On Fri, 2007-10-12 at 13:30 +1000, David Gibson wrote: > On Thu, Oct 11, 2007 at 01:42:30PM -0500, Kumar Gala wrote: > > Move to using PAGE_OFFSET instead of TASK_SIZE or KERNELBASE value on > > 6xx/40x/44x/fsl-booke to determine if the faulting address is a kernel or > > user space address. This mimics how the macro is_kernel_addr() > > works. > > Actually it's ambiguous whether TASK_SIZE or PAGE_OFFSET is correct in > most of these cases (KERNELBASE is certainly wrong, though). > > TASK_SIZE is the top of the userspace mapped area, PAGE_OFFSET is the > bottom of the linear mapping. So, strictly speaking there are 3 paths > for the miss handlers: < TASK_SIZE => user mapping, >= PAGE_OFFSET => > kernel mapping, between the two => immediate fault. > > We get away with a two way comparison on 32-bit because, a) they have > the same value and b) none of the pagetables, user or kernel, should > have any entries in the in between region so we'll end up in > do_page_fault in the end, anyway.
Kumar's other patch removes the gap. He changed the default CONFIG_TASK_SIZE to 0xc0000000. josh _______________________________________________ Linuxppc-dev mailing list [email protected] https://ozlabs.org/mailman/listinfo/linuxppc-dev
