1227 lines
32 KiB
C
1227 lines
32 KiB
C
/*
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* linux/mm/memory.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* demand-loading started 01.12.91 - seems it is high on the list of
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* things wanted, and it should be easy to implement. - Linus
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*/
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/*
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* Ok, demand-loading was easy, shared pages a little bit tricker. Shared
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* pages started 02.12.91, seems to work. - Linus.
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*
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* Tested sharing by executing about 30 /bin/sh: under the old kernel it
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* would have taken more than the 6M I have free, but it worked well as
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* far as I could see.
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*
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* Also corrected some "invalidate()"s - I wasn't doing enough of them.
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*/
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/*
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* Real VM (paging to/from disk) started 18.12.91. Much more work and
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* thought has to go into this. Oh, well..
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* 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
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* Found it. Everything seems to work now.
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* 20.12.91 - Ok, making the swap-device changeable like the root.
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*/
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#include <asm/system.h>
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#include <linux/config.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/head.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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unsigned long high_memory = 0;
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extern unsigned long pg0[1024]; /* page table for 0-4MB for everybody */
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extern void sound_mem_init(void);
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extern void die_if_kernel(char *,struct pt_regs *,long);
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int nr_swap_pages = 0;
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int nr_free_pages = 0;
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unsigned long free_page_list = 0;
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/*
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* The secondary free_page_list is used for malloc() etc things that
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* may need pages during interrupts etc. Normal get_free_page() operations
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* don't touch it, so it stays as a kind of "panic-list", that can be
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* accessed when all other mm tricks have failed.
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*/
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int nr_secondary_pages = 0;
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unsigned long secondary_page_list = 0;
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#define copy_page(from,to) \
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__asm__("cld ; rep ; movsl": :"S" (from),"D" (to),"c" (1024):"cx","di","si")
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unsigned short * mem_map = NULL;
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#define CODE_SPACE(addr,p) ((addr) < (p)->end_code)
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/*
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* oom() prints a message (so that the user knows why the process died),
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* and gives the process an untrappable SIGSEGV.
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*/
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void oom(struct task_struct * task)
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{
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printk("\nout of memory\n");
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task->sigaction[SIGKILL-1].sa_handler = NULL;
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task->blocked &= ~(1<<(SIGKILL-1));
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send_sig(SIGKILL,task,1);
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}
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static void free_one_table(unsigned long * page_dir)
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{
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int j;
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unsigned long pg_table = *page_dir;
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unsigned long * page_table;
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if (!pg_table)
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return;
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*page_dir = 0;
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if (pg_table >= high_memory || !(pg_table & PAGE_PRESENT)) {
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printk("Bad page table: [%p]=%08lx\n",page_dir,pg_table);
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return;
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}
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if (mem_map[MAP_NR(pg_table)] & MAP_PAGE_RESERVED)
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return;
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page_table = (unsigned long *) (pg_table & PAGE_MASK);
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for (j = 0 ; j < PTRS_PER_PAGE ; j++,page_table++) {
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unsigned long pg = *page_table;
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if (!pg)
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continue;
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*page_table = 0;
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if (pg & PAGE_PRESENT)
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free_page(PAGE_MASK & pg);
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else
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swap_free(pg);
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}
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free_page(PAGE_MASK & pg_table);
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}
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/*
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* This function clears all user-level page tables of a process - this
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* is needed by execve(), so that old pages aren't in the way. Note that
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* unlike 'free_page_tables()', this function still leaves a valid
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* page-table-tree in memory: it just removes the user pages. The two
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* functions are similar, but there is a fundamental difference.
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*/
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void clear_page_tables(struct task_struct * tsk)
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{
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int i;
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unsigned long pg_dir;
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unsigned long * page_dir;
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if (!tsk)
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return;
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if (tsk == task[0])
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panic("task[0] (swapper) doesn't support exec()\n");
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pg_dir = tsk->tss.cr3;
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page_dir = (unsigned long *) pg_dir;
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if (!page_dir || page_dir == swapper_pg_dir) {
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printk("Trying to clear kernel page-directory: not good\n");
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return;
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}
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if (mem_map[MAP_NR(pg_dir)] > 1) {
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unsigned long * new_pg;
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if (!(new_pg = (unsigned long*) get_free_page(GFP_KERNEL))) {
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oom(tsk);
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return;
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}
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for (i = 768 ; i < 1024 ; i++)
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new_pg[i] = page_dir[i];
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free_page(pg_dir);
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tsk->tss.cr3 = (unsigned long) new_pg;
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return;
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}
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for (i = 0 ; i < 768 ; i++,page_dir++)
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free_one_table(page_dir);
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invalidate();
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return;
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}
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/*
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* This function frees up all page tables of a process when it exits.
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*/
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void free_page_tables(struct task_struct * tsk)
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{
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int i;
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unsigned long pg_dir;
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unsigned long * page_dir;
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if (!tsk)
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return;
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if (tsk == task[0]) {
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printk("task[0] (swapper) killed: unable to recover\n");
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panic("Trying to free up swapper memory space");
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}
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pg_dir = tsk->tss.cr3;
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if (!pg_dir || pg_dir == (unsigned long) swapper_pg_dir) {
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printk("Trying to free kernel page-directory: not good\n");
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return;
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}
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tsk->tss.cr3 = (unsigned long) swapper_pg_dir;
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if (tsk == current)
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__asm__ __volatile__("movl %0,%%cr3": :"a" (tsk->tss.cr3));
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if (mem_map[MAP_NR(pg_dir)] > 1) {
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free_page(pg_dir);
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return;
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}
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page_dir = (unsigned long *) pg_dir;
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for (i = 0 ; i < PTRS_PER_PAGE ; i++,page_dir++)
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free_one_table(page_dir);
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free_page(pg_dir);
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invalidate();
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}
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/*
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* clone_page_tables() clones the page table for a process - both
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* processes will have the exact same pages in memory. There are
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* probably races in the memory management with cloning, but we'll
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* see..
