersect or are adjacent to a given interval. */ void merge_segments (struct mm_struct * mm, unsigned long start_addr, unsigned long end_addr) { struct vm_area_struct *prev, *mpnt, *next; /* blokujemy semaforem dostęp do mm aby nie bylo sytuacji w której proces odwołuje się do czegoś co zostało zmienione natomiast jeszcze nie uaktualnione*/ down(&mm->mmap_sem); mpnt = find_vma(mm, start_addr); /* pierwsze vma z przedziału */ if (!mpnt) goto no_vma; avl_neighbours(mpnt, mm->mmap_avl, &prev, &next); /* we have prev->vm_next == mpnt && mpnt->vm_next = next */ if (!prev) { prev = mpnt; mpnt = next; } /* prev and mpnt cycle through the list, as long as * start_addr < mpnt->vm_end && prev->vm_start < end_addr */ /*przesuwamy się po kolejnych vma o adresach z żądanego przedziału */ for ( ; mpnt && prev->vm_start < end_addr ; prev = mpnt, mpnt = next) { #if 0 printk("looping in merge_segments, mpnt=0x%lX\n", (unsigned long) mpnt); #endif next = mpnt->vm_next; /* * To share, we must have the same inode, operations.. */ /* vma do połączenia muszą mieć identyczne pola zawierające informacje o nich */ if (mpnt->vm_inode != prev->vm_inode) continue; if (mpnt->vm_pte != prev->vm_pte) continue; if (mpnt->vm_ops != prev->vm_ops) continue; if (mpnt->vm_flags != prev->vm_flags) continue; if (prev->vm_end != mpnt->vm_start) continue; /* * and if we have an inode, the offsets must be contiguous.. */ if ((mpnt->vm_inode != NULL) || (mpnt->vm_flags & VM_SHM)) { /* sprawdzamy czy można je złączyć */ if (prev->vm_offset + prev->vm_end - prev->vm_start != mpnt->vm_offset) continue; } /* * merge prev with mpnt and set up pointers so the new * big segment can possibly merge with the next one. * The old unused mpnt is freed. */ /* natrafiliśmy na dwa vma między którymi nie ma dziury tzn. które można połączyć */ avl_remove(mpnt, &mm->mmap_avl); prev->vm_end = mpnt->vm_end; prev->vm_next = mpnt->vm_next; if (mpnt->vm_ops && mpnt->vm_ops->close) { mpnt->vm_offset += mpnt->vm_end - mpnt->vm_start; mpnt->vm_start = mpnt->vm_end; mpnt->vm_ops->close(mpnt); } remove_shared_vm_struct(mpnt); if (mpnt->vm_inode) mpnt->vm_inode->i_count--; kfree_s(mpnt, sizeof(*mpnt)); mpnt = prev; } no_vma: up(&mm->mmap_sem); /* podnosimy semafor */ }
Radoslaw Szymaszek