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Date: Sat, 20 Apr 2013 11:42:54 +0200 From: Thomas Lange <thomas@...elatus.se> To: ralf@...ux-mips.org CC: linux-kernel@...r.kernel.org Subject: MIPS: c17a6554 broke 64BIT_PHYS_ADDR for 32 bit systems Dear Ralf, commit c17a6554 unintentionally(?) modified the PAGE_MASK type from (int) to (long unsigned int). This breaks ioremap (and possibly more) when using 64BIT_PHYS_ADDR on 32 bit systems. Example of failing code from ioremap.c: phys_addr &= PAGE_MASK; Since phys_addr is 64 bit (unsigned long long) when 64BIT_PHYS_ADDR and PAGE_MASK is 32bit (long unsigned int), the upper 32 bits will always be zeroed which is not what we want/expect. The code above works if PAGE_MASK is a _signed_ 32bit int though. Some possible fixes: A) Simply revert the commit. Makes ioremap work again, but then PAGE_MASK is a signed int. Do we really want a mask that is 'signed'? B) Don't use PAGE_MASK for physical addresses. x86 defines this: /* Cast PAGE_MASK to a signed type so that it is sign-extended if virtual addresses are 32-bits but physical addresses are larger (ie, 32-bit PAE). */ #define PHYSICAL_PAGE_MASK (((signed long)PAGE_MASK) & __PHYSICAL_MASK) Perhaps mips need something similar? This is an issue with 3.8 and doesn't seem to be solved in master either. Regards, /Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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