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*/
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int clone_page_tables(struct task_struct * tsk)
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{
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unsigned long pg_dir;
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pg_dir = current->tss.cr3;
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mem_map[MAP_NR(pg_dir)]++;
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tsk->tss.cr3 = pg_dir;
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return 0;
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}
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/*
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* copy_page_tables() just copies the whole process memory range:
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* note the special handling of RESERVED (ie kernel) pages, which
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* means that they are always shared by all processes.
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*/
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int copy_page_tables(struct task_struct * tsk)
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{
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int i;
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unsigned long old_pg_dir, *old_page_dir;
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unsigned long new_pg_dir, *new_page_dir;
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if (!(new_pg_dir = get_free_page(GFP_KERNEL)))
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return -ENOMEM;
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old_pg_dir = current->tss.cr3;
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tsk->tss.cr3 = new_pg_dir;
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old_page_dir = (unsigned long *) old_pg_dir;
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new_page_dir = (unsigned long *) new_pg_dir;
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for (i = 0 ; i < PTRS_PER_PAGE ; i++,old_page_dir++,new_page_dir++) {
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int j;
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unsigned long old_pg_table, *old_page_table;
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unsigned long new_pg_table, *new_page_table;
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old_pg_table = *old_page_dir;
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if (!old_pg_table)
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continue;
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if (old_pg_table >= high_memory || !(old_pg_table & PAGE_PRESENT)) {
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printk("copy_page_tables: bad page table: "
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"probable memory corruption");
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*old_page_dir = 0;
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continue;
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}
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if (mem_map[MAP_NR(old_pg_table)] & MAP_PAGE_RESERVED) {
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*new_page_dir = old_pg_table;
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continue;
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}
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if (!(new_pg_table = get_free_page(GFP_KERNEL))) {
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free_page_tables(tsk);
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return -ENOMEM;
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}
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old_page_table = (unsigned long *) (PAGE_MASK & old_pg_table);
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new_page_table = (unsigned long *) (PAGE_MASK & new_pg_table);
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for (j = 0 ; j < PTRS_PER_PAGE ; j++,old_page_table++,new_page_table++) {
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unsigned long pg;
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pg = *old_page_table;
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if (!pg)
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continue;
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if (!(pg & PAGE_PRESENT)) {
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*new_page_table = swap_duplicate(pg);
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continue;
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}
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if ((pg & (PAGE_RW | PAGE_COW)) == (PAGE_RW | PAGE_COW))
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pg &= ~PAGE_RW;
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*new_page_table = pg;
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if (mem_map[MAP_NR(pg)] & MAP_PAGE_RESERVED)
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continue;
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*old_page_table = pg;
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mem_map[MAP_NR(pg)]++;
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}
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*new_page_dir = new_pg_table | PAGE_TABLE;
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}
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invalidate();
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return 0;
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}
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/*
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* a more complete version of free_page_tables which performs with page
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* granularity.
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*/
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int unmap_page_range(unsigned long from, unsigned long size)
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{
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unsigned long page, page_dir;
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unsigned long *page_table, *dir;
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unsigned long poff, pcnt, pc;
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if (from & ~PAGE_MASK) {
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printk("unmap_page_range called with wrong alignment\n");
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return -EINVAL;
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}
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size = (size + ~PAGE_MASK) >> PAGE_SHIFT;
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dir = PAGE_DIR_OFFSET(current->tss.cr3,from);
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poff = (from >> PAGE_SHIFT) & (PTRS_PER_PAGE-1);
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if ((pcnt = PTRS_PER_PAGE - poff) > size)
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pcnt = size;
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for ( ; size > 0; ++dir, size -= pcnt,
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pcnt = (size > PTRS_PER_PAGE ? PTRS_PER_PAGE : size)) {
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if (!(page_dir = *dir)) {
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poff = 0;
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continue;
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}
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if (!(page_dir & PAGE_PRESENT)) {
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printk("unmap_page_range: bad page directory.");
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continue;
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}
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page_table = (unsigned long *)(PAGE_MASK & page_dir);
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if (poff) {
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page_table += poff;
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poff = 0;
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}
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for (pc = pcnt; pc--; page_table++) {
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if ((page = *page_table) != 0) {
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*page_table = 0;
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if (1 & page) {
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if (!(mem_map[MAP_NR(page)]
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& MAP_PAGE_RESERVED))
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--current->rss;
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free_page(PAGE_MASK & page);
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} else
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swap_free(page);
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}
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}
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if (pcnt == PTRS_PER_PAGE) {
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*dir = 0;
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free_page(PAGE_MASK & page_dir);
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}
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}
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invalidate();
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return 0;
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}
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int zeromap_page_range(unsigned long from, unsigned long size, int mask)
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{
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unsigned long *page_table, *dir;
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unsigned long poff, pcnt;
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unsigned long page;
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if (mask) {
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if ((mask & (PAGE_MASK|PAGE_PRESENT)) != PAGE_PRESENT) {
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printk("zeromap_page_range: mask = %08x\n",mask);
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return -EINVAL;
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}
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mask |= ZERO_PAGE;
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}
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if (from & ~PAGE_MASK) {
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printk("zeromap_page_range: from = %08lx\n",from);
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return -EINVAL;
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}
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dir = PAGE_DIR_OFFSET(current->tss.cr3,from);
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size = (size + ~PAGE_MASK) >> PAGE_SHIFT;
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poff = (from >> PAGE_SHIFT) & (PTRS_PER_PAGE-1);
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if ((pcnt = PTRS_PER_PAGE - poff) > size)
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pcnt = size;
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while (size > 0) {
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if (!(PAGE_PRESENT & *dir)) {
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/* clear page needed here? SRB. */
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if (!(page_table = (unsigned long*) get_free_page(GFP_KERNEL))) {
