x86: ioremap ram check fix
bdd3cee2 (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: NAndres Salomon <dilinger@debian.org> Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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