diff options
| author | Andres Salomon <dilinger@queued.net> | 2008-04-30 11:30:24 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-04-30 23:15:35 +0200 |
| commit | cb8ab687c32331fb548c613ae74df574bb0908c1 (patch) | |
| tree | 7b6f4258984e7e95dc584de3baf9894429de6acb /arch/x86/mm | |
| parent | 5f464707c8c18fccd3c6278ad46ac94b5cf15a98 (diff) | |
x86: ioremap ram check fix
bdd3cee2e4b7279457139058615ced6c2b41e7de (x86: ioremap(), extend check
to all RAM pages) breaks OLPC's ioremap call. The ioremap that OLPC uses is:
romsig = ioremap(0xffffffc0, 16);
The commit that breaks it is basically:
- for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
- (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+ for (pfn = phys_addr >> PAGE_SHIFT;
+ (pfn << PAGE_SHIFT) < last_addr; pfn++) {
+
Previously, the 'pfn < max_pfn_mapped' check would've caused us to not
enter the loop. Removing that check means we loop infinitely. The
reason for that is because pfn is 0xfffff, and last_addr is 0xffffffcf.
The remaining check that is used to exit the loop is not sufficient;
when pfn<<PAGE_SHIFT is 0xfffff000, that is less than 0xffffffcf; when
we increment pfn and it overflows (pfn == 0x100000), pfn<<PAGE_SHIFT
ends up being 0. That, of course, is less than last_addr. In effect,
pfn<<PAGE_SHIFT is never lower than last_addr.
The simple fix for this is to limit the last_addr check to the PAGE_MASK;
a patch is below.
Signed-off-by: Andres Salomon <dilinger@debian.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/ioremap.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 6d02a36e5e49..71bb3159031a 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -148,8 +148,9 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, /* * Don't allow anybody to remap normal RAM that we're using.. */ - for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped && - (pfn << PAGE_SHIFT) < last_addr; pfn++) { + for (pfn = phys_addr >> PAGE_SHIFT; + (pfn << PAGE_SHIFT) < (last_addr & PAGE_MASK); + pfn++) { int is_ram = page_is_ram(pfn); |