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invalidate();
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return -ENOMEM;
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}
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if (PAGE_PRESENT & *dir) {
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free_page((unsigned long) page_table);
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page_table = (unsigned long *)(PAGE_MASK & *dir++);
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} else
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*dir++ = ((unsigned long) page_table) | PAGE_TABLE;
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} else
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page_table = (unsigned long *)(PAGE_MASK & *dir++);
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page_table += poff;
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poff = 0;
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for (size -= pcnt; pcnt-- ;) {
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if ((page = *page_table) != 0) {
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*page_table = 0;
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if (page & PAGE_PRESENT) {
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if (!(mem_map[MAP_NR(page)]
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& MAP_PAGE_RESERVED))
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--current->rss;
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free_page(PAGE_MASK & page);
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} else
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swap_free(page);
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}
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*page_table++ = mask;
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}
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pcnt = (size > PTRS_PER_PAGE ? PTRS_PER_PAGE : size);
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}
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invalidate();
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return 0;
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}
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/*
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* maps a range of physical memory into the requested pages. the old
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* mappings are removed. any references to nonexistent pages results
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* in null mappings (currently treated as "copy-on-access")
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*/
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int remap_page_range(unsigned long from, unsigned long to, unsigned long size, int mask)
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{
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unsigned long *page_table, *dir;
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unsigned long poff, pcnt;
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unsigned long page;
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if (mask) {
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if ((mask & (PAGE_MASK|PAGE_PRESENT)) != PAGE_PRESENT) {
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printk("remap_page_range: mask = %08x\n",mask);
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return -EINVAL;
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}
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}
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if ((from & ~PAGE_MASK) || (to & ~PAGE_MASK)) {
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printk("remap_page_range: from = %08lx, to=%08lx\n",from,to);
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return -EINVAL;
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}
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dir = PAGE_DIR_OFFSET(current->tss.cr3,from);
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size = (size + ~PAGE_MASK) >> PAGE_SHIFT;
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poff = (from >> PAGE_SHIFT) & (PTRS_PER_PAGE-1);
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if ((pcnt = PTRS_PER_PAGE - poff) > size)
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pcnt = size;
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while (size > 0) {
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if (!(PAGE_PRESENT & *dir)) {
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/* clearing page here, needed? SRB. */
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if (!(page_table = (unsigned long*) get_free_page(GFP_KERNEL))) {
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invalidate();
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return -1;
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}
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*dir++ = ((unsigned long) page_table) | PAGE_TABLE;
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}
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else
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page_table = (unsigned long *)(PAGE_MASK & *dir++);
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if (poff) {
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page_table += poff;
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poff = 0;
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}
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for (size -= pcnt; pcnt-- ;) {
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if ((page = *page_table) != 0) {
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*page_table = 0;
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if (PAGE_PRESENT & page) {
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if (!(mem_map[MAP_NR(page)]
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& MAP_PAGE_RESERVED))
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--current->rss;
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free_page(PAGE_MASK & page);
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} else
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swap_free(page);
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}
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/*
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* the first condition should return an invalid access
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* when the page is referenced. current assumptions
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* cause it to be treated as demand allocation in some
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* cases.
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*/
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if (!mask)
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*page_table++ = 0; /* not present */
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else if (to >= high_memory)
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*page_table++ = (to | mask);
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else if (!mem_map[MAP_NR(to)])
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*page_table++ = 0; /* not present */
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else {
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*page_table++ = (to | mask);
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if (!(mem_map[MAP_NR(to)] & MAP_PAGE_RESERVED)) {
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++current->rss;
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mem_map[MAP_NR(to)]++;
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}
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}
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to += PAGE_SIZE;
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}
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pcnt = (size > PTRS_PER_PAGE ? PTRS_PER_PAGE : size);
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}
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invalidate();
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return 0;
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}
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|
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/*
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* This function puts a page in memory at the wanted address.
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* It returns the physical address of the page gotten, 0 if
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* out of memory (either when trying to access page-table or
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* page.)
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*/
|
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unsigned long put_page(struct task_struct * tsk,unsigned long page,
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unsigned long address,int prot)
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{
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unsigned long *page_table;
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if ((prot & (PAGE_MASK|PAGE_PRESENT)) != PAGE_PRESENT)
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printk("put_page: prot = %08x\n",prot);
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if (page >= high_memory) {
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printk("put_page: trying to put page %08lx at %08lx\n",page,address);
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return 0;
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}
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page_table = PAGE_DIR_OFFSET(tsk->tss.cr3,address);
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if ((*page_table) & PAGE_PRESENT)
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page_table = (unsigned long *) (PAGE_MASK & *page_table);
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else {
|
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printk("put_page: bad page directory entry\n");
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oom(tsk);
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*page_table = BAD_PAGETABLE | PAGE_TABLE;
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return 0;
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}
|
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page_table += (address >> PAGE_SHIFT) & (PTRS_PER_PAGE-1);
|
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if (*page_table) {
|
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printk("put_page: page already exists\n");
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*page_table = 0;
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invalidate();
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}
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*page_table = page | prot;
|
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/* no need for invalidate */
|
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return page;
|
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}
|
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|
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/*
|
|
* The previous function doesn't work very well if you also want to mark
|
|
* the page dirty: exec.c wants this, as it has earlier changed the page,
|
|
* and we want the dirty-status to be correct (for VM). Thus the same
|
|
* routine, but this time we mark it dirty too.
