x86: ioremap ram check fix
bdd3cee2e4
(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>
This commit is contained in:
parent
5f464707c8
commit
cb8ab687c3
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@ -148,8 +148,9 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
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/*
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* Don't allow anybody to remap normal RAM that we're using..
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*/
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for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
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(pfn << PAGE_SHIFT) < last_addr; pfn++) {
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for (pfn = phys_addr >> PAGE_SHIFT;
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(pfn << PAGE_SHIFT) < (last_addr & PAGE_MASK);
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pfn++) {
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int is_ram = page_is_ram(pfn);
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