From: Rusty Russell Date: Tue, 11 Mar 2008 14:35:56 +0000 (-0500) Subject: lguest: fix __get_vm_area usage. X-Git-Tag: v2.6.25-rc6~49^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f14ae652baa3d72ae378f0c06b89cc2c4ef15ff8;p=platform%2Fkernel%2Flinux-3.10.git lguest: fix __get_vm_area usage. Robert Bragg's 5dc331852848a38ca00a2817e5b98a1d0561b116 tightened (ie. fixed) the checking in __get_vm_area, and it broke lguest. lguest should pass the exact "end" it wants, not some random constant (it was possible previously that it would actually get an address different from SWITCHER_ADDR). Also, Fabio Checconi pointed out that we should make sure we're not hitting the fixmap area. Signed-off-by: Rusty Russell Cc: Robert Bragg --- diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 7743d73..c632c08 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");