|
|
*/
|
|
unsigned long put_dirty_page(struct task_struct * tsk, unsigned long page, unsigned long address)
|
|
{
|
|
unsigned long tmp, *page_table;
|
|
|
|
if (page >= high_memory)
|
|
printk("put_dirty_page: trying to put page %08lx at %08lx\n",page,address);
|
|
if (mem_map[MAP_NR(page)] != 1)
|
|
printk("mem_map disagrees with %08lx at %08lx\n",page,address);
|
|
page_table = PAGE_DIR_OFFSET(tsk->tss.cr3,address);
|
|
if (PAGE_PRESENT & *page_table)
|
|
page_table = (unsigned long *) (PAGE_MASK & *page_table);
|
|
else {
|
|
if (!(tmp = get_free_page(GFP_KERNEL)))
|
|
return 0;
|
|
if (PAGE_PRESENT & *page_table) {
|
|
free_page(tmp);
|
|
page_table = (unsigned long *) (PAGE_MASK & *page_table);
|
|
} else {
|
|
*page_table = tmp | PAGE_TABLE;
|
|
page_table = (unsigned long *) tmp;
|
|
}
|
|
}
|
|
page_table += (address >> PAGE_SHIFT) & (PTRS_PER_PAGE-1);
|
|
if (*page_table) {
|
|
printk("put_dirty_page: page already exists\n");
|
|
*page_table = 0;
|
|
invalidate();
|
|
}
|
|
*page_table = page | (PAGE_DIRTY | PAGE_PRIVATE);
|
|
/* no need for invalidate */
|
|
return page;
|
|
}
|
|
|
|
/*
|
|
* This routine handles present pages, when users try to write
|
|
* to a shared page. It is done by copying the page to a new address
|
|
* and decrementing the shared-page counter for the old page.
|
|
*
|
|
* Note that we do many checks twice (look at do_wp_page()), as
|
|
* we have to be careful about race-conditions.
|
|
*
|
|
* Goto-purists beware: the only reason for goto's here is that it results
|
|
* in better assembly code.. The "default" path will see no jumps at all.
|
|
*/
|
|
static void __do_wp_page(unsigned long error_code, unsigned long address,
|
|
struct task_struct * tsk, unsigned long user_esp)
|
|
{
|
|
unsigned long *pde, pte, old_page, prot;
|
|
unsigned long new_page;
|
|
|
|
new_page = __get_free_page(GFP_KERNEL);
|
|
pde = PAGE_DIR_OFFSET(tsk->tss.cr3,address);
|
|
pte = *pde;
|
|
if (!(pte & PAGE_PRESENT))
|
|
goto end_wp_page;
|
|
if ((pte & PAGE_TABLE) != PAGE_TABLE || pte >= high_memory)
|
|
goto bad_wp_pagetable;
|
|
pte &= PAGE_MASK;
|
|
pte += PAGE_PTR(address);
|
|
old_page = *(unsigned long *) pte;
|
|
if (!(old_page & PAGE_PRESENT))
|
|
goto end_wp_page;
|
|
if (old_page >= high_memory)
|
|
goto bad_wp_page;
|
|
if (old_page & PAGE_RW)
|
|
goto end_wp_page;
|
|
tsk->min_flt++;
|
|
prot = (old_page & ~PAGE_MASK) | PAGE_RW;
|
|
old_page &= PAGE_MASK;
|
|
if (mem_map[MAP_NR(old_page)] != 1) {
|
|
if (new_page) {
|
|
if (mem_map[MAP_NR(old_page)] & MAP_PAGE_RESERVED)
|
|
++tsk->rss;
|
|
copy_page(old_page,new_page);
|
|
*(unsigned long *) pte = new_page | prot;
|
|
free_page(old_page);
|
|
invalidate();
|
|
return;
|
|
}
|
|
free_page(old_page);
|
|
oom(tsk);
|
|
*(unsigned long *) pte = BAD_PAGE | prot;
|
|
invalidate();
|
|
return;
|
|
}
|
|
*(unsigned long *) pte |= PAGE_RW;
|
|
invalidate();
|
|
if (new_page)
|
|
free_page(new_page);
|
|
return;
|
|
bad_wp_page:
|
|
printk("do_wp_page: bogus page at address %08lx (%08lx)\n",address,old_page);
|
|
*(unsigned long *) pte = BAD_PAGE | PAGE_SHARED;
|
|
send_sig(SIGKILL, tsk, 1);
|
|
goto end_wp_page;
|
|
bad_wp_pagetable:
|
|
printk("do_wp_page: bogus page-table at address %08lx (%08lx)\n",address,pte);
|
|
*pde = BAD_PAGETABLE | PAGE_TABLE;
|
|
send_sig(SIGKILL, tsk, 1);
|
|
end_wp_page:
|
|
if (new_page)
|
|
free_page(new_page);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* check that a page table change is actually needed, and call
|
|
* the low-level function only in that case..
|
|
*/
|
|
void do_wp_page(unsigned long error_code, unsigned long address,
|
|
struct task_struct * tsk, unsigned long user_esp)
|
|
{
|
|
unsigned long page;
|
|
unsigned long * pg_table;
|
|
|
|
pg_table = PAGE_DIR_OFFSET(tsk->tss.cr3,address);
|
|
page = *pg_table;
|
|
if (!page)
|
|
return;
|
|
if ((page & PAGE_PRESENT) && page < high_memory) {
|
|
pg_table = (unsigned long *) ((page & PAGE_MASK) + PAGE_PTR(address));
|
|
page = *pg_table;
|
|
if (!(page & PAGE_PRESENT))
|
|
return;
|
|
if (page & PAGE_RW)
|
|
return;
|
|
if (!(page & PAGE_COW)) {
|
|
if (user_esp && tsk == current) {
|
|
current->tss.cr2 = address;
|
|
current->tss.error_code = error_code;
|
|
current->tss.trap_no = 14;
|
|
send_sig(SIGSEGV, tsk, 1);
|
|
return;
|
|
}
|
|
}
|
|
if (mem_map[MAP_NR(page)] == 1) {
|
|
*pg_table |= PAGE_RW | PAGE_DIRTY;
|
|
invalidate();
|
|
return;
|
|
}
|
|
__do_wp_page(error_code, address, tsk, user_esp);
|
|
return;
|
|
}
|
|
printk("bad page directory entry %08lx\n",page);
|
|
*pg_table = 0;
|
|
}
|
|
|
|
int __verify_write(unsigned long start, unsigned long size)
|
|
{
|
|
size--;
|
|
size += start & ~PAGE_MASK;
|
|
size >>= PAGE_SHIFT;
|
|
start &= PAGE_MASK;
|
|
do {
|
|
do_wp_page(1,start,current,0);
|
|
start += PAGE_SIZE;
|
|
} while (size--);
|
|
return 0;
|
|
}
|
|
|
|
static inline void get_empty_page(struct task_struct * tsk, unsigned long address)
|
|
{
|
|
unsigned long tmp;
|
|
|
|
if (!(tmp = get_free_page(GFP_KERNEL))) {
|
|
oom(tsk);
|
|
tmp = BAD_PAGE;
|
|
}
|
|
if (!put_page(tsk,tmp,address,PAGE_PRIVATE))
|
|
free_page(tmp);
|
|
}
|
|
|
|
/*
|
|
* try_to_share() checks the page at address "address" in the task "p",
|
|
* to see if it exists, and if it is clean. If so, share it with the current
|
|
* task.
