diff options
Diffstat (limited to 'arch/i386/mm/vmalloc.c')
| -rw-r--r-- | arch/i386/mm/vmalloc.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/arch/i386/mm/vmalloc.c b/arch/i386/mm/vmalloc.c new file mode 100644 index 000000000..0dbd16d54 --- /dev/null +++ b/arch/i386/mm/vmalloc.c @@ -0,0 +1,202 @@ +/* + * linux/mm/vmalloc.c + * + * Copyright (C) 1993 Linus Torvalds + */ + +#include <asm/system.h> +#include <linux/config.h> + +#include <linux/signal.h> +#include <linux/sched.h> +#include <linux/head.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/types.h> +#include <linux/malloc.h> +#include <asm/segment.h> + +struct vm_struct { + unsigned long flags; + void * addr; + unsigned long size; + struct vm_struct * next; +}; + +static struct vm_struct * vmlist = NULL; + +/* Just any arbitrary offset to the start of the vmalloc VM area: the + * current 8MB value just means that there will be a 8MB "hole" after the + * physical memory until the kernel virtual memory starts. That means that + * any out-of-bounds memory accesses will hopefully be caught. + * The vmalloc() routines leaves a hole of 4kB between each vmalloced + * area for the same reason. ;) + */ +#define VMALLOC_OFFSET (8*1024*1024) + +static inline void set_pgdir(unsigned long dindex, unsigned long value) +{ + struct task_struct * p; + + p = &init_task; + do { + ((unsigned long *) p->tss.cr3)[dindex] = value; + p = p->next_task; + } while (p != &init_task); +} + +static int free_area_pages(unsigned long dindex, unsigned long index, unsigned long nr) +{ + unsigned long page, *pte; + + if (!(PAGE_PRESENT & (page = swapper_pg_dir[dindex]))) + return 0; + page &= PAGE_MASK; + pte = index + (unsigned long *) page; + do { + unsigned long pg = *pte; + *pte = 0; + if (pg & PAGE_PRESENT) + free_page(pg); + pte++; + } while (--nr); + pte = (unsigned long *) page; + for (nr = 0 ; nr < 1024 ; nr++, pte++) + if (*pte) + return 0; + set_pgdir(dindex,0); + mem_map[MAP_NR(page)] = 1; + free_page(page); + invalidate(); + return 0; +} + +static int alloc_area_pages(unsigned long dindex, unsigned long index, unsigned long nr) +{ + unsigned long page, *pte; + + page = swapper_pg_dir[dindex]; + if (!page) { + page = get_free_page(GFP_KERNEL); + if (!page) + return -ENOMEM; + if (swapper_pg_dir[dindex]) { + free_page(page); + page = swapper_pg_dir[dindex]; + } else { + mem_map[MAP_NR(page)] = MAP_PAGE_RESERVED; + set_pgdir(dindex, page | PAGE_SHARED); + } + } + page &= PAGE_MASK; + pte = index + (unsigned long *) page; + *pte = PAGE_SHARED; /* remove a race with vfree() */ + do { + unsigned long pg = get_free_page(GFP_KERNEL); + + if (!pg) + return -ENOMEM; + *pte = pg | PAGE_SHARED; + pte++; + } while (--nr); + invalidate(); + return 0; +} + +static int do_area(void * addr, unsigned long size, + int (*area_fn)(unsigned long,unsigned long,unsigned long)) +{ + unsigned long nr, dindex, index; + + nr = size >> PAGE_SHIFT; + dindex = (TASK_SIZE + (unsigned long) addr) >> 22; + index = (((unsigned long) addr) >> PAGE_SHIFT) & (PTRS_PER_PAGE-1); + while (nr > 0) { + unsigned long i = PTRS_PER_PAGE - index; + + if (i > nr) + i = nr; + nr -= i; + if (area_fn(dindex, index, i)) + return -1; + index = 0; + dindex++; + } + return 0; +} + +void vfree(void * addr) +{ + struct vm_struct **p, *tmp; + + if (!addr) + return; + if ((PAGE_SIZE-1) & (unsigned long) addr) { + printk("Trying to vfree() bad address (%p)\n", addr); + return; + } + for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) { + if (tmp->addr == addr) { + *p = tmp->next; + do_area(tmp->addr, tmp->size, free_area_pages); + kfree(tmp); + return; + } + } + printk("Trying to vfree() nonexistent vm area (%p)\n", addr); +} + +void * vmalloc(unsigned long size) +{ + void * addr; + struct vm_struct **p, *tmp, *area; + + size = PAGE_ALIGN(size); + if (!size || size > high_memory) + return NULL; + area = (struct vm_struct *) kmalloc(sizeof(*area), GFP_KERNEL); + if (!area) + return NULL; + addr = (void *) ((high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)); + area->size = size + PAGE_SIZE; + area->next = NULL; + for (p = &vmlist; (tmp = *p) ; p = &tmp->next) { + if (size + (unsigned long) addr < (unsigned long) tmp->addr) + break; + addr = (void *) (tmp->size + (unsigned long) tmp->addr); + } + area->addr = addr; + area->next = *p; + *p = area; + if (do_area(addr, size, alloc_area_pages)) { + vfree(addr); + return NULL; + } + return addr; +} + +int vread(char *buf, char *addr, int count) +{ + struct vm_struct **p, *tmp; + char *vaddr, *buf_start = buf; + int n; + + for (p = &vmlist; (tmp = *p) ; p = &tmp->next) { + vaddr = (char *) tmp->addr; + while (addr < vaddr) { + if (count == 0) + goto finished; + put_fs_byte('\0', buf++), addr++, count--; + } + n = tmp->size - PAGE_SIZE; + if (addr > vaddr) + n -= addr - vaddr; + while (--n >= 0) { + if (count == 0) + goto finished; + put_fs_byte(*addr++, buf++), count--; + } + } +finished: + return buf - buf_start; +} |