diff options
| -rw-r--r-- | drivers/lguest/core.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 7743d73768d..c632c08cbbd 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -69,11 +69,22 @@ static __init int map_switcher(void) switcher_page[i] = virt_to_page(addr); } + /* First we check that the Switcher won't overlap the fixmap area at + * the top of memory. It's currently nowhere near, but it could have + * very strange effects if it ever happened. */ + if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){ + err = -ENOMEM; + printk("lguest: mapping switcher would thwack fixmap\n"); + goto free_pages; + } + /* Now we reserve the "virtual memory area" we want: 0xFFC00000 * (SWITCHER_ADDR). We might not get it in theory, but in practice - * it's worked so far. */ + * it's worked so far. The end address needs +1 because __get_vm_area + * allocates an extra guard page, so we need space for that. */ switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE, - VM_ALLOC, SWITCHER_ADDR, VMALLOC_END); + VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR + + (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE); if (!switcher_vma) { err = -ENOMEM; printk("lguest: could not map switcher pages high\n"); |