|
|
*
|
|
* NOTE! This assumes we have checked that p != current, and that they
|
|
* share the same executable or library.
|
|
*
|
|
* We may want to fix this to allow page sharing for PIC pages at different
|
|
* addresses so that ELF will really perform properly. As long as the vast
|
|
* majority of sharable libraries load at fixed addresses this is not a
|
|
* big concern. Any sharing of pages between the buffer cache and the
|
|
* code space reduces the need for this as well. - ERY
|
|
*/
|
|
static int try_to_share(unsigned long address, struct task_struct * tsk,
|
|
struct task_struct * p, unsigned long error_code, unsigned long newpage)
|
|
{
|
|
unsigned long from;
|
|
unsigned long to;
|
|
unsigned long from_page;
|
|
unsigned long to_page;
|
|
|
|
from_page = (unsigned long)PAGE_DIR_OFFSET(p->tss.cr3,address);
|
|
to_page = (unsigned long)PAGE_DIR_OFFSET(tsk->tss.cr3,address);
|
|
/* is there a page-directory at from? */
|
|
from = *(unsigned long *) from_page;
|
|
if (!(from & PAGE_PRESENT))
|
|
return 0;
|
|
from &= PAGE_MASK;
|
|
from_page = from + PAGE_PTR(address);
|
|
from = *(unsigned long *) from_page;
|
|
/* is the page clean and present? */
|
|
if ((from & (PAGE_PRESENT | PAGE_DIRTY)) != PAGE_PRESENT)
|
|
return 0;
|
|
if (from >= high_memory)
|
|
return 0;
|
|
if (mem_map[MAP_NR(from)] & MAP_PAGE_RESERVED)
|
|
return 0;
|
|
/* is the destination ok? */
|
|
to = *(unsigned long *) to_page;
|
|
if (!(to & PAGE_PRESENT))
|
|
return 0;
|
|
to &= PAGE_MASK;
|
|
to_page = to + PAGE_PTR(address);
|
|
if (*(unsigned long *) to_page)
|
|
return 0;
|
|
/* share them if read - do COW immediately otherwise */
|
|
if (error_code & PAGE_RW) {
|
|
if(!newpage) /* did the page exist? SRB. */
|
|
return 0;
|
|
copy_page((from & PAGE_MASK),newpage);
|
|
to = newpage | PAGE_PRIVATE;
|
|
} else {
|
|
mem_map[MAP_NR(from)]++;
|
|
from &= ~PAGE_RW;
|
|
to = from;
|
|
if(newpage) /* only if it existed. SRB. */
|
|
free_page(newpage);
|
|
}
|
|
*(unsigned long *) from_page = from;
|
|
*(unsigned long *) to_page = to;
|
|
invalidate();
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* share_page() tries to find a process that could share a page with
|
|
* the current one. Address is the address of the wanted page relative
|
|
* to the current data space.
|
|
*
|
|
* We first check if it is at all feasible by checking executable->i_count.
|
|
* It should be >1 if there are other tasks sharing this inode.
|
|
*/
|
|
int share_page(struct vm_area_struct * area, struct task_struct * tsk,
|
|
struct inode * inode,
|
|
unsigned long address, unsigned long error_code, unsigned long newpage)
|
|
{
|
|
struct task_struct ** p;
|
|
|
|
if (!inode || inode->i_count < 2 || !area->vm_ops)
|
|
return 0;
|
|
for (p = &LAST_TASK ; p > &FIRST_TASK ; --p) {
|
|
if (!*p)
|
|
continue;
|
|
if (tsk == *p)
|
|
continue;
|
|
if (inode != (*p)->executable) {
|
|
if(!area) continue;
|
|
/* Now see if there is something in the VMM that
|
|
we can share pages with */
|
|
if(area){
|
|
struct vm_area_struct * mpnt;
|
|
for (mpnt = (*p)->mmap; mpnt; mpnt = mpnt->vm_next) {
|
|
if (mpnt->vm_ops == area->vm_ops &&
|
|
mpnt->vm_inode->i_ino == area->vm_inode->i_ino&&
|
|
mpnt->vm_inode->i_dev == area->vm_inode->i_dev){
|
|
if (mpnt->vm_ops->share(mpnt, area, address))
|
|
break;
|
|
};
|
|
};
|
|
if (!mpnt) continue; /* Nope. Nuthin here */
|
|
};
|
|
}
|
|
if (try_to_share(address,tsk,*p,error_code,newpage))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* fill in an empty page-table if none exists.
