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Commit f14ae652 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: fix __get_vm_area usage. 



Robert Bragg's 5dc33185 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: default avatarRusty Russell <rusty@rustcorp.com.au>
Cc: Robert Bragg <robert@sixbynine.org>
parent f73d1e6c

drivers/lguest/core.c

+13 −2
Original line number Diff line number Diff line
@@ -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");