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| author | Rusty Russell <rusty@rustcorp.com.au> | 2008-03-11 17:35:56 +0300 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-03-11 01:35:56 +0300 |
| commit | f14ae652baa3d72ae378f0c06b89cc2c4ef15ff8 (patch) | |
| tree | 65dfe2b310103bd6f2c981de2e1d0faecd05805c /drivers | |
| parent | f73d1e6ca6985b43a1871467463cba632fbc624d (diff) | |
| download | linux-f14ae652baa3d72ae378f0c06b89cc2c4ef15ff8.tar.xz | |
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 <rusty@rustcorp.com.au>
Cc: Robert Bragg <robert@sixbynine.org>
Diffstat (limited to 'drivers')
| -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 7743d73768df..c632c08cbbdc 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"); |