|
|
*/
|
|
static inline unsigned long get_empty_pgtable(struct task_struct * tsk,unsigned long address)
|
|
{
|
|
unsigned long page;
|
|
unsigned long *p;
|
|
|
|
p = PAGE_DIR_OFFSET(tsk->tss.cr3,address);
|
|
if (PAGE_PRESENT & *p)
|
|
return *p;
|
|
if (*p) {
|
|
printk("get_empty_pgtable: bad page-directory entry \n");
|
|
*p = 0;
|
|
}
|
|
page = get_free_page(GFP_KERNEL);
|
|
p = PAGE_DIR_OFFSET(tsk->tss.cr3,address);
|
|
if (PAGE_PRESENT & *p) {
|
|
free_page(page);
|
|
return *p;
|
|
}
|
|
if (*p) {
|
|
printk("get_empty_pgtable: bad page-directory entry \n");
|
|
*p = 0;
|
|
}
|
|
if (page) {
|
|
*p = page | PAGE_TABLE;
|
|
return *p;
|
|
}
|
|
oom(current);
|
|
*p = BAD_PAGETABLE | PAGE_TABLE;
|
|
return 0;
|
|
}
|
|
|
|
void do_no_page(unsigned long error_code, unsigned long address,
|
|
struct task_struct *tsk, unsigned long user_esp)
|
|
{
|
|
unsigned long tmp;
|
|
unsigned long page;
|
|
struct vm_area_struct * mpnt;
|
|
|
|
page = get_empty_pgtable(tsk,address);
|
|
if (!page)
|
|
return;
|
|
page &= PAGE_MASK;
|
|
page += PAGE_PTR(address);
|
|
tmp = *(unsigned long *) page;
|
|
if (tmp & PAGE_PRESENT)
|
|
return;
|
|
++tsk->rss;
|
|
if (tmp) {
|
|
++tsk->maj_flt;
|
|
swap_in((unsigned long *) page);
|
|
return;
|
|
}
|
|
address &= 0xfffff000;
|
|
tmp = 0;
|
|
for (mpnt = tsk->mmap; mpnt != NULL; mpnt = mpnt->vm_next) {
|
|
if (address < mpnt->vm_start)
|
|
break;
|
|
if (address >= mpnt->vm_end) {
|
|
tmp = mpnt->vm_end;
|
|
continue;
|
|
}
|
|
if (!mpnt->vm_ops || !mpnt->vm_ops->nopage) {
|
|
++tsk->min_flt;
|
|
get_empty_page(tsk,address);
|
|
return;
|
|
}
|
|
mpnt->vm_ops->nopage(error_code, mpnt, address);
|
|
return;
|
|
}
|
|
if (tsk != current)
|
|
goto ok_no_page;
|
|
if (address >= tsk->end_data && address < tsk->brk)
|
|
goto ok_no_page;
|
|
if (mpnt && mpnt == tsk->stk_vma &&
|
|
address - tmp > mpnt->vm_start - address &&
|
|
tsk->rlim[RLIMIT_STACK].rlim_cur > mpnt->vm_end - address) {
|
|
mpnt->vm_start = address;
|
|
goto ok_no_page;
|
|
}
|
|
tsk->tss.cr2 = address;
|
|
current->tss.error_code = error_code;
|
|
current->tss.trap_no = 14;
|
|
send_sig(SIGSEGV,tsk,1);
|
|
if (error_code & 4) /* user level access? */
|
|
return;
|
|
ok_no_page:
|
|
++tsk->min_flt;
|
|
get_empty_page(tsk,address);
|
|
}
|
|
|
|
/*
|
|
* This routine handles page faults. It determines the address,
|
|
* and the problem, and then passes it off to one of the appropriate
|
|
* routines.
|
|
*/
|
|
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
|
|
{
|
|
unsigned long address;
|
|
unsigned long user_esp = 0;
|
|
unsigned int bit;
|
|
|
|
/* get the address */
|
|
__asm__("movl %%cr2,%0":"=r" (address));
|
|
if (address < TASK_SIZE) {
|
|
if (error_code & 4) { /* user mode access? */
|
|
if (regs->eflags & VM_MASK) {
|
|
bit = (address - 0xA0000) >> PAGE_SHIFT;
|
|
if (bit < 32)
|
|
current->screen_bitmap |= 1 << bit;
|
|
} else
|
|
user_esp = regs->esp;
|
|
}
|
|
if (error_code & 1)
|
|
do_wp_page(error_code, address, current, user_esp);
|
|
else
|
|
do_no_page(error_code, address, current, user_esp);
|
|
return;
|
|
}
|
|
address -= TASK_SIZE;
|
|
if (wp_works_ok < 0 && address == 0 && (error_code & PAGE_PRESENT)) {
|
|
wp_works_ok = 1;
|
|
pg0[0] = PAGE_SHARED;
|
|
printk("This processor honours the WP bit even when in supervisor mode. Good.\n");
|
|
return;
|
|
}
|
|
if (address < PAGE_SIZE) {
|
|
printk("Unable to handle kernel NULL pointer dereference");
|
|
pg0[0] = PAGE_SHARED;
|
|
} else
|
|
printk("Unable to handle kernel paging request");
|
|
printk(" at address %08lx\n",address);
|
|
die_if_kernel("Oops", regs, error_code);
|
|
do_exit(SIGKILL);
|
|
}
|
|
|
|
/*
|
|
* BAD_PAGE is the page that is used for page faults when linux
|
|
* is out-of-memory. Older versions of linux just did a
|
|
* do_exit(), but using this instead means there is less risk
|
|
* for a process dying in kernel mode, possibly leaving a inode
|
|
* unused etc..
|
|
*
|
|
* BAD_PAGETABLE is the accompanying page-table: it is initialized
|
|
* to point to BAD_PAGE entries.
|
|
*
|
|
* ZERO_PAGE is a special page that is used for zero-initialized
|
|
* data and COW.
|
|
*/
|
|
unsigned long __bad_pagetable(void)
|
|
{
|
|
extern char empty_bad_page_table[PAGE_SIZE];
|
|
|
|
__asm__ __volatile__("cld ; rep ; stosl":
|
|
:"a" (BAD_PAGE + PAGE_TABLE),
|
|
"D" ((long) empty_bad_page_table),
|
|
"c" (PTRS_PER_PAGE)
|
|
:"di","cx");
|
|
return (unsigned long) empty_bad_page_table;
|
|
}
|
|
|
|
unsigned long __bad_page(void)
|
|
{
|
|
extern char empty_bad_page[PAGE_SIZE];
|
|
|
|
__asm__ __volatile__("cld ; rep ; stosl":
|
|
:"a" (0),
|
|
"D" ((long) empty_bad_page),
|
|
"c" (PTRS_PER_PAGE)
|
|
:"di","cx");
|
|
return (unsigned long) empty_bad_page;
|
|
}
|
|
|
|
unsigned long __zero_page(void)
|
|
{
|
|
extern char empty_zero_page[PAGE_SIZE];
|
|
|
|
__asm__ __volatile__("cld ; rep ; stosl":
|
|
:"a" (0),
|
|
"D" ((long) empty_zero_page),
|
|
"c" (PTRS_PER_PAGE)
|
|
:"di","cx");
|
|
return (unsigned long) empty_zero_page;
|
|
}
|
|
|
|
void show_mem(void)
|
|
{
|
|
int i,free = 0,total = 0,reserved = 0;
|
|
int shared = 0;
|
|
|
|
printk("Mem-info:\n");
|
|
printk("Free pages: %6dkB\n",nr_free_pages<<(PAGE_SHIFT-10));
|
|
printk("Secondary pages: %6dkB\n",nr_secondary_pages<<(PAGE_SHIFT-10));
|
|
printk("Free swap: %6dkB\n",nr_swap_pages<<(PAGE_SHIFT-10));
|
|
printk("Buffer memory: %6dkB\n",buffermem>>10);
|
|
printk("Buffer heads: %6d\n",nr_buffer_heads);
|
|
printk("Buffer blocks: %6d\n",nr_buffers);
|
|
i = high_memory >> PAGE_SHIFT;
|
|
while (i-- > 0) {
|
|
total++;
|
|
if (mem_map[i] & MAP_PAGE_RESERVED)
|
|
reserved++;
|
|
else if (!mem_map[i])
|
|
free++;
|
|
else
|
|
shared += mem_map[i]-1;
|
|
}
|
|
printk("%d pages of RAM\n",total);
|
|
printk("%d free pages\n",free);
|
|
printk("%d reserved pages\n",reserved);
|
|
printk("%d pages shared\n",shared);
|
|
}
|
|
|
|
/*
|
|
* paging_init() sets up the page tables - note that the first 4MB are
|
|
* already mapped by head.S.
|
|
*
|
|
* This routines also unmaps the page at virtual kernel address 0, so
|
|
* that we can trap those pesky NULL-reference errors in the kernel.
|
|
*/
|
|
unsigned long paging_init(unsigned long start_mem, unsigned long end_mem)
|
|
{
|
|
unsigned long * pg_dir;
|
|
unsigned long * pg_table;
|
|
unsigned long tmp;
|
|
unsigned long address;
|
|
|
|
/*
|
|
* Physical page 0 is special; it's not touched by Linux since BIOS
|
|
* and SMM (for laptops with [34]86/SL chips) may need it. It is read
|
|
* and write protected to detect null pointer references in the
|
|
* kernel.
|
|
*/
|
|
#if 0
|
|
memset((void *) 0, 0, PAGE_SIZE);
|
|
#endif
|
|
start_mem = PAGE_ALIGN(start_mem);
|
|
address = 0;
|
|
pg_dir = swapper_pg_dir;
|
|
while (address < end_mem) {
|
|
tmp = *(pg_dir + 768); /* at virtual addr 0xC0000000 */
|
|
if (!tmp) {
|
|
tmp = start_mem | PAGE_TABLE;
|
|
*(pg_dir + 768) = tmp;
|
|
start_mem += PAGE_SIZE;
|
|
}
|
|
*pg_dir = tmp; /* also map it in at 0x0000000 for init */
|
|
pg_dir++;
|
|
pg_table = (unsigned long *) (tmp & PAGE_MASK);
|
|
for (tmp = 0 ; tmp < PTRS_PER_PAGE ; tmp++,pg_table++) {
|
|
if (address < end_mem)
|
|
*pg_table = address | PAGE_SHARED;
|
|
else
|
|
*pg_table = 0;
|
|
address += PAGE_SIZE;
|
|
}
|
|
}
|
|
invalidate();
|
|
return start_mem;
|
|
}
|
|
|
|
void mem_init(unsigned long start_low_mem,
|
|
unsigned long start_mem, unsigned long end_mem)
|
|
{
|
|
int codepages = 0;
|
|
int reservedpages = 0;
|
|
int datapages = 0;
|
|
unsigned long tmp;
|
|
unsigned short * p;
|
|
extern int etext;
|
|
|
|
cli();
|
|
end_mem &= PAGE_MASK;
|
|
high_memory = end_mem;
|
|
start_mem += 0x0000000f;
|
|
start_mem &= ~0x0000000f;
|
|
tmp = MAP_NR(end_mem);
|
|
mem_map = (unsigned short *) start_mem;
|
|
p = mem_map + tmp;
|
|
start_mem = (unsigned long) p;
|
|
while (p > mem_map)
|
|
*--p = MAP_PAGE_RESERVED;
|
|
start_low_mem = PAGE_ALIGN(start_low_mem);
|
|
start_mem = PAGE_ALIGN(start_mem);
|
|
while (start_low_mem < 0xA0000) {
|
|
mem_map[MAP_NR(start_low_mem)] = 0;
|
|
start_low_mem += PAGE_SIZE;
|
|
}
|
|
while (start_mem < end_mem) {
|
|
mem_map[MAP_NR(start_mem)] = 0;
|
|
start_mem += PAGE_SIZE;
|
|
}
|
|
#ifdef CONFIG_SOUND
|
|
sound_mem_init();
|
|
#endif
|
|
free_page_list = 0;
|
|
nr_free_pages = 0;
|
|
for (tmp = 0 ; tmp < end_mem ; tmp += PAGE_SIZE) {
|
|
if (mem_map[MAP_NR(tmp)]) {
|
|
if (tmp >= 0xA0000 && tmp < 0x100000)
|
|
reservedpages++;
|
|
else if (tmp < (unsigned long) &etext)
|
|
codepages++;
|
|
else
|
|
datapages++;
|
|
continue;
|
|
}
|
|
*(unsigned long *) tmp = free_page_list;
|
|
free_page_list = tmp;
|
|
nr_free_pages++;
|
|
}
|
|
tmp = nr_free_pages << PAGE_SHIFT;
|
|
printk("Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data)\n",
|
|
tmp >> 10,
|
|
end_mem >> 10,
|
|
codepages << (PAGE_SHIFT-10),
|
|
reservedpages << (PAGE_SHIFT-10),
|
|
datapages << (PAGE_SHIFT-10));
|
|
/* test if the WP bit is honoured in supervisor mode */
|
|
wp_works_ok = -1;
|
|
pg0[0] = PAGE_READONLY;
|
|
invalidate();
|
|
__asm__ __volatile__("movb 0,%%al ; movb %%al,0": : :"ax", "memory");
|
|
pg0[0] = 0;
|
|
invalidate();
|
|
if (wp_works_ok < 0)
|
|
wp_works_ok = 0;
|
|
return;
|
|
}
|
|
|
|
void si_meminfo(struct sysinfo *val)
|
|
{
|
|
int i;
|
|
|
|
i = high_memory >> PAGE_SHIFT;
|
|
val->totalram = 0;
|
|
val->freeram = 0;
|
|
val->sharedram = 0;
|
|
val->bufferram = buffermem;
|
|
while (i-- > 0) {
|
|
if (mem_map[i] & MAP_PAGE_RESERVED)
|
|
continue;
|
|
val->totalram++;
|
|
if (!mem_map[i]) {
|
|
val->freeram++;
|
|
continue;
|
|
}
|
|
val->sharedram += mem_map[i]-1;
|
|
}
|
|
val->totalram <<= PAGE_SHIFT;
|
|
val->freeram <<= PAGE_SHIFT;
|
|
val->sharedram <<= PAGE_SHIFT;
|
|
return;
|
|
}
|
|
|
|
|
|
/* This handles a generic mmap of a disk file */
|
|
void file_mmap_nopage(int error_code, struct vm_area_struct * area, unsigned long address)
|
|
{
|
|
struct inode * inode = area->vm_inode;
|
|
unsigned int block;
|
|
unsigned long page;
|
|
int nr[8];
|
|
int i, j;
|
|
int prot = area->vm_page_prot;
|
|
|
|
address &= PAGE_MASK;
|
|
block = address - area->vm_start + area->vm_offset;
|
|
block >>= inode->i_sb->s_blocksize_bits;
|
|
|
|
page = get_free_page(GFP_KERNEL);
|
|
if (share_page(area, area->vm_task, inode, address, error_code, page)) {
|
|
++area->vm_task->min_flt;
|
|
return;
|
|
}
|
|
|
|
++area->vm_task->maj_flt;
|
|
if (!page) {
|
|
oom(current);
|
|
put_page(area->vm_task, BAD_PAGE, address, PAGE_PRIVATE);
|
|
return;
|
|
}
|
|
for (i=0, j=0; i< PAGE_SIZE ; j++, block++, i += inode->i_sb->s_blocksize)
|
|
nr[j] = bmap(inode,block);
|
|
if (error_code & PAGE_RW)
|
|
prot |= PAGE_RW | PAGE_DIRTY;
|
|
page = bread_page(page, inode->i_dev, nr, inode->i_sb->s_blocksize, prot);
|
|
|
|
if (!(prot & PAGE_RW)) {
|
|
if (share_page(area, area->vm_task, inode, address, error_code, page))
|
|
return;
|
|
}
|
|
if (put_page(area->vm_task,page,address,prot))
|
|
return;
|
|
free_page(page);
|
|
oom(current);
|
|
}
|
|
|
|
void file_mmap_free(struct vm_area_struct * area)
|
|
{
|
|
if (area->vm_inode)
|
|
iput(area->vm_inode);
|
|
#if 0
|
|
if (area->vm_inode)
|
|
printk("Free inode %x:%d (%d)\n",area->vm_inode->i_dev,
|
|
area->vm_inode->i_ino, area->vm_inode->i_count);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Compare the contents of the mmap entries, and decide if we are allowed to
|
|
* share the pages
|
|
*/
|
|
int file_mmap_share(struct vm_area_struct * area1,
|
|
struct vm_area_struct * area2,
|
|
unsigned long address)
|
|
{
|
|
if (area1->vm_inode != area2->vm_inode)
|
|
return 0;
|
|
if (area1->vm_start != area2->vm_start)
|
|
return 0;
|
|
if (area1->vm_end != area2->vm_end)
|
|
return 0;
|
|
if (area1->vm_offset != area2->vm_offset)
|
|
return 0;
|
|
if (area1->vm_page_prot != area2->vm_page_prot)
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
struct vm_operations_struct file_mmap = {
|
|
NULL, /* open */
|
|
file_mmap_free, /* close */
|
|
file_mmap_nopage, /* nopage */
|
|
NULL, /* wppage */
|
|
file_mmap_share, /* share */
|
|
NULL, /* unmap */
|
|
};
|